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WCDMA/HSPA Aida Botonji ć

WCDMA/HSPA Aida Botonji ć. 1 st generation. 3 rd generation. 2 nd generation. Analogue speech. Multimedia services (<2 Mbps) + 2nd gen. services. Digital speech + low-rate data (<64 kbps). NMT, AMPS, TACS. UMTS/IMT-2000. GSM, PDC, IS-95, IS-136 (D-AMPS ). Background.

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WCDMA/HSPA Aida Botonji ć

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  1. WCDMA/HSPA Aida Botonjić Tieto

  2. 1st generation 3rd generation 2nd generation Analogue speech Multimedia services (<2 Mbps) + 2nd gen. services Digital speech + low-rate data (<64 kbps) NMT, AMPS, TACS UMTS/IMT-2000 GSM, PDC, IS-95,IS-136 (D-AMPS) Background 4th generation Faster Multimedia services (30-100Mpbs) + 3rd gen. services LTE LTE 2000 2010 1980 1990 Tieto

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

  4. Why WCDMA/HSPA? • Applications: • E-mail • 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 Tieto

  5. Core network (Internet, PSTN) Iu Iur RNC RNC dedicated channels Iub Node B UE Node B WCDMA network architecture Tieto

  6. Frame structure Time slot is the shortest repetitive period Radio frame is the shortest transmission duration Tieto

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

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

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

  10. User 1 User 2 #1 #2 #1 #2 #1 #2 #1 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 TTI Scheduled user high data rate low data rate Time Tieto

  11. 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) rate adaptation (HSDPA HS-DSCH) Bad channelconditions  low data rate Good channelconditions  high data rate Fast Link Adaptation power control (HSUPA E-DCH) Bad channelconditions  more power Good channelconditions  less power Tieto

  12. QPSK 16QAM Higher Order Modulation • 16QAM may be used as a complement to QPSK • 16QAM allows for twice the peak data rate compared to QPSK 2 bits/symbol 4 bits/symbol Release 99: only QPSK Tieto

  13. 2 ms Rel 5 2 ms Earlier releases 10 ms 20 ms 40 ms 80 ms 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 Tieto

  14. ACK Transmitter Receiver Fast Hybrid ARQ with Soft Combining TO RNC • 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 Tieto

  15. NACK ACK Transmitter Receiver Fast Hybrid ARQ with Soft Combining TO RNC • 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 Tieto

  16. P Power Power t Unused power HS-DSCH (rate controlled) Total cell power Total cell power Dedicated channels (power controlled) Dedicated channels (power controlled) Common channels Common channels t t Power usage with dedicated channels channels Downlink channel with dynamic power allocation Dynamic Power allocation 3GPP Release 99 3GPP Release 5 Tieto

  17. Conclusion Tieto

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