System Modeling And Performance Analysis Of Power Saving Class Of Type Ⅱ In IEEE 802.16e

To improve the energy efficiency of the mobile station, in wireless broadband metropolitan area network, IEEE 802.16e standard propose three kinds of sleep modes. In this paper, we study power saving class of type Ⅱ, which is recommended for Unsolicited Grant Service (UGS) and Real-Time Variable Rate (RT-VR) traffics in modern wireless network.Firstly, according to the work principle of the conventional power saving class of type Ⅱ, the time period before transmitting data frames in the listen window is seen as an awake-delay, and the time period for transmitting data frames is seen as a busy period, a multiple vacation queueing model with an awake-delay is built. The formula for the average response time of data frames is given. The time period for transmitting data frames in the listen window is seen as a special vacation, a multiple vacation queueing model with two kinds of vacation mechanisms, during one of the vacation mechanisms, some data frames could be transmitted. The performance measures for the conventional power saving class of type Ⅱ are given.Secondly, in order to avoid frequent switches between the awake state and the sleep state, we introduce a sleep-delay mechanism into the conventional power saving class of type II, and propose an enhanced power saving class of type Ⅱ. Based on the multiple vacation queueing models used in the conventional power saving class of type Ⅱ, we built two multiple vacation queueing models with vacation-delay. The performance measures for the enhanced power saving class of type Ⅱ are given.Finally, considering the energy saving ratio, the system handover and the average response time of data frames, two different cost functions are built to describe the conventional power saving class of type Ⅱ and the enhanced power saving class of type II, respectively. The optimal value for the sleep window size is given. With numerical results, the influence of the system load on the system performance is numerically evaluated, and the validity of the enhanced power saving class of type Ⅱ is verified.