Research And Improvement Of Sleep Mode In IEEE802.16e

Wireless Metropolitan Area Networks (Wireless MAN) is emerging as a highly promising Broadband Wireless Access (BWA) technology to provide high-speed, high-bandwidth and high-capacity multimedia services. On 7, Dec. 2005, IEEE released the latest version IEEE 802.16e (MBWA) enhancing the original standard with mobility, targeting at the service provision to the Mobile Subscriber Stations (MSSs) that can move during services. As an enhancement to IEEE802.16-2004, IEEE802.16e support fixed and mobile services for both enterprise and consumer markets. It will fill the gap between very high data rate wireless local area network and very high mobility cellular system.But, due to the promising mobility capacity in IEEE802.16e, MS will be severely constrained by battery capacity. The mechanism which can effectively manage the limited energy is an important component for the standard of IEEE802.16e. In order to manage the limited energy effectly, the sleep mode mechanism is introduced. Sleep mode is a state in which an MS conducts prenegotiated periods of absence from the Serving BS air interface. Observed from the Serving BS, these periods are characterized by the unavailability of the MS to downlink and uplink traffic. The sleep mode can minimize the MS power consumption and decrease usage of the Serving BS air interface resources.This paper firstly introduce Wimax standard specifications, then focus on the description of sleep mode operation and performance analysis of sleep mode key parameters, at last give some improved idea .My work is described as follows:1. This paper characterizes the standardized sleep mode in IEEE802.16e and gives a model based on the hyper-Erlang for an extensive analysis of the energy consumption and packet delay. Through the simulation we can see the performance of the energy consumption and packet delay. At last we study the impact of key parameters on the performance. 2. This paper firstly gives an analysis of energy consumption and delay performance about two modes. Then we give a sleep mode selection algorithm to meet the requirement of energy consumption and delay performance by using the Markov Decision Processes. We highlight the trade-offs between energy consumption and delay performance among different operational modes. Through the simulation we can see the performance of this selection algorithm.3. This paper proposes an improved sleep mode control algorithm, which adjusts adaptively the sleep mode interval according to the traffic rate. Then we compare the 802.16e standard algorithm and the improved algorithm under four actual models. It has been observed that our proposed algorithm for sleep mode saves substantial amount of energy at lower traffic and almost same at higher traffic as compared to 802.16e.4. This paper analyzes the power consumption and the delay of IEEE802.16e sleep mode operation with a theoretical Markov chain model. The analytical results show that there is a tradeoff between the power consumption and the delay, and the key of the tradeoff is the initial sleep window. Then we present an adaptive algorithm to adjust the initial sleep window dynamically according to the traffic load. Through the simulation we can see the proposed algorithm can improve the power consumption up to 20% compared to the IEEE802.16e standard, the price is just little increase of the delay.5. This paper characterizes the standardized sleep mode in IEEE802.16e, and then we give an improved mechanism based on variable sleep interval power and compare with the standard mechanism under four actual models. Through the simulation we can see the performance of the improved mechanism is better than the standard mechanism in power saving, at last we study the impact of key parameters on the improved mechanism performance.