1. Advanced Mechanisms for Sleep Mode Optimization of VoIP Traffic over IEEE 802.16m IEEE Globecom 2010 Ritesh K. Kalle, Maruti Gupta, Aran Bergman, Elad Levy, Shantidev Mohanty, Muthaiah Venkatachalam and Debabrata Das Speaker: Wun-Cheng Li

2. Outline Introduction Goal VoIP Specific Advanced Power Save Mechanisms ▫ Sub-frame level sleep operation ▫ Discrete Listening Window Extension (DLWE) ▫ Different sleep cycle configuration for active and inactive periods Simulation Conclusion 2

3. Introduction IEEE 802.16m standard provide VoIP traffic services over WiMAX channels. VoIP traffic is uniquely characterized by small packets sent regularly at periodic. 3

4. Introduction Power saving is a critical issue for mobile wireless devices ▫ Mobile devices are normally battery-operated In IEEE 802.16m, four power saving types are defined for different connections with the specific QoS requirement 4

5. Introduction Three IEEE 802.16e/m power saving classes 5 … T S_init 2 x T S_init TLTL (T S_max ) TLTL TSTS … TSTS normal operation sleep windows listening windows Type I : Type II : Type III :

6. Introduction Three IEEE 802.16m power saving classes ▫ Type IV 6

7. Introduction Opportunities for long idle time 7

8. Introduction A typical VoIP session is a two-way conversation characterized by silence and talk periods. 8 AB AB AB AB Talks Silent

9. Introduction A typical VoIP session is a two-way conversation characterized by silence and talk periods. ▫ Let P ij represent the probability of transition from state i to state j. 9

10. Goal The proposed VoIP Specific Advanced Power Saving Mechanisms reduces the average power consumption 10

11. VOIP Specific Advanced Power Save Mechanisms Sub-frame level sleep operation ▫ The MAP information is sent during every DL sub-frame ▫ MS has to remain awake for the entire duration of DL sub-frames 11 DL Subframe UL Subframe DL Sleep UL Sleep DL MAPHARQ FB Listening Window Sleeping Window UL VoIP DL:UL 4:4 subframes

12. VOIP Specific Advanced Power Save Mechanisms Sub-frame level sleep operation ▫ Limiting the MS to remain awake sub-frames  MAP information elements (IEs)  VoIP traffic  HARQ control 12 HARQ FBDL MAP UL VoIP Listening Window Sleeping Window DL:UL 4:4 subframes DL Subframe UL Subframe DL Sleep UL Sleep

13. VOIP Specific Advanced Power Save Mechanisms Discrete Listening Window Extension (DLWE) 13 DL MAPHARQ FB UL VoIP DL:UL 4:4 subframes DL Subframe UL Subframe DL Sleep UL Sleep NAK + DL MAP HARQ FB ACK + DL MAP UL HARQ Retx

14. VOIP Specific Advanced Power Save Mechanisms Different sleep cycle configuration for active and inactive periods ▫ Persistent allocation to reduce scheduling overhead which would reduce the activity period per frame to schedule the VoIP or SID packet. 14

15. Simulation MATLAB 15 Parameter Settings IEEE 802.16m Frame Time5 ms UL: DL ratio5:3 Max. no. of HARQ retransmissions (RTT =5 ms)4 VoIP codec AMR Total number of VoIP users 200 Length of AAI_SLP-REQ/ AAI_SLP-REQ 64/80 bits Length of SCH/SCEH 24 bits Total simulation time 2000 s

16. Simulation 16

17. Simulation 17

18. Simulation Sleep Cycle 18

19. Simulation Signaling Overhead 19

20. Conclusions This paper proposed novel mechanisms to substantially improve power savings for VoIP traffic in IEEE 802.16m. These mechanisms lead to power savings of up to 70% and can improve further with sleep cycle adaptation for mutual silence periods. 20

21. Thank you! 21