Study On Random Multiple Access Technology By Distributed Queuing With Priority

The ALOHA protocol is widely used in various low power wide area network(LPWAN)technologies,including random multiple access such as Lo Ra and Sigfox,as well as initial random access and connection requests of LTE narrowband internet of things(NB-IOT)terminals.It does not limit the access time of terminals to access the shared channel.There is a high collision probability,and its throughput performance shows an unstable trend with the increase of load.The distributed queuing(DQ)technology using the time division structure has relatively stable system throughput performance,and can realize data contention-free transmission through scheduling.This thesis based on DQs tudies the technical extension of priority terminal access.This thesis firstly discusses the technical characteristics and types of wireless access network,random multiple access protocol and the working mechanism of DQ.According to the access requirement of high-priority end-device,DQ with priority(DQ-P)is extended and designed,and the shared channel contention resolution algorithm,the workflow of terminals and coordinator stations,and the typical sequence of distributed scheduling are given.Secondly,for the back-off process of the contention resolution queue,depth-first is selected as the back-off tree traversal method to reduce the transmission overhead.The contention resolution time is analyzed by using the state transition method,and the iterative calculation expression is given.Finally,the system throughput,delay and energy consumption are analyzed by numerical simulation.It was found that when the proportion of high-priority terminals was low,the system throughput and energy efficiency decreased slightly.Compared with ordinary end-device,the access delay of high-priority end-device was significantly reduced,with a maximum of about 65%.