Probabilistic sleep interval decision method in wireless network

Abstract

In a wireless networks, power saving mechanism is essential to prolong the life time of mobile station because of the limited battery life of mobile station (MS). The most important component of PSM is the length of sleep interval, since it determines the performances of power-saving mode (PSM), such as energy consumption and transmission delay. Up to now, a pre-determined and fixed length of sleep interval has been used in practical wireless networks such as Wideband Code Division Multiple Access (W-CDMA) system, CDMA 2000 system, and Wireless LAN system. On the other hand, IEEE 802.16e Mobile WiMAX system adopts PSM based on a binary truncated exponent (BTE) algorithm for sleep interval determination. In this thesis, we suggest a new sleep interval determination method, which decides the length of sleep interval based on the probability distribution function (pdf) of next packets arrival. The main properties of the proposed probabilistic sleep interval decision (PSID) algorithm are discussed compared to those of the BTE algorithm. Two traffic patterns are considered to apply the proposed algorithm. One is TCP connection in slow-start phase and the other is conversational traffic using Voice over IP (VoIP). For the application of PSID algorithm to TCP connection in slow-start phase, we survey the distributions of packet arrival in TCP connection in slow-start phase considering round-trip time (RTT). Detailed PSID algorithm is described together with BTE algorithm. To evaluate the performances of these two algorithms, the theoretical frameworks for average delay caused by sleep intervals and energy consumption of an MS are provided. The numerical results show that the performance of PSID algorithm for the TCP connection in slow-start phase is better than that of BTE algorithm. In the case of application of PSID algorithm to conversational traffic, Brady model is adopted to model the behavior of bidirectional speech pattern. The pdf of length of mut...