UNIT 3 AMC

OFDM. Non-Orthogonal Multiple Access (NOMA), carrier aggregation.5G NR

requirements 5G Core Network Architecture Radio-Access Network (RAN)-
Radio Protocol Architecture -User Plane Protocols. Control Plane Protocols -
Network Slicing- RAN virtualization, 5G deployment challenges. dynamic
spectrum access. Explain all the topics in very details with deep theory detail
and their diagram also in Advance mobile communication

ChatGPT

Here is a detailed explanation of each of the advanced mobile communication

topics, along with their theoretical foundation and importance in 5G technology.
I’ll cover each topic comprehensively, discussing their deep theory,
functionality, and key features. Additionally, I will explain the structure and
provide insights into diagrams, which will help you visualize the concepts.

1. OFDM (Orthogonal Frequency Division Multiplexing)

Overview:
OFDM is a digital multi-carrier modulation technique used to split a wide
frequency band into a number of smaller, orthogonal sub-carriers. Each sub-
carrier is modulated with a lower data rate stream, allowing efficient use of
bandwidth.

Theory:

 Orthogonality: The concept of orthogonality in OFDM means that sub-

carriers are spaced in such a way that they do not interfere with each
other, even though their spectra overlap. This is achieved by ensuring that
at the center frequency of each sub-carrier, the neighboring sub-carriers
have zero power, which reduces interference.
 FFT (Fast Fourier Transform): OFDM uses FFT algorithms for
modulation and demodulation, which simplifies signal processing.
 Guard Intervals: To combat the issue of inter-symbol interference (ISI),
OFDM introduces guard intervals (Cyclic Prefix), which provide a buffer
between consecutive symbols.

Advantages:

 High spectral efficiency.

  Robustness to multi-path fading.
 Reduced ISI through cyclic prefixes.

Use in 5G:

In 5G, OFDM is adopted for both downlink and uplink. The flexible
numerology of OFDM in 5G allows varying subcarrier spacing (15 kHz, 30
kHz, 60 kHz, etc.) to address different deployment scenarios (low latency, high
bandwidth).

2. Non-Orthogonal Multiple Access (NOMA)

Overview:
NOMA is an advanced multiple access technique used in 5G that allows
multiple users to share the same time and frequency resources by superimposing
signals at different power levels.

Theory:

 Superposition Coding: In NOMA, signals for multiple users are

superimposed in the power domain. Users closer to the base station (with
better channel conditions) are allocated less power, while users farther
away are allocated more power.
 Successive Interference Cancellation (SIC): At the receiver, users with
good channel conditions first decode and subtract the signal of users with
higher power, then decode their own signal.
 Mathematical Model: The superimposed signal can be modeled as:

y=h1x1+h2x2+noisey = h_1x_1 + h_2x_2 + \text{noise}y=h1x1+h2x2

+noise

where x1x_1x1 and x2x_2x2 represent the signals for two users, and
h1h_1h1 and h2h_2h2 are their respective channel gains.

Diagram: A NOMA diagram typically shows multiple users sharing the same
frequency resource block, with users closer to the base station being allocated
less power, and further users getting more power. It also shows the SIC process.

Advantages:

 Increased spectral efficiency.

 Supports a larger number of users.
  Improved fairness among users with different channel conditions.

Use in 5G:

NOMA is crucial for supporting massive connectivity in 5G, especially in dense

urban environments and for IoT devices.

3. Carrier Aggregation (CA)

Overview:
Carrier Aggregation is a technique that combines multiple frequency bands
(carriers) to increase the available bandwidth for data transmission, improving
overall throughput.

Theory:

 Component Carriers: In carrier aggregation, multiple carriers

(component carriers) are used simultaneously. Each carrier operates as an
independent transmission channel, but they are combined to offer a
higher effective data rate.
 Types of Aggregation:
o Intra-band contiguous: Aggregating adjacent carriers within the
same band.
o Intra-band non-contiguous: Aggregating non-adjacent carriers
within the same band.
o Inter-band: Aggregating carriers from different frequency bands.

Diagram: A carrier aggregation diagram shows multiple component carriers

combined, highlighting the increase in total bandwidth available for data
transmission.

Advantages:

 Higher data rates by combining bandwidth from multiple carriers.

 Improved capacity and user experience.
 Efficient use of spectrum resources.

Use in 5G:

Carrier aggregation is used in 5G to combine 5G NR carriers across different

frequency bands, including low, mid, and high bands, optimizing bandwidth and
coverage.
4. 5G NR Requirements

Overview:
5G New Radio (NR) is the air interface standard for 5G, defined by 3GPP. The
requirements for 5G NR are centered on delivering enhanced performance in
terms of speed, latency, and capacity.

Key Requirements:

 Enhanced Mobile Broadband (eMBB): Delivering gigabit-level data

rates for applications like HD video streaming and AR/VR.
 Ultra-Reliable Low-Latency Communication (URLLC): Low-latency,
high-reliability communication for mission-critical services like
autonomous vehicles and industrial automation.
 Massive Machine-Type Communication (mMTC): Supporting massive
IoT devices, focusing on energy efficiency and coverage.

Diagram: A 5G NR requirement diagram typically illustrates the three core use

cases: eMBB, URLLC, and mMTC, showing how each meets different
performance criteria (throughput, latency, connection density).

5. 5G Core Network Architecture

Overview:
The 5G Core Network represents a fundamental shift from the 4G core network.
It uses a service-based architecture (SBA) and supports diverse services via
network slicing.

Key Components:

 Service-Based Architecture (SBA): Functions in the core network are

modular and interact via APIs.
 Core Network Functions:
o AMF (Access and Mobility Management Function): Manages
access and mobility-related tasks.
o SMF (Session Management Function): Handles session
establishment, modification, and release.
o UPF (User Plane Function): Responsible for routing user data
traffic.
  Control Plane and User Plane Separation: This architecture separates
the control and user planes, providing more flexibility and scalability.

Diagram: A diagram of 5G core architecture typically shows the key network

functions and how they interact in a service-based manner, highlighting control
and user plane separation.

Advantages:

 Flexible and modular design.

 Supports diverse use cases via network slicing.
 Improved scalability and resource allocation.

6. Radio Access Network (RAN)

Overview:
The Radio Access Network (RAN) connects user equipment (UE) to the core
network and is responsible for managing radio resources.

Key Components:

 gNodeB: The 5G base station, which manages the radio link with UEs.
 Fronthaul and Backhaul: In 5G, fronthaul and backhaul are essential for
connecting the RAN to the core network, especially in dense
deployments.

Diagram: A typical RAN diagram shows the gNodeB connected to UEs and the
core network, with fronthaul and backhaul links.

7. Radio Protocol Architecture

Overview:
The radio protocol stack in 5G is divided into two planes: user plane (for data
transmission) and control plane (for signaling).

User Plane Protocols:

 PDCP (Packet Data Convergence Protocol): Ensures data integrity and

encryption.
 RLC (Radio Link Control): Handles error correction and in-sequence
delivery.
  MAC (Medium Access Control): Manages radio resource allocation.

Control Plane Protocols:

 RRC (Radio Resource Control): Manages connection establishment,

mobility, and resource configuration.
 NAS (Non-Access Stratum): Handles session management and mobility
across the core network.

Diagram: A radio protocol stack diagram typically shows the layered

architecture, from the physical layer up to the application layer.

8. Network Slicing

Overview:
Network slicing is a key feature of 5G that enables the creation of virtualized
and isolated network segments for different use cases (e.g., eMBB, URLLC,
mMTC).

Theory:

 End-to-End Slicing: Network slices span the RAN, transport network,

and core network, each optimized for specific requirements.
 Dynamic Slice Management: Slices can be dynamically created and
adjusted based on demand and service level agreements (SLAs).

Diagram: A network slicing diagram typically shows multiple slices running in

parallel on the same physical network infrastructure, each with its own QoS and
performance requirements.

9. RAN Virtualization

Overview:
RAN virtualization allows the separation of hardware and software components
in the RAN, making it possible to deploy base station functions on generic
hardware.

Key Concepts:

 vRAN: Virtualized RAN functions are deployed on cloud-based

infrastructure, which increases scalability and flexibility.
  Benefits: Reduces costs, enables flexible resource allocation, and
supports faster upgrades.

Diagram: A vRAN diagram shows how traditional RAN functions are

virtualized and run on a cloud-based infrastructure.

10. 5G Deployment Challenges

Challenges:

 Spectrum Allocation: Finding and efficiently using spectrum, especially

in the millimeter-wave range.
 Infrastructure: Densification of small cells requires significant
investment.
 Interference Management: Handling interference from dense
deployments of devices and base stations.

11. Dynamic Spectrum Access

Overview:
Dynamic Spectrum Access (DSA) enables more efficient use of spectrum by
allowing devices to opportunistically use underutilized frequencies.

Theory:

 Cognitive Radio: Devices can sense the environment and dynamically

access available spectrum.
 Licensed Shared Access (LSA): Allows mobile operators to share
spectrum with incumbents under controlled conditions.

Diagram: A DSA diagram shows how devices intelligently access available

spectrum, sensing for interference and adjusting accordingly.

Orthogonal frequency-division multiplexing (OFDM)

Orthogonal frequency-division multiplexing is a method of data transmission
where a single information stream is split among several closely spaced
narrowband subchannel frequencies instead of a single Wideband channel
frequency. It is mostly used in wireless data transmission but may be employed
in wired and fiber optic communication as well.

In a traditional single-channel modulation scheme, each data bit is sent serially

or sequentially one after another. In OFDM, several bits can be sent in parallel,
or at the same time, in separate substream channels. This enables each
substream's data rate to be lower than would be required by a single stream of
similar bandwidth. This makes the system less susceptible to interference and
enables more efficient data bandwidth.

Find out the differences among orthogonal frequency-division multiplexing,

standard frequency-division multiplexing and a single wideband channel
frequency wireless data transmission scheme.

How orthogonal frequency-division multiplexing works

In the traditional stream, each bit might be represented by a 1 nanosecond
segment of the signal, with 0.25 ns spacing between bits, for example. Using
OFDM to split the signal across four component streams lets each bit be
represented by 4 ns of the signal with 1 ns spacing between. The overall data
rate is the same, 4 bits every 5 ns, but the signal integrity is higher.

As an illustration, imagine you were sending a letter to your grandmother. You

could write your letter on a single piece of paper and mail it to her in an
envelope. This would be like using a single frequency (one piece of paper) to
send your entire message. But, because your grandmother can't see well, you
instead write the same message in larger letters (a slower data rate) on several
pieces of paper (representing data streams on different channels) but put them
all in the same envelope (using same overall frequency spectrum).

OFDM builds on simpler frequency-division multiplexing (FDM). In FDM, the

total data stream is divided into several subchannels, but the frequencies of the
subchannels are spaced farther apart so they do not overlap or interfere. With
OFDM, the subchannel frequencies are close together and overlapping but are
still orthogonal, or separate, in that they are carefully chosen and modulated so
that the interference between the subchannels is canceled out.

OFDM advantages and disadvantages

Orthogonal frequency-division multiplexing has many advantages over a single-
channel data transmission approach. Primarily, OFDM is more resilient to
electromagnetic interference, and it enables more efficient use of total available
bandwidth because the subchannels are closely spaced. It is also more resistant
to interference because several channels are available.

Advanced error correction can be used to spread out the overall data and
compensate for small errors. So, narrowband interference on a single
subchannel will not affect the other channels, enabling the overall system to still
operate. Frequency-selective interference fading due to multipath echo effects
can also be corrected. The lower data rate on the individual subchannels enables
guard intervals to be used between symbols, which eliminates intersymbol
interference and helps with multipath errors.

There are two primary disadvantages with OFDM compared to single-channel

systems. OFDM systems must have closely tuned transmitters and receivers.
This requires the timing on signal modulators and demodulators be closely
matched and produced to tight tolerances. It also makes the system more
sensitive to Doppler shift and, therefore, less effective for high-speed moving
vehicles.

OFDM also has several advantages compared to standard frequency-division

multiplexing. The radio frequency receiver is simpler in OFDM because the
entire signal can be received in a single frequency selective filter and separated
in software using a fast Fourier transform, while an FDM system requires a
separate RF bandpass filter for each channel. It also has better overall
bandwidth efficiency. There are some disadvantages in that the higher overall
peak-to-average power (PAPR) ratio requires less efficient linear transmission
circuitry.

OFDM applications
Orthogonal frequency-division multiplexing is used in many technologies,
including the following:

 Digital radio, Digital Radio Mondiale, and digital audio

broadcasting and satellite radio.
 Digital television standards, Digital Video Broadcasting-
Terrestrial/Handheld (DVB-T/H), DVB-Cable 2 (DVB-C2). .
 Wired data transmission, Asymmetric Digital Subscriber Line (ADSL),
Institute of Electrical and Electronics Engineers (IEEE) 1901 powerline
networking, cable internet providers.
 Wireless LAN (WLAN) data transmission.
 Cellular data.
 Other proprietary systems.

Non-orthogonal multiple access (NOMA)

We consider orthogonal frequency division multiplexing (OFDM) as the
modulation scheme and NOMA as the multiple access scheme. In conventional
4G networks, as natural extension of OFDM, orthogonal frequency division
multiple access (OFDMA) is used where information for each user is assigned
to a subset of subcarriers. In NOMA, on the other hand, all of the subcarriers
can be used by each user. Figure 1 illustrates the spectrum sharing for OFDMA
and NOMA for two users. The concept applies both uplink and downlink
transmission.
Figure 1.

Spectrum sharing for OFDMA and NOMA for two users.

Superposition coding at the transmitter and successive interference cancellation

(SIC) at the receiver makes it possible to utilize the same spectrum for all users.
At the transmitter site, all the individual information signals are superimposed
into a single waveform, while at the receiver, SIC decodes the signals one by
one until it finds the desired signal. Figure 2 illustrates the concept. In the
illustration, the three information signals indicated with different colors are
superimposed at the transmitter. The received signal at the SIC receiver includes
all these three signals. The first signal that SIC decodes is the strongest one
while others as interference. The first decoded signal is then subtracted from the
received signal and if the decoding is perfect, the waveform with the rest of the
signals is accurately obtained. SIC iterates the process until it finds the desired
signal.
Figure 2.

Successive interference cancellation.

The success of SIC depends on the perfect cancellation of the signals in the
iteration steps. The transmitter should accurately split the power between the
user information waveforms and superimpose them. The methodology for
power split differs for uplink and downlink channels.

Carrier Aggregation (CA) is a feature of LTE-Advanced that

allows mobile operators to combine two or more LTE carriers into single data
channel to increase the capacity of the network and the data rates by exploiting
fragmented spectrum allocations.

This technology can be applied to either the FDD or TDD variants of LTE with
a maximum of five component carriers, each with a bandwidth of up to 20
MHz, resulting in a total transmission bandwidth of up to 100 MHz.

Types of Carrier Aggregation (CA)

Intra-band Carrier Aggregation: This form of carrier aggregation uses a

single band. It is further divided in to two parts:

 Contiguous: This is the easiest form of LTE carrier aggregation to

implement. In this, the carriers are adjacent to each other. In this case,
you only need a single transceiver as the signal is considered to be a
single enlarged signal.
  Non-contiguous: This one is slightly complicated as the carriers use the
same operating band but are not adjacent to each other. So you need two
transceivers because the signal can’t be treated as a single signal, adding
to complexity and cost.

Inter-band non-contiguous: This form of carrier aggregation uses different

bands. This is more challenging as the carriers are from different operating
bands. So you need multiple transceivers to transmit/receive signals using this
type of CA, adding to cost, complexity and creating space constraints.

What Is 5G NR?
5G New Radio access technology was designed to improve high-band
communication for mobile networks. 5G NR includes the following
benefits:

 Low latency
 Greater user capacity
 Network slicing
 Enhanced speed
These improvements help make technology such as remote controlled vehicles,
smart city IoT applications, augmented reality and many others possible. Before
we dive into use cases, let’s explore exactly how 5G NR is different from other
types of 5G.

How Is 5G NR Different?
The 5G spectrum covers a wide range of bands to achieve specific
communication goals. For example, low-band 5G enables long-distance
communication while the high band offers the best performance across shorter
distances.
5G NR focuses on the higher bands, operating between either 410 MHz–7125
MHz or 24250 MHz–52600 MHz. The goal of 5G NR is to provide wired-like
performance to support the growing demand for new devices and bandwidth-
hungry applications.
This specific focus on low-latency performance will support future
technologies, much like how 4G was a foundation for the first modern
smartphones.

5G NR Use Cases
Before we explore how 5G NR works, let's touch on technologies that are
already leveraging 5G NR.
Ultra-Reliable Low-Latency Communication
5G NR supports URLLC that can provide few millisecond latency for packet
transmission and supports network reliability greater than five 9s. These
performance milestones make URLLC popular among enterprises and service
providers who must meet specific network requirements.
The following are a few examples of URLLC applications:

 Autonomous robotics/vehicles
 Augmented reality
 Smart City infrastructure
  Industrial IoT and automation

Massive Machine-Type Communications

5G NR can support widespread mMTC across thousands of devices and
applications with more efficient signal processing and lower energy
consumption. 5G NR will play a significant role in ubiquitous 5G IoT as
enterprises build more extensive networks with more sensors and applications.
The following are a few examples of mMTC applications:

 General enterprise device orchestration

 Healthcare sensors on patients, inventory, and lifesaving equipment
 Industrial sensors that monitor safety systems like air quality and pipe
pressure
 Sensors that monitor machine health, performance levels, and track
products through assembly

Enhanced Mobile Broadband

Lastly, 5G NR will enhance mobile broadband performance and help shape the
future evolutions of cellular technology. Higher efficiency combined with
improved data rates and lower energy consumption is better for both consumers
and businesses.
By utilizing new higher frequency bands in the millimeter-wave spectrum, 5G
NR can reach users in shorter amounts of time by deploying alongside 4G
infrastructure through dynamic spectrum sharing. This makes widespread use of
5G NR easier and less expensive for network operators to implement.
The following are a few examples of EMB applications:

 Targeted and blanket coverage across smart cities

 Improved cellular service for commercial carriers
 Faster downloads and more efficient video streaming
 Less energy consumption across all cellular networks

How Does 5G NR Work?

5G NR uses a variety of new technologies to achieve enhanced performance and
latency across mobile networks.
OFDM Optimization
OFDM allows networks to carry data in parallel for improved spectrum
efficiency, better time synchronization, and reduced intersymbol interference.
5G NR adopts this approach by using the cyclic prefix OFDM across its
waveforms.
New Higher Radio Spectrum Bands
As mentioned earlier, 5G NR utilizes two high-frequency bands for
communication. These higher bands are much wider and thus support higher
data transmission and throughput rates. While these higher frequency signals
have a shorter range, they can be extended through repeaters and small cells to
reach specific target areas.
Beamforming
Beamforming allows network operators to “beam” 5G NR communications
from the mobile base station to the target device. Beamforming helps improve
reliability through antenna beam patterns that reduce interference and provide
enhanced reliability.
Small Cell Coordination
5G small cells can be used to expand the coverage and capacity of public 5G
networks from mobile operators, especially when cells are grouped together.
Administrators can coordinate these networks of small cells for load balancing
as well as overcome physical obstructions that are more prevalent when
broadcasting over higher frequencies.

5G NR Deployment
With private 5G, enterprises can now deploy and control their own 5G NR
networks much like an enterprise Wi-Fi platform. Below are a few requirements
and different deployment models you can use to design your network.
Before you begin your journey, be sure to check out the Celona Network
Planner to help you estimate the size of your private 5G LAN based on your
coverage area, private spectrum availability, device density and application
performance requirements.
5G NR Requirements
In order for a signal to be classified as 5G NR, a number of requirements must
be met to ensure that signal can meet the latency and reliability requirements of
5G NR.

 The network must support wireless mobile connectivity.

 The connection must support IoT, specifically the multitude of sensor
types as well as both wired and wireless connections.
 Then connection uses adaptive bandwidth, allowing lower bandwidth and
power consumption when possible.
 The connection enforces data transmission requirements by forcing users
to adhere to specific rules.

5G NR Deployment Modes
5G NR can be deployed in a number of different ways. This flexibility allows
for wide adoption of 5G NR, especially in places where there is already 4G
cellular architecture.

 Standalone Mode - Uses a 5G packet core for both information transfer

and signaling.

 Non-Standalone Mode (NSA) - Uses the existing control plane of a 4G

network for control functions, while using 5G NR across the user plane.
This improves implementation times and reduces hardware costs.

 Dynamic Spectrum Sharing (DSS) - Shares spectrum between 4G LTE

and 5G NR based on demand. This deployment is typically used where
4G LTE infrastructure is compatible with the 5G NR terminal. Like NSA
mode, DSS allows for faster implementation and reduced hardware costs.

What is 5G Architecture?

The primary goal of previous mobile network generations was to offer fast,
reliable mobile data services to network users. 5G has broadened this scope to
offer a wide range of wireless services delivered to the end user across multiple
access platforms and multi-layer networks.

5G creates a dynamic, coherent, and flexible framework of advanced

technologies to support a variety of applications. 5G utilizes a more intelligent
architecture, with Radio Access Networks (RANs) no longer constrained by
base station proximity or complex infrastructure. 5G leads the way towards
disaggregated, flexible, and virtual RAN with new interfaces creating additional
data access points.

3GPP
The 3rd Generation Partnership Project (3GPP) covers telecommunication
technologies including RAN, core transport networks and service capabilities.
The 3GPP has provided complete system specifications for 5G network
architecture which is much more service oriented than previous generations.

Services are provided via a common framework to network functions that are
permitted to make use of them. Modularity, reusability, and self-containment of
these network functions are additional design considerations for the 5G network
architecture described by the 3GPP specifications.

5G Spectrum and Frequency

Multiple frequency ranges are now being dedicated to 5G new radio (NR). The
portion of the radio spectrum with frequencies between 30 GHz and 300 GHz is
known as the millimeter wave, since wavelengths range from 1-10 mm.
Frequencies between 24 GHz and 100 GHz have been allocated to 5G in
multiple regions worldwide.

 In addition to the millimeter wave, underutilized UHF frequencies

between 300 MHz and 3 GHz and C-band frequencies between 3.7 and
3.98 GHz have also been repurposed for 5G.
 The diversity of frequencies employed can be tailored to the unique
application. Higher frequencies are characterized by higher bandwidth
and shorter range.

Millimeter wave frequencies are ideal for densely populated areas, but
ineffective for long distance communication.

 Within the various frequency bands dedicated to 5G, each carrier has
begun to carve out their own individual portions of the 5G spectrum.

MEC
Multi-Access Edge Computing (MEC) is an important element of 5G
architecture. MEC is an offshoot of cloud computing that brings applications
from centralized data centers to the network edge, closer to end users and their
devices. This essentially creates a shortcut in content delivery between the user
and host, bypassing the long-distance network path that once separated them.
This technology is not exclusive to 5G but is certainly integral to its efficiency.

 Characteristics of MEC include the low latency, high bandwidth,

and real time access to RAN information that distinguish 5G architecture
from its predecessors.
 5G networks based on the 3GPP 5G specifications are an ideal
environment for MEC deployment. These specifications define the
enablers for edge computing, allowing MEC and 5G to collaboratively
route traffic.
 Distribution of computing power enables the high volume of connected
devices inherent to 5G deployment and the Internet of Things (IoT), in
addition to the latency and bandwidth benefits.
 Convergence of RAN and core networks will require operators to
leverage new approaches to network testing and validation.

NFV and 5G
Network function virtualization (NFV) decouples software from hardware by
replacing various network functions such as firewalls, load balancers, and
routers with virtualized instances running as software. This eliminates the need
to invest in many expensive hardware elements and can also accelerate
installation times, thereby providing revenue generating services to the
customer faster.

NFV enables the 5G ecosystem by virtualizing appliances within the 5G

network. This includes the network slicing technology that enables multiple
virtual networks to run simultaneously. NFV addresses other 5G challenges
through virtualized computing, storage, and network resources that are
customized based on the applications and customer segments.

5G RAN Architecture
The concept of NFV extends to the RAN through the network dis-aggregation
promoted by alliances such as O-RAN. Open RAN architecture eases the
deployment of new RAN features and technology to scale by encouraging open
interfaces and open-source development practices. This evolution increases
flexibility and creates new opportunities for competition.

The O-RAN ALLIANCE objective is to allow multi-vendor deployment with

off-the shelf hardware for improved inter-operability. Network dis-aggregation
also allows more components of the network to be virtualized, providing a
means to scale and improve user experience quickly as capacity grows.
Virtualized RAN is essential for controlling hardware and software costs in the
rapidly expanding ecosystem of IoT applications.

eCPRI
Network dis-aggregation with the functional split also brings other cost benefits,
particularly with the introduction of new interfaces such as eCPRI. RF
interfaces are not cost effective when testing large numbers of 5G carriers as the
RF costs rapidly multiply. The original CPRI interface developed for 4G was
vendor specific in many instances, which made it problematic for operators.
eCPRI interfaces provide a more efficient solution as fewer interfaces can be
used to test multiple 5G carriers. eCPRI has been designated as a standard
interface for 5G O-RAN fronthaul elements such as the DU.

Network Slicing
A key ingredient for enabling the full potential of 5G architecture is network
slicing.

This technology adds an extra dimension to the NFV domain by allowing

multiple logical networks to run simultaneously on top of a shared physical
network infrastructure. This capability supports 5G architecture by creating end-
to-end virtual networks that include both networking and storage functions.

 Operators can effectively manage diverse 5G use cases with differing

throughput, latency and availability demands by partitioning network
resources to multiple users or “tenants”.
 Network slicing becomes extremely useful for applications like the IoT
where the number of users may be extremely high, but the overall
bandwidth demand is low.
 5G verticals each have their own requirements, so network slicing is an
important design consideration for 5G network architecture.
 Operating costs, resource management, and flexibility of network
configurations can be optimized with the level of customization afforded
by network slicing.
 Expedited trials for potential new 5G services and quicker time-to-
market are also enabled by network slicing.

Beamforming
Another breakthrough technology integral to the success of 5G is beamforming.
Conventional base stations transmit signals in multiple directions without regard
to the position of targeted users or devices. Using multiple-input, multiple-
output (MIMO) arrays featuring dozens of small antennas combined in a single
formation, signal processing algorithms are used to determine the most efficient
transmission path to each user. Individual packets can be sent in multiple
directions then choreographed to reach the end user in a predetermined
sequence.

Click to Expand

With 5G data transmission occupying the millimeter wave, free space

propagation loss, proportional to the smaller antenna size, and diffraction loss,
inherent to higher frequencies and lack of wall penetration, are much greater.
On the other hand, the smaller antenna size also enables much larger arrays to
occupy the same physical space. With each of these smaller antennas potentially
adjusting or reassigning beam direction several times per millisecond, massive
beamforming to support the challenges of 5G bandwidth becomes more
feasible. With a larger antenna density in the same physical space, narrower
beams can be achieved with massive MIMO, providing high throughput and
more effective user tracking.

5G Core
The 5G core network architecture is at the heart of the new 5G specification and
enables the increased throughput demand that 5G must support. The new 5G
core, as defined by 3GPP, utilizes cloud-aligned, service-based architecture
(SBA) that spans across all 5G functions and interactions including
authentication, security, session management and aggregation of traffic from
end devices. The 5G core emphasizes NFV with virtualized software functions
deployed using the MEC infrastructure that is central to 5G architectural
principles.
Click to Expand

Differences from 4G Architecture

Changes at the core level are among the myriad of architectural changes that
accompany the shift from 4G to 5G, including the migration to millimeter wave,
massive MIMO, network slicing, and essentially every other element of the
diverse 5G ecosystem. The 4G Evolved Packet Core (EPC) is significantly
different from the 5G core, with the 5G core leveraging virtualization and cloud
native software design at unprecedented levels.

Among the other changes that differentiate the 5G core from its 4G predecessor
are user plane function (UPF) to decouple packet gateway control and user
plane functions, and access and mobility management function (AMF) to
segregate session management functions from connection and mobility
management tasks.

5G Architecture Options
Bridging the gap between 4G and 5G requires incremental steps and a well-
orchestrated game plan. Emblematic of this shift is the gradual transition from
non- standalone mode to standalone mode 5G architecture options. The 5G non-
standalone standard was finalized in late 2017 and utilizes existing LTE RAN
and core networks as an anchor, with the addition of a 5G component carrier.
Despite the reliance on 4G architecture, non-standalone mode increases
bandwidth by tapping into millimeter wave frequencies.

5G standalone mode is essentially 5G deployment from the ground up with the

new core architecture and full deployment of all 5G hardware, features, and
functionality. As non-standalone mode gradually gives way to all new 5G
mobile network architecture deployments, careful planning and implementation
will make this transition seamless for the user base.

LTE Radio Protocol Architecture

The radio protocol architecture for LTE can be separated into control
plane architecture and user plane architecture as shown below:
At user plane side, the application creates data packets that are processed by
protocols such as TCP, UDP and IP, while in the control plane, the radio
resource control (RRC) protocol writes the signalling messages that are
exchanged between the base station and the mobile. In both cases, the
information is processed by the packet data convergence protocol (PDCP), the
radio link control (RLC) protocol and the medium access control (MAC)
protocol, before being passed to the physical layer for transmission.

User Plane

The user plane protocol stack between the e-Node B and UE consists of the
following sub-layers:

 PDCP (Packet Data Convergence Protocol)

 RLC (radio Link Control)
 Medium Access Control (MAC)

On the user plane, packets in the core network (EPC) are encapsulated in a
specific EPC protocol and tunneled between the P-GW and the eNodeB.
Different tunneling protocols are used depending on the interface. GPRS
Tunneling Protocol (GTP) is used on the S1 interface between the eNodeB and
S-GW and on the S5/S8 interface between the S-GW and P-GW.
Packets received by a layer are called Service Data Unit (SDU) while the packet
output of a layer is referred to by Protocol Data Unit (PDU) and IP packets at
user plane flow from top to bottom layers.

Control Plane

The control plane includes additionally the Radio Resource Control layer (RRC)
which is responsible for configuring the lower layers.

The Control Plane handles radio-specific functionality which depends on the

state of the user equipment which includes two states: idle or connected.

Mode Description
Idle The user equipment camps on a cell after a cell selection or
reselection process where factors like radio link quality, cell status
and radio access technology are considered. The UE also monitors
a paging channel to detect incoming calls and acquire system
information. In this mode, control plane protocols include cell
selection and reselection procedures.
Connected The UE supplies the E-UTRAN with downlink channel quality and
neighbour cell information to enable the E-UTRAN to select the
most suitable cell for the UE. In this case, control plane protocol
includes the Radio Link Control (RRC) protocol.

The protocol stack for the control plane between the UE and MME is shown
below. The grey region of the stack indicates the access stratum (AS) protocols.
The lower layers perform the same functions as for the user plane with the
exception that there is no header compression function for the control plane.
7 challenges of 5G network deployment
Telecom companies will likely encounter several challenges as they continue
designing and installing 5G networks. Preparing for these issues will be
essential to successfully deploying 5 G.

1. The cost of spectrum

Around the world, telecom companies are paying enormous sums of money on
5G spectrum auctions. For instance, the four major telcos in the United States
spent an extraordinary $100bn on 5G midbands in 2022. Similar spending is
being seen elsewhere. Nevertheless, there remains much uncertainty about the
potential return on their investment.

2. The cost of hardware

5G components and equipment are also very expensive. Prices vary, but
according to

TechTarget, 5G macrocells (a core part of network architecture) cost around

$200,000 to set up. Individual small cells are priced at around $10,000.

3. Planning permissions

Planning permits remain a major obstacle to 5G network deployment,

particularly with the mmWave spectrum base stations. These will need to be
installed in dense networks around urban areas - on street lamps, bridges,
buildings and so on. However, local planning laws must be navigated in many
cities to install this technology. This can delay deployments of 5G public
networks.
4. Site evaluation and selections

When planning coverage areas for 5G, technicians and engineers will need to
spend much time visiting sites to plan the precise location and position of base
stations. Since high-band mmWave 5G attenuates rapidly over short distances
and can be disrupted by obstacles such as foliage, engineers must conduct
meticulous line-of-sight analysis.

5. Fiber connectivity for backhaul

For 5G to offer the promised speeds, a backhaul network that can handle the
high volumes of data transmitted from the 5G core network will be required.
Therefore, telecom firms may need to invest in expanding fibre optic networks,
too - and the cost of fibre optic cabling and installation is often very high.

6. Management of assets

As telecom companies deploy 5G, they must manage an ever-larger array of

hardware and equipment in the field. This must be monitored, maintained,
upgraded, and replaced over time. Managing this inventory will be challenging.

Furthermore, since much of this hardware will be in easy-to-access places (such

as lampposts), it may be a more likely target for theft, interference or accidental
damage than traditional cell towers.

7. Shortages of skilled staff

In certain countries, there is a shortage of skilled technicians, engineers and

project managers who are essential for network deployment. Recruiting,
training and upskilling staff to support 5G network deployment will be critical.

What is Dynamic Spectrum Access?

DSA technology enables radios to safely share multiple frequency bands

without interfering with legacy and other protected wireless systems. DSA-
enabled devices accomplish this through a novel combination of RF, signal
processing, networking and detection technologies that are coupled with DSA
software algorithms to provide substantially more communications capacity
than is available through current static spectrum access practices.

DSA improves spectrum utilization in three dimensions: frequency, location and

time. It enables a network to opportunistically use a wide range of frequencies
at points in time and space when and where they are authorized and available.
When a non-cooperative user is detected on the same channel, a DSA-enabled
device immediately moves to an unoccupied channel. Because many
frequencies are utilized only a small portion of the time and in a fraction of
locations, DSA enables two or more networks to share a given spectrum band. It
also enables a wireless service provider or spectrum user to deploy more than
one application or service in a given band.