Power Consumption Study of Listening State in the 802.16e HSING MEI a , JIA-SHENG R. CHEN b , and YUAN-CHANG CHANG c a Department of Computer Science and Information Engineering Fu Jen Catholic University, Taiwan b Graduate Institute of Applied Science and Engineering Fu Jen Catholic University, Taiwan c Department of Electrical Engineering Lee-Ming Institute of Technology, Taiwan Abstract: - In this paper, we analytically study the power consumption of listening state and sleep state operations of IEEE 802.16e. A Mobile Station (MS) goes to sleep state for a pre-defined time, and wake up periodically to listening state to check if the Base Station (BS) has any buffered downlink traffic destined to itself. Although the listening interval is shorter than sleep interval, the power consumption should include both of listening state and sleep state operations. Our proposed model proves the listening state may consume up to 90% of the total power consumption in some case. Key-Words: - WiMAX, Power consumption, Listening state, Sleep mode, 802.16e. 1. Introduction With the mature of IEEE 802.11 wireless local area network (WLAN), we have the ability to access high speed internet connection at any location. But it does not have vehicle mobility function. During the past years, the mobile devices have become more popular, and people desire to have a ubiquitous internet access network. The Worldwide Interoperability for Microwave Access (WiMAX) [1] [2] has been designed for fixed and mobile broadband network through broadband radio access technology. It utilizes the Orthogonal Frequency Division Multiple Access (OFDMA) air interface, Adaptive Modulation and Coding (AMC) modulation and Multi-Input Multi-Output (MIMO) antenna technologies. Due to the high speed moving capability in WiMAX, the Mobile Station (MS) need to use battery as its major power source, and therefore the power management becomes a very important issue. From the hardware perspective, radio frequency (RF) module dominates the power consumption of MS, and how/when to turn off the RF module becomes the critical concern of power saving. For this reason, the 802.16e defines the sleep mode operation for the MS to extend battery lifetime. Sleep mode is a state in which an MS conducts pre-negotiated periods of absence from the Serving Base Station (BS) air interface. Under the 802.16e sleep mode operation, an MS starts to sleep for a fixed amount time, called initial-sleep window, and wakes up in order to listen if the BS has any buffered downlink traffic destined to itself. If there is no such traffic, MS adjusts the sleep window size and goes to sleep state again. Otherwise, it enters the awake mode. Sleep mode is intended to minimize MS power usage and decrease usage of Serving BS air interface resources. Implementation of sleep mode is optional for the MS and mandatory for the BS. There are three types of Power Saving Classes, which differ by their parameter sets, procedures of activation/deactivation, and policies of MS availability for data transmission. Power Saving Classes of type I is recommended for Best Effort (BE) and non-real-time variable rate (NRT-VR) type, Power Saving Class of type II for unsolicited grant service (UGS) and real-time variable rate (RT-VR), and Power Saving Class of type III for management operation and multicast connections, respectively. In the literature, Jang [3] presents a model to adapt the length of sleeping period according to the traffic statue. The authors in [4] evaluate the effect of initial sleep window, final sleep window and average interarrival time of MAC frame on the performance of power saving. Both of them do not count the power consumption of listening state. 12th WSEAS International Conference on COMMUNICATIONS, Heraklion, Greece, July 23-25, 2008 ISSN: 1790-5117 391 ISBN: 978-960-6766-84-8