5G tutorial | 5G system basics tutorial

This page of tutorials section covers 5G tutorial basics which mentions need for 5G
wireless, 5G technology features, advantages of 5G and key 5G projects.
As we know we can not live without modern wireless technologies. This makes our life
cosy and easy. The world has compressed due to advent of wireless technologies. Both
indoor and outdoor wireless technologies are evolving very rapidly.
2G, 3G and 4G cellular wireless technologies have been mass deployed throughout the
world. Moreover personal area network based technologies such as wifi, bluetooth and
zigbee have become predominant in our daily life.
5G is the short form of 5th Generation. It is used to designate fifth generation of mobile
technologies. 5G has made it possible to use mobile phone with larger bandwidth
possible. It is a packet switched wireless system. It is used to cover wide area and used
to provide higher throughput. It uses CDMA, BDMA and also millimeter wave(for
backhaul wireless connectivity). It uses improved and advanced data
coding/modulation techniques. It provides about 100 Mbps at full mobility and 1 Gbps
at low mobility. It uses smart antenna techniques to support higher data rate and
coverage.

5G technology features or advantages

The 5G technology makes use of all the existing cellular wireless technologies(2G, 3G
and 4G). Apart from high throughput it provides following features to the users and
providers of this technology.
• Better revenue for the service providers.
• Interoperability will become feasible and easier.
• Low battery power consumption.
• Better coverage and high data rates at the edge of cell.
• Multiple data transfer paths concurrently.
• More secure
• Flexible architecture based on SDR(Software Defined Radio).
• Higher system spectral efficiency
• Harmless to human health
• Cheaper fees due to lower costs of deployment infrastructure
• Better QoS(Quality of Service)
• Ultimate download and upload speed provides user great experience like broadband
cable internet
• Most of the devices such as 5G dongle works on USB power and hence better in
developing countries where electric power cuts are very common.
Specification / Feature 5G Support
Bandwidth 1Gbps or higher
Frequency range 3 to 300 GHz
Standard(access
CDMA/BDMA
technologies)
Unified IP, seamless integration of broadband,
Technologies
LAN/PAN/WAN/WLAN and 5G based technologies
wearable devices, dynamic information access, HD streaming,
Applications/Services
smooth global roaming
core network flatter IP network, 5G network interfacing (5G-NI)
Handoff vertical, horizontal
Peak Data Rate Approx. 10 Gbps
Cell Edge Data Rate 100 Mbps
Latency less than 1 ms

5G Channel Types
5G channel types cover logical channels and transport channels used in uplink and
downlink with mapping between them. The 5G logical channels include xBCCH,
xCCCH, xDCCH, xDTCH etc. The 5G transport channels include xBCH, xDL-SCH,
xRACH, xUL-SCH etc. This page covers 5G channel types viz. logical channels and
transport channels used in uplink and downlink with mapping between them. The 5G
logical channels include xBCCH, xCCCH, xDCCH, xDTCH etc. The 5G transport
channels include xBCH, xDL-SCH, xRACH, xUL-SCH etc.
These 5G channels are used to provide different kinds of data transfer services by MAC
layer in 5G protocol stack.

5G Logical Channels | xBCCH, xCCCH, xDCCH, xDTCH

The 5G logical channels are further divided into control channels and traffic channels
based on their functionalities. They are described below.
Each of the 5G logical channels are defined by what information type is transferred by
them. Logical channels are classified into two groups as follows.
• Control channel: It is used to transfer control plane related information.
• Traffic channel: It is used to transfer user plane related information.
5G Control Channels
Following table-1 mentions 5G control channels used to transfer control plane
information only. The control channels offered by 5G-MAC are xBCCH, xCCCH and
xDCCH.
5G control
Description
channel type
This channel is used in the downlink to broadcast system control
xBCCH
information.
This channel is used to transmit control information between UEs and
xCCCH network (i.e. 5G-Node B or base station). It is used for UEs having no RRC
connection with network.
This channel is bi-directional and point to point. It carries dedicated
xDCCH control information between UE and network. It is used by UEs having
RRC connection.
5G traffic channel | xDTCH
• The 5G traffic channel is used to transfer user plane information only.
• The xDTCH is the only dedicated traffic channel used in 5G wireless technology.
• It is a point to point channel which is dedicated to single UE.
• It carries user information.
It exists both in the downlink (From 5G-NB to UE) and uplink (From UE to 5G-NB).

Mapping between Logical Channels and Transport Channels

The figure depicts mapping between logical channels and transport channels in the
uplink and downlink.
As shown following are the mapping in uplink side.
• xCCCH channel can be mapped to channel xUL-SCH
• xDCCH channel can be mapped to channel xUL-SCH
• xDTCH channel can be mapped to channel xUL-SCH
As shown following are the mapping in downlink side.
• xBCCH channel can be mapped to channel xBCH
• xCCCH channel can be mapped to channel xDL-SCH
• xDCCH channel can be mapped to channel xDL-SCH
• xDTCH channel can be mapped to channel xDL-SCH

5G Transport Channels | xBCH, xDL-SCH, xRACH, xUL-SCH

The 5G transport channels are used by 5G physical layer (i.e. layer-1) based on their
functionalities. They are described below.
5G transport
Description
channel type
It is 5G broadcast channel which carries system control information of 5G
xBCH
MAC layer.
It is 5G Downlink Shared Channel which carries data of all the UEs in the
xDL-SCH
downlink direction from 5G Base station.
It is 5G Uplink Shared Channel which carries data from UEs to 5G base
xUL-SCH
station in the uplink direction.
It is 5G Random Access Channel which is used by UE in the uplink
direction to establish connection with 5G base station. It is used to
xRACH
establish 5G-RRC Connection between UE and 5G-RAN in RRC
connection setup procedure.
5G Protocol Stack

The 5G layer-1 is PHYSICAL Layer. The 5G layer-2 include MAC, RLC and PDCP.The
5G layer-3 is RRC layer as shown in 5G protocol stack.
Key research projects based on 5G
Various projects based on 5G are in progress and are administered and managed by 5G-
PPP. The projects include 5G-NORMA, 5G-ENSURE, CHARISMA, COGNET, XHAUL,
mmMAGIC, SPEED-5G, Flex5Gware, FANTASTIC 5G etc.
5G-PPP is the short form of 5G Infrastructure Public Private Partnership. It has been
initiated by EU commission, manufacturers, operators, researchers and SMEs. The 5G-
PPP will provide next generation solutions, technologies, standards, architectures to be
used for telecommunications.
5G NR Physical layer processing for PDSCH and PUSCH

This article describes 5G NR physical layer. The physical layer processing for 5G NR
PDSCH channel and 5G NR PUSCH channel have been covered stepwise. This 5G
physical layer description is as per 3GPP physical layer specifications.

5G NR MAC Layer Overview

This page describes overview of 5G NR MAC layer. It covers 5G NR MAC functions, 5G
NR MAC architecture, 5G NR MAC channel mapping, 5G NR MAC procedures and
format of 5G NR MAC header and sub-headers.
5G NR RLC Layer Overview

This page describes overview of 5G NR RLC layer including functions. It covers 5G NR

RLC modes (TM mode,UM mode, AM mode),data structures (TMD, UMD, AMD),RLC
PDUs (TMD PDU, UMD PDU, AMD PDU), data transfers (TM, UM and AM) and RRC
parameters which defines RLC layer.

5G NR PDCP Layer Overview

This page describes overview of 5G NR PDCP layer including functions. It covers PDCP
architecture (structure, entities), PDCP procedures for data transfer during
transmit/receive operation, Data PDU and Control PDU formats of PDCP layer etc.
5G network architecture | 5G protocol stack
This page of 5G tutorial covers 5G network architecture and 5G protocol stack. The 5G
network architecture consists of all RANs, aggregator, IP network,nanocore etc. The 5G
protocol stack consists of Open Wireless Architecture, lower and upper network layer,
open transport protocol and application layer. These have been explained below with
the figures. The tutorial also provides 5G NR (New Radio) architecture as per 3GPP
document published in dec. 2017.

5G network architecture
Figure-1 depicts 5G network architecture. This is generic architecture. As shown 5G
network uses flat IP concept so that different RANs (Radio Access Networks) can use
the same single Nanocore for communication. RANs supported by 5G architecture are
GSM, GPRS/EDGE, UMTS, LTE, LTE-advanced, WiMAX, WiFi, CDMA2000, EV-DO,
CDMA One, IS-95 etc.
Flat IP architecture identify devices using symbolic names unlike hierarchical
architecture where in normal IP addresses are used. This architecture reduces number
of network elements in data path and hence reduces cost to greater extent. It also
minimizes latency.
5G aggregator aggregates all the RAN traffics and route it to gateway. 5G aggregator is
located at BSC/RNC place. 5G mobile terminal houses different radio interfaces for each
RAT in order to provide support for all the spectrum access and wireless technologies.
Another component in the 5G network architecture is 5G nanocore. It consists of
nanotechnology, cloud computing, All IP architecture.
Cloud computing utilizes internet as well as central remote servers to maintain data and
applications of the users. It allows consumers to use applications without any
installation and access their files from any computer across the globe with the use of
internet.Global content service providers support following applications:
• Search engine• education• public portal• private portal• government•
medical• transportation• banking etc.

5G NR (New Radio) architecture

5G NR overall architecture is shown in the following figure-2. This is as defined in the
3GPP TS 38.300 specification.
As shown in the figure, gNB node provides NR user plane and control plane protocol
terminations towards the UE (i.e. 5G terminal device such as smartphone, tablet, laptop
etc.) and it is connected via the NG interface to the 5GC. The ng-eNB node providing E-
UTRA (i.e. LTE) user plane and control plane protocol terminations towards the UE,
and connected via the NG interface to the 5GC.
Here AMF stands for Access and Mobility Management Function and UPF stands for
User Plane Function.
3GPP TS 38.401 describes 5G NR user plane and control plane as well as 5G NR RAN
architecture with various interfaces (NG, Xn and F1) and their interaction with the radio
interface (Uu). The same have been depicted in the following figure-3 and figure-4. 5G
smartphones interact with 5G-RAN over Uu radio interface. 5G RAN interacts with
5GC (5G Core Network).

The protocols over Uu and NG interfaces are categorized into user plane protocols and
control plane protocols. User plane protocols implement actual PDU Session service
which carries user data through the access stratum. Control plane protocols control
PDU Sessions and connection between UE and the network from various aspects which
includes requesting the service, controlling different transmission resources, handover
etc. The mechanism for transparent transfer of NAS messages is also included.
The NG-RAN consists of a set of gNBs connected to the 5GC through the NG interface.
An gNB can support FDD mode, TDD mode or dual mode operation. gNBs can be
interconnected through the Xn interface. A gNB may consist of a gNB-CU and one or
more gNB-DU(s). A gNB-CU and a gNB-DU is connected via F1 interface. NG, Xn and
F1 are logical interfaces.
5GC (5G Core) Network architecture is highly flexible, modular and scalable. It offers
many functions including network slicing to serve vivid customer requirements. It
offers distributed cloud, NFV (Network functions virtualization) and SDN (Software
Defined Networking).

5G Protocol Stack
The figure-5 below depicts 5G protocol stack mentioning 5G protocol layers mapped
with OSI stack. As whown 5G protocol stack consists of OWA layer, network layer,
Open transport layer and application layer.
OWA Layer: OWA layer is the short form of Open Wireless Architecture layer. It
functions as physical layer and data link layer of OSI stack.
Network Layer: It is used to route data from source IP device to the destination IP
device/system. It is divided into lower and upper network layers.
Open Transport Layer: It combines functionality of both transport layer and session
layer.
Application Layer: It marks the data as per proper format required. It also does
encryption and decryption of the data. It selects the best wireless connection for given
service.

5G NR Radio protocol architecture

Following figure-6 depicts radio protocol architecture of 5G NR (New Radio) as defined
in 3GPP TS 38.300.

Protocol layers at UE and gNB side are shown in the figure for both user plane and
control plane functionalities.
5G NR network interfaces-Xn,NG,E1,F1,F2 interface types in 5G
This page on 5G NR network interfaces describes various 5G interfaces used in 5G
architecture. It includes Xn interface, NG interface, E1 interface, F1 interface and F2
interface used in 5G NR (New Radio) network architecture. It covers functions and
locations of these 5G NR interfaces used between 5G RAN and 5GC.
5G NR overall architecture is shown in the following figure-2. This is as defined in the
3GPP TS 38.300 specification. The 5G NR network composed of NG RAN (Next
Generation Radio Access Network) and 5GC (5G Core Network). As shown, NG-RAN
composed of gNBs (i.e. 5G Base stations) and ng-eNBs (i.e. LTE base stations).
• Xn interface exists between these base stations viz. between gNB-gNB, between
(gNB)-(ng-eNB) and between (ng-eNB)-(ng-eNB). Xn is the network interface between
NG-RAN nodes. Xn-U stands for Xn User Plane interface and Xn-C stands for Xn
Control Plane interface.
• NG interface exists between 5GC and these base stations (i.e. gNB & ng-eNB).

Following are the interfaces and nodes as shown in the figure-1 and figure-2.
• NG-C: control plane interface between NG-RAN and 5GC.
• NG-U: user plane interface between NG-RAN and 5GC.
• gNB: node providing NR user plane and control plane protocol terminations towards
the UE, and connected via the NG interface to the 5GC. The 5G NR (New Radio) gNB is
connected to AMF (Access and Mobility Management Function) and UPF (User Plane
Function) in 5GC (5G Core Network). The protocol layers are mapped into three units
viz. RRH (Remote Radio Head), DU (Distributed Unit) and CU (Central Unit) as shown
in the figure-2.
• ng-eNB: node providing E-UTRA user plane and control plane protocol terminations
towards the UE and connected via the NG interface to the 5GC.

As shown in the figure-2, there are control plane and user plane interfaces towards the
5G Core network (5GC). Following are the locations and functions of 5G NR interfaces.
5G NR Xn Interface
• Location: Xn interface lies between NG-RAN Nodes viz. gNB & ng-eNB.
• Control Plane Functions are as follows:
-interface management and error handling (e.g. setup, reset, removal, configuration
update)
-connected mode mobility management (handover procedures, sequence number status
transfer, UE context retrieval)
-support of RAN paging
-dual connectivity functions (secondary node addition, reconfiguration, modification,
release, etc.)
• User Plane Functions are as follows:
-Data Forwarding
-Flow Control
5G NR NG Interface
• Location: Between 5G RAN and 5G Core Network. Both control plane and user plane
lies between them and hence there are two interfaces under NG interface viz. NG-C and
NG-U. It is similar to LTE interfaces viz. S1-C and S1-U respectively.
• Functions/Objectives:
-NG interface supports the exchange of signalling information between NG-RAN and
5GC.
-It defines inter connection of NG-RAN nodes with AMFs supplied by different
manufacturers.
-It specifies the separation of NG interface Radio Network functionality and Transport
Network functionality to facilitate introduction of future technology.
• Capabilities:
-procedures to establish, maintain and release NG-RAN part of PDU sessions
-procedures to perform intra-RAT handover and inter-RAT handover
-the separation of each UE on the protocol level for user specific signalling management
-the transfer of NAS signalling messages between UE and AMF
-mechanisms for resource reservation for packet data streams
• References: From TS 38.410 to TS 38.414
5G NR E1 Interface
• Location: From logical perspective, E1 interface is point-to-point interface between a
gNB-CU-CP and a gNB-CU-UP as shown in fig-2.
• Functions:
-E1 interface supports the exchange of signalling information between the endpoints.
-It separates Radio Network Layer and Transport Network Layer.
-It enables exchange of UE associated information and non-UE associated information.
• References: From TS 38.460 to TS 38.463
5G NR F1 Interface
• Location: Between gNB-CU and gNB-DU. It is also separated into F1-C and F1-U
based on control plane and user plane functionalities.
• Functions:
-F1 interface defines inter-connection of a gNB-CU and a gNB-DU supplied by different
manufacturers.
-It supports control plane and user plane separation.
-It separates Radio Network Layer and Transport Network Layer.
-F1 interface enables exchange of UE associated information and non-UE associated
information.
• References: From TS 38.470 to TS 38.475
5G NR F2 Interface
This interface lies between lower and upper parts of the 5G NR physical layer. It is also
separated into F2-C and F2-U based on control plane and user plane functionalities.
Whenever tests are performed on fiber optic networks, the results are displayed on a
meter readout in “dB.” Optical loss is measured in “dB” while optical power is
measured in “dBm.” Loss is a negative number (like –3.2 dB) as are most power
measurements.

5G Overview:-
5G performance targets high data rate, reduced latency, energy saving, cost reduction,
higher system capacity, and massive device connectivity. The first phase of 5G
specifications in Release-15 will be completed by April 2019 to accommodate the early
commercial deployment. The second phase in Release-16 is due to be completed by
April 2020 for submission to the International Telecommunication Union (ITU) as a
candidate of IMT-2020 technology.

The ITU IMT-2020 specification demands speeds up to 20 Gbps, achievable with wide
channel bandwidths and massive MIMO.[2] 3rd Generation Partnership Project (3GPP)
is going to submit 5G NR (New Radio) as its 5G communication standard proposal. 5G
NR can include lower frequencies (FR1), below 6 GHz, and higher frequencies (FR2),
above 24 GHz and into the millimeter waves range. However, the speed and latency in
early deployments, using 5G NR software on 4G hardware (non-standalone), are only
slightly better than new 4G systems, estimated at 15% to 50% better.[3][4][5] Simulation
of standalone eMBB deployments showed improved throughput between 2.5×, in the
FR1 range, and nearly 20×, in the FR2 range.[6]
Usage
Capability Description 5G target
scenario
Peak data rate Maximum achievable data rate 20 Gbit/s eMBB
User experienced Achievable data rate across the coverage
1 Gbit/s eMBB
data rate area
Radio network contribution to packet
Latency 1 ms URLLC
travel time
Maximum speed for handoff and QoS eMBB/URLL
Mobility 500 km/h
requirements C
Connection density Total number of devices per unit area 106/km2 MMTC
Data sent/received per unit energy
Energy efficiency Equal to 4G eMBB
consumption (by device or network)
Spectrum Throughput per unit wireless bandwidth
3–4x 4G eMBB
efficiency and per network cell
Area traffic 1000
Total traffic across coverage area eMBB
capacity (Mbit/s)/m2
Note that, for 5G NR, according to 3GPP specification when using spectrum below
6 GHz, the performance would be closer to 4G.
5G modems
Traditional cellular modem suppliers have significant investment in the 5G modem
market. Qualcomm announced its X50 5G Modem in October 2016,[49] and in
November 2017, Intel announced its XMM8000 series of 5G modems, including the
XMM8060 modem, both of which have expected productization dates in 2019.[50][51] In
February 2018, Huawei announced the Balong 5G01 terminal device[52] with an
expected launch date for 5G-enabled mobile phones of 2018[53] and Mediatek
announced its own 5G solutions targeted at 2020 production.[54] Samsung is also
working on the Exynos 5G modem, but has not announced a production date.[55]
Frequency range 1 (< 6 GHz)
The maximum channel bandwidth defined for FR1 is 100 MHz, due to the scarcity of
continuous spectrum in this crowded frequency range. The band that is most likely to
be universally used for 5G in this range is around 3.5 GHz.
Frequency range 2 (> 24 GHz)
The minimum channel bandwidth defined for FR2 is is the 50 MHz and the maximum
is 400 MHz, with two-channel aggregation supported in 3GPP Release 15. The
maximum Physical layer (PHY) rate potentially supported by this configuration is
approximately 40 Gbit/s. There is no particular band that is likely to be universally used
for 5G in this range, though there are some regional proposals do converge around
certain bands.[57]
Massive MIMO
Massive MIMO (multiple input and multiple output) antennas increases sector
throughput and capacity density using large numbers of antennae and Multi-user
MIMO (MU-MIMO). Each antenna is individually-controlled and may embed radio
transceiver components. Nokia claimed a five-fold increase in the capacity increase for a
64-Tx/64-Rx antenna system. The term "massive MIMO" was coined by Nokia Bell Labs
researcher Dr. Thomas L. Marzetta in 2010, and has been launched in 4G networks, such
as Softbank in Japan.[citation needed]
Edge computing
Edge computing is a method of optimizing cloud computing systems by taking the
control of computing applications, data, and services away from some central nodes
(the "core area"). In a 5G network, it would promote faster speeds and low-latency data
transfer on edge devices
Radio convergence
One expected benefit of the transition to 5G is the convergence of multiple networking
functions to achieve cost, power and complexity reductions. LTE has targeted
convergence with Wi-Fi via various efforts, such as License Assisted Access (LAA) and
LTE-WLAN Aggregation (LWA), but the differing capabilities of cellular and Wi-Fi
have limited the scope of convergence. However, significant improvement in cellular
performance specifications in 5G, combined with migration from Distributed Radio
Access Network (D-RAN) to Cloud- or Centralized-RAN (C-RAN) and rollout of
cellular small cells can potentially narrow the gap between Wi-Fi and cellular networks
in dense and indoor deployments. Radio convergence could result in sharing ranging
from the aggregation of cellular and Wi-Fi channels to the use of a single silicon device
for multiple radio access technologies.
NOMA (non-orthogonal multiple access)
NOMA (non-orthogonal multiple access) is a proposed multiple-access technique for
future cellular systems. In this, same time, frequency, and spreading-code resources are
shared by the multiple users via allocation of power. The entire bandwidth can be
exploited by each user in NOMA for entire communication time due to which latency
has been reduced and users' data rates can be increased. For multiple access, the power
domain has been used by NOMA in which different power levels are used to serve
different users. 3GPP also included NOMA in LTE-A due to its spectral efficiency and is
known as multiuser superposition transmission (MUST) which is two user special case
of NOMA.
Channel coding
The channel coding techniques for 5G NR have changed from turbo in 4G to polar for
the control channel and LDPC for the data channel.[61][62]
Operation in unlicensed spectrum
Like LTE in unlicensed spectrum, 5G NR will also support operation in unlicensed
spectrum (NR-U).[63] In addition to License Assisted Access (LAA) from LTE that
enable carriers to use those unlicensed spectrum to boost their operational performance
for users, in 5G NR it will support standalone NR-U unlicensed operation which will
allow new 5G NR networks to be established in different environments without
acquiring operational license in licensed spectrum, for instance for localized private
network or lower the entry barrier for providing 5G internet services to the public.[
Initial 5G NR launches will depend on existing LTE 4G infrastructure in non-standalone
(NSA) mode, before maturation of the standalone (SA) mode with the 5G core network.
Non-Standalone mode
Non-Standalone (NSA) mode of 5G NR refers to an option of 5G NR deployment that
dependent on the control plane of existing LTE network for control functions, while 5G
NR exclusively focused on user plane.[6][7] The advantage of doing so is reported to
speed up 5G adoption, however some operators and vendors have criticized
prioritizing the introduction of 5G NR NSA on the grounds that it could hinder the
implementation of the standalone mode of the network.[8][9]
Standalone mode
Standalone (SA) mode of 5G NR refers to using 5G cells for both signalling and
information transfer.[6] It includes the new 5G Packet Core architecture instead of
relying on the 4G Evolved Package Core.[10][11] It mean it would allow the
deployment of 5G without LTE network.[12] It is expected to have lower cost, better
efficiency, and assist development of new use cases.[8][13]

5G FDD vs 5G TDD | difference between FDD and TDD in 5G

This page compares 5G FDD vs 5G TDD and describes difference between FDD and
TDD in 5G wireless network. FDD stands for Frequency Division Duplex and TDD
stands for Time Division Duplex.
Introduction:
• Both FDD and TDD are two spectrum usage techniques used in mobile
communication networks such as Mobile WiMax, LTE, 5G etc.
• In FDD mode, both uplink and downlink can transmit at the same time at different
spectrum frequencies.
• In TDD mode, both uplink and downlink use the same spectrum frequencies but at
different times.
• Refer use of FDD vs TDD >> in LTE wireless network.
• The figure-1 depicts TDD and FDD topologies.
• As shown two different carrier frequencies "Fc1" and "Fc2" are used for uplink and
downlink respectively at the same time "t1". Downlink is related to upper part of the
spectrum while uplink is related to lower part of the spectrum with guard band (i.e.
duplex gap) between these parts.
• Same carrier frequency "Fc" is used at different time instants "t1" and "t2" for uplink
and downlink transmission purpose.
In 28 GHz TDD mode, 5G-TF uses frequency range from 27500.5 (Low) to 28349.5 MHz
(High) with center frequency of 27925 MHz and bandwidth of 850 MHz. This 5G band
is used for both the downlink and uplink chains. Downlink refers to transmission from
5G Base Station (or NB) to 5G UE or mobile phone. Uplink refers to transmission from
5G UE to 5G NB.
5G FDD

The figure-2 describes 5G FDD scenario. As shown same antenna array element is
interfaced with diplexer. The device RF diplexer separates transmit and receive
frequencies for PA (Power Amplifier) and LNA (Low Noise Amplifier) respectively. As
mentioned FDD uses two unique frequencies one for downlink and another for uplink.
Hence communication takes place simultaneously in both the directions.
The local oscillator in 5G beamforming module uses frequency in the range from 23.2 to
23.9 GHz. This LO frequency beats with received RF frequency will produce IF
frequency at about 4.4 GHz in down conversion. This down converted frequency is
provided to LNA module. This LO frequency beats with IF frequency will produce RF
frequency at 28 GHz band in up conversion. This up converted frequency is provided to
PA module.
5G TDD
The figure-3 describes 5G TDD scenario. As shown same antenna array element is
interfaced with SPDT Switch/Filters. It uses only one RF frequency for transmit/receive
operations at different time instants. As shown, SPDT (Single Pole Double Throw)
switch is used to interface single antenna element with PA/LNA one at a time at same
frequency. PA output is filtered before connection with SPDT switch. Similarly received
RF signal is filtered before connection with LNA. Both the figure-2 and figure-3 are part
of the beam forming module used in 5G mobile phone or 5G smart phone.

Following table summarizes 5G FDD and 5G TDD versions.

Feature 5G FDD 5G TDD
FDD version is used where both TDD version is used where both
Application uplink and downlink data rates are uplink and downlink data rates
symmetrical. are asymmetrical.
TDD frame structure type is
Frame structure FDD frame structure type is used.
used.
Interference with
neighboring Base Less More
Stations
Not suitable for very dense It is used in very dense
Deployment type
environments. deployments with low-power
 nodes.
It is preferable for higher
It is preferable for lower frequency
Frequency bands frequency bands usually above
bands.
10 GHz.
Downlink and uplink channel It matches and hence TDD
responses would not match perfectly delivers better performance in
Channel response
due to different frequency bands MIMO/Beamforming algorithms
used in both these directions. compare to FDD.

4G vs 5G-Difference between 4G and 5G

The telecommunication industry is seeing rapid growth in the last few decades. The
wireless mobile communication standards are the major contributors. This growth has
seen many generations from 1G, 2G, 3G, 4G and 5G. Each of these generations have
various wireless technologies, data rates, modulation techniques, capacities and
features compare to the other.
4G-Fourth Generation Mobile Communication System
This generation of systems are totally IP based technology with capacity of 100Mbps to
1Gbps. It is used for both indoor and outdoor applications. The main function of 4G
technology is to deliver high quality, high speed, high capacity, low cost services. It is
mainly used for voice, multimedia and internet over IP based traffic. The technologies
driving 4G growth are LTE and WiMAX.
5G-Fifth Generation Mobile Communication System
These 5th generation of systems are driven by OFDM, MC-CDMA, LAS-CDMA, UWB,
Network LMDS and IPV6.
Following table 4G vs 5G and difference between 4G and 5G wireless technologies.
Specifications 4G 5G
Full form Fourth Generation Fifth Generation
Peak Data Rate 1 Gbps 10 Gbps
Data Bandwidth 2Mbps to 1Gbps 1Gbps and higher as per need
Spectral
30 b/s/Hz 120 b/s/Hz
Efficiency
TTI (Transmission
1 ms Varying (100 µs (min.) to 4ms (max.) )
Time Interval)
Latency 10 ms (radio) <1 ms (radio)
Mobility 350 Kmph 500 Kmph
Connection
1000/Km2 1000000/Km2
Density
Frequency Band 2 to 8 GHz 3 to 300 GHz
Al access convergence
Standards including OFDMA,MC- CDMA and BDMA
CDMA,network-LMPS
unified IP, seamless Unified IP, seamless integration of
integration of broadband broadband LAN/WAN/PAN/WLAN and
Technologies
LAN/WAN/PAN and advanced technologies based on OFDM
WLAN modulation used in 5G
Dynamic information access, Dynamic information access, werable
Service wearable devices, HD devices, HD streaming, any demand of
streaming, global roaming users
Multiple Access CDMA CDMA,BDMA
Flatter IP network, 5G network
Core network All IP network
interfacing(5G-NI)
Handoff Horizontal and vertical Horizontal and vertical
Initiation from year-2010 year-2015
7G Mobile Communication System
The 7G network will be same as 6G. In addition 7G defines satellite functionalities in
wireless mobile communication. This will provide many features and take care of all the
drawbacks of previous generation of mobile wireless communication systems. The
major factor here will be cost of phone call and other services. It provides seamless
movement of mobile phone from one country to the other. This will be major benefits
for frequent international travellers.

5G frequency bands in INDIA, USA, Europe, CHINA, JAPAN, Korea |

5G Bands
This page covers 5G frequency bands in India, USA, Europe, CHINA, JAPAN, Korea
etc. It mentions 5G frequency bands in sub 6GHz and above 6 GHz. These 5G bands are
used across the world for cellular and IoT applications.
The frequencies used in 5G wireless technologies are categorized into three divisions
viz. Sub-1 GHz, 1-6 GHz and above 6 GHz bands.
Lower 5G Bands in sub 6GHz
The table-1 below lists countrywise 5G band allocations across the world. These are
lower 5G frequency bands used below 6 GHz.
Country 5G Bands
Europe 3400 - 3800 MHz ( for trial )
China 3300 - 3600 MHz , 4400 - 4500 MHz, 4800 - 4990
 MHz
Japan 3600 - 4200 MHz , 4400 - 4900 MHz
Korea 3400 - 3700 MHz
USA 3100 - 3550 MHz, 3700 - 4200 MHz
INDIA 3300 MHz and 3400 MHz
Ireland 3.4 - 3.8 GHz
Spain 3.6 - 3.8 GHz
5G bands in India are auctioned by government for telecom carrier operators to acquire
in order to provide service.
Higher 5G Frequency Bands in mm wave
The table-2 below lists countrywise 5G frequency band allocations across the world.
These are higher 5G millimeter wave bands used above 6 GHz.
Country 5G Frequency Bands
USA 27.5 - 28.35 GHz , 37 - 40 GHz
Korea 26.5 - 29.5 GHz
Japan 27.5 - 28.28 GHz
China 24.25 - 27.5 GHz, 37 - 43.5 GHz
Sweden 26.5 - 27.5 GHz
EU 24.25 - 27.5 GHz
At the time (i.e. 25th April 2017) when this page has been written, trial and testing was
in progress before commercial roll out of the 5G wireless technology. In addition to the
above 5G bands other frequencies in which 5G services will be provided include
600MHz, 700MHz, 800MHz, 900MHz, 1.5GHz, 2.1GHz, 2.3GHz, 2.6GHz etc. These
frequencies are used for various applications including home and industry automation,
IoT (Internet of Things) etc.

5G NR Reference signals | DMRS,PT-RS,CSI-RS,SRS

This page mentions 5G NR Reference signals viz. DMRS, PT-RS, CSI-RS, SRS. These 5G
NR reference signals are used in the downlink and uplink. Functions,contents and
mapping of DMRS, PT-RS, CSI-RS, SRS are covered. The page also mentions tabular
difference between 4G LTE SRS and 5G NR SRS.
5G NR DMRS
• DMRS refers to Demodulation Reference Signal.
• It is used by 5G NR receiver to produce channel estimates for demodulation of
associated physical channel.
• The design and mapping of DMRS is specific to each of the 5G physical channels viz.
PBCH, PDCCH, PDSCH, PUSCH and PUCCH.
• DMRS is UE specific which is transmitted on demand.
• DMRS is used to acquire PBCH, PDSCH etc. DMR for PBCH is spread across same
bandwidth as used for PBCH (on same symbols).
• It does not extend outside of the scheduled physical resource of the channel it
supports.
• DMRS supports massive multi-user MIMO.
• It can be beamformed and supports upto about 12 orthogonal layers.
• DMRS sequence for CP-OFDM version is QPSK based on Gold Sequences.
PDSCH DMRS
Front loaded DMRS symbols (either 1 or 2) are located as follows.
➤Slot based (DMRS mapping type-A): Fixed OFDM symbol regrdless of PDSCH
assignment. It configurable between lo = {2,3}
➤Non-slot based (DMRS mapping type-B): First OFDM symbol assigned for PDSCH
i.e. Mini-slots
Additional DMRS symbols can also be configured for high speed scenarios. Additional
symbols are always present for broadcast/multicast PDSCH.
PUSCH DMRS
In uplink two waveform types are supported viz. CP-OFDM and DFT-S-OFDM. Gold
sequence is used in CP-OFDM where as Zadoff-chu is used in DFT-S-OFDM.
Front loaded DMRS symbols (either 1 or 2) are located at first OFDM symbol assigned
for PUSCH.
5G NR PT-RS
• PTRS stands for Phase Tracking Reference signal.
• It's main function is to track phase of the LO at transmitter and receiver.
• This will enable suppression of phase noise and common phase error specially at
higher mmwave frequencies.
• It is present both in uplink (in PUSCH) and downlink (in PDSCH) channels.
• Due to phase noise properties, PTRS has low density in frequency domain and high
density in time domain.
• PTRS is associated with one DMRS port during transmission. Moreover it is confined
to scheduled BW and duration used for PDSCH/PUSCH.
5G NR CSI-RS
• Like LTE, it is used for DL CSI acquisition.
• It is also used for RSRP measurements used during mobility and beam management.
It is also used for frequency/time tracking, demodulation and UL reciprocity based
precoding.
• CSI-RS is configured specific to UE. But multiple users can also share the same
resource.
• 5G NR standard allows high level of flexibility in CSI-RS configurations.
• A resource can be configured with up to 32 ports.
• CSI-RS resource may start at any OFDM symbol of the slot and it usually occupies
1/2/4 OFDM symbols depending upon configured number of ports.
• CSI-RS can be periodic, semi-persistent or aperiodic (due to DCI triggering)
• For time/frequency tracking, CSI-RS can either be periodic or aperiodic. It is
transmitted in bursts of two or four symbols which are spread across one or two slots.
5G NR SRS
• SRS stands for Sounding Reference signal.
• It is used for UL channel sounding.
• In contrast to LTE, it is configured specific to UE.
• In time domain, it spans 1/2/4 consecutive symbols which are mapped within last six
symbols of the slot.
• Multiple SRS symbols allow coverage extension and increased sounding capacity.
• The design of SRS and its frequency hopping mechanism is same as used in LTE.
Difference between 4G LTE SRS and 5G NR SRS
Following pdf describes Sounding Reference Signals used in 4G LTE and 5G NR. It also
mentions difference between 4G LTE SRS and 5G NR SRS.
SRS:-Sounding Reference Signal gNB
Two types of Reference Signal are there in UL which gives information about the
channel quality:-
1. DMRS:-Demodulation Reference Signal
2. SRS:-Sounding Reference Signal
With the help of above Two RS, gNB takes smart decisions for resource allocation for
uplink transmission, link adaptation and to decode transmitted data from UE.SRS is a
UL reference signal which is transmitted by UE to Base station.SRS gives information
about the combined effect of multipath fading, scattering, Doppler and power loss of
transmitted signal. Hence Base Station estimates the channel quality using this reference
signal and manages further resource scheduling, Beam management, and power control
of signal. So SRS provides information to gNB about the channel over full bandwidth
and using this information gNB takes decision for resource allocation which has better
channel quality comparing to other Bandwidth regions.
One reference signal(DMRS) is always associated with each channel (PUCCH/PUSCH),
which provides information about the radio channel then why this separate reference
signal is required?
Answer:-●DMRS provides information about the frequency region which is being used
byPUSCH/PUCCH specifically.●If gNB assigns resources over full bandwidth region
for a UE then there is no choice leftfor UE to select specific frequency region Hence SRS
is optional. BUT DMRS will alwaysbe transmitted with PUSCH/PUCCH for coherent
demodulation and channel estimation.

5G NR PRACH | contents, function, physical layer processing

This page covers 5G NR PRACH function, 5G NR PRACH contents, mapping and
physical layer processing of 5G NR PRACH (Physical Random Access Channel).
5G NR PRACH function, contents and mapping

• PRACH is used to carry random access preamble from UE towards gNB (i.e. 5G NR
base station).
• It helps gNB to adjust uplink timings of the UE in addition to other parameters.
• Zadoff chu sequences are used to generate 5G NR random access preamble similar to
LTE technology.
• Unlike LTE, 5G NR random access preamble supports two different sequence lengths
with various format configurations as shown in the figure. The different formats help in
wide deployment scenarios.
The 839 long sequence uses four preamble formats like LTE. These formats are designed
for large cell deployment in FR1 (Sub-6 GHz range). They use subcarrier spacing of 1.25
KHz or 5 KHz.
The 139 short sequence uses nine preamble formats. These formats are designed for
small cell deployment including indoor coverage. These preamble formats are used for
both FR1 (sub-6 GHz) and FR2 (mmwave) ranges. In FR1, it supports 15 or 30 KHz
where as in FR2, it supports 60 or 120 KHz. subcarrier spacing.
5G NR PRACH physical layer processing
• PRACH uses same FFT as used for data.
• OFDM baseband signal generation for PRACH is defined in 3GPP TS 38.211
• Engineers often come across situations (test cases) in which UE does not receive
response from gNB for the PRACH message transmitted by it. During such scenario,
they need to analyze the test case with respect to various layers such as radio link,
physical layer (L1) and last upper layer messages. This helps them find root cause of the
problem.

5G NR SSB-SS, PBCH, contents, function, physical layer processing

This page covers 5G NR SSB function, mapping and 5G NR SSB physical layer
processing. The 5G NR SSB consists of SS (i.e. PSS and SSS) and PBCH channels.
In LTE and 5G NR resource grid consists of subcarriers in frequency domain and
symbols in time domain. Resource grid is combination of resource blocks (RBs). One RB
(resource Block) consists of 12 consecutive subcarriers in frequency domain.
5G NR SSB | PSS, SSS and PBCH
In 5G NR, combination of SS and PBCH (Physical Broadcast Channel) is known as SSB.
There two frequency bands supported in 5G NR technology viz. FR1 (Sub-6 GHz) and
FR2 (millimeter wave). There are various subcarrier spacing supported in 5G NR viz. 15
KHz, 30 KHz, 60 KHz, 120 KHz and 240 KHz. SSB utilizes subcarrier spacing of 15 or 30
KHz in FR1 and 120 or 240 KHz in FR2.

SS Block : { 1 symbol PSS, 1 symbol SSS, 2 symbols PBCH }

SS Burst : One or multiple SS Block(s)
SS Burst Set : One or multiple SS burst(s), Transmission periodic (default: 20 ms),
Confined in 5ms window
As shown, SSB is mapped to 4 OFDM symbols in the time domain versus 20 BRs (i.e.
240 subcarriers) in the frequency domain. Beam sweeping concept is employed in 5G
NR for SSB transmission. Multiple SSBs are transmitted periodically at about 20 ms
intervals. About 64 SSBs are transmitted in different beams within SS burst set period.
SS blocks transmission within single SS burst set is limited to about 5ms window.
Frequency location of SSB is condifured by upper layer stack to support sparser search
raster in order to detect SSB.
Following are the possible candidate SSB locations (L) within SS Burst Set. Each slot in
time domain consists of 2 SS block locations for < 6 GHz for 15 KHz/30 KHz. Each slot
consists of 2 SS blocks in 120 KHz for > 6 GHz.
• L = 4 (upto 3 GHz)
• L = 8 (From 3 GHz to 6 GHz)
• L = 64 (From 6 GHz to 52.6 GHz)
• Both SS and PBCH detection helps UE synchronize with the gNB (i.e. 5G base station)
during initial network entry phase.
• 5G NR SS consists of PSS (Primary SS) and SSS (Secondary SS). A BPSK modulated m-
sequence of length 127 is used for NR PSS where as BPSK modulated Gold sequence of
length 127 is used for NR SSS. Both PSS and SSS combination help to identify about
1008 physical cell identities.
• By detecting and decoding SS, UE can obtain physical cell identity, achieve downlink
synchronization in time/frequency domain and acquire time instants of PBCH channel.
Center frequency of PSS/SSS is aligned with center frequency of PBCH.
• PBCH carries very basic 5G NR system informations for UEs. Any 5G NR compatible
UE must have to decode information on PBCH in order to access the 5G cell.
• Information carried by PBCH include following.
-Downlink System BW
-Timing information in radio frame
-SS burst set periodicity
-System frame number
-Other upper layer informations
5G NR PBCH
• PBCH TTI : 80 ms
• PBCH payload : 56 bits including CRC
• PBCH channel coding scheme: Polar code
• The figure depicts physical layer processing for PBCH information. The coded bits of
PBCH code blocks are mapped across REs in PBCH. Two scrambling operations are
performed as shown.

What is 5G NR SLIV | Value of SLIV for PDSCH and PUSCH

This page describes 5G NR SLIV definition. SLIV stands for Start and Length Indicator
Value. SLIV values for PDSCH and PUSCH are also mentioned along with PDSCH and
PUSCH time domain resource allocation.
What is SLIV?:
The starting symbol S relative to the start of the slot, and the number of consecutive
symbols L counting from the symbol S allocated for the PDSCH are determined from
the start and length indicator (SLIV). The formula for SLIV is as follows. It is defined in
3GPP TS 38.214 document.

It is used for time domain allocation for PDSCH and PUSCH. It defines start symbol
and number of consecutive symbols for the respective allocation. Following table
mentions valid S and L combination values used for SLIV for PDSCH.

Following table mentions valid S and L combination values used for SLIV for PUSCH.

5G NR SLIV for PDSCH and PUSCH IEs

Following structures for SLIV used for PDSCH and PUSCH are defined in 3GPP TS
38.331 RRC specification document. Following are the values used in "PDSCH-
TimeDomainResourceAllocationList" information element (IE).
PDSCH-TimeDomainResourceAllocation ::= SEQUENCE
{
k0 INTEGER(0..32)
mappingType ENUMERATED {typeA, typeB},
startSymbolAndLength INTEGER (0..127)
}
Following are the values used in "PUSCH-TimeDomainResourceAllocation"
information element(IE).
PUSCH-TimeDomainResourceAllocation ::= SEQUENCE
{
k2 INTEGER(0..32)
mappingType ENUMERATED {typeA, typeB},
startSymbolAndLength INTEGER (0..127)
}

Difference between LTE and 5G NR Physical Layer Timing

This page mentions difference between LTE physical layer timing units and 5G NR
physical layer timing units. It mentions formula for 5G NR Physical layer sampling
time, 5G NR frame duration and 5G NR subframe duration.
Introduction:
As shown in the figure-1, a 5G NR frame is of 10ms duration. A frame has 10 subframes
having 1ms duration each. The number of slots per subframe depends on subcarrier
spacing. Each slot can have either 14 OFDM symbols or 12 OFDM symbols based on
cyclic prefix type.

Refer 5G NR Frame structure >> and LTE frame structure >> for more information.
Physical layer sampling instant depends on number of FFT points and subcarrier
spacing. Let us understand physical layer parameters.
5G NR Physical layer Sampling Time
Following formula-1 is used to calculate 5G NR physical layer time unit (Tc). It is
known as sampling time in time domain.

➤Example:
• For ΔFmax = 480000 Hz (i.e. 480 KHz subcarrier spacing)
• Nf = 4096 (i.e. FFT size)
• Tc = 0.509 ns
5G NR Frame duration and subframe duration
Following formula-2 is used to express 5G NR frame duration and 5G NR subframe
duration.

➤Tf = (480000*4096/100)*0.509*10-9 = 0.010 sec = 10 ms

➤Tsf = Tf/10 = 1 ms
LTE Physical layer Sampling Time
Using LTE system bandwidth of 20 MHz having 2048 FFT points and subcarrier spacing
of 15 KHz, LTE sampling time unit (Ts) is derived as follows using formula-1 above.
• ΔFmax = 15000, Nf = 2048
➤ Ts = (1/(15000*2048)) = 3.2552 x 10 -8
➤ Ts = 32.552 ns
Relation between LTE and 5G NR Sampling Times
➤ K = LTE sampling time/5G NR sampling time = Ts/Tc
➤ K =64

What is 5G NR Mini-slot | Function of Mini-slot in 5G NR

This page mentions 5G NR Mini-slot basics including function of Mini-slot. The
difference between slot and mini-slot in 5G NR is also mentioned.
Introduction:
As shown in the figure-1, a frame in 5G NR consists of 10 ms duration. A frame consists
of 10 subframes with each having 1ms duration similar to LTE. Each subframe consists
of 2μ slots. Each slot can have either 14 (normal CP) or 12 (extended CP) OFDM
symbols.

Slot is typical unit for transmission used by scheduling mechanism. NR allows

transmission to start at any OFDM symbol and to last only as many symbols as required
for communication. This is known as "mini-slot" transmission. This facilitates very low
latency for critical data communication as well as minimizes interference to other RF
links. Mini-slot helps to achieve lower latency in 5G NR architecture. Table below
mentions typical fixed slots used in a 5G NR frame structure.
μ, (subcarrier spacing) Slots/slot Slots/subframe Slots/frame Slot duration
0 (15 KHz) 14 1 10 1 ms
1 (30 KHz) 14 2 20 500 µs
2 (60 KHz), normal CP 14 4 40 250 µs
2 (60 KHz), Extended CP 12 4 40 250 µs
3 (120 KHz) 14 8 80 125 µs
4 (240 KHz) 14 16 160 62.5 µs
Unlike slot, mini-slots are not tied to the frame structure. It helps in puncturing the
exising frame without waiting to be scheduled.
Difference between slot and mini-slot in 5G NR
➤As mentioned normal slot occupies either 14 (normal CP) or 12 (Extended CP) OFDM
symbols. It enables slot based scheduling. One slot is the possible scheduling unit and
slot aggregation is also allowed. Slot length scales with subcarrier spacing.
• Slot length = 1 ms/2μ,
➤Mini-slot occupies 2, 4 or 7 OFDM symbols. It enables non-slot based scheduling. It is
minimum scheduling unit used in 5G NR. As mentioned mini-slots can occupy as little
as 2 OFDM symbols and are variable in length. They can be positioned asynchronously
with respect to the beginning of a standard slot.

5G NR UCI | Uplink Control Information (UCI) in 5G NR

This page describes 5G NR UCI (Uplink Control Information). It mentions PUCCH
formats used to carry various UCI payload sizes in 5G NR uplink.
Introduction:
UCI (Uplink Control Information) is carried by PUCCH channel in 5G NR. UCI consists
of HARQ (Hybrid Automatic Repeat Request) feedback, CSI (Channel State
Information) and SR (Scheduling Request).
Refer 5G NR PUCCH >> for more information. There are two types of PUCCH viz.
short and long. Various PUCCH formats are mentioned in the following table.
Length of OFDM Number of
PUCCH Format
symbols Bits
0 (Short) 1-2 <=2
1 (Long) 4 to 14 <=2
2 (Short) 1 to 2 >2
3 (Long) 4 to 14 >2, <N
4 (long) 4 to 14 >N
• 5G NR PUCCH is flexible in time domain and frequency domain.
• The PUCCH channel utilizes five PUCCH formats.
• PUCCH format 0 and 2 occupies 1 or 2 OFDM symbols. It is known as short PUCCH.
• PUCCH format 1, 3 and 4 occupies 4 to 14 OFDM symbols. It is known as long
PUCCH.
• PUCCH format 0 and 1 carry UCI payloads having 1 or 2 bits.
• Other PUCCH formats carry UCI payloads having more than 2 bits.
• In PUCCH formats 1, 3 and 4 symbols with DMRS are time division multiplexed with
UCI symbols to achieve low PAPR while in PUCCH format 2, DMRS is frequency
multiplexed with data subcarriers.
A UE can be configured with PUCCH resources for CSI reporting or SR. For UCI
transmission including HARQ-ACK bits, a UE may be configured with up to 4 PUCCH
resource sets based on the UCI size. The first set can only be used for a maximum of 2
HARQ-ACK bits (with a maximum of 32 PUCCH resources) and other sets are
applicable for more than 2 bits of UCI (each with a maximum of 8 PUCCH resources).
A UE determines the set based on the UCI size. It indicates a PUCCH resource in the set
based on a 3-bit field in DCI.
PUCCH format-0 (<=2 bits)
• PUCCH is based on sequence selection with low PAPR.
• Sequence length is 12 REs.
• Information is delivered by transmitting different sequences/codes.
• It can transmit HARQ-ACK and SR.

PUCCH format-1 (<=2 bits)

• DMRS always occur in every other symbol in the long PUCCH.

• BPSK and QPSK modulations
• Sequence length is 12 REs
• Modulated symbol is spread with a zadoff-chu sequence with OCC in the time
domain.
PUCCH format-2 (> 2 bits)

• DMRS is mapped on REs {1,4,7,10} for each PRB.

• DMRS sequence is based on PUSCH
• Contiguous PRB allocation
• PUCCH format-3 (>2 bits, <N bits)
• PUCCH format-4 (>N bits)

5G NR DCI Formats | Fields in 5G NR DCI formats

This page mentions 5G NR DCI Formats tables. It describes functions and fields used in
5G NR DCI formats viz. format 0_0, format 0_1, format 1_0, format 1_1, format 2_0,
format 2_1, format 2_2 and format 2_3.
Introduction:
DCI is the short form of Downlink Control Information. It is used to transport downlink
control information for one or more cells with one RNTI. Following coding steps can be
identified which include Information Element multiplexing, CRC attachment, channel
coding and rate matching.
Following table mentions functions of DCI format types defined in 3GPP TS 38.212 V15
published in June 2018. Its function is same as LTE DCI. It is used to schedule PUSCH
and PDSCH.
5G NR DCI
Usage description
Format type
Format 0_0 Scheduling of PUSCH in one cell
Format 0_1 Scheduling of PUSCH in one cell
Format 1_0 Scheduling of PDSCH in one cell
Format 1_1 Scheduling of PDSCH in one cell
Format 2_0 Notifying a group of UEs of the slot format.
Notifying a group of UEs of the PRB(s) and OFDM symbol(s) where UE
Format 2_1
may assume no transmission is intended for the UE.
Format 2_2 Transmission of TPC commands for PUCCH and PUSCH.
Transmission of a group of TPC commands for SRS transmissions by
Format 2_3
one or more UEs.

What is 5G NR Bandwidth Part | Function of Bandwidth Part

This page mentions 5G NR Bandwidth Part basics including function of bandwidth
part. The different use cases of bandwidth part in 5G NR standard are also mentioned.
Introduction:
The bandwidth part concept is introduced in the 5G NR in order to reduce power
consumption of 5G NR devices. For this UE is active on wide bandwidth in bursty
traffic situation for short time period and it will be active on narrow bandwidth for rest
of the time duration. This is known as bandwidth adaptation.
A bandwidth part (BWP) is subset of contiguous RBs on a carrier. A bandwidth part is a
subset of contiguous RBs on the carrier. Upto four bandwidth parts can be configured
in the UE for each of the UL and DL, But at a given time, only one bandwidth part is
active per transmission direction (either UL or DL). Due to BWP concept, UE can
receive on narrow bandwidth part and when required network informs UE to switch on
wider BW for reception.

• Carrier bandwidth part (BWP) is contiguous subset of PRBs (Physical Resource

Blocks) defined for given 5G NR numerology on a given component carrier.
• One or multiple BWP configuration for each component carrier can be assigned to UE.
But only one BWP in the downlink (DL) and one in the uplink (UL) is active at given
time instant.
Hence UE cannot transmit PUSCH or PUCCH and cannot receive PDSCH or PDCCH
outside an active BWP.
• Configuration parameters for each BWP includes numerology, bandwidth size,
frequency location and CORESET (Control Resource Set).
Use cases of Bandwidth part in 5G NR

• The different use cases of bandwidth part in 5G NR standard based devices are
shown in the figure-2.
• (A)-Supports reduced UE bandwidth capability
• (B)-Supports reduced UE energy consumption
• (C)-Supports FDM of different numerologies
• (D)-Supports non-contiguous spectrum
• (E)-Supports forward compatibility

5G NR RSRP RSRQ SINR measurements | Define RSRP RSRQ SINR

This page mentions RSRP, RSRQ and SINR measurements used in 5G NR system. The
definitions and use of RSRP, RSRQ and SINR in 5G NR are also mentioned.RRC
Information Elements (IEs) which carries these measurements (i.e. RSRP, RSRQ, SINR)
are also mentioned. It defines SS-RSRP, CSI-RSRP, SS-RSRQ, CSI-RSRQ, SS-SINR and
CSI-SINR.
Introduction:
➤In LTE, RSRP and RSRQ are associated with CRS (Cell Specific Reference Signal).
➤In 5G NR, CRS is not used. Instead SS (Synchronization Signal) and CSI (Channel
State Information) are used.
➤As a result RSRP, RSRQ and SINR are associated with SS and CSI.
➤They are defined for FR1 and FR2. FR1 (Frequency Range 1) lies from 450 MHz to
6000 MHz and FR2 (Frequency Range 2) lies from 24250 MHz to 52600 MHz. FR1 uses
subcarrier spacing of 15/30/60 KHz where as FR2 uses 60/120 KHz. FR1 supports
transmission BWs from 5 MHz (min.) to 100 MHz(max.) where as FR2 supports 50MHz
(min.), 100MHz, 200 MHz and 400 MHz(max.).
5G NR RSRP | SS-RSRP, CSI-RSRP
• SS-RSRP stands for SS reference signal received power.
• It is defined as linear average over the power contributions (in Watts) of the resource
elements which carry secondary synchronization signals.
• The measurement time resource(s) for SS-RSRP are confined within SS/PBCH Block
Measurement Time Configuration (SMTC) window duration.
• For frequency range 1, the reference point for the SS-RSRP shall be the antenna
connector of the UE.
• For frequency range 2, SS-RSRP shall be measured based on the combined signal from
antenna elements corresponding to a given receiver branch.
SS-RSRP is used for following.
If SS-RSRP is used for L1-RSRP,
RRC_CONNECTED intra-frequency.
Otherwise,
RRC_IDLE intra-frequency,
RRC_IDLE inter-frequency,
RRC_INACTIVE intra-frequency,
RRC_INACTIVE inter-frequency,
RRC_CONNECTED intra-frequency,
RRC_CONNECTED inter-frequency
• CSI-RSRP stands for CSI reference signal received power.
• It is defined as linear average over the power contributions (in Watts) of the resource
elements which carry CSI reference signals configured for RSRP measurements.
• For CSI-RSRP determination CSI reference signals transmitted on antenna port 3000.
(TS 38.211).
• For frequency range 1 (FR1), the reference point for the CSI-RSRP shall be the antenna
connector of the UE.
• For frequency range 2 (FR2), CSI-RSRP shall be measured based on the combined
signal from antenna elements corresponding to a given receiver branch.
CSI-RSRP is used for following.
If CSI-RSRP is used for L1-RSRP,
RRC_CONNECTED intra-frequency.
Otherwise,
RRC_CONNECTED intra-frequency,
RRC_CONNECTED inter-frequency
5G NR RSRQ | SS-RSRQ, CSI-RSRQ
• SS-RSRQ stands for Secondary synchronization Signal Reference Signal Received
Quality.
• It is defined as ratio of N x SS-RSRP/NR carrier RSSI. Here N refers to number of
resource blocks in NR carrier RSSI measurement Bandwidth. The measurements in N
(Numerator) and D (Denominator) shall be made over same set of resource blocks
(RBs).
• NR carrier RSSI is linear average of the total received power (Watts). It is observed
only in certain OFDM symbols of measurement time resources, in the measurement
bandwidth, over N number of resource blocks from all sources. The sources include co-
channel serving and non-serving cells, adjacent channel interference, thermal noise etc.
SS-RSRQ is used for following.
RRC_IDLE intra-frequency,
RRC_IDLE inter-frequency,
RRC_INACTIVE intra-frequency,
RRC_INACTIVE inter-frequency,
RRC_CONNECTED intra-frequency,
RRC_CONNECTED inter-frequency
• CSI-RSRQ stands for CSI Reference Signal Received Quality.
• It is defined as ratio of N x CSI-RSRP to CSI-RSSI.
• Here N is number of RBs in CSI-RSSI measurement BW.
• The measurement in N and D shall be made over same set of resource blocks (RBs).
• CSI Received Signal Strength Indicator (CSI-RSSI), comprises the linear average of the
total received power (Watts). • It is observed only in OFDM symbols of measurement
time resource(s), in the measurement bandwidth, over N number of RBs from all
sources.
• This sources include co-channel serving and non-serving cells, adjacent channel
interference, thermal noise etc.
• The measurement time resources for CSI-RSSI corresponds to OFDM symbols
containing configured CSI-RS occasions.
CSI-RSRQ is used for following.
RRC_CONNECTED intra-frequency,
RRC_CONNECTED inter-frequency
5G NR SINR | SS-SINR, CSI-SINR
• SS-SINR stands for SS signal-to-noise and interference ratio (SS-SINR).
• It is defined as the linear average over the power contribution (in Watts) of the
resource elements carrying secondary synchronisation signals divided by the linear
average of the noise and interference power contribution (in Watts) over the resource
elements carrying secondary synchronisation signals within the same frequency
bandwidth.
SS-SINR is used for following.
RRC_CONNECTED intra-frequency,
RRC_CONNECTED inter-frequency
• CSI-SINR stands for CSI signal-to-noise and interference ratio.
• It is defined as the linear average over the power contribution (in Watts) of the
resource elements carrying CSI reference signals divided by the linear average of the
noise and interference power contribution (in Watts) over the resource elements
carrying CSI reference signals reference signals within the same frequency bandwidth.
CSI-SINR is used for following.
RRC_CONNECTED intra-frequency,
RRC_CONNECTED inter-frequency
RRC IEs carrying RSRP, RSRQ and SINR
Following pdf mentions RRC IEs (Information Elements) carrying RSRP, RSRQ and
SINR measurements used in 5G NR system.
5G NR SRS
• SRS stands for Sounding Reference signal.
• It is used for UL channel sounding.
• In contrast to LTE, it is configured specific to UE.
• In time domain, it spans 1/2/4 consecutive symbols which are mapped within last six
symbols of the slot.
• Multiple SRS symbols allow coverage extension and increased sounding capacity.
• The design of SRS and its frequency hopping mechanism is same as used in LTE.
Following tables are as per 3GPP TS 38.133 V15.2.0 specifications released in June 2018.
The values in the tables are subjected to change as per latest releases from 3GPP.
Absolute Accuracy SS-RSRP Intra Frequency measurement
The requirements for absolute accuracy of SS-RSRP apply to a cell on the same carrier
frequency as used by the serving cell.

Relative Accuracy SS-RSRP Intra Frequency measurement

The relative accuracy of SS-RSRP is defined as SS-RSRP from one cell in comparison to
SS_RSRP measured on another cell as the same frequency.

Absolute Accuracy SS-RSRP Inter Frequency measurement

The requirements for absolute accuracy of SS-RSRO apply to a cell which has different
carrier frequency from the serving cell.
Relative Accuracy SS-RSRP Inter Frequency measurement
The relative accuracy of SS-RSRP in inter-frequency test case is defined as RSRP
measured from one cell in comparison to RSRP measured from another cell on different
frequency.

5G NR Physical layer | Physical layer as per 5G NR New Radio

This article describes 5G NR physical layer. The processing of PDSCH channel through
5G NR physical layer and PUSCH channel through 5G NR physical layer have been
covered stepwise. This 5G physical layer description is as per 3GPP physical layer
specifications mentioned in TS 38.200 series of documents.
Introduction:
The 5th generation wireless access tachnology is known as NR (New Radio). It follows
3GPP series of standards similar to GSM, CDMA and LTE. 3GPP organization has been
developing specifications for 5G NR since few years. First specifications have been
published in Dec. 2017 which suppors NSA (Non Standalone) where in 5G compliant
UE relies on existing LTE for initial access and mobility. In June 2018, SA versions of 5G
NR spefications have been finalized which works independent of LTE. There are three
different use cases of 5G NR technology viz. eMBB (Enhanced Mobile Broadband),
mMTC (Massive machine type communications) and URLLC (Ultra Reliable Low
Latency Communication).
There are two main components in 5G NR network viz. UE (i.e. mobile subscriber) and
gNB (i.e. base station). gNBs are connected with 5G Core in the backend. The
connection from gNB to UE is known as downlink which uses PBCH, PDSCH and
PDCCH channels for carrying different data/control informations. The connection from
UE to gNB is known as uplink which uses PRACH, PUSCH and PUCCH channels.
5G NR Numerology
5G NR Supports two frequency ranges FR1 (Sub 6GHz) and FR2 (millimeter wave
range, 24.25 to 52.6 GHz). NR uses flexible subcarrier spacing derived from basic 15
KHz subcarrier spacing used in LTE. Accordingly CP length is choosen.
μ Δf = 2μ.15 Cyclic Prefix
0 15 KHz Normal
1 30 KHz Normal
Normal,
2 60 KHz
Extended
3 120 KHz Normal
4 240 KHz Normal
5 480 KHz Normal
Table-1: μ, Subcarrier spacing, CP, PRBs
Both frequency ranges FR1 and FR2 use different 5G numerology as mentioned in the
table-2. Subcarrier Spacing of 15/30 KHz is supported for below 6 GHz 5G NR where as
60/120/240 KHz is supported for mmwave bands. Maximum bandwidth of 100 MHz is
supported in sub-6 GHz where as 400 MHz is supported in mmwave frequency ranges.
In LTE, maximum BW of 20 MHz was used.
Parameters Sub-6 GHz range mmWave range
Carrier
upto 16 carriers
aggregation
5/10/15/20/25/40/50/60/80/100
BW per carrier 50/100/200/400 MHz
MHz
Subcarrier spacing 15/30/60 KHz 60/120/240 KHz
Modulation
DL/UL: 256 QAM
Scheme
DL: upto 8 layers, DL: upto 2 layers,
MIMO
UL: upto 4 layers UL: upto 2 layers
Duplex mode TDD (focus), FDD TDD
Access scheme DL: CP-OFDM, UL:CP-OFDM, DFT spread OFDM
Table-2: 5G NR Sub-6 GHz and mmwave parameters as per 3GPP Rel.15
Subcarrier spacing (KHz) 15 30 60 120 240
Symbol duration (µs) 66.7 33.3 16.7 8.33 4.17
1.2 (Normal CP), 4.13 (Extended
CP duration (µS) 4.7 2.3 0.59 0.29
CP)
Max. nominal system BW
50 100 100 (sub-6 GHz), 200 (mmwave) 400 400
(MHz)
FFT size (max.) 4096 4096 4096 4096 4096
Symbols per slot 14 14 14 (normal CP), 12 (extended CP) 14 14
Slots per subframe 1 2 4 8 16
Slots per frame 10 20 40 80 160

Table-3: Subcarrier spacing, Number of OFDM symbols and slots

5G NR Frame Structure

A frame has duration of 10 ms which consists of 10 subframes having 1ms duration

each similar to LTE technology. Each subfame can have 2μ slots. Each slot typically
consists of 14 OFDM symbols. The radio frame of 10 ms are transmitted continuously as
per TDD topology one after the other. Subframe is of fixed duration (i.e. 1ms) where as
slot length varies based on subcarrier spacing and number of slots per subframe. As
shown below, it is 1 ms for 15 KHz, 500 µs for 30 KHz and so on. Each slot occupies
either 14 OFDM symbols or 12 OFDM symbols based on normal CP and extended CP
respectively.
5G NR supports Mini Slot concept which helps in achieving very low latency in data
transmission. It supports 2, 4 or 7 OFDM symbols.

The figure depicts resource grid of 5G NR with symbols in time axis and subcarriers in
frequency axis. 12 subcarriers form one PRB (Physical Resource Block). 5G NR supports
24 to 275 PRBs in a single slot. Occupied BW of 34.56 MHz (minimum) and 396 MHz
(maximum) can be achieved for 120 KHz subcarrier spacing. One SS/PBCH Block
occupies 4 OFDM Symbols in time domain and 24 PRBs in frequency domain. 5G NR SS
consists of PSS and SSS as specified for LTE.
5G NR Physical layer
In 5G NR there are various physical channels in the downlink (from gNB to UE) and
uplink (from UE to gNB). Downlink channels: PDSCH, PDCCH, PBCH
Uplink channels: PRACH, PUSCH, PUCCH
There are specific physical signals present in both downlink and uplink for various
purposes. Front loaded DMRS (Demodulation Reference signal) is used for both
PDSCH and PUSCH channels. We will consider OFDM with CP for both downlink and
uplink chain. Uplink also uses DFT Spread OFDM with CP for improved coverage.
5G NR Physical layer processing of PDSCH channel

The PDSCH channel is used to carry DL user data, UE specific upper layer informations
(layer-2 and above), system informations and paging. Let us understand PDSCH
channel data (i.e. transport block) processing through 5G NR physical layer modules or
blocks. Transport block size calculation is mentioned in 3GPP TS 38.214(section 5.1.3.2).
One can also refer transport block size calculation at TBS calculation page >>
➤As shown in the figure, CRC is added to each of the transport blocks to provide error
detection.
➤This is following by LDPC base graph as per transport block size (small or large).
➤Now transport block is segmented into code blocks. CRC is appended to each of these
code blocks.
➤Each of the code blocks are individually encoded using LDPC encoder, which are rate
matched after encoding process.
➤Code block concatenation is performed to form codewords for transmission over
PDSCH channel. About 2 codewords are transmitted simultaneously on single PDSCH
channel. Single codeword is used for 1 to 4 layers where as 2 codewords are used for 5
to 8 number of layers.
➤All the codewords are scrambled and modulated to generate complex data symbols
before layer mapping. It uses QPSK, 16QAM, 64QAM and 256QAM modulation
schemes.
➤The modulated data symbols are mapped to either 4 or 8 layers.
➤The layers are mapped with number of antenna ports reserved for PDSCH use and
complex modulated data symbols are mapped to RBs (Resource Blocks) in the resource
grid as per subcarrier spacing. Antenna ports range is {1000,...,1011}. DMRS values are
inserted during resource element mapping used for channel estimation and
equalization at the UE receiver. OFDM signal is generated after RE (Resource Element)
mapping.
➤The downlink PDSCH is received by UE which consists of reverse modules of 5G NR
physical layer in order to decode the transport block back before passing the
information to upper layers.
5G NR Physical layer processing of PUSCH channel
PUSCH channel is used for transmission of UL SCH and layer-1 and layer-2 control
information. Let us understand PUSCH channel data (i.e. transport block) processing
through 5G NR physical layer modules or blocks. The procedure for UL transport block
in PUSCH processing is same as described above. It uses additional π/2-BPSK
modulation scheme in addition to the one listed above in PDSCH processsing. It also
uses DMRS signals for channel estimation and equalization process to help in decoding
process.
➤In addition to above blocks, the PUSCH processing uses transform precoding after
layer mapping operation. This is optional and UE implementation specific. DFT
transform precoding is used for single layer transmissions. PUSCH supports single
codeword which can be mapped maximum upto 4 layers.
➤5G NR UE uses codebook based transmission and non codebook based transmissions.
➤In 5G NR mapping to resource grid is done frequency wise first before time in order
to have easier decoding proceess at the gNB receiver
 .

5G NR MAC layer-architecture, channel mapping, procedures, header,

subheaders
This page describes overview of 5G NR MAC layer. It covers 5G NR MAC functions, 5G
NR MAC architecture, 5G NR MAC channel mapping, 5G NR MAC procedures and
format of 5G NR MAC header and subheaders.
Introduction:
5G NR (New Radio) is the latest cellular wireless technology developed to deliver ten
times faster data rate compare to its previous LTE technology. It follows 3GPP
specifications release 15 and above.
Following are the features of 5G NR technology.
• It works on two frequency bands viz. sub-6 GHz and millimeter wave (above 20
GHz).
• It supports massive MIMO with 64 to 256 antennas.
• It offers 10 Gbps within 100 meters using 100MHz bandwith.

The figure-1 depicts 5G NR protocol stack showing position of MAC layer. As shown
MAC layer provide services to the upper layers and it expects some services from the
physical layer>>. Physical layer offers transport channels to MAC layer to support
transport services for data transfer over radio interface. MAC layer offers logical
channels to RLC sublayer. The logical channels exist between MAC and PHY where as
transport channels exist between PHY and radio layer. Hence MAC is the interface
between logical channels and PHY transport channels.
The figure depicts data flow through various protocol layers of 5G NR stack.

5G NR MAC layer Architecture | 5G NR MAC layer functions

Following figure-2(a) and (b) depicts 5G NR MAC layer architecture for MCG (Master
Cell Group) and SCG (Secondary Cell Group).
Physical layer provides following services to the MAC sublayer.
• Data Transfer
• HARQ feedback signaling
• Scheduling Request signaling
• CQI (Channel Quality Indication) measurements
The MAC sublayer provides two main services to upper layers viz. data transfer and
radio resource allocation. The other functions of 5G NR MAC are as follows.
• Mapping between logical and transport channels (Both Downlink and Uplink).

• Multiplexing of MAC SDUs onto TBs (Transport Blocks) (In Uplink), SDUs belong to
logical channels and transport blocks belong to transport channels.
• Demultiplexing of MAC SDUs from TBs (In Downlink)
• Scheduling information reporting (In Uplink)
• Error correction through HARQ (In Downlink and Uplink)
• Logical Channel Prioritisation (In Uplink)
5G NR MAC channel mapping

The figure-3 depicts MAC logical channels and PHY layer transport channels used in
5G NR technology. They have specific functions in the downlink or uplink. PDSCH,
PBCH and PDCCH are used in the downlink where as PUSCH, PUCCH and RACH are
used in the uplink. The reference signals in the downlink are DMRS, PT-RS, CSI-RS, PSS
and SSS. The reference signals in the uplink are DMRS, PTRS and SRS.

The figure-4 depicts 5G NR channel mapping. It does mapping of logical channels to

transport channels and vice versa.
5G NR MAC procedures
Following table mentions different 5G NR MAC procedures. These procedures have
their respective functionality in the 5G NR MAC layer.
5G NR MAC
Description
Procedures
Get the initial uplink grant for UE and helps in performing
synchronization with the gNB (i.e. network). It covers Random Access
Random Access procedure initialization, Random Access Resource selection, Random
Procedure Access Preamble transmission, Random Access Response reception,
Contention Resolution and Completion of the Random Access
procedure.
DL-SCH data
It does everything needed to perform downlink data transfer.
transfer
UL-SCH data
It does everything needed to perform uplink data transfer.
transfer
Scheduling It is used by UE to transmit request to gNB (i.e. network) to obtain UL
request (SR) grant.
PCH reception It helps in monitoring paging message in special time period.
BCH reception It carry basic informations regarding the 5G NR cell (e.g. MIB, SFN etc.).
DRX It helps in monitoring PDCCH as per special pattern in discontinuous
(Discontinuous manner. Due to this discontinuous monitoring, energy consumption
Reception) can be achieved.
The other 5G NR MAC procedures include transmission and reception
without dynamic scheduling, activation/deactivation of SCells,
Other
activation/deactivation of PDCP duplication, BWP (Bandwidth Part)
procedures
operation, handling of measurement gaps, handling of MAC CEs, beam
failure detection and recovery operation etc.
5G NR MAC Header and subheaders
A MAC PDU consists of one or more MAC sub-PDUs. Each MAC sub-PDU consists of
one of the following fields:
• A MAC subheader only (including padding)
• A MAC subheader and a MAC SDU
• A MAC subheader and a MAC CE (Control Element)
• A MAC subheader and padding
The MAC SDUs are of variable sizes. Each MAC subheader corresponds to either a
MAC SDU, a MAC CE, or padding
The figure-5 depicts 5G NR MAC PDU examples for downlink (DL) and uplink (UL).
Following figure-6 depicts MAC subheader types. Let us understand header and
subheader fields and their respective meanings in the 5G system.
The MAC subheader consists of fields such as LCID, "L", "F" and "R".
• LCID field: LCID stands for Logical Channel ID. It identifies logical channel instance
of corresponding MAC SDU or type of corresponding MAC CE or padding. The values
of LCID for DL-SCH and UL-SCH are mentioned in the tables below. There is only one
LCID field exists for one MAC subheader. LCID field has 6 bits in size.
• L-Field: "L" indicates length field of corresponding MAC SDU or variable sized MAC
CE in units of bytes. One "L-field" exists for one MAC subheader. More number of "L-
fields" exist for subheaders corresponding to fixed-sized MAC CEs and padding. The
"L-field" size is indicated by F-field;
• F-field: It refers to length field size. It is one bit in size. There is one F field per MAC
subheader except for subheaders corresponding to fixed-sized MAC CEs and padding.
The value 0 in F-field refers to 8 bits of Length field. The value 1 in F-field refers to 16
bits of Length field.
• R: Reserved bit, set to zero.
LCID values for DL-SCH and UL-SCH

Table above mentions LCID values for DL-SCH channel where as table below mentions
LCID values for UL-SCH channel.
5G NR RLC layer | functions, modes, data structure, RRC parameters
This page describes overview of 5G NR RLC layer including functions. It covers 5G NR
RLC modes (TM mode, UM mode, AM mode), data structures (TMD, UMD, AMD),
RLC PDUs (TMD PDU, UMD PDU, AMD PDU), data transfers (TM, UM and AM) and
RRC parameters which defines RLC layer.
Introduction:
• RLC stands for Radio Link Control. 3GPP specifications TS 38.322 defines RLC
protocol for UE and NR radio interface.
• As shown it lies between MAC on lower side and PDCP on higher side of the stack.
• Like previous cellular standards such as WCDMA and LTE, this standard (5G NR)
also supports RLC modes viz. Transparent mode (TM mode), Unacknowledge Mode
(UM mode) and Acknowledge mode (AM mode).
The figure-1 depicts 5G NR protocol stack showing position of RLC layer. As shown
RLC layer provide services to the upper layers and it expects some services from the
MAC layer>> and PHY layer>>.

The figure depicts data flow through various protocol layers of 5G NR stack.
RLC Modes | TM mode, UM mode, AM mode
RLC configuration does not depend on 5G NR numerologies and it is associated with
logical channels. TM mode is used for SRB0, paging and broadcast of system
information. AM mode is used for SRBs. Either UM or AM mode is used for DRBs.
ARQ procedure is supported within RLC sublayer.
Functions of RLC sublayer are as follows.
• Transfer of upper layer PDUs
• Sequence numbering independent of the one in PDCP (UM and AM)
• Error Correction through ARQ (AM only)
• Segmentation (AM and UM) and re-segmentation (AM only) of RLC SDUs
• Reassembly of SDU (AM and UM)
• Duplicate Detection (AM only)
• RLC SDU discard (AM and UM)
• RLC re-establishment
• Protocol error detection (AM only)
RLC layer expects following services from lower layer (i.e. MAC layer).
• Data transfer
• Notification of transmission opportunity.
TM mode and TM data transfer procedure

• A TM RLC entity uses logical channels viz. BCCH, DL CCCH, UL CCCH and PCCH
to transmit or receive RLC PDUs.
• A TM RLC entity uses TMD PDU to transmit/receice data PDUs.
• During transmission, TMD PDUs are formed from RLC SDUs. It does not segment
RLC SDUs and does not include any RLC headers in the TMD PDUs. During reception,
TM RLC entity receives TMD PDUs and pass it to upper layers.
UM mode and UM data transfer procedure

It uses logical channels viz. DL DTCH or UL DTCH. It uses UMD PDU which can carry
one complete RLC SDU or one RLC SDU segment. Complete transmission and
reception process is defined in 3GPP TS 38.322 document which is shown in the figure.
AM mode and AM data transfer procedure
AM RLC entity uses DL/UL DCCH or DL/UL DTCH logical channels. It transmits and
receiver AMD PDUs which can carry either one complete RLC SDU or one RLC SDU
segment. AM RLC entity transmits and receives STATUS PDU as control PDU which is
mentioned below. Complete transmitting side and receiving side procedure is shown in
the figure. The same has been described in detail in 38.322 document.
data structures | TMD, UMD, AMD
RLC PDU is a bit string. RLC SDUs are bit strings which are byte aligned in length.
Following are structures of TMD, UMD and AMD.
TMD structure

UMD structure
AMD structure

Here SI (Segmentation Info) field is of 2 bits in length. It can be interpreted as follows.

00 : Data field contains all bytes of an RLC SDU
01 : Data field contains the first segment of an RLC SDU.
10 : Data field contains the last segment of an RLC SDU.
11 : Data field contains neither the first nor last segment of an RLC SDU.
➤SN refers to Sequence number field. It can be 12 bits or 18 bits for AMD PDU. It can
be 6 bits or 12 bits for UMD PDU.
➤SO refers to Segment Offset which is about 16 bits in length.
➤D/C field indicates Data/Control Field. Value of "0" indicates it is control PDU where
as value of "1" indicates it is data PDU.
➤P field indicates polling bit of length equals 1 bit. Value of "0" indicates "status report
not requested" where as value of "1" indicates "status report is requested".
➤CPT field is 3 bits in size. value of "000" indicates it is "STATUS PDU" and value of
"001" is reserved.
RRC parameters for RLC
Following RRC parameters are used to define RLC layer. The IE (Information Elements)
are RLC-Bearerconfig IE and RLC config IE.
See Through Link:- http://www.rfwireless-world.com/5G/5G-NR-RLC-layer-
overview.html

5G NR PDCP layer | functions, architecture, procedures, PDU formats

This page describes overview of 5G NR PDCP layer including functions. It covers
PDCP architecture (structure, entities), PDCP procedures for data transfer during
transmit/receive operation, Data PDU and Control PDU formats of PDCP layer etc.
Introduction:
• PDCP stands for Packet Data Convergence Protocol. 3GPP specifications TS 38.323
defines PDCP protocol.
• As shown it lies between RLC on lower side and RRC on higher side of the control
protocol stack.
• In the data user plane it lies on the top as shown.
The figure-1 depicts 5G NR protocol stack showing position of PDCP layer. As shown
PDCP layer provide services to the upper layers (RRC or SDAP) and it expects some
services from the RLC layer>>, MAC layer>> and PHY layer>>.

The figure depicts data flow through various protocol layers of 5G NR stack. PDCP
provides following services to the upper layers.
• Transfer of user plane data and control plane data
• Header compression/decompression using ROHC
• Ciphering/Deciphering
• Integrity protection
PDCP expects following services supported from lower layers.
• Acknowledged data transfer service
• Unacknowledges data transfer service
5G NR PDCP layer functions
Functions of PDCP layer are as follows.
• transfer of data (user plane or control plane)
• maintenance of PDCP SNs
• header compression and decompression using ROHC protocol
• ciphering and deciphering
• integrity protection and integrity verification
• timer based SDU discard
• for split bearers, routing is performed
• Activation/Deactivation of PDCP duplication
• reordering and in-order delivery
• out-of-order delivery
• duplicate discarding
PDCP architecture (structure, entities)

• The architecture is based on radio interface protocol.

• PDCP sublayer is configured by RRC.
• It is used for RBs mapped on logical channels which include DCCH and DTCH.
• Each RB is associated with 1 PDCP entity. Each PDCP entity is associated with 1/2/4
RLC entities which depends on RB characteristics or RLC modes. RB characteristics are
uni-directional / bi-directional or split/non-split.
• For non-split bearers , each PDCP entity is associated with 1 UM RLC entity/2 UM
RLC entities/1 AM RLC entity.
• For split bearers, each PDCP entity is associated with 2 UM RLC entities/4 UM RLC
entities/2 AM RLC entities(same direction).
PDCP entity:
• The PDCP entities are located in the PDCP sublayer. Several PDCP entities may be
defined for a UE. Each PDCP entity is carrying the data of one radio bearer.
• A PDCP entity is associated either to the control plane or the user plane depending on
which radio bearer it is carrying data for.
The figure depicts functional view of PDCP entity used for the PDCP sublayer.
• The data can be either uncompressed PDCP SDU or compressed PDCP SDU.
Uncompressed data is associated with user plane or control plane. Compressed data is
associated with user plane only.
As per Plane, PDU can be of two types viz. control PDU or data PDU.
• Control PDU types include either PDCP status report or interspersed ROHC
feedback.
 .
PDCP Procedures for data transfer
• There are three main PDCP entity handling procedures viz. PDCP entity
establishment, re-establishment and release.
• After establishment, PDCP procedures are associated with either transmitting
operation or receiving operation.
• As shown during transmit operation, PDCP entity receives SDU from upper layer. On
this received SDU various operations are performed before it is given to lower layers. It
is later passed to radio interface (Uu).
• When UE transmits NG-RAN receives and when NG-RAN transmits UE receives.
• Similar functionalities are performed when data PDU is received from lower layers.
• PDCP SDU size and PDCP control PDU size are both 9000 bytes (maximum).
• The length of PDCP SN is either 12 bits or 18 bits. It is configured by upper layers.
PDCP layer data PDU and control PDU formats
• A PDCP PDU is a bit string that is byte aligned (i.e. multiple of 8 bits) in length.
• PDCP SDUs are bit strings that are byte aligned (i.e. multiple of 8 bits) in length.
• A compressed or uncompressed SDU is included into a PDCP Data PDU from the
first bit onward.
Following figure depicts PDCP Data PDU format with 12 bits PDCP SN. This format is
applicable for SRBs.

Following figure depicts PDCP Data PDU format with 12 bits PDCP SN. This format is
applicable for UM DRBs and AM DRBs.
PDCP Control PDU format carrying one interspersed ROHC feedback is applicable for
UM DRBs and AM DRBs.
Following figure depicts PDCP Data PDU format with 18 bits PDCP SN. This format is
applicable for UM DRBs and AM DRBs.
Following figure depicts PDCP Control PDU format which carries one PDCP status
report. This format is applicable for AM DRBs.

5G NR PDCCH | contents, function, physical layer processing

This page covers 5G NR PDCCH function, 5G NR PDCCH contents, mapping and
physical layer processing of 5G NR PDCCH.
Following channels are supported by 5G NR wireless system.
Downlink channels: PDSCH (DL shared channel), PBCH (Broadcast channel), PDCCH
(DL control channel)
Uplink channels: PRACH (Random Access Channel), PUSCH (UL shared channel),
PUCCH (UL control channel)
5G NR PDCCH function, contents and mapping

• PDCCH channel is used to carry DCI (Downlink Control Information) e.g. downlink
scheduling assignments and uplink scheduling grants.
• The figure-1 depicts 5G NR PDCCH.
• Unlike LTE control channels which occupies entire system BW, 5G NR PDCCH
channels occupy certain subcarriers and OFDM symbols. These channels are
transmitted in CORESET (configurable control resource set). 5G NR is flexible in time
domain and frequency domain. Moreover certain 5G numerologies are also
configurable to address various use cases.
• Frequency allocation in CORESET is either contiguous or non-contiguous. In time
domain, it occupies about 1 to 3 consecutive OFDM symbols.
• The REs in CORESAT are arranged in REGs (RE groups). Each REG consists of 12 REs
of one OFDM symbol in single RB.
5G NR PDCCH physical layer processing

• In 5G NR, PDCCH is confined to single CORESET and it is transmitted with its own
DMRS. This enables UE specific beamforming for control channel.
• A PDCCH channel is transported by 1/2/4/8/16 control channel elements (CCEs) in
order to accommodate different DCI payload sizes or coding rates.
• Each CCE consists of about 6 REGs. The mapping for CCE to REG may be interleaved
or non-interleaved (for local beamforming). Interleaving is used for frequency diversity.
• The number of bits to be transmitted on the physical channel, is scrambled before
modulation block.
• After scrambling, QPSK modulation is applied which results into complex modulated
symbols.
• Next these complex symbols are mapped to physical resources with appropriate
antenna port (p=2000) taking into consideration DMRS mapping.
• PDCCH channel follows the same modules with modifications as described in the
3GPP TS 38.211, 38.212, 38.213 and 38.214 specifications.
5G NR PUCCH | contents, function, physical layer processing
This page covers 5G NR PUCCH function, 5G NR PUCCH contents, mapping and
physical layer processing of 5G NR PUCCH.
Following channels are supported by 5G NR wireless system.
Downlink channels: PDSCH (DL shared channel), PBCH (Broadcast channel), PDCCH
(DL control channel)
Uplink channels: PRACH (Random Access Channel), PUSCH (UL shared channel),
PUCCH (UL control channel)
5G NR PUCCH function, contents and mapping

• PUCCH channel is used to transport UCI (Uplink Control Information) e.g. HARQ
feedback, CSI (Channel State Information) and SR (Scheduling Request).
• 5G NR PUCCH is flexible in time domain and frequency domain.
• The PUCCH channel utilizes five PUCCH formats.
• PUCCH format 0 and 2 occupies 1 or 2 OFDM symbols. It is known as short PUCCH.
• PUCCH format 1, 3 and 4 occupies 4 to 14 OFDM symbols. It is known as long
PUCCH.
• PUCCH format 0 and 1 carry UCI payloads having 1 or 2 bits.
• Other PUCCH formats carry UCI payloads having more than 2 bits.
Length of OFDM Number of
PUCCH Format
symbols Bits
0 1-2 <=2
1 4 to 14 <=2
2 1 to 2 >2
3 4 to 14 >2
4 4 to 14 >2
• In PUCCH formats 1/3/4, symbols having DMRS are time multiplexed with UCI
symbols to achieve low PAPR .
• In PUCCH format 2, DMRS is frequency multiplexed with data subcarriers.
• Multi user multiplexing on same time/frequency resources is supported for PUCCH
formats 0/1/4 only with the help of unique cyclic shifts.
• UE can also be configured for CSI reporting or SR with the help of PUCCH resources.
• For transmission of UCI + (HARQ-ACK) , 4 PUCCH resource sets are used based on
UCI size. For first set is used for maximum of 2 HARQ-ACK bits (i.e. max. 32 PUCCH
resources). The other sets are used for 2 bits of UCI (i.e. max. 8 PUCCH resources).
• 5G NR UE determines set based on UCI size and also indicates PUCCH resource in
the set based on DCI's 3 bit field.
5G NR PUCCH physical layer processing

The physical layer processing for PUSCH is shown in the figure-1. Refer complete
article on 5G NR Physical layer >> for more information. PUCCH channel follows the
same modules with modifications as described in the 3GPP TS 38.211, 38.212, 38.213 and
38.214 specifications.
5G Layer 3 | 5G RRC Layer
Following are the functions of 5G layer 3 i.e. RRC Layer.
• Broadcasting of system informations to NAS and AS.
• Establishment, maintenance and release of RRC connection.
• Security including key management
• Establishment, configuration, maintenance and release of point-point radio bearers.
• Mobility functions along wth cell addition and cell release
• UE measurement reporting, control of UE reporting, UE based mobility
• NAS direct message transfer to/from NAS from/to UE
• Refer 5G NR UE RRC states >> and their functions and RRC IEs >> (Information
Elements) used in 5G NR UE/gNB and 5G NR system for various purposes.
The Radio Resource Control (RRC) protocol is used in on the Air Interface. The major
functions of the RRC protocol include connection establishment and release functions,
broadcast of system information, radio bearer establishment, reconfiguration and
release, RRC connection mobility procedures, paging notification and release and outer
loop power control.By means of the signaling functions, the RRC configures the user
and control planes according to the network status and allows for Radio Resource
Management strategies to be implemented.
The RRC Services and Functions
The main services and functions of the RRC sublayer include:
• Broadcast of System Information related to AS and NAS
• Paging initiated by 5GC or NG-RAN
• Establishment, maintenance, and release of an RRC connection between the UE
and NG-RAN including
• Addition, modification, and release of carrier aggregation
• Addition, modification, and release of Dual Connectivity in NR or between E-
UTRA and NR.
• Security functions including key management
• Establishment, configuration, maintenance, and release of Signalling Radio
Bearers (SRBs) and Data Radio Bearers (DRBs);
• Mobility functions including:
• Handover and context transfer
• UE cell selection and reselection and control of cell selection and reselection
• Inter-RAT mobility
• QoS management functions
• UE measurement reporting and control of the reporting
 • Detection of and recovery from radio link failure
• NAS message transfer to/from NAS from/to UE.
What is RRC State?
The operation of the RRC is guided by a state machine which defines certain specific
states that a UE may be present in. The different RRC states in this state machine have
different amounts of radio resources associated with them and these are the resources
that the UE may use when it is present in a given specific state.
The RRC States in 5G New Radio (5GNR)
Appart form RRC connected and RRC IDLE state, 5G NR has introduced a new RRC
state names as RRC Inactive state.
• NR-RRC CONNECTED
• NR-RRC INACTIVE
• NR-RRC IDLE
When UE is power up it is in Disconnected mode/Idle mode, It can move RRC
connected with initial attach or with connection establishment. If there is no activity
from UE for a short time, It can suspend its session by moving to RRC Inactive and can
resume its session moving to RRC connected mode.
A UE can move to RRC Idle mode from RRC connected or RRC Inactive state.
Image Source: Nokia Presentation
RRC Idle Mode Operations:
• PLMN selection
• Broadcast of system information
• Cell re-selection mobility
• Paging for mobile terminated data is initiated by 5GC
• Paging for mobile terminated data area is managed by 5GC
• DRX for CN paging configured by NAS
RRC Inactive Mode Operation:
• Broadcast of system information
• Cell re-selection mobility
• Paging is initiated by NG-RAN (RAN paging)
• RAN-based notification area (RNA) is managed by NG- RAN
• DRX for RAN paging configured by NG-RAN
• 5GC – NG-RAN connection (both C/U-planes) is established for UE
• The UE AS context is stored in NG-RAN and the UE
• NG-RAN knows the RNA which the UE belongs to
RRC Connected Mode Operation:
• 5GC – NG-RAN connection (both C/U-planes) is established for UE
• The UE AS context is stored in NG-RAN and the UE
• NG-RAN knows the cell which the UE belongs to
• Transfer of unicast data to/from the UE
• Network controlled mobility including measurements
Why a new RRC state model required in 5G NR
The RRC States is a solution to the system access, power saving, and mobility
optimization. 5G has to support eMBB, URLLC, and Massive IoT services at same cost
and energy dissipation per day per area.
5G system access and requested services have different characteristics => Control of
connectivity for future services need to flexible and programmable. To meet these
different services characteristics it requires new RRC state model.
• To support URLLC services which transmits small packets that require ultra-low
latency and/or high reliability
• Massive IoT Devices wakes up seldom power saving mode to transmit and
receive a small payload.
 • Devices need to camp in low activity state, and sporadically transmits UL data
and/or status reports with small payload to the network.
• Devices need periodic and/or sporadic DL small packet transmission.
• When UE is in the connected state, and sporadically transmit UL data and/or
status reports with small payload to the network.
• Smartphones and consumer devices which eMBB UE have periodic and/or
sporadic UL and/or DL small packet transmission and extreme data rates.
5G NR NAS Layer

The present document specifies the non-access stratum (NAS) procedures in the 5G
system (5GS) used by the protocols for:

• mobility management between the UE and the AMF for both 3GPP access and
non-3GPP access; and
• session management between the UE and the SMF for both 3GPP access and non-
3GPP access.
The 5GS mobility management (5GMM) protocol defined in the present document
provides procedures for the control of mobility when the UE is using the NG radio
access network (NG-RAN) and/or non-3GPP access network. The 5GMM protocol also
provides control of security for the NAS protocols.
The 5GS session management (5GSM) protocol defined in the present document
provides procedures for the handling of 5GS PDU session contexts. Together with the
bearer control provided by the access stratum, this protocol is used for the control of
user plane bearers.
For both NAS protocols the present document specifies procedures for the support of
inter-system mobility between the NG-RAN and the E-UTRAN connected to the EPC
and between the NG-RAN and the non-3GPP access network.
TTI Bundling
In normal case, when network send a grant (DCI 0), UE transmit PUSCH at only one
specific subframe (4 ms after the DCI 0 reception). TTI Bundling is a method in which
UE transmit a PUSCH in multiple subframes in a row (4 subframes according to current
specification). In other words, UE transmit a PUSCH in a 'BUNDLED TTI'.
Typical case of TTI Bundling can be illustrated as shown below.
 In some aspect, you may say this is a kind of wasting resources. Then Why we need
this kind of method ?
The simple answer is to increase the possibility of data reception at the destination.
Then you may ask "Why not just rely on normal HARQ retransmission mechanism ?". If
the destination fail to decode a data, it would send NACK or do DTX and then UE can
retransmit it and then the data delivery would be guaranteed.
That is true, but this kind of normal retransmission mechnism cause a certain time
delay (e.g, in FDD case, single retransmission would case 8 ms delay. see here for
general UL scheduling) This delay can cause a very bad user experience in time critical
data communication like VoLTE.
Therefore, in a case where the communication is for time critical communication and
UE is in the area of poor coverage (e.g, cell edge), it would not be a bad idea to enable
TTI bundling. (But I haven't seen any case in which this is enabled in live network, at
least as of now Aug, 2013).
How to enable TTI bundling for a specific UE ?
It is simple. Just enable a ttiBundling IE as shown below. (But the real implementation
and optimization may not as easy as it sound).
HARQ
What is H-ARQ ? Why it uses the term "Hybrid" ?
First think about the term ARQ. ARQ stands for Automatic Repeat Request and you
would have heard this a lot if you had experience of studying IP communication (I
think you can google a lot of tutorials on this, so I would not explain about what is ARQ
here). The "H" in HARQ means "Hybrid" which implies that HARQ is a combination of
"Something" and "ARQ".
Then what would be the "Something" ? The "Something" is FEC (forward error
correction). FEC is also not LTE specific technology and a kind of generic error
correction mechanism. So I would like you to google something about FEC.
Basic concept of HARQ in NR is similar to LTE HARQ, but there is some mintor
differences in terms of the details. In this page, I will try to explain NR HARQ in
comparison to LTE HARQ. So if you are already familiar with LTE HARQ, it will be a
great help to understand NR HARQ.
Asynchronous HARQ in both downlink and Uplink : In LTE HARQ, downlink use
Asynchronous mechanism but Uplink uses Synchronous mechanism. In contrast, in NR
both downlink and Uplink Asynchronous mechanism is used. (For the definition of
Ascynchronous HARQ and Synchronous HARQ, refer to LTE HARQ). Just to give you
an practical aspect of Asynchronous HARQ, it operates the multiple HARQ processes in
any order. To keep track of each HARQ process even when they are not running in
order, the sender and reciever in the HARQ process should know the exact HARQ
process number for each transmission/reception of the HARQ data. For this, DCI carries
the field called HARQ Processor number. In LTE, only the DCI for downlink scheduling
(i.e, DCI 1, DCI 2 etc) carries this field (since LTE DL use Asynchronous HARQ) and the
DCI for uplink schedule(i.e, DCI 0) does not carry this field(since LTE UL
use Synchronous HARQ). However in NR, both Downlink Scheduling DCI (i.e, DCI
1_0, 1_1) and Uplink Scheduling DCI (i.e, DCI 0_0, 0_1) carries the field HARQ
Processor Number since they both use Asychronous HARQ.
Flexible Timing between Data Transmission and HARQ response : In LTE the timing
between data transmission and HARQ response is fixed. It is fixed as 4 ms in FDD. The
timing is determined in a little bit complicated way in LTE TDD. But this timing is
flexibly set in NR in combination of DCI and RRC. In NR, RRC message defined a table
listing multiple possible timing between data and HARQ and DCI specifies a specific
elements of the table defined in the RRC message.
Codebook Based HARQ Bit Construction : The number of bits and the meaning of
each bits in HARQ response is quite a straightforward, but in NR the number of the
HARQ bits is constructed in pretty complicated way as described in HARQ-ACK
Codebook page.
NO ACK/NACK for PUSCH : At the very high level view, NR PUSCH HARQ
mechanism is very similar to NB IoT PUSCH mechanism. There is no explicit HARQ
ACK/NACK for PUSCH. Then, how UE can figure out whther the PUSCH is
successfully delivered or not ? It figures it out based on whether it gets retransmission
request from gNB or not. If gNB does not send retransmission request (i.e, DCI 0_0/0_1
with NDI not toggled) for a certain period of time, UE assumes that PUSCH is
successfully recieved and decoded by gNB.
ACK/NACK Timing in Slot Configuration
Even though both TDD and FDD are allowed in NR, it is likely that TDD will be used in
most case of NR operation. So it would be beneficial if you have good understandings
on how HARQ ACK/NACK timing is determined in TDD LTE (See here if you are not
familiar with TDD LTE HARQ Timing). As you know, TDD LTE HARQ ACK/NACK
timing is specified by a predefined table. But in TDD NR, HARQ ACK/NACK timing is
fully configurable. You can configure HARQ ACK/NACK timing for a specific PDSCH
by specifying the parameter K1.
As an example, let's supposed your slot configuration is DDDDU with 2.5 ms period.
You can configure in such a way that HARQ ACK/NACK for all the PDSCH is
transmitted at the same UL slot by specifying K1 as follows. (If you are not familiar
with what is K1 and how these values can be configured and informed to UE, see here).

If necessary, you can configure HARQ ACK/NACK timing as flexible as shown below.
What is 5G?
So basically, according to them, 5G is whatever comes after 4G. That’s great, yet not
very helpful. But that’s probably the only safe assessement one can tell today about
what exactly 5G is. This is because as of now, the development of the 5G standard is far
from being finalized.
In December 2014 the GSMA has listed eight criteria for 5G. A network connection
should meet a majority of the eight in order to qualify as 5G:
• 1-10Gbps connections to end points in the field (i.e. not values measured in a lab)
• 1 millisecond end-to-end round trip delay (latency)
• 1000x bandwidth per unit area
• 10-100x number of connected devices
• (Perception of) 99.999% availability
• (Perception of) 100% coverage
• 90% reduction in network energy usage
• Up to 10 year battery life for low power, machine-type devices
Looking at those technical goals, we can see 3 general objectives that 5G will address.

Why do we need 5G?

Performance
We need to allow a huge amount of simultaneous connections and a significant
increase of speed and latency of each individual connections at the same time.
By 2020 you can expect to see Artificial Intelligence and Virtual Reality to be out there
in every home and pockets. These applications will require significant uplink and
downlink performances to sustain the real-time experience they need, to collect data
from the device, analyze it in the cloud and send back the appropriate response, action,
video stream that the user needs.
On the same network, a massive amount of smart devices will be connected in what we
call the Internet of Things (IoT). According to Cisco, by 2020, there will be more than 25
billions of connected devices, while at the same time the number of connected users will
be just above 4 billions.
Efficiency
Efficiency: a dramatic reduction of network energy usage and a significant
improvement of battery life expecially for low-power devices.
The picture above is a joke, but it’s funny because it’s true: while our old brick-style
Nokia 3310 could last more than a week without a charge, today’s smartphones barely
make it through the day without being recharged.
The network connectivity is not the main offender in battery consumption, the screen
probably is, but the increase of data throughout, the support of multiple frequency
bands, the more frequent reselection between band drain the battery faster. Spend one
day on WiFi versus one day on 4G with your phone to see the difference.
The IoT also needs low consumption to connect to 5G so that devices can be small
enough to be embedded everywhere.
Ubiquity
Perception of 100% coverage and availability, that we can be phrased as “Everything
everywhere and always connected”.
Allowing more and more frequency bands and technologies to not only co-exist (take
WiFi and 4G for instance) but also converging to become interoperable so that there is
always a way to be connected. The radio access will use a combination of low bands for
coverage and millimeter waves above 20GHz for ultra high speed on very short
distances, while wired connections (fibre), WiFi and Satellite communications will also
be included in this objective of convergence.

What is Massive MIMO?

MIMO stands for Multiple-input multiple-output. While it involves multiple
technologies, MIMO can essentially be boiled down to this single principle: a wireless
network that allows the transmitting and receiving of more than one data signal
simultaneously over the same radio channel.
There’s no set figure for what constitutes a Massive MIMO set-up, but the description
tends to be applied to systems with tens or even hundreds of antennas. For example,
Huawei, ZTE, and Facebook have demonstrated Massive MIMO systems with as many
as 96 to 128 antennas.
Ericsson’s AIR 6468, which the company claims is "the world's first 5G NR radio", uses
64 transmit and 64 receive antennas
What are the advantages of Massive MIMO?
The advantage of a MIMO network over a regular one is that it can multiply the
capacity of a wireless connection without requiring more spectrum. Reports point to
considerable capacity improvements, and could potentially yield as much as a 50-fold
increase in future.
The more antennas the transmitter/receiver is equipped with, the more the possible
signal paths and the better the performance in terms of data rate and link reliability.
A Massive MIMO network will also be more responsive to devices transmitting in
higher frequency bands, which will improve coverage. In particular, this will have
considerable benefits for obtaining a strong signal indoors (though 5G’s higher
frequencies will have their own issues in this regard).
The greater number of antennas in a Massive MIMO network will also make it far more
resistant to interference and intentional jamming than current systems that only utilise a
handful of antennas.
It should be noted, too, that Massive MIMO networks will utilise beamforming
technology, enabling the targeted use of spectrum. Current mobile networks are rather
dumb in the way they apportion a single pool of spectrum between all users in the
vicinity, which results in a performance bottleneck in densely populated area. With
Massive MIMO and beamforming such a process is handled far more smartly and
efficiently, so data speeds and latency will be far more uniform across the network.

LTE Security Concept

2.1 Scope and Concept of LTE Security
Figure 1 below shows the scope and overall concept of the LTE Security
documents. The scope of these documents will include the following three areas:
LTE Authentication: performs mutual authentication between a UE and
a network.
NAS Security: performs integrity protection/verification and ciphering
(encryption/decryption) of NAS signaling between a UE and an MME.
AS Security
 • performs integrity protection/verification and ciphering of RRC
signaling between a UE and an eNB.
• performs ciphering of user traffic between a UE and an eNB.

Figure 1. Scope and concept of LTE security

LTE Authentication
In mobile communication networks, authentication refers to the process of
determining whether a user is an authorized subscriber to the network that he/she
is trying to access. Among various authentication procedures available in such
networks, EPS AKA (Authentication and Key Agreement) procedure is used in
LTE networks for mutual authentication between users and networks.
The EPS AKA procedure consists of two steps. First, an HSS (Home Subscriber
Server) generates EPS authentication vector(s) (RAND, AUTN, XRES, KASME) and
delivers them to an MME. Then in the second step, the MME selects one of the
authentication vectors and uses it for mutual authentication with a UE and shares
the same authentication key (KASME) each other. Mutual authentication is the
process in which a network and a user authenticate each other. In LTE networks,
since the ID of the user's serving network is required when generating
authentication vectors, authentication of the network by the user is performed in
addition to authentication of the user by the network.
ASME (Access Security Management Entity) is an entity that receives top-level
key(s), from an HSS, to be used in an access network. In EPS, an MME serves as
ASME and KASME is used as the top-level key to be used in the access network. The
MME, on behalf of an HSS, conducts mutual authentication with a UE using
KASME. Once mutually authenticated, the UE and MME get to share the same
KASME as an authentication key.
To avoid any possible eavesdropping or manipulation of data across radio links,
KASME is not delivered to the UE via E-UTRAN. Instead, the MME delivers part of
authentication vector to the UE, which uses it to authenticate the network and
generates KASME as the HSS does.
NAS Security
NAS security, designed to securely deliver signaling messages between UEs and
MMEs over radio links, performs integrity check (i.e., integrity
protection/verification) and ciphering of NAS signaling messages. Different keys are
used for integrity check and for ciphering. While integrity check is a mandatory
function, ciphering is an optional function. NAS security keys, such as integrity
key (KNASint) and ciphering key (KNASenc), are derived by UEs and MMEs from KASME.
AS Security
AS security is purposed to ensure secure delivery of data between a UE and an
eNB over radio links. It conducts both integrity check and ciphering of RRC
signaling messages in control plane, and only ciphering of IP packets in user
plane. Different keys are used for integrity check/ciphering of RRC signaling
messages and ciphering of IP packets. Integrity check is mandatory, but ciphering
is optional.
AS security keys, such as KRRCint, KRRCenc and KUPenc, are derived from KeNB by a UE
and an eNB. KRRCint and KRRCenc are used for integrity check and ciphering of
control plane data (i.e., RRC signaling messages), and KUPenc is used for ciphering
of user plane data (i.e., IP packets). Integrity check and ciphering are performed at
the PDCP (Packet Data Convergence Protocol) layer.
A UE can derive K eNB from KASME. However, since KASME is not transferred to an
eNB, an MME instead generates KeNB from KASME and forwards it to the eNB.
2.2 Overview of LTE Security Procedure
displays LTE authentication procedure while and demonstrate security
setup procedures for NAS and AS respectively. A brief description of each
procedure will be given below first. Then, a detailed explanation on the LTE
authentication procedures and NAS and AS security setup procedures will be
given in Chapter III hereof and again in Part II, LTE Security II, that follows.
LTE Authentication
When a user requests for access to a LTE network, mutual authentication between
the user and the network is conducted using EPS AKA procedure. An MME, upon
receipt of such request, identifies the user using his/her IMSI and requests
authentication vector(s) (AVs) from an HSS1. The HSS then generates AV(s) using
EPS AKA algorithm, AV={RAND, XRES, AUTNHSS, KASME}, and forwards them to
the MME.
After storing the AVs, the MME selects one of them and uses it to perform mutual
authentication with the UE2. The MME forwards RAND and AUTNHSS to the UE,
which then computes RES, AUTNUE and KASME using EPS AKA algorithm. The UE
now compares its own AUTNUE and AUTNHSS received from the MME for
network authentication. Once authenticated, RES is forwarded to the MME, which
then compares the XRES received from the HSS and the RES received from the UE
for user authentication. If the UE and network have authenticated each other, they
share the same key KASME (KASME is not transferred between UE and MME, though).
NAS Security
Once the UE and MME have authenticated each other and the same key KASME is
shared, NAS security setup procedure begins. In this procedure, NAS security
keys to be used when delivering NAS signaling messages are derived from
KASME for secure delivery of these messages. This procedure consists of a round
trip of NAS signaling messages (Security Mode Command and Security Mode
Complete message), and begins when the MME delivers a Security Mode
Command message to the UE.
First, the MME selects NAS security algorithms (Alg-ID: Algorithm ID) and uses
them to create an integrity key (KNASint ) and a ciphering key (KNASenc) from
KASME. Then, it applies KNASint to the Security Mode Command message to generate
an NAS message authentication code (NAS-MAC, Message Authentication Code
for NAS for Integrity). The MME then delivers the Security Mode
Command message including the selected NAS security algorithms and the NAS-
MAC to the UE. As the UE does not know the selected encryption algorithm yet,
this message is integrity protected only but not ciphered.
Upon receiving the Security Mode Command message, the UE verifies the
integrity thereof by using the NAS integrity algorithm selected by the MME and
uses NAS integrity/ciphering algorithm to generate NAS security keys (K NASint and
KNASenc) from KASME. Then it ciphers the Security Command Complete message
with KNASenc and generates a message authentication code, NAS-MAC with
KNASint to the ciphered message. Now it forwards the ciphered and integrity
protected message to the MME with the NAS-MAC included.
Once the MME successfully verifies the integrity of the received Security Mode
Complete message and has them decrypted using the NAS security keys
(KNASint and KNASenc), the NAS security setup procedure is completed.
Once the NAS security is set up, NAS signaling messages between the UE and the
MME are ciphered and integrity protected by the NAS security keys and then
securely delivered over radio links.
AS Security
After NAS security setup is finished, AS security setup procedure between a UE
and an eNB begins. In this procedure, AS security keys to be used when
delivering RRC signaling messages and IP packets are derived from KeNB for
secure delivery of these data. This procedure consists of a round trip of RRC
signaling messages (Security Mode Command and Security Mode
Complete message), and begins when an eNB delivers Security Mode
Command message to the UE.
First, the MME calculates K eNB from KASME and delivers it to the eNB, which uses it
to perform the AS security setup procedure. The eNB selects AS security
algorithms (Alg-ID: Algorithm ID) and uses them to create an integrity key
(KRRCint) and a ciphering key (KRRCenc), from KeNB. to be used for RRC signaling
messages, and a ciphering key (KUPenc) to be used in the user plane. Then, it applies
KRRCint to the Security Mode Command message to generate a message
authentication code (MAC-I, Message Authentication Code for Integrity). The
eNB now delivers the Security Mode Command message including the selected
AS security algorithms and the MAC-I to the UE.
Upon receiving the Security Mode Command message from the eNB, the UE
verifies the integrity thereof by using the AS integrity algorithm selected by the
eNB and uses AS integrity/ciphering algorithm to generate AS security keys
 (KRRCint, KRRCenc and KUPenc). Then it generates a message authentication code, MAC-
I, with the RRC integrity key to the Security Command Complete message, and
then forwards the message including the MAC-I to the eNB.
When the eNB successfully verifies the integrity of the received Security Mode
Complete message by using the AS integrity key, the AS security setup procedure
is completed.
After the AS security is set up, RRC signaling messages between the UE and the
eNB are ciphered and integrity protected by the AS security keys, and user IP
packets are encrypted and then securely delivered over radio links.

5G testing parameters | 5G test equipments Keysight

This page of 5G tutorial covers 5G testing parameters or features. It also mentions 5G
test equipments from Keysight technologies.
The 5G device development requires testing at various stages starting from design
phase till the final deployment phase. It involves tests at various protocol stack level of
the 5G device. Following table lists out main test cases required to be done at various
phases of 5G product life cycle.

5G testing test cases

Transmitter
Conformance Power spectrum mask, transmit power vs time, CCDF, I/Q vs time
testing
Receiver
Conformance EVM, channel response, spectral flatness
testing
Interoperability This tests ensures that 5G devices from one vendor will work with 5G
testing devices from the other vendors in the network without any issues.
Network stability 5G system works without having any issues at long run during
tests handover and other tests.
This test ensures 5G device works well across all the RATs (Radio
Inter-RAT tests
Access Technologies) for which it has been desiged for.
Other than the above, RF tests for 5G device such as phase noise, 1dB
RF Related tests compression, third order intercept points, harmonics, spurious, noise
figure, image rejection are only equally important to be performed.
One can refer conformance documents and other test case documents published by
respective 5G standard bodies for more details.
Keysight 5G test equipments

The figure-1 depicts 5G test bed using Keysight equipments. Following table lists out
all the 5G test equipments.
Keysight 5G test
Description
equipment
Arbitrary Waveform Generator which generates baseband IQ
M8190A
data
PSG signal generator, which takes IQ data as input and
E8267D
generates modulated IF output.
Used to generate RF signal used as LO (Local Oscillator) input
N5183 MXG
for both up converter and Down converter
DSO-Z634A (63 GHz
Used as Oscilloscope, it analyzes the 5G signal in time domain
Oscilloscope)
Used as Signal Analyzer, used to analyze 5G signal in
N9030A , N9040B
frequency domain
In addition to the above tools, 5G test bed requires, Waveform Creation Application
Software and VSA application. Waveform Creation allows user to configure 5G
baseband parameters (i.e. PHY and MAC frame related). VSA application allows user to
analyze various baseband related parameters such as EVM, channel response, IQ
impairments, power spectrum, CCDF etc.

List of 5G NR RRC IEs | 5G NR RRC Information Elements

http://www.rfwireless-world.com/5G/5G-NR-RRC-IEs-Information-Elements.html

5G NR Slot Formats | 5G NR slot format combination

http://www.rfwireless-world.com/5G/5G-NR-Slot-Formats.html