Research On Wireless Network Adaptive And Exponential Backoff Alogrithm

With the continuous development of the Internet and wireless communicationtechnology, WLAN has been increasingly applied to everyday life, which has become animportant communication way to people work and learn. IEEE802.1l standard hasbecome one of the most widely used standards and accelerated the development of WLAN.Although the IEEE802.11standard supports multiple data rates to transmission, due toinstability (e.g., signal attenuation due to distance, the transmission frames have acollision, and the interference from other sources) of the wireless medium. So, with the802.11wireless networks is widely used, how to select the best data transmission rates andimprove throughput according to channel quality conditions within a specific time is a keytopic of current research.First, we proposes a new rate adaptation method based on the IEEE802.11,it useautomatic threshold and recipient and the sender feedback mechanisms to decide the rate,the method called Threshold Mutual Feedback (TMutfed). In TMutfed, the recipient andthe sender to work closely with each others, receiver records all the received frames signalenergy from the sender, sent the feedback information to sender timely.Feedback messageinclude the propagation rate of recipient suggsting in the current channel, the sender canaccept or reject the proposal. Simply, transmitter reduce the transmission rates is admittingor not by the receiver, the feedback information from one side of the other party to acceptis determined by the TMutfed.Secondly, in order to increase the throughput of the network, reduce the collisionproduced, through the study of Markov chain model for IEEE802.11DCF mode find thatthe widely used binary backoff algorithm exists the many problems, because time slots isnot uniform distributed,which making the collision probability increases and systemthroughput degradation.In view of these problems, a segmented binary exponentialbackoff algorithm(SBEB) is proposed, and its essence to decresing the collision probablityof the stations, achieving the goal that uniform distribution by backoff counter selectbackoff number. Finally, using MATLAB to design and implement adaptive rate algorithm and binaryexponential backoff algorithm, tset and verity the above simulation algorithm,theexperiments result show that the use this method can effectively improve the throughputand reduce the number of retransmissions experiments to improve the efficiency of thenetwork.