Research On The Algorithms Of Short-Range Radom Access

With the rapid development of wireless communication, the requirement ofcommunication quality has raised from originally passing simple message to communicatingwith high-quality, high-speed, diversification and access at any time. At present, long-rangeand middle-range wireless coverage solutions have been almost mature, and LTE technologyis becoming the core of the development in this field. Short-range and high-speed wirelesscommunication technology has provided satisfactory solutions,but for a shared networkowning intensive users, the existing programs still fail to take account of both transmissionefficiency and fairness effectively.The short-range wireless communication generally refers to wireless communicationtechnology in a smaller area of a few hundred meters, including802.11wireless LANstandards, Bluetooth, ZigBee and Ultra-broadband transmission etc. In these technologiesabove, the access protocol of medium access layer is a key factor of the system performance,so it has great significance to study the access algorithms of MAC layer in the field ofshort-range wireless communication.As short-range wireless communication network generally has the characters ofself-organization, temporality and simple topology etc, it’s common to use the method ofrandom access to content the channel. Unfortunately, random access contention always tendsto bring unfairess, besides, fierce contention in the scene of contentive access caused byintensive users would bring to the waste of resources, in the meanwhile, as the channelenvironment of short-range wireless communication is generally more stable, the problem ofQoS guarantee in MAC layer is always ignored, however, the contetion of the channel accesscan also have a negative impact on the transmission quality. To avoid excessive contention ofthe random access, enhance the fairness of the traffic access, and improve the quality ofservice, this paper proposes a new program about access control protocol, the performance ofwhich is analyzed in detail through network simulation.To solve the problems of short-range wireless communication access algorithm aboutback-off mechanism,this paper proposes new back-off algorithms on the basis of the802.11eEDCA,not only providing QoS guarantees but also maintaining network efficiency andfairness is proposed. Firstly, the algorithm classifies the transmission traffics according toreal-time demands, and traffics of different priorities adopt different back-off algorithmswhich can provide the QoS guarantees for high-priority traffic. Then, BEB algorithm has been improved, that is, the back-off process is divided into two stages named back-off counterlinear decrease and exponential decrease,as result, the calculation of the back-off threshold isoptimized, the value of which can better reflect the real network condition,achieve theback-off algorithm rapidly, and improve the network throughput as well. Finally, theintroduction of Most Successful Consecutive Transformation Times and Most SuccessfulConsecutive Transformation Times mechanisms simplifies the continuous transmission TXOPmechanism of EDCA, and improves the fairness of the network.