Requirements for GPRS Evolution Towards Providing Third Generation Services

Transcription

1 Requirements for GPRS Evolution Towards Providing Third Generation Services Håkan Olofsson Ericsson Radio Systems AB

2 Outline GPRS Background GPRS Role in Future Communications Higher bit rates: EGPRS Improved QoS Handling Real-time Support Summary: Standardization Activities

3 General Packet Radio Service (GPRS) Network Architecture BSC MSC HLR IP Network BTS SGSN SGSN GGSN GGSN Backbone Network X.25 Network Radio Access Network Core Network

4 GPRS as Basis for TDMA/136 3G Evolution BTS ANSI 41 MSC RNC 136 SGSN SGSN HLR GGSN GGSN IP Network Backbone Network X.25 Network

5 4 s a k d j a s l d f q w e r r s a k d j f a s l d f q w e r r s a k d j f a s l d f q w e r r 4 s a k d j a s l d f q w e r Evolution Towards 3G in GSM Environments PSTN/ ISDN+ Internet/ Intranet+ GSM Access A, Gb CSN GSM/UMTS Core network PSN lu UMTS Access Existing GSM spectrum GSM Radio Access UMTS Radio Access New UMTS spectrum or modified spectrum C h a n n e l C h a n n e l s a k d j f a s l d f q w e r r s a k d j f a s l d f q w e r r GSM GSM/UMTS UMTS

6 Evolution to IMT-2000 Radio Access GSM TDMA/136 GSM+ TDMA/136+ IMT-2000 Capable Systems EDGE/ 136HS Existing Spectrum PDC WCDMA New or Modified Spectrum

7 GPRS Modifications for Full 3G Support Enhanced Radio Interface bit rates More advanced QoS handling Enhanced support for real-time services

8 Room for GPRS Bit Rate Enhancements Bit rate [kbps] EGPRS GPRS C/I [db] C/I [db]

9 EDGE Radio Interface Key Characteristics New modulation: 8-PSK data rate > 384 kbps Many other parameters as in GSM Packet-switched access (EGPRS) Circuit-switched access (ECSD) Q (d3i, d3i+1, d3i+2)= Dynamic radio resource sharing with GSM speech and GPRS Advanced Link Quality Control (0,0,1) (1,0,1) (0,0,0) (0,1,0) (0,1,1) (1,1,1) I (1,1,0) (1,0,0)

10 EGPRS Link Quality Control Link Adaptation and Incremental Redundancy Scheme Modulation Maximum rate [kbps] Code Rate Blocks per 20 ms Family 6 x 104 MCS-8 8PSK A MCS B 5 4 MCS A MCS B MCS-4 GMSK C MCS A MCS B Throughput [bps] MCS C C/I [db]

11 EGPRS Link Quality Control Segmentation principle (coding scheme MCS-6) 3 bits 32 bits 612 bits RLC block USF RLC/MAC CRC FBI E Data = 74 octets = 592 bits BCS TB Rate 1/3 convolutional coding 36 bits 96 bits 1836 bits puncturing SB = 4 36 bits 96 bits 1256 bits 1256 bits P1 P2 8-PSK bursts 1392 bits

12 EGPRS Performance Simulations Models and Assumptions: Multiple Cells Simulator Equally sized 3-sector macro cells 3/9 frequency reuse Propagation model 35log(d) with lognormal fading 6 db Frequency hopping Dynamic simulations (20ms time step) ARQ included Measurement based WWW traffic model Downlink only users base stations

13 Simulation Result: Capacity C.D.F. [%] normalized delay at 90th percentile [s/kbit] standard GSM EDGE normalized packet delay [s/kbit] spectral efficiency [bps/hz/site] Spectral efficiency more than doubled

14 Simulation Result: Fairness C.D.F. [%] 50 standard GSM EDGE (80) 20(160) 30(240) 40(320) 50(400) 60(480) 70(560) Average packet bitrate per user per timeslot (bitrate per 8 timeslots in brackets) [kbps] 30% of users: >384 kbps, 97%: >144 kbps

15 Simulation Result: Coverage Assume empty system with C/N as in standard GSM system Standard GSM C.D.F. [%] EDGE (80) 20(160) 30(240) 40(320) 50(400) 60(480) 70(560) Average packet bitrate per user per timeslot (bitrate per 8 timeslots in brackets) [kbps]

16 Why Quality of Service Handling in GPRS? Motivation: Spectral Efficiency! GPRS Bearer End-to-End Service BSC SGSN GGSN External Network BTS Radio Access Network Core Network

17 Current GPRS QoS Support QoS requested QoS negotiated GPRS Bearer with certain QoS Profile QoS Profile: Precedence Reliability Delay Max throughput BSC SGSN GGSN Mean throughput BTS Radio Access Network Core Network Problem: BSC and BTS are not involved!

18 QoS Comparison GPRS / UMTS GPRS Bearer GPRS BSS SGSN GGSN Traffic handling priority etc Radio Access Bearer UMTS Bearer UMTS UTRAN SGSN GGSN Bearer Negotiation Radio Access Network Core Network Goal: Harmonization in GSM standards release 99

19 Real-time Services Support in GPRS One Future Scenario: Multimedia over IP over GPRS Key requirement areas: Data transfer delay Cell re-selection delay QoS handling

20 Bottle-necks for Real-time Support SGSN SGSN QoS BSS BSS BSS RLC/ MAC Inter-SGSN cell re-selection

21 Standardization Activities LQC scheme stable (SMG2) Total EGPRS concept stable (GSM release 99, SMG2, SMG3 etc) EGPRS Increased BSS role (GSM release 98, SMG12) GPRS Quality of Service Harmonization GPRS/UMTS (GSM release 99, SMG12 UMTS phase 1, 3GPP TSG SAWG2)