1. IMA Summer Program on Wireless Communications VoIP over Wireless Phil Fleming Network Advanced Technology Group Network Business Motorola, Inc.

2. IMA Summer Program on Wireless Communications Outline Push to talk over GPRS –Description –GPRS simulator –Performance results VoIP over Broadband Wireless –History and evolution of broadband wireless –Voice path delay and user satisfaction –VoIP over HRPD-A (EV-DO-A) Why it is going to happen Voice path delay results from simulation –VoIP over HSDPA/HSUPA –VoIP over 802.16e

3. IMA Summer Program on Wireless Communications PTT over GPRS - Simulation Modeling and Analysis Pranav Joshi John Harris Motorola Inc., Networks Business

4. IMA Summer Program on Wireless Communications Overview: Push to Talk (PTT) PTT over GPRS –service has been available for over a year –it is the first true commercial VoIP over cellular service. Walkie-talkie-type service –focus on person-to-person rather than group call Simulator – GENeSyS Performance Results

5. IMA Summer Program on Wireless Communications Push-to-Talk between Alice and Bob Alice (Originator) –Pushes the PTT button to talk with Bob –Waits for TPT (Talk-Permit-Tone) –Continues to hold button while speaking, –Releases when she is done Bob (Target) –Audio from Alice plays out –TPT “beep” indicates Alice has released her PTT button –Pushes the button and waits for TPT –Continues to hold button until he is done speaking Single user can transmit at given time (half-duplex channel) Mobile plays “Bonk” if –User is not available –Any other user is speaking Group Call: three or more users on single PTT call

6. IMA Summer Program on Wireless Communications PTT over GPRS, initial call setup UL TBF Setup Alice Presses PTT Alice Bob DL TBF Setup DL Trans- mission UL Trans- UL TBF Setup UL Trans- mission DL TBF Setup DL Trans- mission : MS processing UL TBF Setup Alice Presses PTT Alice Bob DL TBF Setup DL Trans- mission UL Trans- mission UL TBF Setup UL Trans- mission DL TBF Setup DL Trans- mission : MS processing & packet Assembly Incl paging delay Talk Proceed Tone Infrastructure 1 st PTT setup delay

7. IMA Summer Program on Wireless Communications PTT over GPRS, subsequent PTT UL TBF Setup Bob Presses PTT Bob Alice Talk Proceed Tone Infrastructure UL Trans- mission DL TBF Setup DL Trans- mission Server processing Server keeps state information, i.e is aware of Alice’s situation Subsequent Push timeline : MS processing & packet assembly EtoE Packet delay Response time EtoE Packet delay

8. IMA Summer Program on Wireless Communications Performance and Capacity User experience metrics –initial call setup delay –subsequent PTT delay –mouth-to-ear audio delay –audio turn around time – time from when Alice stops talking until she hears Bobs response playing out. Service Provider Business Metrics –erlangs - average number of subscribers supported at sufficient user experience per RF carrier network element system –system resources used per call

9. IMA Summer Program on Wireless Communications Features of the GENeSyS System Simulator C, C++ Discrete time simulator –Basic time unit of 20ms (one block period) –8 timeslots per carrier Simulator has: –Detailed modeling of RLC/MAC –Air Interface (RF) –Various traffic profiles –Simplified version of Core Network –Multi-carrier, multi-cell, various reuse patterns etc

10. IMA Summer Program on Wireless Communications GENeSyS Schematic Layout

11. IMA Summer Program on Wireless Communications GPRS Adaptive Coding Schemes Throughput per slot vs C/I 2 4 6 8 10 12 14 16 18 20 012345678910111213141516171819202122232425 C/I Throughput (kbps) CS1 CS2 CS3 CS4 System planning for GSM voice

12. IMA Summer Program on Wireless Communications Simulation Configuration 4.75 kbps vocoder with 20 msec. framing –95 bits every 20 msec. when the user is speaking 6 frames per IP packet 43 bytes of overhead per IP packet –uncompressed IP header Overall audio bit stream of 7.6 kbps –6*95 + 43*8 = 570 + 344 = 914 bits per IP packet –914 * 50 / 6 = 7616.7 bits per second One PTT talk spurt ~ 5 sec of Audio RLC Acknowledge Mode –radio frame (20 msec.) re-transmission protocol

13. IMA Summer Program on Wireless Communications Impact of Increasing Number of Dedicated Slots 1 Uplink timeslot mode, coding scheme 1-2, dedicated timeslot 1 to 6 Trunking benefit similar to that of Erlang-B formula observed: –Doubling the number of dedicated slots more than doubles the PTT capacity. –For example, increasing number of dedicated slots from three, up to six, increases the capacity by 3.1x Capacities quoted correspond to knee of delay versus load curve

14. IMA Summer Program on Wireless Communications Impact of mobile station capability 1 Uplink timeslot mode Vs. 2 Uplink timeslot mode Increasing the number of uplink timeslots the mobile is capable of from 1  2 significantly improves performance: –Audio delay 1 UL timeslot: Light load ~2.0 sec and typical load ~2.4 sec 2 UL timeslot: Light load ~1.6 sec and typical load ~2.1 sec This benefit results from better fractional timeslot utilization with the improved mobile station capability – see next slide for visualization

15. IMA Summer Program on Wireless Communications Impact of mobile station capability 1 Uplink timeslot mode Vs. 2 Uplink timeslot mode This benefit results from better fractional timeslot utilization with the improved mobile station capability Consider a system with 2 dedicated non–hopped slots, & three CS2 mobiles If 1 slot uplink capable  –Capacity = 2 PTTs or 1/TS If 2 slot uplink capable  –Capacity = 3 PTTs ~12 Kbps Slot 1 ~12 Kbps Slot 2 MS1MS2 ~12 Kbps Slot 1 ~12 Kbps Slot 2 MS1MS2 MS3

16. IMA Summer Program on Wireless Communications Impact of CS3/4 CS 3-4 –Higher Throughput –Higher BLER or FER High load  Lower delay Light load  Higher delay due to additional re-tx

17. IMA Summer Program on Wireless Communications Changing Vocoder and Packetization Vocoder & Packetization (scenarios) 1.4.75 kbps, 6 frames/IP packet, service bit rate 7.6 kbps 2.5.15 kbps, 10 frames/IP packet, service bit rate 6.9 kbps Scenarios 2 has lower service bit rate over scenario 1 Scenario 2 accumulated lower delay especially at high load

18. IMA Summer Program on Wireless Communications Performance Impact Study Capacity improvement as numbers of dedicated slots increase Delay and capacity benefit with 2 uplink timeslot mode Effect on delay and capacity as we add coding scheme 3 & 4 capable system Trunking efficiency improvement with switchable timeslots Impact of vocoded frames per IP packets with different vocoder rate

19. IMA Summer Program on Wireless Communications VoIP over Broadband Wireless Phil Fleming Network Advanced Technology Group Motorola, Inc.

20. IMA Summer Program on Wireless Communications Evolution of Broadband Access Technology : Air-Interface

21. IMA Summer Program on Wireless Communications Source: ITU-T G114

22. IMA Summer Program on Wireless Communications 3GPP2 HRPD-A VoIP Performance

23. IMA Summer Program on Wireless Communications mix: Ped A/B, Veh A 3 km/h *DO-A results assume mobile diversity; Additional capacity in the FL w/ MAC mux 2-frame bundling = Encapsulation of 2 EVRC frames into 1 RTP/UDP/IP packets Performance Analysis Summary Air Interface CDMA2000 1X (Circuit Voice) CDMA2000 1xEV-DO-A (VoIP with 2-frame)+MAC Mux Voice Delay M-M (msec) 250248 Vocoder FER (1% RL + 2% FL-delay) 3% Voice Erlangs (Voice only) 18-23 (mix) 40* (mix) Set-up Time M-M (sec) 8-109-11

24. IMA Summer Program on Wireless Communications Internet MGX 8800 Access Node Base Site (Access Point) Packet Core Packet Core Interface to the Public Network Base Site Controller Packet Core Packet Core Client

25. IMA Summer Program on Wireless Communications VoIP Delay Components (2-Frame Bundling) Reverse Link =173 msForward Link = 160 ms 10 ms Voc DecodeVoc Accum 40 ms @ 2-frm bundling 20ms Voc De-jitterVoc Encode 15 ms 38 ms BSC/PDSN Network/Cor e Mob-Mob = 248 ms BSC/PDSN Network/Cor e 35 ms 50 ms @ 40 Erlangs Air (HARQ) 40 ms @ 40 Erlangs 15 ms Voc EncodeVoc De-jitter 20 ms 40 ms @ 2-frm bundling Voc AccumVoc Decode 10 ms

26. IMA Summer Program on Wireless Communications HRPD Channel Structure DRC. Lock

27. IMA Summer Program on Wireless Communications Forward Channel Structure HRPD-0 Forward Channel Fundamentals –Time multiplexed channels Pilot –initial acquisition, phase & timing recovery, channel estimation & combining, –means for predicting received C/I for setting DRC (data rate control), MAC – three sub-channels (all users’ RPC+DRCLock CDMed along with RA) –Reverse Power Control (users RPC CDMed using MACIndex – size 64 Walsh) »RPC data rate = 600*(1- 1/DRCLockPeriod) bps –Reverse Activity (RA)  one reverse link bit (RAB) per slot (MACIndex=4) »combined busy bit (CBB) is set to 1 if any sector sets RAB=1 else CBB=0 »CBB & Reverse link persistence value used by AT to determine max uplink rate allowed –DRCLock  AN admission control – when asserted AT to stop selecting sector Traffic (Forward Traffic Channel or FTC) –PHY Packet based variable rate traffic channel, data rates 38.4 Kbps to 2.4576 Mbps –QPSK, 8-PSK, and 16-QAM modulation ---- R=1/5, 1/3 Turbo Codes –PHY Packet sizes: QPSK: 1024 & 2048 bits, 8PSK: 3072 bits, 16QAM: 4096 bits –Frame length from 1 to 16 slots, slot length = 1.67ms Control –Combines functions of IS-95 sync & paging channels w. rates of 38.4 & 76.8 Kbps –Transmitted 8 out of every 256 slots.

28. IMA Summer Program on Wireless Communications Forward Channel Structure No power control: full cell power when transmitting. –Time division nature of the burst versus code division for cdma2000-1x Scheduling done at access point (base station) –Multi-user diversity benefit Provision for receive diversity (two antennas) at Access Terminal

29. IMA Summer Program on Wireless Communications Forward Channel Structure Transmit slots use a 4-slot interlacing technique. Subsequent transmissions occur until decoding successful or maximum allowed re-transmissions. –Data sent @153.6 kbps is sent in four slots and repeated the following four slots Maximum # of re-transmissions is dependent on the data rate selected. Users can be scheduled for consecutive slots. Users can be scheduled for consecutive slots

30. IMA Summer Program on Wireless Communications Slot Structure of Forward Channel No data transmissions occur at the same time as pilot (TDM) –High SNR for pilot signal resulting in accurate channel estimates

31. IMA Summer Program on Wireless Communications HRPD-0 Reverse Link Similar to IS-2000-1x with the addition of the following channels –Reverse Rate Indicator (RRI) Channel --MAC-- Indicate whether data channel is being transmitted or not & its corresponding rate –Data Rate Control (DRC) Channel --MAC-- Indicate supportable forward traffic channel data rate Best serving sector on the forward channel –Acknowledgement (ACK) Channel The data packet transmitted on the forward traffic received successfully? (600Hz rate) Parameters for Reverse Link –Traffic Channel Data Rate Support -- 9.6, 19.2, 38.4, 76.8 and 153.6 Kbps –HPSK (variation of BPSK modulation with better peak to average) –Packet duration of 26.67 msec (fixed frame length), 16 slots of 1.67msec –R=1/2 and R=1/4 Turbo encoder –CDM & SHO supported for reverse link traffic channels (not fast cell sel.) –Fast reverse power control supported (600*(1- 1/DRCLockPeriod) bps)

32. IMA Summer Program on Wireless Communications Physical Layer Enhancements in HRPD-A Reverse Link Enhancements –Higher data rates and finer quantization Support of data rates ranging from 4.8 kbps to 1.8 Mbps with 48 payload sizes –4 slot sub-packets (6.66 ms) –Hybrid ARQ using fast re-transmission (re-tx) and early termination –Support of QPSK and 8-PSK modulation –Flexible rate allocation at each AT via autonomous as well as scheduled mode –3-channel synchronous stop-and-wait protocol Forward Link Enhancements –Peak rates increased from 2.4 Mbps to 3.1 Mbps –Additional small payload sizes (128, 256, 512 bits) Improves frame fill efficiency –Data Source Control (DSC) Channel introduced (on RL) to indicate the desired forward-link serving cell Minimize service interruption due to server switching on FL –Multi-user packet support

33. IMA Summer Program on Wireless Communications System Simulation Assumption: Forward Link VoIP-only and mixture of VoIP and web browsing are modeled. Voice traffic modeled by 4 state Markov chain. 1/8 th rate frames are blanked and not blanked Vocoder frame bundling (multiple voice frames per IP packet) –2-frame bundling and no-bundling Overhead used in the simulation –3 bytes RTP/UDP/IP, 5 bytes for PPP, and 3 bytes for RLP (11 bytes) –6 bytes overhead (PPP header elimination) Hybrid-ARQ included Channel model: –34/33/33% Ped-A/Ped-B/Veh-A Scheduler –Proportional fair scheduler with delay multiplier. –Delay multiplier is a function of delay constraint. –Multi-user MAC multiplexing included ( up to 8 users) AT Receive diversity –2 way Advanced Receiver –Have capability, not currently used

34. IMA Summer Program on Wireless Communications System Simulation Assumption : Reverse Link VoIP-only Voice traffic modeled by 4 state Markov chain. 1/8 th rate frames are blanked and not blanked Vocoder frame bundling –2-frame bundling and no-frame bundling Overhead –3 bytes RTP/UDP/IP, 5 bytes for PPP, and 3 bytes for RLP (11 bytes) –Also modeled a total of 6 bytes overhead HARQ included Channel model: –34/33/33% Ped-A/Ped-B/Veh-A Scheduler –Rate control scheduling Reverse link overhead –DRC and Pilot channel (DRC to Pilot power ratio is set to –6 dB for repetition 8) –Ack/Nack channel (Ack/Nack to Pilot power ratio is set to 4 dB) BTS Rx Diversity –2-way Interference Canceller at the BTS –Not included

35. IMA Summer Program on Wireless Communications System Simulation Parameters

36. IMA Summer Program on Wireless Communications Reverse Link Delay: 2 Frame Bundling, Ped-A+Ped-B+Veh-A, RF Delay only (Maximum allowable pathloss = 130 dB) 40 users can be supported with RF delay of 50 ms with 11 byte overhead Users out of range are assumed dropped. 40 Erl

37. IMA Summer Program on Wireless Communications Reverse Link Delay: 2 Frame Bundling, Ped-A+Ped-B+Veh-A, RF Delay only (Max allowable pathloss = 160dB) 40 users can be supported with RF delay of 50 ms with 11 byte overhead No restriction on location of users Capacity drops by 5 Erlangs when the restriction is removed

38. IMA Summer Program on Wireless Communications Reverse Link Delay: No Frame Bundling, Ped-A+Ped-B+Veh-A, RF Delay only (Maximum allowable pathloss = 160 dB) 40 users can be supported with RF delay of 50 ms with 11 byte overhead and no-frame bundling

39. IMA Summer Program on Wireless Communications Reverse Link Delay: 6 bytes overhead, Ped-A+Ped-B+Veh-A, RF Delay only (Maximum allowable pathloss = 130 dB) With a 40 ms delay bound the 2-frame bundling performs better than no- frame bundling If the delay bound is increased to 50 ms the performance with no frame and 2-frame bundling are identical (need some explanation)

40. IMA Summer Program on Wireless Communications Reverse Link Delay: 6 bytes overhead, Ped A+Ped-B+Veh-A, 1/8 rate frames included Capacity drops from 45 to 40 Erlangs if 1/8 rate frame is included with a RF delay of 50 ms Complete blanking of 1/8 th rate frames causes poor voice quality at the beginning of a talk spurt Loss in performance not as significant as in forward link

41. IMA Summer Program on Wireless Communications Forward Link Delay: 2 Frame Bundling, Ped A+Ped-B+Veh-A, RF Delay only, w/ MAC Mux MAC multiplexing of up to 8 users 40 Erlangs can be supported with RF delay of 40 ms Significant increase in capacity with MAC multiplexing

42. IMA Summer Program on Wireless Communications Forward Link Delay: 6 bytes overhead, Ped A+Ped-B+Veh-A, 1/8 rate frames suppression, w/ MAC Mux 40-45 Erlangs can be supported with RF delay of approximately 50 ms

43. IMA Summer Program on Wireless Communications Forward Link Delay: 6 bytes overhead, Ped A+Ped-B+Veh-A, 1/8 rate frames included, w/ MAC Mux Capacity drops from 45 to 30 Erlangs if 1/8 rate frame is included with a RF delay of 50 ms Blanking of 1/8 th rate frame results in a drop in voice quality at the beginning of a talk spurt

44. IMA Summer Program on Wireless Communications VoIP over HRPD-A Capacity: Conclusions VoIP only capacity is balanced between forward and reverse links 40-45 VoIP (Mobile to Mobile) Erlangs with a mixture of channels and 2 frame bundling with Mobile to Mobile delay of less than 250 ms Two frame bundling has slightly greater capacity to no-frame bundling Inclusion of 1/8 th rate frames significantly degrades VoIP Capacity –Need to study the effect on MOS with various 1/8 th rate frame blanking schemes –Trade-off between capacity and quality Two frame or no frame bundling is the desired mode of operation since gaps in speech will lead to inferior voice quality with loss of packets with frame bundling greater than 2. Mixture of VoIP and Web services can be supported. –Graceful degradation in data capacity as VoIP users are increased ~250 kbps of FL data traffic with 25 Erlangs in both directions  Mobile diversity brings extra FL data throughput Advance receiver at the MS will further increase FL throughput Work in progress includes –Performance with both advanced receiver and RX diversity enabled in FL –Performance with 4-way RX diversity at BTS –Performance of RL with Interference Canceller

45. IMA Summer Program on Wireless Communications 3GPP HSDPA/HSUPA VoIP Performance

46. IMA Summer Program on Wireless Communications High Speed Downlink Packet Access 3G (WCDMA Rel-99 & CDMA2000-1x Rel-C ) spectral efficiency ~ 2.5G (GSM/GPRS) for wireless packet data SE significantly increased with technology enablers: –Fast distributed scheduling (at Node-B) –Fast AMC: H-ARQ + IR, higher-order modulation (ala EDGE), multi-code tx, smaller frame sizes, fast channel quality feedback. HSDPA (Rel-5 WCDMA) is the evolution of WCDMA Rel-99/4 using technology enablers –2ms sub-frames (vs 10ms frames), Peak Rate 14Mb/s –QPSK, 16QAM w. Stop&Wait H-ARQ and IR –Fast scheduling, Fast Ack/Nack & ch. quality feedback HSDPA Background

47. IMA Summer Program on Wireless Communications HS-PDSCH Physical Channels

48. IMA Summer Program on Wireless Communications HS-PDSCH Physical Channel Fundamentals –Partitioned into static 2ms (3 timeslot) periods or “sub-frames” (2560 chips) i.e. HSDPA Transmission Time Interval (TTI) is 2ms sub-frame 5 sub-frames per 10ms frame –QPSK and 16-QAM modulation –Fixed length-16 symbol spreading –Code division multiplexing (CDM) of users per TTI HS-PDSCH Physical Channel

49. IMA Summer Program on Wireless Communications HSUPA Concept  lower delay & higher capacity High Speed Uplink Packet Access E-DCH – enhanced uplink dedicated channel –Fast Node-B scheduling with HARQ and IR control & minimize Rise over Thermal (RoT) variation avoid RLC re-transmission delay and benefit from previous tx energy –#UEs per TTI depends on assignment of available RoT margin (left over R99/4/5) –Higher Rates BPSK or QPSK modulation Variable length (64 to 2) symbol spreading

50. IMA Summer Program on Wireless Communications E-DCH Physical Channel Structure

51. IMA Summer Program on Wireless Communications Physical Layer Features for HSDPA/EUL: VoIP Duplexing: FDD Multiple access: CDMA TTI: 2 ms for both UL and DL –For EUL both 2ms and 10ms TTI is supported Wide range of payload size supported –137 bits-28000 bits for HSDPA Bandwidth: 5 MHz Modulation levels –Downlink: QPSK, 16QAM –Uplink: BPSK, QPSK AMC support H-ARQ at uplink and downlink –Key feature for VoIP –6 and 8-channel stop-and-wait protocol on DL and UL respectively Fast CQI feedback and Ack/Nack Node-B based scheduling for both DL and UL Vocoders: AMR at 12.2 kbps

52. IMA Summer Program on Wireless Communications VoIP Delay Components Reverse Link = 40+35+70=145 Forward Link = 40+55+80=195 10 ms Voc DecodeVoc Accum 40 ms @ 4-frm bundling 20 ms Voc De-jitterVoc Encode 15 ms 40 ms Network RNC/GSN Mob-Mob = 255 ms Network RNC/GSN 40 ms 20 ms @ 70 UEs, 99%-tile Air (HARQ) 70 ms @ 70 UEs, 98%-tile 15 ms Voc EncodeVoc De-jitter 20 ms 40 ms @ 2-frm bundling Voc AccumVoc Decode 10 ms

53. IMA Summer Program on Wireless Communications Vocoder Modeling 12.2 kbps vocoder Number of information bits in 20 msec –12.2 kbps : 244 information + 16 CRC = 260 bits Two state Markov Model –Voice activity factor should be set to 0.32 by randomly choosing on and off periods of appropriate duration. No and two frame vocoder frame bundling (20 ms and 40 ms) Results shown without SID frame modeling (no “comfort noise”)

54. IMA Summer Program on Wireless Communications DL/UL VoIP Simulation Parameters 7 Bytes Packet Overhead RTP 3 bytes RLC 3 bytes for unacknowledged mode PDCP 1 byte

55. IMA Summer Program on Wireless Communications VoIP RF Capacity for DL (HSDPA): 2 Frame Bundling A UE is in outage if it has more than 2% of voice frames either lost or arrive later than the delay bound RF capacity with 2-frame bundling Without RxDiv: 60-70 Erlangs/sector; With RxDiv: 140-160 Erlangs/sector. Need F-DPCH to support Rx-Diversity Without RxDivWith RxDiv

56. IMA Summer Program on Wireless Communications VoIP RF Capacity for DL (HSDPA): No Bundling Without RxDiv: 70 Erlangs/sector with a delay bound of 70 ms No difference in performance between 2 frame bundling and no bundling case Without RxDiv

57. IMA Summer Program on Wireless Communications VoIP RF Capacity for UL (EUL) : 2 Frame Bundling Approx 80 Erlangs/sector can be supported with a delay bound of 30 ms

58. IMA Summer Program on Wireless Communications VoIP RF Capacity for UL (EUL) : No Bundling Approx 80 Erlangs/sector can be supported with a delay bound of 30 ms

59. IMA Summer Program on Wireless Communications 3GPP VoIP RF Capacity: Conclusions VoIP capacity with one UE Rx antenna is 70-80 Erlangs/sector with a mobile-to-mobile delay bound of approx 255 ms (NO SID) Circuit voice from EUL SI was ~70 erlangs/sector Significant improvement in FL capacity with 2 UE Rx antenna –Requires implementation of F-DPCH –Capacity bounded by uplink –Increase in Uplink RF delay bound numbers Effect of SID frames on VoIP capacity currently being studied

60. IMA Summer Program on Wireless Communications 802.16e VoIP Performance

61. IMA Summer Program on Wireless Communications Emerging 802.16 Standards Specifications: completed and in-progress –802.16d – was due May 2004, but significant technology insertion Jan.-May 2004 Examples: CTC coding + H-ARQ, Tx Diversity, MIMO, Adaptive Antenna System enhancements Will be approved in July 2004, but additional ‘corrigendum’ document created to accept changes Corrigendum will be proposed as PAR to 802.16#32 –802.16e – L1 changes (‘Scalable OFDMA’, LDPC codes etc.), plus detailed mobility support Spec.Pub.ScopeComments 802.16Apr. 2002MAC & PHY (10-66GHz) mm-wave (LOS, line of sight) operation 802.16cJan. 2003Profiles802.16 ‘reduction to practice’ specification – analogous to RAN4 (25.101/104) & UE capability specifications 802.16aApr. 2003PHY (2-11GHz)Extended 802.16 LOS operation to non-LOS 802.16d (802.16- 2004) July 2004 (?) (+ Corrigendum) PHY (<11GHz)Enhanced fixed operation – but also radical changes to PHY – H- ARQ, MIMO, Tx Diversity etc. Primary support: fixed, nomadic operation. 802.16e Q3-2005MAC & PHY (<11GHz) MAC changes: handoff, sleep modes. PHY changes: scalable FFT length for PHY (variable BW channelisation) Primary support: nomadic, mobile operation.

62. IMA Summer Program on Wireless Communications Scope of 802.16d&e Specifications 802.16d Specification (published as 802.16-2004) –Physical layer specification 3 physical layers defined: Single Carrier, OFDM-256, OFDMA-2048 Signalling, FEC (H-ARQ, RV), multi-antenna operation –MAC layer specification MAC management –Addressing, MAC PDU/SDU definitions, fragmentation/concatenation support etc. –MAC-layer ARQ, window management etc. QoS management Security sub-layer 802.16e Specification (Enhancements) –Mobility management Inter-BS (AP) HO, scanning (adjacent cell measurement), sleep modes (paging) –Now vehicle for Scalable OFDMA (SOFDMA) Elements Not Specified by IEEE 802.16 –Network management (OMC functionality etc.) –Layer 3 & Core Network (CN) interfaces Inter-BS (AP) interface, BS-CN interface, BS-RNC interface etc.

63. IMA Summer Program on Wireless Communications 802.16e OFDMA Key Attributes Band AMC mode: Frequency-selective adaptive modulation and coding and scheduling Scalable bandwidth mode support Low-complexity Subscriber Station (SS) receiver design Sustainable Base Station transmitter efficiency –Peak-average ratio similar to HSDPA in DL Improved broadcast mode performance –Using synchronous or quasi- synchronous network operation Freq. Selective Scheduling and AMC

64. IMA Summer Program on Wireless Communications OFDM DL Waveform Requirements Basic OFDM DL Waveform Requirements –Simple OFDM waveform construction Classical approach to OFDM waveform (inc. cyclic prefix) construction –Simplifies UE receiver and BS PA out-of-band emission control Low complexity baseline receiver, including simple extension to MIMO Design goal: –Occupied bandwidth ~90% –Inter sub-carrier separation ~11.6 kHz Consistent with target Doppler frequency range and BS/UE impairments –Regular scaling in time and frequency domains Integer sample cyclic prefix and guard sub-carrier allocations desirable but not essential when required to support flexible bandwidth modes

65. IMA Summer Program on Wireless Communications 802.16e Scalable Channel Bandwidths and Duplexing 802.16e nominally limited to ‘operation in <11GHz licensed spectrum’ –But, could be modified to include unlicensed operation 802.16e ‘Scalable OFDMA’ nominal system bandwidths: Constant symbol duration = 100.8us Constant sub-carrier frequency = 11.6kHz 12.5% guard period = 12.6us; 6.25% guard period = 6.3us –Other 802.16e bandwidths also specifiable e.g. 3.5MHz (European fixed wireless allocations), 7MHz Scalable OFDM approach to realizing these bandwidths under study –Options: OFDM sample rate scaling or sub-carrier suppression 802.16e Duplexing –Observes same duplexing rules as 802.16d Nominally, FDD, TDD and Half-Duplex FDD (HD-FDD) supported Most popular option is TDD FFT Length 12825651210242048 System BW (MHz) 1.252.551020 Sub-carrier Separation (kHz) 11.2 Symbol Duration (Tb) (us) 100.8

66. IMA Summer Program on Wireless Communications 802.16 OFDMA Frequency Re-Use Frequency Re-Use Modes –Full Usage of Sub-channels (FUSC) (mandatory mode) All frequencies re-used in every sector of every cell (1/1, or full re-use) 2004/D5 Section 8.4.6.1.2.2 –Partial Usage of Sub-Channels (PUSC) (mandatory mode) Nominal 1/3 re-use pattern – used for FCH & DL Map signalling 2004/D5 Section 8.4.6.1.2.1 –Full Usage of Sub-Channels (FUSC) (optional mode) 2004/D5 Section 8.4.6.1.2.3 –Also, ‘adjacent’ or ‘AMC’ DL sub-channelisation mode 2004/D5 Section 8.4.6.3 Frequency (Logical Sub-channel Number) Segment 1 (Sector A) Segment 2 (Sector B) Segment 3 (Sector C) Note – Adjacent logical sub-channels are not necessarily adjacent in physical frequency domain.

67. IMA Summer Program on Wireless Communications Typical 802.16d/e TDD Frame Structure Key Elements –DL and UL maps indicate per burst data regions, modulation, coding etc. –DL bursts are arbitrary congruent blocks – uplink follow in sequence –Allocated regions for UL for random access, channel quality (CQI), ACK’s

68. IMA Summer Program on Wireless Communications Peak Data Rate Summary : Example Peak Data Rate Summary –Assumes 5MHz channel bandwidth – length-512 FFT –Assumes 802.16e/D3 mandatory DL FUSC sub-channelisation (Table 272c) –Assumes 70/30 DL/UL split DL Peak Data Rate Limitation –Is MSS restricted to 1 data region per frame, peak data rate is limited by maximum block size that can be signaled. –For H-ARQ mode, maximum block size is 24000 bits –Resulting user peak data rate = 4.8Mbps (5ms frame) QPSK 16-QAM 64-QAM BPSK

69. IMA Summer Program on Wireless Communications VoIP characteristics and requirements VoIP traffic –One packet every 20 ms (full, half, quarter, null) –Strict delay latency requirement (RF delay 70 ms in simulation) Outdated packets are dropped Outage should be less than 1% Scheduling and resource allocation for VoIP –Channel adaptive only (e.g. proportional fair) scheduler does not perform good –Multi user diversity gain is less for VoIP –Delay constraint must be included in the scheduler –Similar scheduler for NRTSV has been applied for VoIP and performs good VoIP packet is usually small, but requires high transmission reliability –Small Packet size should be supported –High R ratio (spreading gain * (1/coding rate)) should be supported –Channel diversity (e.g. multiple antenna) can significantly improve the coverage and capacity Ped-B/Veh-A has higher capacity than flat fading –Multiple user multiplexing is critical OFDMA: 32 users in every 5 ms per sector HSDPA: 4 users in every 2 ms per sector DO-A: 8 users in every 1.667 ms per sector

70. IMA Summer Program on Wireless Communications System Simulation Parameters ( 802.16e – DL)

71. IMA Summer Program on Wireless Communications System Simulation Parameters ( 802.16e – UL)

72. IMA Summer Program on Wireless Communications Scheduling and resource allocation Scheduling –Two major classes Frequency non-selective –PUSC, FUSC (Random/Interleaved) Frequency Selective –Band AMC (Contiguous) Resource allocation –Resource requests are satisfied according to user priority –Allocated resources are calculated based on CQI feedback and scheduled packet size Retransmission –Retransmission resources are determined according to the left-over information in a scheduled packet size

73. IMA Summer Program on Wireless Communications VoIP Performance (5 MHz, 50/50 DL/UL Split, FER<1%) Downlink Uplink

74. IMA Summer Program on Wireless Communications

75. VoIP Performance (5 MHz, 50/50 DL/UL Split, FER<2%) Downlink Uplink

76. IMA Summer Program on Wireless Communications 802.16e VoIP Delay Components

77. IMA Summer Program on Wireless Communications 802.16e VoIP RF Capacity: Conclusions VoIP capacity with one UE Rx antenna is ~200 Erlangs/sector for DL and ~ 80 Erlangs /sector for UL with a mobile-to-mobile delay bound of approx 240 ms (no SID) Capacity limited by RL Analysis very preliminary Performance will improve with frequency selective scheduling Effect of SID frames on VoIP capacity currently being studied

78. IMA Summer Program on Wireless Communications Summary of VoIP Performance over Broadband Wireless

79. IMA Summer Program on Wireless Communications FeaturesHRPD-AWCDMA- Rel 5/Rel6WCDMA- Rel-99802.16e Specturm Occupancy1.25 MHz (FDD)5 MHz (FDD) 5/10/20 MHz (TDD/FDD) Data shown for TDD mode only Chip rate or #sub-carriers1.2288 Mcps3.84 Mcps 512/1024/2048 F/L 3.1 Mbps13.97 Mbps1.92 Mbps 11/22/44 Mbps (TDD, 70% DL with 64-QAM and R=3/4 code) R/L 1.8 Mbps4.0 Mbps (Tentative)384 kbps 2.7/5.5/11 Mbps (TDD, 30% UL with 16-QAM and R=3/4) F/L 1.66662105 (TDD, 70% DL) R/L 6.662 and 10105 (TDD, 30% UL) F/L QPSK/8-PSK/16-QAMQPSK/16-QAMQPSKBPSK/QPSK/16-QAM/64-QAM R/L BPSK/QPSK/8-PSKBPSK/QPSKBPSKBPSK/QPSK/16-QAM/64-QAM (?) HARQ, IR, Chase, AMC Fast 4-channel HARQ stop-and- wait protocol on FL Fast 6-channel HARQ stop-and -wait protocol on FL No Fast HARQ stop-and -wait protocol on FL Tx Diversity at BTS Yes (open loop only)Yes (Open loop and Closed loop) Yes (Open loop and Closed loop) Yes (STBC and MIMO) Advanced ReceiverYes NoYes Adaptive Antenna SupportNoYes using Dedicated Pilots Yes using Dedicated Pilots Yes Multiple Access TD-CDMA (MAC multiplexing used on the FL) CDMA (Up to 4 users can be CDM'ed per TTI) CDMAMultiple users scheduled per TTI Enhanced broadcast Present: Plain broadcast using CDMA Proposal for OFDM based MBMS support is being discussed in 3GPP2) MBMS (Upto 256 kbps can be supported using selection/soft combining) NA MBMS (3 Mbps in 5 MHz using SFN) Max Data Rate per User w/o MIMO TTI Size (msec) Modulation

80. IMA Summer Program on Wireless Communications Broadband Access Technology VoIP Capacity Comparison