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Performance Analysis of Scheduling Algorithms for VoIP Services in IEEE 802.16e Systems

Performance Analysis of Scheduling Algorithms for VoIP Services in IEEE 802.16e Systems. Advisor: Dr. Kai-Wei Ke Speaker: Jaw-Woei Ma Date:11/28/2006. Outline. Introduce Scheduling algorithms Analysis of Resource Utilization Efficiency Analysis of VoIP capacity Conclusions References.

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Performance Analysis of Scheduling Algorithms for VoIP Services in IEEE 802.16e Systems

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  1. Performance Analysis of Scheduling Algorithms for VoIP Services in IEEE 802.16e Systems Advisor: Dr. Kai-Wei Ke Speaker: Jaw-Woei Ma Date:11/28/2006

  2. Outline • Introduce • Scheduling algorithms • Analysis of Resource Utilization Efficiency • Analysis of VoIP capacity • Conclusions • References

  3. Outline • Introduce • Scheduling algorithms • Analysis of Resource Utilization Efficiency • Analysis of VoIP capacity • Conclusions • References

  4. WiMAX • Worldwide Interoperability for Microwave Access(全球微波存取互通性) • A wireless broadband network connection technique. • the last mile. • Cost saving. • Easy to employ

  5. WiMAX

  6. WiMAX • Bandwidth:134Mbps, 300kbps~2Mbps (末端用戶) • Range:48km • Fixed : IEEE 802.16-2004 • Mobile : IEEE 802.16e

  7. Outline • Introduce • Scheduling algorithms • Analysis of Resource Utilization Efficiency • Analysis of VoIP capacity • Conclusions • References

  8. Service class • UGS (Unsolicited Grant Service) : VoIP • rtPS (real-time Polling Service) : MPEG • nrtPS (non-realtime Polling Service) : FTP • BE (Best Effort) : HTTP • ertPS (extended real-time Polling Service) : VoIP (IEEE 802.16e)

  9. Service class • Non-real time Service : nrtPS BE • Real time Service : UGS rtPS ertPS nrtPS and BE are not suitable for VoIP service in IEEE 802.16e systems

  10. Voice Traffic • Markov source model • Enhanced Variable Rate Codec (EVRC) frame duration (Tvc) = 20ms • Voice activity factor = 0.403 • Talk-spurt duration ( 29% Rate 1,4% Rate ½ ,7% Rate ¼ ) • Silence duration ( 60% Rate 1/8 )

  11. Voice Traffic

  12. UGS Algorithm • Generate fixed-size data packets periodically • BS periodically assigns Fixed-size grants to the voice users • The grants size and grants period are negotiated in the initialization process of the voice session

  13. UGS Algorithm

  14. UGS Algorithm • Minimize MAC overhead and uplink access delay • The waste of uplink resources

  15. rtPS Algorithm • Generate variable-size data packets periodically • BS assigns uplink resources that are sufficient for unicast bandwidth request • The grants period are negotiated in the initialization process of the voice session ( bandwidth request process or polling process)

  16. rtPS Algorithm

  17. rtPS Algorithm • More efficiently than UGS • Lager MAC overhead and access delay than UGS and ertPS

  18. ertPS Algorithm • Generate variable-size data packets on a periodically basis • The size of a voice data packet is decreased : Grant Management subheader increased : Bandwidth request header

  19. ertPS Algorithm • The size of data is decreased : using extended PBR (PiggyBack Request) bits of Grant Management subheader • BS assigns uplink resources according to the requested size periodically, until user requests another size of the bandwidth

  20. ertPS Algorithm • The size of data is increased : using BR (Bandwidth Request) bits of Bandwidth request header • BS assigns uplink resources according to the requested size periodically, until user requests another size of the bandwidth

  21. ertPS Algorithm • First bandwidth Allocation the next MAC frame after this bandwidth request process • Second bandwidth Allocation after the bandwidth allocation interval of service flow based on time

  22. ertPS Algorithm

  23. ertPS Algorithm • Reduce MAC overhead and acess delay of the rtPS • Prevent the waste of uplink resources of the UGS

  24. Outline • Introduce • Scheduling algorithms • Analysis of Resource Utilization Efficiency • Analysis of VoIP capacity • Conclusions • References

  25. Resource Utilization Efficiency • UGS algorithm : MAC header ( L h , 6 bytes)

  26. Resource Utilization Efficiency • rtPS algorithm :assume a min polling size ( L1/8 + Lbh ) Lbh : request header : 6 bytes

  27. Resource Utilization Efficiency • ertPS algorithm :

  28. Resource Utilization Efficiency

  29. Resource Utilization Efficiency • Frame Structure

  30. Preamble Broadcast Control DIUC = 0 TDM DIUC a TDM DIUC a TDM DIUC a Preamble DL_MAP UL_MAP Transition Gap Resource Utilization Efficiency • Downlink Subframe

  31. Resource Utilization Efficiency • Size of UL-MAP message is 36 bits ( 4.5bytes ) • UL-MAP message use very robust burst profile (QPSK modulation and 1/12 coding) • When M users use only VoIP Services in one MAC frame, the UGS and ertPS can save (36*M) bits of downlink resources compared with the rtPS

  32. Resource Utilization Efficiency

  33. Resource Utilization Efficiency • OFDMA Systems • One basic resource unit consists of 48 subcarriers • Voices packet are transmitted by QPSK ½ • UL-MAP are transmitted by QPSK 1/12

  34. Resource Utilization Efficiency

  35. Resource Utilization Efficiency • The total number of wasted resources in the rtPS is larger than that of the UGS • ertPS can save a lot of uplink and downlink resources

  36. Outline • Introduce • Scheduling algorithms • Analysis of Resource Utilization Efficiency • Analysis of VoIP capacity • Conclusions • References

  37. Analysis of VoIP capacity • VoIP capacity is restricted by packet transmission delay bound and radio resource saturation • Analyze packet transmission delay of MAC SDUs (Service Data Units) for the UGS, rtPS and ertPS

  38. Analysis of VoIP capacity • Using OPNET simulator • OFDMA Systems 36 Symbols (Time Domain) 1024 subcarriers (Frequency Domain) downlink : uplink = 2 : 1

  39. Analysis of VoIP capacity • Total number of downlink and uplink resources are 384 and 140 one resource unit consists of 48 subcarries downlink / uplink resources are scheduled by RR ( round-robin )

  40. Analysis of VoIP capacity

  41. Analysis of VoIP capacity • Delay bound is 60 ms, the max supportable number: UGS : 68 / rtPS : 76 / ertPS : 92 • ertPS can support more 21% : UGS / 35% : rtPS

  42. Outline • Introduce • Scheduling algorithms • Analysis of Resource Utilization Efficiency • Analysis of VoIP capacity • Conclusions • References

  43. Conclusions • ertPS can solve these problems of the UGS and rtPS UGS : waste of uplink resources rtPS : MAC overhead and access delay • VoIP capacity : ertPS > UGS > rtPS

  44. Conclusions • ertPS could be used efficiently in any wireless communication systems that support VoIP services with variable data rates and slience suppression

  45. References [1] Howon Lee, Taesoo Kwon, Dong-Ho Cho, Geunhwi Lim and Yong Chang“Performance Analysis of Scheduling Algorithms for VoIP Services in IEEE 802.16e Systems” Vehicular Technology Conference, 2006. VTC 2006-Spring. IEEE 63rd [2] IEEE 802.16 standard [3] IEEE 802.16e

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