14.06.2006 1
HSDPA High Speed Downlink Packet Access
Technology Updateadare GmbH
www.adare.deMarija Skoda
Email: [email protected]
March 2006
14.06.2006 2
HSDPA - Agenda
GSM and UMTS evolutionGSM and UMTS evolutionTechnological approachProtocol architectureHDSPA channels in UTMS Release 5Mobility aspectsOutlook beyond Release 5
14.06.2006 3
Evolution of GSM and UMTS in Europe
Phase1 Phase2 Phase 2+
R‘96 R‘97R‘98
R‘99
R‘99
R’4R’5
R’6
R’7
2G2G 2,5G2,5G3G3G
3.5G3.5G
Increase in data transmission
speed from 2Mbps to 30-50Mbps
Phase 2+: HSCSD, GPRS, EDGE Enhanced Bearer Services
(14.4kbps-50kbps-128kbps)
UMTSUMTS
Phase 2: Tele (HR speech, SMS)/ Bearer(9.6kbps)/Supplementary Services
Phase 1: Tele (FR speech, SMS)/ Bearer(9.6kbps)/Supplementary Services
1990-1991 1994 1997 1998 1999 1999-2000 2001 2002 2005 2007
Year
GSMGSM R’99: UTRAN, WCDMA, MMS (up to 2Mbps)
R’4-R’7: VHE, IMS, HSDPA, HSUPA, PoC, E-DCH, MBMS, MIMO, WLAN integration
* See the apendix for the abbreviation list
14.06.2006 4
UMTS FDD radio access basics
Channel bandwidth 5 MHz 5 MHz QPSK modulationQPSK modulationPulse shapingPulse shapingDirect sequence CDMADirect sequence CDMAOVSF spreading codesOVSF spreading codesTiming structureTiming structureTransmission rate 3.84 Transmission rate 3.84 MchipMchip/s/sFrequency reuse = 1Frequency reuse = 1Soft handoverSoft handover
CDMACDMA – Code Division Multiple Access
OVSFOVSF – Orthogonal Variable Spreading Factor
QPSKQPSK – Quadrature Phase Shift Keying
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CDMA principle
CDMACDMA-Code Division Multiple Access:
- Narrow-band signal is spreadedspreaded with an OVSF code:to increase the signal bandwidthto achieve the orthogonality between signals from the
same source
- Wide-band signal then is scrambledscrambled with a scrambling code to distinguish between different sources
-- Spreading factorSpreading factor SF =Chiprate/Bitrate
NearNear--far problemfar problem: - power control necessary to limit the interference between sources
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Spreading example
1 symbol
1 chip
+1
Bipolar data
-1
Spreading code SF=8
(channelisationcode x scrambling
code)
+1
-1
+1
Coded data
-1
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HSDPA Motivation
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
Requirements:- Short set-up and transfer delays- High system capacity- High peak data rates- Low mobility (user speed max 3km/h)- Low data transfer costs
14.06.2006 8
Rel.´99 vs. Release 5
Release’99 Release 5 - HSDPA
High speedHigh speeddownlink
broadcast shared channel for data
Support of IP and radio bearers for IP-based services
Voice & data over DCH;
Max download rate 384 kbit/s, GPRS latency 700 ms
Mode of Transmission
Release’99 Cellsand
mixed Rel.’99 – Rel.5 cellse.g. in hotspots
NetworkView
Release’99 cells
14.06.2006 9
HSDPA - Agenda
GSM and UMTS evolutionTechnological approachTechnological approachProtocol architectureHDSPA channels in UTMS Release 5Mobility aspectsOutlook beyond Release 5
14.06.2006 10
High speed downlink broadcast channel
NodeB
HSDPA- capableUEs
Service aspect:
•Allow higher data rates for users in favourable positions
•Decrease latency
Network aspect:
•Increase radio efficiency/capacity for data
Major objectives:Major objectives:
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Technologies for HSDPA support
Adaptive Modulation and Coding (AMC)
Hybrid Automatic Repeat Request (H-ARQ)
Fast transmission/retransmission scheduling
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Technologies for HSDPA support
Adaptive Modulation and Coding (AMC)Adaptive Modulation and Coding (AMC)
Hybrid Automatic Repeat Request (H-ARQ)
Fast transmission/retransmission scheduling
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AMC principle
Power level: β
Modulation: QPSK
Turbo Code R=1/3
Power level: α
Modulation: 16-QAM
Turbo Code R=1/3,
rate matching: 3/4
Power level: α
Modulation: QPSK
Turbo Code R=1/3,rate matching: 1/4
Power level: α
Modulation: QPSK
Turbo Code R=1/3
UE1 UE1
UE2UE2
NodeBNodeB
Release ’99 HSDPAHSDPA
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Adaptive Modulation and Coding (AMC)
Main principle – to dynamically modifySignal modulationSignal modulation and Coding schemeCoding scheme
to compensate the variations in cannel conditions
Benefits:- Increased average cell throughput- Reduced interference variation- Higher data rates for users in favourable positions
Effective in a combination with scheduling techniques
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Data throughput
9604/4
7203/4
4802/4
16-QAM
3603/4
2402/4
1201/4
QPSK
Throughput in kbps
(1 code of SF=16)
Coding RateModulation
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Technologies for HSDPA support
Adaptive Modulation and Coding (AMC)
Hybrid Automatic Repeat Request Hybrid Automatic Repeat Request (H(H--ARQ)ARQ)
Fast transmission/retransmission scheduling
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H-ARQ-type-III
Chase combining with one redundancy version: the data are retransmitted with a little redundancyredundancy. The retransmitted signal is weighted by SNR and then combined with the first received signal.
Coded data bits with redundancy Data Bits
Error detected:store a packet, request a retransmission
Decode combined data
Data Bits
NACK
+UE
NodeB
1st transmission
2nd transmission
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H-ARQ-type-II
Incremental redundancy: only correctioncorrection data to the original data is retransmitted. The additional redundant data will be sent incrementally if NACK is received
Coded data bits with redundancy Data Bits
NACK
Error detected:store a packet, request retransmission
Combine the stored packet
with a received redundancy Decode combined data
Data Bits
UE
NodeB
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Timing structure Rel’99
In UMTS Rel’99 the transmission time interval for transport channels is always multiple to 10 ms (10/20/40/80)
2/3 ms
2560 chips
TS0 TSi TS14
F0 Fi F71
720 ms
Time Slot TSTime slot is the shortest
repetitive period
1Frame =15TS Frame is the shortest transmission duration10 ms
Superframe=72F
TTITTI--Transmission Time IntervalTransmission Time Interval
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Shorter time transmission interval (TTI)
HSDPA introduces short TTI concept, where TTI=2ms
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 21
Technologies for HSDPA support
Adaptive Modulation and Coding (AMC)
Hybrid Automatic Repeat Request Hybrid Automatic Repeat Request (H(H--ARQ)ARQ)
Fast transmission/retransmission scheduling
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Fast and fair scheduling in NodeB
UE1
UE2
t
P
P
CQI 1
CQI 2tScheduled Packet Buffer
Fast scheduling is based on a knowledge of an instantaneous channel quality and thus effectively avoids channel fading during the transmission of data
UE capabilities, QoS requirements, Uuresources availability are also taken into
account for the efficient scheduling
CQI-Channel Quality Indicator
NodeBData for UE1
Data for UE2
2ms
t
14.06.2006 23
HSDPA - Agenda
GSM and UMTS evolutionTechnological approachProtocol architectureProtocol architectureHDSPA channels in UTMS Release 5Mobility aspectsOutlook beyond Release 5
14.06.2006 24
Need for an architectural change to Rel’99
ARQ mechanism is placed in RNC- Disadvantage: latency time up to 100 ms!- Solution: move it to node B- Profit: latency below 10 ms
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
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New protocol entities
PHY PHY
MAC hs
MAC hs
MAC c/sh
MAC c/sh
HS-DSCH
FP
HS-DSCH
FP
L1 L1
L2 L2
MAC d MAC d
RLC
PDCP
RLC
PDCP
Slow handshake
(RLC acknowledged mode)
NodeBUE RNC
Fast handshake
Uu Iub/Iur
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Impact on the network
New type of cell – Rel’5 cell, complement to Rel’99 cell and ensures HSDPA functioning
New NodeB fast scheduling functionality that takes into account- Buffer status and resource availability- QoS and priority- UE capabilities and quality feedback
Flow control mechanism on the Iub interface
14.06.2006 27
HSDPA - Agenda
GSM and UMTS evolutionTechnological approachProtocol architectureHDSPA channels in UTMS Release 5HDSPA channels in UTMS Release 5Mobility aspectsOutlook beyond Release 5
14.06.2006 28
HSDPA code allocation example
Other channels
HSHS--DSCHDSCH – High Speed Downlink Shared Channel
SF=1
SF=2
SF=4
SF=8
SF=16
HS-DSCH
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HSPDA multiplexing
2 ms
Data for UE1
Time Domain
Cod
e D
omai
n
TTI = 2ms
Data for UE2
Data for UE3
15
Users share channel resources in time domain and code domain.
Control channel is needed to transmit a resource allocation
information
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Data throughput
14.49.64.84/4
10.77.23.63/4
7.24.82.42/4
16-QAM
5.43.61.83/4
3.62.41.22/4
1.81.20.61/4
QPSK
Throughput in Mbps
(15 codes)
Throughput in Mbps
(10 codes)
Throughput in Mbps
(5 codes)Coding RateModulation
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Throughput calculation example
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
Formula:
Calculation:
Chips per Sec x Number of Bits per Modulation Symbol x R x NChips per Sec x Number of Bits per Modulation Symbol x R x NSF SF
2560 x 3/2 ms x 4 x 3/4 x 5
16= 3.6 Mbps
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HSDPA terminal classes
1.8
0.9
14.4
10.8
7.2
7.2
3.6
3.6
1.8
1.8
1.2
1.2
Peak rateMbps
28800QPSK1512
14400QPSK1511
172800both21510
172800both1159
134400both1108
1152100both1107
67200both156
57600both155
38400both254
28800both253
28800both352
19200both351
Soft channel bits
ModulationMin TTIHS-DSCH channels
Class
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Channel set comparison
DSCH
HS-DSCH
HS-DCCH
HS-SCCHUE
Rel’99UE
Rel’5
Dedicated channels Dedicated channels
Shared channels Shared channels
DCH DCH
Release ‘99Release ‘99 HSDPA HSDPA
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Associated Signalling
Uplink:- Fast link adaptation (AMC) signalling- H-ARQ signalling
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)
CPICHCPICH – Common Pilot Channel
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Packet exchange
N slotsN slots
7.5 slots7.5 slotsACK/NACK CQI
Data bits
UE NodeB
HS-DSCH frame
HS-DCCH frame
Time between Time between transmission of HStransmission of HS--
SCCH and HSSCCH and HS--DSCH framesDSCH framesUE-id, codes,
modulation H-ARQ information, CRCHS-SCCH frame
2 slots2 slots
Time for packet Time for packet scheduling based scheduling based
on received on received informationinformation2 slots =
1.33ms
UE-id, codes, modulation H-ARQ information, CRCTime for a Time for a
feedback feedback information information generationgeneration 1 slot =
0.67mst
t
14.06.2006 36
HSDPA - Agenda
GSM and UMTS evolutionTechnological approachProtocol architectureHDSPA channels in UTMS Release 5 Mobility AspectsMobility AspectsOutlook beyond Release 5
14.06.2006 37
Mobility management
Only hard handover hard handover for HSDPA transmissionsfor HSDPA transmissions
HSDPA handover types:- Intra NodeB handover- Inter NodeB handover- HS-DSCH to Dedicated Channel handover
14.06.2006 38
Intra-NodeB HSDPA handover
UESource Serving HS-DSCH Cell Target Serving HS-DSCH Cell
NodeB
No need to reset MAC-hs entity
If necessary, the radio bearer reconfiguration procedure
should be performed
At activation time
HS-DSCHHS-DSCH
DC
H
HS-SCCH
HS-S
CCH
S-RNC
S-RNC commands NodeB to prepare for the serving HS-DSCH cell change at the activation time
14.06.2006 39
Inter-NodeB HSDPA handover
HS-DSCH HS-DSCH
DCH DCH
HS-SCCH HS-SCCH
At activation time
NodeBNodeB
RLC for a transmission reception on HS-DSCH is stopped both at UE and UTRAN prior to and until the reconfiguration is completed
UESource Serving HS-DSCH Cell Target Serving HS-DSCH Cell
Transport channel reconfiguration message includes MAC-hs reset flag
S-RNC
14.06.2006 40
HSDPA - Agenda
GSM and UMTS evolutionTechnological approachHDSPA channels in UTMS Release 5Protocol architecturePhysical layer modificationsOutlook beyond Release 5Outlook beyond Release 5
14.06.2006 41
High speed downlink broadcast channel
NodeB
Service aspect:Higher data rated for users in favourable positionsDecrease delays
Network aspect:Increase throughput in the uplinkDownward compatibility to Rel’99, Rel’4 and Rel’5Soft handover
HSUPA- capableUEs
Need to deploy an Enhanced Dedicated Channel (EE--DCHDCH) in UL/DL for UE for scheduling and H-ARQ operations
Major objectives:Major objectives:
14.06.2006 42
MIMO example
Despread
Despread
Despread
Spread
Spread
Spread
DeMUX MUX
Detector
Detector
Detector
Space-time rake combiner……
Sender Receiver
IN OUT
MIMO technique allows to achieve higher data rates either:
when using the same spreading code on different antennasattaining better channel quality by improved antenna transmit and receive diversity
14.06.2006 43
HSPDA in Germany, Sample March 2006
Commercial offer T-Mobile (1,8 Mbit/s),large city coverageTariff example:
5 € p.m. Data Connect +35 € p.m. Option web'n'walk i.e. incl. 5 GB (quasi-flat)+1 € p.d. used
Notebook card 1 €24 month contract
UEs availability:
Today:Only notebook cards(1,8 Mbit/s)
HSDPA Mobiles announced for Summer: e.g. BenQ EF 91(3,6 Mbit/s)
Vodafone: - Home zone DSL-like tariff e.g. 36 €, incl.5 GB p.m.- Surcharge for mobility
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