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Hybrid Power Saving Mechanism for VoIP Services with Silence Suppression in IEEE 802.16e Systems. Hyun-Ho Choi, Jung-Ryun Lee, and Dong-Ho Cho IEEE Communications Letters Volume 11, Issue 5, May 2007 Page(s):455 - 457. Outline. Introduction Proposed Hybrid Power Saving Mechanism
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Hybrid Power Saving Mechanism for VoIP Services with Silence Suppression in IEEE 802.16e Systems Hyun-Ho Choi, Jung-Ryun Lee, and Dong-Ho Cho IEEE Communications Letters Volume 11, Issue 5, May 2007 Page(s):455 - 457
Outline • Introduction • Proposed Hybrid Power Saving Mechanism • Numerical Analysis • Simulation Results • Conclusion
Introduction • IEEE 802.16e (mobile WiMAX) is targeting for Mobile Subscriber Stations (MSSs) • To efficiently manage energy in IEEE 802.16e systems • Sleep-mode operation
Power saving classes (PSCs) • PSC I is used for nonreal-time traffic with bursty behavior • PSC II is designed for real-time traffic, such as VoIP services • Enhanced voice codecs, can use a silence suppression scheme • It is known that silent periods occupy about 60 percent of the total duration of a VoIP call
The overview of the IEEE 802.16e power management (PSC I) 2n until reach its Tmax Fixed size
The overview of the IEEE 802.16e power management (PSC II) Fixed length BS Tk-1 MSs L L L L Sleep mode
When some data to transmit in IEEE 802.16e sleep mode SDU transmission a SDU want to transmit interarrival time TI Response delay BS MOB-TRF-IND MOB-TRF-IND Data Data Data Tk-1 Tk MSs awake mode L L BS MOB-TRF-IND Request Data Data Data Tk-1 Tk MSs awake mode L a SDU want to transmit
Hybrid Power Saving Mechanism Silence Insertion Descriptor (SID) frame
Sleep Interval • PSC I • PSC II • The MS sleeps during a sleep interval with fixed size TS Ti: the length of the i-th sleep interval Tmax: a maximum sleep cycle TP: a minimum sleep cycle TL: listening interval with fixed size
Numerical Analysis • Brady proposed a general six-state model that provides good statistical analysis of two-way conversation 19%
Numerical Analysis • Each MAC SDU is assumed to arrive at an MSS with Poisson process with rate λ (MAC SDUs per unit of time) • 1/λ, equal to TI M: the value of k when Tk= Tmax
Numerical Analysis (cont.) • The probability that there is a arriving SDU during t • At least one arriving MAC SDU in wi sleep cycle
Numerical Analysis (cont.) • The average duration of PSC I • The average buffering delay
Energy Consumption • The energy consumption per unit time in PSC I • The energy consumption per unit time in PSC II
Simulation Results • the frame length is 5 ms • TP=4 frames, TS=3 frames, TL=1 frame, ES=0.045 W, EL=1.5 W • VoIP end-to-end delay requirement: 270 ms • delay constraint: 88 ms • We change the value of Tmaxfrom 4 to 1024
Conclusion • the proposed HPSM can result • energy being saved by up to 20%, • maintaining a low drop probability of less than 1.9% • The results can be used to select an appropriate value of Tmax according to the various delay constraints to current IEEE 802.16e systems.