3g/4g mobile communications systems - universität bremen & 4g mobile... · mimo techniques,...

Dr. Stefan BrückQualcomm Corporate R&D Center Germany

3G/4G Mobile Communications Systems

Chapter V: Physical Layer of UMTS (R99/HSPA)

2

(R99/HSPA)

Slide 2

Physical Layer of UMTS (R99/HSPA)

� Basic CDMA Concept

� Selected Physical Layer Aspects� UMTS (R99)

� High-Speed Downlink Packet Access (HSDPA)

� High-Speed Uplink Packet Access (HSUPA, E-DCH)

3 Slide 3

Basic CDMA Concept

4

� Code Division Multiple Access (CDMA) is a method in which multiple users occupy the same time and frequency allocations

Slide 4

Orthogonal Spreading - Basics

5

� Transmission using the entire bandwidth is achieved by spreading each symbol with a pre-defined sequence with fixed chip rate → Increase of the utilized bandwidth

� The figure shows an example of a spreading sequence (-1, 1, 1, -1)

Slide 5

Despreading – Basics

6

� The receiver despreads the chips by using the same orthogonal sequence used at the transmitter

� Note that under no noise conditions, the symbols are completely recovered without any errors

Slide 6

OVSF Tree

7

� Orthogonal Variable Spreading Factor (OVSF) codes are used to spread to the chip rate on both the UL and the DL� The chip rate in UMTS is 3.84 Mcps

� On the UL, different OVSF codes separate dedicated Physical Channels (e.g. DPCCH, DPDCH) from a single terminal

� On the DL, different OVSF codes separate UEs within a single cell Slide 7

Scrambling Codes

� In DL (usually) one OVSF tree per cell, in UL one OVSF tree per terminal is used for spreading� The spreading codes are also called channelization codes

� Strong interference would occur if a neighbor cell in DL or neighbor terminal is UL would use the same channelization code → additional protection is needed

� The solution is applying a scrambling sequence per cell (DL) and per

8

terminal (UE)� The chip rate of the scrambling sequence is 3.84 Mcps as well

� For the DL there are 512 so-called primary scrambling codes� Re-use of the scrambling codes is needed in the network

� For the UL there are roughly 224 different scrambling codes

Slide 8

Physical Channels in UMTS

� Primary common control physical channel, PCCPCH (DL)

� Secondary common control physical channel, SCCPCH (DL)

� Physical layer only channels� Synchronization channel, SCH (DL)

� Common pilot channel, CPICH (DL)

� Paging indicator channel, PICH (DL)

� Acquisition indicator channel, AICH (DL)

9

� Acquisition indicator channel, AICH (DL)

� Physical random access channel, PRACH (UL)

� Dedicated physical channel, DPCH, DL

� Dedicated physical channel DPCH,UL

Slide 9

Physical Layer Timing in UMTS (R99)

� Frame Timing� Transmission Time Interval (TTI)

� TTI: 10, 20, 40, 80 ms boundaries

� 10 ms radio frames, 15 slots per frame

� 38400 chips per frame

� Slot Timing� 2560 chips per slot, 0.67 ms

10

� 2560 chips per slot, 0.67 ms

� Symbol Timing� Symbol consists of a number of

chips

� OVSF determines chips/symbol

� OVSF ranges from 4 to 512 chips/symbol (640 to 5 symbols per slot)

Slide 10

Multiplexing and Coding Procedure

11

� The transport channel data is broken into blocks and delivered every transport time interval (TTI) for that particular transport channel.

� The end result of the Physical Layer’s actions on the transport channel data is a Coded Composite Transport Channel (CCTrCH)

Slide 11

Downlink Generic Physical Layer Procedure

� Transport channel data delivered every TTI

� CRC Attachment

� Channel Coding

� Rate Matching

� Interleaving

� Mapping data onto physical channels

12


� Spreading using OVSF Channel codes

� Scrambling

� QPSK Modulation

Slide 12

Downlink Channel Coding

� In UMTS, two types of forward error correction coding are applied

� Convolutional codes� Used for common and dedicated transport channels

� Applied for data rates ≤ 32 kbps (roughly)

� Constraint length K = 9

� Coding rate R = 1/2 and R = 1/3 depending on the transport channel

� Turbo codes� Used for dedicated transport channels

13

� Used for dedicated transport channels� Applied for data rates ≥ 64 kbps (roughly)

� Based on parallel concatenated convolutional codes

� Mother code rate is R = 1/3

Slide 13

Downlink Spreading and Scrambling

14

� The symbols are spread using the same channelization code� Cch,SF,m is the mth OVSF code of spreading factor SF

� Afterwards, the signal is scrambled using either a primary or secondary scrambling code (PSC, SSC)

� The Gs are the DL weight factors: G is for the Physical Channels, Gp, Gs for the Primary and Secondary Synchronization Channels (not covered)

Slide 14

Downlink Physical Channel

15

� The DPDCH and the DPCCH are time multiplexed into the DPCH

� The DPCCH includes TPC, TFCI and Pilot bits� TPC bits are power control commands for the uplink

� TFCI bits include information of the transport format

� Pilots bits are used for channel estimation

Slide 15

Uplink Generic Physical Layer Procedure

� Transport channel data delivered every TTI

� CRC Attachment

� Channel Coding

� Interleaving

� Rate Matching


16


� Spreading using OVSF Channel codes

� PN Scrambling

� QPSK Modulation

Slide 16

Uplink Spreading and Scrambling

17

� The physical channels are spread to the chip rate with individual channelization codes and then scrambled with the same scrambling code

� In the UL, the DPCCH is always on the Q branch

� The DPDCHs can be on both the I and Q branch� If there is only one DPDCH, it is on the I branch (BPSK modulation)

� βs are the UL weight factors, βd is for data and βc is for controlSlide 17

Uplink Physical Channel

18

� UL DPCH is consists of two Physical Channels, the DPDCH and the DPCCH

� UL Dedicated Physical Data Channel (DPDCH) sent on I data branch

� UL Dedicated Physical Control Channel (DPCCH) sent on Q data branch

Slide 18

Common Pilot Channel

19

� The Common Pilot Channel (CPICH) provides an in-cell timing reference and is used for DL channel estimation

� There are two types of Common Pilot Channels� Primary CPICH (P-CPICH)

� Secondary CPICH (S-CPICH)

Slide 19

Primary and Secondary Common Pilot Channel

� The properties of the P-CPICH are as follows:� The same channelization code is always used for the P-CPICH, Cch,256,0

� The P-CPICH is scrambled by the PSC

� There is one and only one P-CPICH per cell

� The P-CPICH is broadcast over the entire cell� Typically 10% of the DL power are allocated to the P-CPICH

� The properties of the S-CPICH are as follows:� An arbitrary channelization code of SF 256 is used for the S-CPICH

20

� An arbitrary channelization code of SF 256 is used for the S-CPICH

� An S-CPICH is scrambled by either the PSC or an SSC

� There may be zero, one, or several S-CPICH per cell

� An S-CPICH may be transmitted over the entire cell or only over part of the cell

� When a S-CPICH is used, it is scrambled with a PSC or SSC

Slide 20

HSDPA Background

� Initial goals� Establish a more spectral efficient way of using DL resources providing data rates

beyond 2 Mbit/s, (up to a maximum theoretical limit of 14.4 Mbps)

� Optimize interactive & background packet data traffic, support streaming service

� Design for low mobility environment, but not restricted

� Techniques compatible with advanced multi-antenna and receivers

� Standardization started in June 2000

21

� Standardization started in June 2000� Broad forum of companies

� Major feature of Release 5

� Enhancements in R7 � HSPA+� Advanced transmission to increase data throughput

� Signaling enhancements to save resources

Slide 21

HSDPA Basics

� Evolution from R99/Rel. 4� 5 MHz Bandwidth

� Same spreading by OVSF and scrambling codes

� Turbo coding

� New concepts in Rel. 5� Adaptive modulation (QPSK vs. 16QAM), coding and multicodes

(fixed SF = 16)

22

(fixed SF = 16)

� Fast scheduling in NodeB (TTI = 2ms)

� Hybrid ARQ

� Enhancements in Rel. 7 � HSPA+� Signaling enhancements

� 64QAM

� MIMO techniques, increase of the bandwidth (dual carrier)

Slide 22

Higher Order Modulation

� Standard modulation scheme in UMTS networks� QPSK 2 bit per symbol

� With HSDPA, modulation can be switched between two schemes� QPSK 2 bit per symbol

� 16-QAM 4 bit per symbol

23

Low bitrate → robust to High bitrate → Sensitive to disturbances disturbances

Slide 23

HS-DSCH Principle I

� Channelization codes at a fixed spreading factor of SF = 16

� Up to 15 codes in parallel

SF=8

SF=4

SF=2

C16,0C16,15

24

� OVSF channelization code tree allocated by CRNC

� HSDPA codes autonomously managed by Node B MAC-hs scheduler

� Example: 12 consecutive codes reserved for HS-DSCH, starting at C16,4

� Additionally, HS-SCCH codes with SF = 128 (number equal to simultaneous UEs)

SF=16

Physical channels (codes) to which HS-DSCH is mapped CPICH, etc.

C16,0C16,15

Slide 24

HS-DSCH Principle II

� Resource sharing in code as well as time domain:� Multi-code transmission, UE is assigned to multiple codes in the same TTI� Multiple UEs may be assigned channelization codes in the same TTI

Code

25

� Example: 5 codes are reserved for HSDPA, 1 or 2 UEs are active within one TTI

Data to UE #1 Data to UE #2 Data to UE #3

Time (per TTI)

not used

Slide 25

UMTS Channels with HSDPA

Cell 1 Cell 2

26

Cell 1

UEUE

Cell 2

R99 DCH (in SHO)� UL/DL signalling (DCCH)� UL PS service� UL/DL CS voice/ data

Rel-5 HS-DSCH

� DL PS service

� (Rel-6: DL DCCH)

= Serving HS-DSCH cell

Slide 26

HSDPA Channels

� HS-PDSCH� Carries the data traffic

� Fixed SF = 16; up to 15 parallel channels

� QPSK: 480 kbps/code, 16QAM: 960 kbps/code

� HS-SCCH� Signals the configuration to be used in this TTI

� HS-PDSCH codes, modulation format, TB information

27

� HS-PDSCH codes, modulation format, TB information

� Fixed SF = 128

� Sent two slots (~1.3msec) in advance of HS-PDSCH

� HS-DPCCH� Feedbacks ACK/NACK and channel quality information (CQI)

� Fixed SF = 256, code multiplexed to UL DPCCH

� Feedback sent ~5msec after received data

Slide 27

Timing Relations (DL)

TB size & HARQ Info

Downlink DPCH

HS-SCCH

3 × Tslot (2 msec)

HS-DSCH TTI = 3 × T (2 msec)

Tslot (2560 chips)

ch. code & mod

28

� NodeB Tx view

� Fixed time offset between the HS-SCCH information and the start of the corresponding HS-DSCH TTI: τHS-DSCH-control (2 × Tslot= 1.33msec)

� HS-DSCH and associated DL DPCH not time-aligned

DATA HS-PDSCH HS-DSCH TTI = 3 × Tslot (2 msec)

τHS-DSCH-control = 2 × Tslot

Slide 28

Timing Relations (UL)

DATA

Uplink DPCCH

HS-PDSCH 3 × Tslot (2ms)

0-255 chips

Tslot (0.67 ms)

29

� UE Rx view

� Alignment to m × 256 to preserve orthogonality to UL DPCCH

� HS-PDSCH and associated UL DPCH not time-aligned (but “quasi synch”)

HS-DPCCH

m × 256 chips

τUEP = 7.5 × Tslot (5ms) 0-255 chips

CQI A/NCQI A/NCQI A/NCQI A/N

Slide 29

Hybrid Automatic Repeat Request

� HARQ is a stop-and-wait ARQ � Up to 8 HARQ processes per UE

� In HSDPA the HARQ is asynchronous and adaptive

� Retransmissions are done at MAC-hs layer, i.e. in the Node B� Triggered by NACKs sent on the HS-DPCCH

� The mother code is a R = 1/3 Turbo code

� Code rate adaptation done via rate matching, i.e. by puncturing and repeating

30

� Code rate adaptation done via rate matching, i.e. by puncturing and repeating bits of the encoded data

� Two types of retransmission� Incremental Redundancy

� Additional parity bits are sent when decoding errors occured

� Gain due to reducing the code rate

� Chase Combining� The same bits are retransmitted when decoding errors occured

� Gain due to maximum ratio combining

� HSDPA uses a mixture of both types

Slide 30

HARQ Processes

1 2 23 4 5 31

RTTHARQ

DataHS-PDSCH

31

� HARQ is a simple stop-and-wait ARQ

� Example� RTTmin = 5 TTI� Synchronous retransmissions (MAC-hs decides on transmission)

� UE support up to 8 HARQ processes (configured by Node B)� Min. number: to support continuous reception� Max. number: limit of HARQ soft buffer� Number of HARQ processes configured specifically for each UE category

1 2 3 4 5ACK/NACKHS-DPCCH

Slide 31

Adaptive Modulation and Coding

� In HSDPA adaptive Modulation and Coding is applied� The data rate can be changed per TTI by changing the transport block size as well

as the number of codes being used in parallel

� The mother code rate is R = 1/3

� Codes rates up to R = 1 are achieved by puncturing

� Users in favorable channel conditions (based on Channel Quality indication) are assigned higher code rates and higher order modulation (16QAM, 64 QAM)

32

QAM)

� It is the task of the scheduler to decide on the instantaneous data rate

Slide 32

Supported Transport Block Sizes (Rel. 5)Index TB Size Index TB Size Index TB Size

1 137 86 1380 171 6324

2 149 87 1405 172 6438

3 161 88 1430 173 6554

4 173 89 1456 174 6673

5 185 90 1483 175 6793

6 197 91 1509 176 6916

7 209 92 1537 177 7041

8 221 93 1564 178 7168

9 233 94 1593 179 7298

10 245 95 1621 180 7430

11 257 96 1651 181 7564

12 269 97 1681 182 7700

13 281 98 1711 183 7840

14 293 99 1742 184 7981

15 305 100 1773 185 8125

16 317 101 1805 186 8272

17 329 102 1838 187 8422

18 341 103 1871 188 8574

19 353 104 1905 189 8729

20 365 105 1939 190 8886

46 674 131 3090 216 14155

47 686 132 3145 217 14411

48 699 133 3202 218 14671

49 711 134 3260 219 14936

50 724 135 3319 220 15206

51 737 136 3379 221 15481

52 751 137 3440 222 15761

53 764 138 3502 223 16045

54 778 139 3565 224 16335

55 792 140 3630 225 16630

56 806 141 3695 226 16931

57 821 142 3762 227 17237

58 836 143 3830 228 17548

59 851 144 3899 229 17865

60 866 145 3970 230 18188

61 882 146 4042 231 18517

62 898 147 4115 232 18851

63 914 148 4189 233 19192

33

20 365 105 1939 190 8886

21 377 106 1974 191 9047

22 389 107 2010 192 9210

23 401 108 2046 193 9377

24 413 109 2083 194 9546

25 425 110 2121 195 9719

26 437 111 2159 196 9894

27 449 112 2198 197 10073

28 461 113 2238 198 10255

29 473 114 2279 199 10440

30 485 115 2320 200 10629

31 497 116 2362 201 10821

32 509 117 2404 202 11017

33 521 118 2448 203 11216

34 533 119 2492 204 11418

35 545 120 2537 205 11625

36 557 121 2583 206 11835

37 569 122 2630 207 12048

38 581 123 2677 208 12266

39 593 124 2726 209 12488

40 605 125 2775 210 12713

41 616 126 2825 211 12943

42 627 127 2876 212 13177

43 639 128 2928 213 13415

44 650 129 2981 214 13657

45 662 130 3035 215 13904

63 914 148 4189 233 19192

64 931 149 4265 234 19538

65 947 150 4342 235 19891

66 964 151 4420 236 20251

67 982 152 4500 237 20617

68 1000 153 4581 238 20989

69 1018 154 4664 239 21368

70 1036 155 4748 240 21754

71 1055 156 4834 241 22147

72 1074 157 4921 242 22548

73 1093 158 5010 243 22955

74 1113 159 5101 244 23370

75 1133 160 5193 245 23792

76 1154 161 5287 246 24222

77 1175 162 5382 247 24659

78 1196 163 5480 248 25105

79 1217 164 5579 249 25558

80 1239 165 5680 250 26020

81 1262 166 5782 251 26490

82 1285 167 5887 252 26969

83 1308 168 5993 253 27456

84 1331 169 6101 254 27952

85 1356 170 6211

Slide 33

HSDPA UE Categories

� The specification allows some freedom to the UE vendors

� 12 different UE categories for HSDPA with different capabilities (Rel.5)

� The UE capabilities differ in� Max. transport block size (data rate)

� Max. number of codes per HS-DSCH

� Modulation alphabet (QPSK only)

� Inter TTI distance (no decoding of HS-DSCH in each TTI)

34

� Inter TTI distance (no decoding of HS-DSCH in each TTI)

� Soft buffer size

� The MAC-hs scheduler needs to take these restrictions into account

Slide 34

HSDPA – UE Physical Layer Capabilities (Rel. 5)

HS-DSCH Category

Maximum number of HS-DSCH

multi-codes

Minimum inter-TTI interval

Maximum MAC-hs TB size

Total number of soft channel

bits

Theoretical maximum data rate (Mbit/s)

Category 1 5 3 7298 19200 1.2

Category 2 5 3 7298 28800 1.2

Category 3 5 2 7298 28800 1.8

Category 4 5 2 7298 38400 1.8

Category 5 5 1 7298 57600 3.6

35

Category 6 5 1 7298 67200 3.6

Category 7 10 1 14411 115200 7.2

Category 8 10 1 14411 134400 7.2

Category 9 15 1 20251 172800 10.1

Category 10 15 1 27952 172800 14.0

Category 11* 5 2 3630 14400 0.9

Category 12* 5 1 3630 28800 1.8

cf. TS 25.306Note: UEs of Categories 11 and 12 support QPSK only

Slide 35

Channel Quality Information (CQI)

� Signalled to the Node B in UL each 2ms on HS-DPCCH

� Integer number from 0 to 30 corresponds to a Transport Format Resource Combination (TFRC) given by� Modulation

� Number of channelisation codes

� Transport block size

� For the given conditions the BLER for this TFRC shall not exceed 10%

36

� For the given conditions the BLER for this TFRC shall not exceed 10%

� Mapping defined in TS 25.213 for each UE category

Slide 36

CQI – Mapping Table (Rel. 5)

� Tables specified in TS 25.214

� For each UE category� Condition: BLER ≤ 10%

� Example for UE category 10

CQI value Transport Block Size

Number of HS-PDSCH Modulation

Reference power adjustment ∆∆∆∆

NIR XRV

0 N/A Out of range

1 137 1 QPSK 0

…

6 461 1 QPSK 0

7 650 2 QPSK 0

…

15 3319 5 QPSK 0

16 3565 5 16-QAM 0

28800 0

37 Slide 37

16 3565 5 16-QAM 0

…

23 9719 7 16-QAM 0

24 11418 8 16-QAM 0

25 14411 10 16-QAM 0

26 17237 12 16-QAM 0

27 21754 15 16-QAM 0

28 23370 15 16-QAM 0

29 24222 15 16-QAM 0

30 25558 15 16-QAM 0

Background

� E-DCH is a Rel. 6 feature with following targets� Improve coverage and throughput, and reduce delay of the uplink dedicated

transport channels

� Priority given to services such as streaming, interactive and background services, conversational (e.g. VoIP) also to be considered

� Full mobility support with optimizing for low/ medium speed

� Simple implementation

� Special focus on co-working with HSDPA

38

� Special focus on co-working with HSDPA

� Standardization started in September 2002� Study item completed in February 2004

� Stage II/ III started in September/ December 2004

� Release 6 frozen in December 2005/ March 2006

� Various improvements have been introduced in Rel. 7 & Rel. 8

Slide 38

E-DCH Basics

� E-DCH is a modification of DCH – It is not a shared channel, such as HSDPA in the downlink !!

� PHY taken from R99� Turbo coding and QPSK modulation

� In Rel. 7 also 16QAM modulation is supported

� Power Control� 10 msec/2 msec TTI� Spreading on separate OVSF code, i.e. code multiplexing with existing PHY

channels

39

channels

� MAC similarities to HSDPA� Fast scheduling� Stop and Wait HARQ: but synchronous

� New principles� Intra Node B “softer” and Inter Node B “soft” HO should be supported for the E-

DCH with HARQ� Scheduling distributed between UE and Node B

Slide 39

UMTS Channels with E-DCH

Cell 1 Cell 2

40

Cell 1

UEUE

Cell 2

R99 DCH (in SHO)� UL/DL signalling (DCCH)� UL/DL CS voice/ data

Rel-5 HS-DSCH (not shown)� DL PS service (DTCH)� DL signalling (Rel-6, DCCH)

Rel-6 E-DCH (in SHO)� UL PS service (DTCH)� UL Signalling (DCCH)

= Serving E-DCH cell

Slide 40

E-DCH Channels

� E-DPDCH� Carries the data traffic

� Variable SF = 256 … 2

� UE supports up to 4 E-DPDCH in parallel

� E-DPCCH� Contains the configuration as used on E-DPDCH

� Fixed SF = 256

41

� E-RGCH/ E-HICH� E-HICH carries the HARQ acknowledgements

� E-RGCH carries the relative scheduling grants

� Fixed SF = 128

� Up to 40 users multiplexed onto the same channel by using specific signatures

� E-AGCH� Carries the absolute scheduling grants

� Fixed SF = 256

� E-RGCH and E-AGCH are used for providing scheduled grants to the UE

Slide 41

E-DPDCH and E-DPCCH Physical Layer Structure Data, Ndata bits

Slot #1 Slot #14 Slot #2 Slot #i Slot #0

Tslot = 2560 chips, Ndata = M*10*2k bits (k=0…7)

Tslot = 2560 chips

E-DPDCH E-DPDCH

E-DPCCH 10 bits

Slot #3

42 Slide 42

1 subframe = 2 ms

1 radio frame, Tf = 10 ms

Subframe #0 Subframe #1 Subframe #2 Subframe #3 Subframe #4

Slot Format #i Channel Bit Rate (kbps)

Bits/SymbolM

SF Bits/ Frame

Bits/ Subframe

Bits/SlotNdata

0 15 1 256 150 30 101 30 1 128 300 60 202 60 1 64 600 120 403 120 1 32 1200 240 804 240 1 16 2400 480 1605 480 1 8 4800 960 3206 960 1 4 9600 1920 6407 1920 1 2 19200 3840 12808 1920 2 4 19200 3840 12809 3840 2 2 38400 7680 2560

Spreading for E-DPDCH and E-DPCCH

43

� ced,1 – ced,K are the channelization codes for the E-DPDCH’s, cec is the channelisation code for the E-DPCCH

� βed,1 – βed,K are the gain factors for the E-DPDCH’s, βec is the gain factor for the E-DPCCH

Slide 43

Uplink DPCCH

10 msec

CFN

15 × Tslot (10 msec)

CFN+1

0.4 × Tslot (1024 chips) ±148chips

Downlink DPCH

10 msec TTI

CFN

Timing Relation (UL)

44

� E-DPDCH/ E-DPCCH time-aligned to UL DPCCH

Subframe #0

E-DPDCH/ E-DPCCH

3 × Tslot (2 msec)

Subframe #1 Subframe #2 Subframe #3 Subframe #4

10 msec 10 msec TTI 2msec TTI

Slide 44

E-AGCH Physical Layer Structure

45

� The E-AGCH carries the absolute scheduling grant, which represents the maximum E-DPDCH / DPCCH power ratio (5 bits)

� It is convolutional encoded with a R = 1/3 code

� The spreading factor is SF = 256

Slide 45

E-RGCH/E-HICH Physical Layer Structure

46

� For E-RGCH and E-HICH the same channel structure is applied

� The E-RGCH is a dedicated or common downlink physical channel, which carries the relative scheduling grants from the Node B

� In each slot a sequence of 40 ternary values is transmitted → Up to 40 users can be multiplexed on the same channel

� In each cell EHICH and E-RGCH for the same user are on the same code

Slide 46

E-DCH Category

Max. num.Codes

Min SF EDCH TTI Maximum MAC-e TB size

Theoretical maximum PHY data rate (Mbit/s)

Category 1 1 SF4 10 msec 7110 0.71

Category 2 2 SF4 10 msec/2 msec

14484/2798

1.45/1.4


Category 4 2 SF2 10 msec/ 20000/ 2.0/

HSUPA UE Categories

47

� When 4 codes are transmitted, 2 codes are transmitted with SF2 and 2 with SF4� UE Category 7 supports 16QAM modulation


20000/5772

2.0/2.89



20000/11484

2.0/5.74

Category 7(Rel. 7)

4 SF2 10 msec/2 msec

20000/22996

2.0/11.5

Slide 47

Hybrid ARQ Operation

� N-channel parallel HARQ with stop-and-wait protocol� Number of HARQ processes N to allow uninterrupted E-DCH transmission

� 10 msec TTI: 4

� 2 msec TTI: 8

� Synchronous retransmissions� Retransmission of a MAC-e PDU follows its previous HARQ (re)transmission

after N TTI = 1 RTT

� Incremental Redundancy via rate matching

48

� Incremental Redundancy via rate matching

� Max. # HARQ retransmissions specified in HARQ profile

New Tx 2 New Tx 3 New Tx 4 Re-Tx 1 New Tx 2 Re-Tx 3 New Tx 4 Re-Tx 1 Re-Tx 2New Tx 1

ACK

ACK

NACK

NACK

NACK

NACK

Slide 48

Transport Block Size Table for 10ms TTI

49 Slide 49

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