Study On Key Techniques Of Channel Access In Distributed Wireless Communication System

In the last decades, the shortage of radio resource became increasingly seriouswhile wireless communication techniques are widely used. Strategies that aim toimprove spectrum efficiency are always hot research topics. The thesis focuses on thekey technologies of channel access in a novel system, Distributed WirelessCommunication System. Some new algorithms have been proposed to improvechannel utilization base on the system characteristic.The thesis analyzes the influence of architecture changing on system designingand system resource changing due do movement of mobiles. And an idea ofindependently processing channel allocation and antennas selection is proposed.After investigating the previous works on channel allocation strategies, a method,channel carrying, is proposed to utilize channel resource in the novel system. And thewhole problem can be decomposed into three parts, including Channel Selection,Access Control and Handoff Control. And then the thesis proposes an algorithm,named Dynamic Channel Allocation with Search the Farthest Channel. Thesimulation shows that compared with cellular based dynamic algorithms, theproposed algorithm can significantly reduce channel handoff frequency and handofffailure amount, and those result in system capacity improvement of the system.The thesis also designs a handoff control scheme, called Decision Delay HandoffControl. Compared with the scheme that makes decision based on current channelstatus, the novel scheme can avoid unnecessary channel handoff due to channelquality fluctuation caused by shadowing fading.Finally, the related algorithms are classified as two parts according to processingorder of Channel Selection and Access Control. Comparison and analysis are madeamong different algorithms with regard to their performance and cost. And thesimulation results demonstrate that system capacity can be improved at the expense ofsignal quality deterioration and the increasing of channel handoff amount andinformation exchange in the system.