带有时间约束的机载自组网自适应退避算法  

An Adaptive Backoff Algorithm with Time Constraint for Airborne Ad hoc Networks

作　　者：赵玮[1] 郑博[1] 张衡阳[1] 刘炜伦 ZHAO Wei;ZHENG Bo;ZHANG Hengyang;LIU Weilun(Information and Navigation College,Air Force Engineering University,Xi’an 710077,China)

机构地区：[1]空军工程大学信息与导航学院,西安710077

出　　处：《西安交通大学学报》2018年第4期158-164,共7页Journal of Xi'an Jiaotong University

基　　金：国家自然科学基金资助项目(61202490);航空科学基金资助项目(20161996010;20150896010)

摘　　要：针对传统媒质接入控制(MAC)层退避算法无法满足机载自组网中高优先级业务高可靠、低时延的QoS传输需求,以及重负载时算法性能下降严重的问题,提出一种带有时间约束的多优先级自适应退避算法。首先,针对不同优先级业务的QoS需求,建立相应的时间约束机制和竞争窗口自适应调整机制,当网络处于重负载时,通过限制低优先级业务接入信道来保证高优先级业务的传输;其次采用三维马尔科夫链对多优先级自适应退避算法进行建模,求解不同网络负载时各优先级分组受时间约束条件下的退避状态转移概率,理论推导出网络吞吐量和平均MAC时延的数学表达式。仿真结果表明,该算法在重负载时能够有效保障高优先级业务低时延(<2ms)、高可靠(>99%)的QoS需求,相比增强型分布式信道接入访问和区分企业优先级的自适应退避算法,当网络负载大于9 000包/s时,吞吐量分别提升了33.4%和21.5%。A multipriority adaptive backoff algorithm with tolerable time constraint is proposed to solve the problems that the traditional medium access control(MAC)backoff algorithms cannot meet the demands of high reliability and low latency for high priority traffic in airborne Ad hoc networks and their performances are poor under heavy load.This algorithm introduces the time constraint mechanism and adaptive contention window for each service through considering different QoS requirements for different services.The mechanism guarantees the transmission of high priority service by confining the access of the low priority service when the network is in heavy load.Moreover,the 3-D Markov chain is adopted to model the algorithm.The backoff state transfer probability of different services with time constraint conditions is obtained in various network loads,and the mathematical expressions of average throughput and average MAC delay are derived.Simulation results show that the proposed algorithm effectively guarantees the low latency(<2 ms)and high reliability(>99%)QoS demand for high priority in heavy loads,and comparisons with enhanced distributed channel access and priority adaptive backoff algorithms show that the throughput is improved by 33%and 21.5%when the load is greater than 9 000 packets/s,respectively.

关 键 词：机载自组网 时间约束 自适应 退避算法 马尔科夫链 

分 类 号：TP393[自动化与计算机技术—计算机应用技术]