Performance evaluation for delay time estimation in IEEE 802.16m sleep mode

Frequent use of various mobile application services consumes a great amount of battery power in mobile devices. In order to satisfy user convenience and keep the portability of mobile devices, a power saving mechanism is essential for the success of mobile communication technologies. This paper evaluates performances of the power saving mechanism of IEEE 802.16m, one of the solutions for the fourth generation mobile communication technology. When a mobile device does not communicate with a base station, it temporarily shuts down communication-related modules and circuits in order to save the battery power. During that period, the device cannot listen to incoming traffic from the base station, which causes an inevitable delay at the expense of reducing power consumption. Arriving packets are transmitted only after the device enters either the awake mode or the listening window in the sleep mode. Four power saving mechanisms are examined in the simulation:1) fixed maximum operating parameters, 2) fixed minimum operating parameters, 3) moving average policy, and 4) exponential increase policy. To evaluate the performance of the sleep mode operation in IEEE 802.16m, an analytical model is developed for delay time based on M/D/1 queueing system. Performances of the power saving mechanisms are evaluated with Poisson and traffic models for five applications: WEB, FTP, GAME, VIDEO, and VOICE, which reflects real service environment.