Adaptive Radio Resource Allocation Algorithms And Their Performances Analysis In IEEE 802.11n System

High data-rate,high reliable transmission and guarantee end-to-end QoS are the primary objectives of the next generation mobile communication system. Many technologies such as Multiple-input Multiple-output (MIMO), Orthogonal Frequency Division Multiplexing (OFDM) and Adaptive transmission and so on are adopted in IEEE802.11n system, therefore, the transmission rate is more than 100Mbps, even can reach up to 600Mbps. Meanwhile IEEE802.11n is backward compatible with IEEE802.11a/b/g and its capacity of resisting disturbance is enhanced, all of this can be able to meet the multimedia services and the high quality voice requirements. However, the wireless signal coverage is enlarged as well as the subscriber's mobile area is expanded.Base station, channel, transmitting power, bandwidth, code words, frequency, time slot and space angle and so on are included in the scope of the radio resources. Radio Resource Management (RRM) is the planning and scheduling for the air interface resources of the mobile communication system. It hopes to access as many subscribers as possible with limited radio resource as well as a certain planning coverage and service quality. The technology related to power control, channel allocation, access control, switch, load control and packet scheduling and other information. The goal of the RRM is to provide quality assurance for radio subscriber terminals under the limited bandwidth conditions. The basic starting point is to allocate and adjust the available resources flexibly and dynamically, improve the utilization of wireless spectrum, prevent the network congestion and maintain the signaling load as small as possible when the network business distribution is uneven or the channel characteristics are ever-changing.It aims to seek the methods to improve system capacity and reduce the transmission power by studying different adaptive bits and power allocation algorithms in IEEE802.11n system. Based on the adaptive MIMO-OFDM transmission model, the Water Filling (WF) theorem and the maximization of the harmonic mean signal-to-noise ratio algorithm (HARM) are analyzed and integrated after investigating their application limitations. A novel algorithm called First Water-filling Last HARM (FWLH) is proposed. At the same time, another study found that Campello algorithm allocates bits by using the idea of greedy algorithm and its adjustment step is 1, which lead to slower bit allocation and high computational complexity. Then adaptive variable step Campello algorithm is proposed. Finally, the single-bit emerging in the channels is processed.Simulation results show that the system capacity with FWLH algorithm is quite close to Water-filling algorithm and superior to HARM algorithm, furthermore, the system BER (Bit Error Ratio) with FWLH algorithm is about 100 times lower than that of with Water-filling algorithm and about 20 times lower than that of with HARM algorithm. However, the improved adaptive variable step Campello algorithm can increase the bits allocation speed and reduce the system computational effort, besides, it can maintain the original performance.