Research On Key Techniques Of WiMAX MAC Layer

IEEE802.16standard known as WiMAX can provide30-mile coverage, and79Mbit/s transmission speed. WiMAX Wireless Network serves the field ofemergency communications of the electricity, petroleum, water conservancy, civilairport industry. Sleep mode and network resources (bandwidth and power) allocationstrategies are utilized to support mobility and high data transfer rate in WiMAX mediaaccess control (MAC) layer.In this paper, we focus on the key techniques of MAC layer——sleep mode andresources allocation strategies. The andvanced algorithms and methods are considedin detailed.Firstly, the sleep mode is utilized to reduce the energy consumption of the mobilestation and the resource occupation of the air interface of serving base station inWiMAX network. The practical sleep mode based on traffic is proposed to improvethe efficiency of energy saving. Simulations have been undertaken to verify theproposed scheme and analyze the effect of the threshold of counters on mean energyconsumption and mean response time. The simulation results show that, the proposedscheme compared with the standard method can save at least30%of energy.Secondly, the more andvanced algorithm with multi-counter is proposed. Theperformance of the method is evaluated based on the derivation of Markov’s analysismodel. Then, the relationship between the average energy consumption﹑averagedelivery latency and the threshold values of counters is investigated. Finally, thethreshold parameters configuration scheme of counter for different QoS connection ispresented. User’s work mode can be determined according to the user’s active leveland the frequent that user switch between wake mode and sleep mode can be reducedin the proposed scheme.Finally, we focus on resource allocation strategies. In this paper, a distributedresource allocation strategy with joint bandwidth and power allocation is proposed incase of relay and OFDMA techniques. Different resource allocation strategy based onthe maximization of the sum capacity of all user，the maximization of the worst usercapacity and the minimization of the total power consumption of all users respectivelyare presented to solve the problem of networks resource allocation. The optimalsolution of bandwidth and power allocation in each optimal model is offered by theconvex optimization algorithm. Simulation results show that the proposed strategy canimprove the system capacity and reduce the power consumption.