Aida BotonjićTieto1 WCDMA/HSPA Aida Botonjić

Aida BotonjićTieto st generation Analogue speech NMT, AMPS, TACS 2 nd generation Digital speech + low-rate data (<64 kbps) GSM, PDC, IS-95, IS-136 (D-AMPS ) Multimedia services (<2 Mbps) + 2nd gen. services 3 rd generation UMTS/IMT Background LTE 2010 Faster Multimedia services (30-100Mpbs) + 3rd gen. services 4 th generation LTE

Aida BotonjićTieto3 3GPP releases R99: WCDMA Evolved R5: HSDPA – High Speed Downlink Packet Access R6: HSUPA – Enhanced Uplink LTE – Long-Term Evolution Enhanced Uplink (HSUPA) MIMO CPC Enhanced Downlink (HSDPA) Rel 4Rel 5Rel 6 HSPA WCDMA R99 Rel 7Rel 8 HSPA Evolution LTE = Third Generation Partnership Project

Aida BotonjićTieto4 Why WCDMA/HSPA? Applications: Video telephony Web browsing Content sharing, e.g. Picture/video upload. Devices (UE): Broadband modem Mobile phones with Large color screen Gbyte memories HSPA Targets: Adapt to fast variations in radio conditions Reduced delays Improved High-Bitrate Availability Improved Capacity

Aida BotonjićTieto5 WCDMA network architecture Node B RNC dedicated channels Iur Iub Iu Core network (Internet, PSTN) UE

Aida BotonjićTieto6 Frame structure Time slot is the shortest repetitive period Radio frame is the shortest transmission duration

Aida BotonjićTieto7 HSDPA Basic Principles Shared Channel Transmission Dynamically shared in time & code domain Higher-order Modulation 16QAM in complement to QPSK for higher peak bit rates 2 ms Short TTI (2 ms) Reduced latency Fast Hybrid ARQ with Soft Combining Reduced round trip delay Fast Radio Channel Dependent Scheduling Scheduling of users on 2 ms time basis Fast Link Adaptation Data rate adapted to radio conditions on 2 ms time basis t P Dynamic Power Allocation Efficient power & spectrum utilisation = HS-DSCH

Aida BotonjićTieto8 HSUPA Basic Principles Fast Retransmissions Roundtrip time ~2 ms possible Soft combination of multiple attempts Fast Radio-Dependent Scheduling 2 ms time basis 2 ms Short TTI (2 ms) Reduced latency = E-DCH

Aida BotonjićTieto9 Shared Channel Transmission A set of radio resources dynamically shared among multiple users, in time and code domain Efficient code utilization Efficient power utilization Channelization codes allocated for HS-DSCH transmission 8 codes (example) SF=16 SF=8 SF=4 SF=2 SF=1 TTI User #1User #2User #3User #4 Shared channelization codes time

Aida BotonjićTieto10 Fast Channel-dependent Scheduling Scheduling = which UE to transmit to at a given time instant and at what rate Basic idea: transmit at fading peaks May lead to large variations in data rate between users Tradeoff: fairness vs cell throughput high data rate low data rate Time #2#1#2 #1 Scheduled user User 1 User 2 TTI

Aida BotonjićTieto11 Fast Link Adaptation Adjust transmission parameters to match instantaneous channel conditions HS-DSCH: Rate control (constant power) Adaptive coding Adaptive modulation (QPSK or 16QAM) Adapt on 2 ms TTI basis  fast Release 99: Power control (constant rate) Good channel conditions  less power Bad channel conditions  more power power control (HSUPA E-DCH) Good channel conditions  high data rate Bad channel conditions  low data rate rate adaptation (HSDPA HS-DSCH)

Aida BotonjićTieto12 Higher Order Modulation 16QAM may be used as a complement to QPSK 16QAM allows for twice the peak data rate compared to QPSK 16QAM 2 bits/symbol4 bits/symbol QPSK Release 99: only QPSK

Aida BotonjićTieto13 Short 2 ms TTI Reduced air-interface delay Improved end-user performance Necessary to benefit from other HS-DSCH features Fast Link Adaptation Fast hybrid ARQ with soft combining Fast Channel-dependent Scheduling 10 ms 20 ms 40 ms 80 ms Earlier releases 2 ms Rel 5 2 ms

Aida BotonjićTieto14 ACK TO RNC Transmitter Receiver Rapid retransmissions of erroneous data Hybrid ARQ protocol terminated in Node B  short RTT (typical example: 2 ms) Soft combining in UE of multiple transmission attempts  reduced error rates for retransmissions Fast Hybrid ARQ with Soft Combining

Aida BotonjićTieto15 NACK TO RNC ACK Transmitter Receiver Fast Hybrid ARQ with Soft Combining Rapid retransmissions of erroneous data Hybrid ARQ protocol terminated in Node B  short RTT (typical example: 2 ms) Soft combining in UE of multiple transmission attempts  reduced error rates for retransmissions

Aida BotonjićTieto16 Dynamic Power allocation Dedicated channels (power controlled) Common channels Power usage with dedicated channels channels t Unused power Power Total cell power 3GPP Release 993GPP Release 5 t P Downlink channel with dynamic power allocation t Total cell power Power Dedicated channels (power controlled) Common channels HS-DSCH (rate controlled)

Aida BotonjićTieto17 Conclusion Rel 99HSPA (Rel 5 & 6) Channel transmission in time domain Channel transmission in time and space domain SchedulingChannel dependent scheduling QPSK modulationQPSK and 16 QAM modulation TTI min = 10msTTI min = 2ms ARQHARQ Static power allocationDynamic power allocation -Link adaptation