HSDPA

High Speed Downlink Packet Access

Technology Update
adare GmbH
www.adare.de
Marija Skoda
Email: marija.skoda@adare.de

March 2006

14.06.2006 1
 HSDPA - Agenda

ƒ GSM and UMTS evolution

ƒ Technological approach
ƒ Protocol architecture
ƒ HDSPA channels in UTMS Release 5
ƒ Mobility aspects
ƒ Outlook beyond Release 5

14.06.2006 2
 Evolution of GSM and UMTS in Europe

UMTS
Phase 2+: HSCSD, GPRS, EDGE
Enhanced Bearer Services
(14.4kbps-50kbps-128kbps)
Phase 2: Tele (HR speech, SMS)/ R’7
Bearer(9.6kbps)/Supplementary Services
R’6
R’5
Phase 1: Tele (FR speech, SMS)/
R’4
Bearer(9.6kbps)/Supplementary Services
R‘99 Increase in data transmission

R‘99 speed from 2Mbps to 30-50Mbps

R‘98
R‘96 R‘97 3.5G
3G
2,5G
2G
Phase1 Phase2 Phase 2+

1990-1991 1994 1997 1998 1999 1999-2000 2001 2002 2005 2007

Year
R’99: UTRAN, WCDMA, MMS (up to
GSM 2Mbps)

R’4-R’7: VHE, IMS, HSDPA, HSUPA, PoC,

14.06.2006 3
E-DCH, MBMS, MIMO, WLAN integration
* See the apendix for the abbreviation list
 UMTS FDD radio access basics

ƒ Channel bandwidth 5 MHz

ƒ QPSK modulation CDMA – Code Division Multiple Access
OVSF – Orthogonal Variable Spreading Factor
ƒ Pulse shaping QPSK – Quadrature Phase Shift Keying
ƒ Direct sequence CDMA
ƒ OVSF spreading codes
ƒ Timing structure
ƒ Transmission rate 3.84 Mchip/s
ƒ Frequency reuse = 1
ƒ Soft handover

14.06.2006 4
 CDMA principle

ƒ CDMA-Code
CDMA Division Multiple Access:

- Narrow-band signal is spreaded with an OVSF code:

ƒ to increase the signal bandwidth
ƒ to achieve the orthogonality between signals from the
same source

- Wide-band signal then is scrambled with a scrambling

code to distinguish between different sources

- Spreading factor SF =Chiprate/Bitrate

ƒ Near-far problem:
problem - power control
necessary to limit the interference
between sources
14.06.2006 5
 Spreading example
1 symbol
+1

Bipolar data

-1

Spreading code +1
SF=8
(channelisation
code x scrambling -1
code)
+1

Coded data

-1

1 chip
14.06.2006 6
 HSDPA Motivation

ƒ Reasons to deploy HSDPA:

- Saturated voice communication market
- Growing demand and user expectation for the data
services like broadband internet access, streaming,
gaming, etc.
- Competing High Speed wireless technologies
- WLAN
- WiMAX
- 1xEvDo in CDMA 2000

ƒ Requirements:
- Short set-up and transfer delays
- High system capacity
- High peak data rates
- Low mobility (user speed max 3km/h)
14.06.2006
- Low data transfer costs 7
 Rel.´99 vs. Release 5

Release’99 Release 5 - HSDPA

Voice & data over High speed

DCH; downlink
Mode of broadcast shared
Transmission Max download rate
384 kbit/s, GPRS channel for data
latency 700 ms Support of IP and
radio bearers for
IP-based services

Release’99 Cells
Network Release’99 cells and
View mixed Rel.’99 – Rel.5 cells
e.g. in hotspots

14.06.2006 8
 HSDPA - Agenda

ƒ GSM and UMTS evolution

ƒ Technological approach
ƒ Protocol architecture
ƒ HDSPA channels in UTMS Release 5
ƒ Mobility aspects
ƒ Outlook beyond Release 5

14.06.2006 9
 High speed downlink broadcast channel

Major objectives:

ƒ Service aspect:
•Allow higher data rates for
users in favourable positions NodeB
•Decrease latency

ƒ Network aspect:
HSDPA- capable •Increase radio
UEs efficiency/capacity for data

14.06.2006 10
 Technologies for HSDPA support

ƒ Adaptive Modulation and Coding (AMC)

ƒ Hybrid Automatic Repeat Request

(H-ARQ)

ƒ Fast transmission/retransmission
scheduling

14.06.2006 11
 Technologies for HSDPA support

ƒ Adaptive Modulation and Coding (AMC)

ƒ Hybrid Automatic Repeat Request

(H-ARQ)

ƒ Fast transmission/retransmission
scheduling

14.06.2006 12
 AMC principle
Release ’99 HSDPA
Power level: α
Power level: α
Modulation: 16-QAM
Modulation: QPSK
Turbo Code R=1/3,
Turbo Code R=1/3
rate matching: 3/4

UE1 UE1
NodeB NodeB

Power level: β Power level: α

Modulation: QPSK Modulation: QPSK

UE2 Turbo Code R=1/3 Turbo Code R=1/3,

UE2
14.06.2006 rate matching: 1/4 13
 Adaptive Modulation and Coding (AMC)

ƒ Main principle – to dynamically modify

ƒ Signal modulation and
ƒ Coding scheme
to compensate the variations in cannel conditions

ƒ Benefits:
- Increased average cell throughput
- Reduced interference variation
- Higher data rates for users in favourable positions

ƒ Effective in a combination with scheduling

techniques

14.06.2006 14
 Data throughput

Throughput
Modulation Coding Rate in kbps
(1 code of
SF=16)
1/4 120

QPSK 2/4 240

3/4 360

2/4 480

16-QAM 3/4 720

4/4 960
14.06.2006 15
 Technologies for HSDPA support

ƒ Adaptive Modulation and Coding (AMC)

ƒ Hybrid Automatic Repeat Request

(H-ARQ)

ƒ Fast transmission/retransmission
scheduling

14.06.2006 16
 H-ARQ-type-III

ƒ Chase combining with one redundancy version: the

data are retransmitted with a little redundancy.
redundancy The
retransmitted signal is weighted by SNR and then
combined with the first received signal.

Coded data bits

Data Bits with redundancy

NodeB NACK

Data Bits
Error detected: 1st transmission
UE store a packet, request +
a retransmission 2nd transmission
14.06.2006 Decode combined data 17
 H-ARQ-type-II

ƒ Incremental redundancy: only correction data to

the original data is retransmitted. The additional
redundant data will be sent incrementally if NACK
is received
Coded data bits
Data Bits with redundancy

NodeB NACK

Data Bits
Error detected: Combine the
UE store a packet, request stored packet
retransmission with a received
14.06.2006 redundancy 18
Decode combined data
 Timing structure Rel’99

ƒ In UMTS Rel’99 the transmission time interval

for transport channels is always multiple to
10 ms (10/20/40/80)

2560 chips Time Slot TS

Time slot is the shortest
2/3 ms repetitive period

TS0 TSi TS14 1Frame =15TS

Frame is the shortest
10 ms transmission duration

F0 Fi F71 Superframe=72F
720 ms
TTI-Transmission Time Interval
14.06.2006 19
 Shorter time transmission interval (TTI)

ƒ HSDPA introduces short TTI concept, where

TTI=2ms

ƒ Advantages:
- Less probability of an error due to the change of
the channel conditions
- More efficient when packet retransmission is
necessary
- Decreased buffer size

14.06.2006 20
 Technologies for HSDPA support

ƒ Adaptive Modulation and Coding (AMC)

ƒ Hybrid Automatic Repeat Request

(H-ARQ)

ƒ Fast transmission/retransmission
scheduling

14.06.2006 21
 Fast and fair scheduling in NodeB
2ms Fast scheduling is based on a
P knowledge of an
instantaneous channel quality
and thus effectively avoids
UE1 CQI 1 channel fading during the
transmission of data
t

CQI-Channel Quality Indicator

CQI 2
Scheduled Packet Buffer t

NodeB
P Data for UE1
Data for UE2

UE2
UE capabilities, QoS requirements, Uu
resources availability are also taken into
t account for the efficient scheduling
14.06.2006 22
 HSDPA - Agenda

ƒ GSM and UMTS evolution

ƒ Technological approach
ƒ Protocol architecture
ƒ HDSPA channels in UTMS Release 5
ƒ Mobility aspects
ƒ Outlook beyond Release 5

14.06.2006 23
 Need for an architectural change to Rel’99

ƒ ARQ mechanism is placed in RNC

- Disadvantage: latency time up to 100 ms!
- Solution: move it to node B
- Profit: latency below 10 ms

ƒ Scheduling is controlled by RNC

- Disadvantage: important channel measurement
information can be delayed
- Solution: move scheduling close to the air
interface
- Profit: rescheduling is made within a short time

14.06.2006 24
 New protocol entities

PDCP PDCP

Slow handshake
RLC RLC
(RLC acknowledged
mode)
MAC d MAC d

MAC MAC
c/sh c/sh

Fast
HS-
handshake HS-
DSCH
MAC MAC DSCH
FP
hs hs FP

L2 L2

PHY PHY L1 L1

Uu Iub/Iur

14.06.2006 UE NodeB RNC 25

 Impact on the network

ƒ New type of cell – Rel’5 cell, complement to

Rel’99 cell and ensures HSDPA functioning

ƒ New NodeB fast scheduling functionality that

takes into account
- Buffer status and resource availability
- QoS and priority
- UE capabilities and quality feedback

ƒ Flow control mechanism on the Iub interface

14.06.2006 26
 HSDPA - Agenda

ƒ GSM and UMTS evolution

ƒ Technological approach
ƒ Protocol architecture
ƒ HDSPA channels in UTMS Release 5
ƒ Mobility aspects
ƒ Outlook beyond Release 5

14.06.2006 27
 HSDPA code allocation example

HS-DSCH – High
SF=1 Speed Downlink
Shared Channel
SF=2

SF=4

SF=8

SF=16

Other
HS-DSCH
channels

14.06.2006 28
 HSPDA multiplexing
Data for UE1
Users share channel resources in time domain
and code domain.
Data for UE2
15

Data for UE3

Code Domain

Control channel
is needed to
transmit a
resource
allocation
information

2 ms
Time Domain
TTI = 2ms
14.06.2006 29
 Data throughput
Throughput Throughput Throughput
Modulation Coding Rate in Mbps in Mbps in Mbps
(5 codes) (10 codes) (15 codes)
1/4 0.6 1.2 1.8

QPSK 2/4 1.2 2.4 3.6

3/4 1.8 3.6 5.4

2/4 2.4 4.8 7.2

16-QAM 3/4 3.6 7.2 10.7

4/4 4.8 9.6 14.4

14.06.2006 30
 Throughput calculation example

ƒ Calculate user data throughput in Mbps for a

given transmission parameters:
- Modulation: 16-QAM
- Effective code rate: R=3/4
- Number of allocated codes: N=5
ƒ Formula:
Chips per Sec x Number of Bits per Modulation Symbol x R x N
SF
ƒ Calculation:
2560 x 3/2 ms x 4 x 3/4 x 5
= 3.6 Mbps
16
14.06.2006 31
 HSDPA terminal classes

Class HS-DSCH Min TTI Modulation Peak rate Soft channel

channels Mbps bits
1 5 3 both 1.2 19200
2 5 3 both 1.2 28800
3 5 2 both 1.8 28800
4 5 2 both 1.8 38400
5 5 1 both 3.6 57600
6 5 1 both 3.6 67200
7 10 1 both 7.2 1152100
8 10 1 both 7.2 134400
9 15 1 both 10.8 172800
10 15 2 both 14.4 172800
11 5 1 QPSK 0.9 14400
12 5 1 QPSK 1.8 28800
14.06.2006 32
 Channel set comparison

Release ‘99 HSDPA

Dedicated channels Dedicated channels

HS-DCCH

DCH DCH

UE UE
HS-SCCH Rel’5
Rel’99
DSCH

HS-DSCH

Shared channels Shared channels

14.06.2006 33
 Associated Signalling

ƒ Uplink:
- Fast link adaptation (AMC) signalling
- H-ARQ signalling

ƒ Downlink:
- UE-Id for a given HSDPA TTI
- Transport Format and Resource Indicator (TFRI):
- TB set size
- Channelisation codes
- H-ARQ information
- Relative CPICH to HSDPA power ratio (for TTI)

14.06.2006 CPICH – Common Pilot Channel 34

 Packet exchange Time between
transmission of HS-
SCCH and HS-
UE-id, codes, DSCH frames
modulation H-ARQ information, CRC
HS-SCCH frame

HS-DSCH frame
2 slots
Data bits

7.5 slots
ACK/NACK HS-DCCH frame
CQI

UE NodeB
N slots
Time for a UE-id, codes, Time for packet
feedback modulation H-ARQ information, CRC
scheduling based
information on received
generation 1 slot = 2 slots = information
t
t 0.67ms 1.33ms
14.06.2006 35
 HSDPA - Agenda

ƒ GSM and UMTS evolution

ƒ Technological approach
ƒ Protocol architecture
ƒ HDSPA channels in UTMS Release 5
ƒ Mobility Aspects
ƒ Outlook beyond Release 5

14.06.2006 36
 Mobility management

ƒ Only hard handover for HSDPA transmissions

ƒ HSDPA handover types:

- Intra NodeB handover
- Inter NodeB handover
- HS-DSCH to Dedicated Channel handover

14.06.2006 37
 Intra-NodeB HSDPA handover
No need to reset MAC-hs entity
S-RNC commands NodeB to
prepare for the serving HS-
DSCH cell change at the
S-RNC
activation time
If necessary, the radio bearer
reconfiguration procedure
should be performed
NodeB
HS
H
SC

- DS
-D

CH

HS
H

DCH
HS

SCC

- SC
HS-

CH

UE Target Serving HS-DSCH Cell

Source Serving HS-DSCH Cell

14.06.2006 38
At activation time
 Inter-NodeB HSDPA handover
Transport channel reconfiguration
message includes MAC-hs reset flag

At activation time
DCH
DCH

H
HS- DSC
DSC
H HS-
H
HS- -SCC
SCC HS
H

NodeB
NodeB
UE
Source Serving HS-DSCH Cell Target Serving HS-DSCH Cell

RLC for a transmission reception on HS-DSCH is stopped both

at UE and UTRAN prior to and until the reconfiguration is S-RNC
completed

14.06.2006 39
 HSDPA - Agenda

ƒ GSM and UMTS evolution

ƒ Technological approach
ƒ HDSPA channels in UTMS Release 5
ƒ Protocol architecture
ƒ Physical layer modifications
ƒ Outlook beyond Release 5

14.06.2006 40
 High speed downlink broadcast channel

Major objectives:

Service aspect:
ƒ Higher data rated for users in favourable
positions
NodeB
ƒ Decrease delays
ƒ Network aspect:
ƒ Increase throughput in the uplink
ƒ Downward compatibility to Rel’99, Rel’4
HSUPA- capable and Rel’5
UEs
ƒ Soft handover

Need to deploy an Enhanced

Dedicated Channel (E-DCH)
DCH in
UL/DL for UE for scheduling and
14.06.2006 H-ARQ operations 41
 MIMO example

Sender Receiver

Spread Despread Detector

Spread Despread Space- Detector

IN OUT
DeMUX time rake MUX
combiner

…
…

Spread Despread Detector

MIMO technique allows to achieve higher data rates either:

when using the same spreading code on different antennas
attaining better channel quality by improved antenna
14.06.2006 transmit and receive diversity 42
 HSPDA in Germany, Sample March 2006

Commercial offer T-
Mobile (1,8 Mbit/s),
large city coverage
Tariff example:
UEs availability:
5 € p.m. Data Connect
+ Today:
35 € p.m. Only notebook cards
Option web'n'walk (1,8 Mbit/s)
i.e. incl. 5 GB (quasi-flat)
+ HSDPA Mobiles announced
1 € p.d. used for Summer:
e.g. BenQ EF 91
Notebook card 1 € (3,6 Mbit/s)
24 month contract

14.06.2006
Vodafone: - Home zone DSL-like tariff e.g. 36 €, incl.5 GB p.m. 43
- Surcharge for mobility
 Questions and Discussion

Thank you

14.06.2006 44