无人机自组网中基于优先级和发送概率的低时延MAC协议设计

Design of Low Latency MAC Protocol Based on Priority and Transmission Probability in UAV Ad-hoc Network

媒体接入控制(MAC)协议是满足数据传输质量服务需求的一项关键技术,其性能的优劣直接决定了网络的整体运行效率。相较于其他经典MAC协议,基于统计优先级的多址接入(SPMA)协议采用了多优先级接入、信道检测和流量控制等机制,因此它能更好地满足无人机自组网的低时延、区分服务、大规模组网等重要需求。其中,不同优先级阈值是影响该协议性能的关键指标之一,而现有研究中的阈值设置策略会导致无人机自组网吞吐量波动较大的问题。除此之外,在大规模节点组网的情况下,由于特殊的发送机制,该协议面临数据包冲突加剧的问题。针对以上问题,本文提出了一种新的阈值设置方法和低优先级数据概率性接入信道的方法。在大规模节点网络高业务量的情况下,该改进策略根据新的阈值和周期性负载统计的比较结果决定是否延迟或者拒绝相关数据的接入。与此同时,将SPMA协议的多优先级接入机制和排队论基本原理相结合,通过计算设定发送概率对不同低优先级数据进行接入控制。仿真结果表明,所提方法能够使得无人机自组网的吞吐量保持稳定,并为不同类型业务的差异性服务质量(QoS)需求提供良好支持,提高不同优先级数据的首发传输成功率的同时不会带来较大的额外时延损耗,性能优于现有的SPMA协议。

Unmanned Aerial Vehicle(UAV)ad-hoc networks feature dynamic topology,self-organization,and multi-hop routing.The Media Access Control(MAC)protocol outlines how nodes can efficiently transmit data while utilizing limited channel resources.It is an important technology for satisfying data transmission quality of service requirements,and its performance directly determines the operational efficiency of UAV ad-hoc networks.Design optimization of pro-tocols is critical to enhancing the stability and reliability of UAV ad-hoc networks.Compared with other classical MAC protocols,the Statistical Priority-Based Multiple Access(SPMA)protocol uses mechanisms such as multi-priority ac-cess,channel detection,and flow control.Therefore,it can better meet the requirements of UAV ad-hoc networks with low latency,differentiated services,and large-scale connectivity.However,this protocol faces the problem of increased packet collisions in the case of high bursts and high loads of network traffic.Therefore,this paper introduces a new threshold-setting method and probabilistic access control for low-priority data.In the case of high network traffic,the proposed method decides whether to delay or deny access to the service based on the comparison results of the new threshold value and periodic load statistics.Meanwhile,the access control of different low-priority data was conducted by calculating their transmission probabilities.Simulation results verify that the proposed method can maintain a more stable throughput of UAV ad-hoc networks and support better differentiated Quality of Service(QoS)requirements for different types of services,compared to the existing SPMA protocol.However,there are still some shortcomings,and future research can consider the following aspects:1)Priority threshold setting strategy in multi-hop scenarios.The cur-rent threshold studies are all proposed based on all-pass network scenarios,and dynamically adjusting the priority thresh-olds in multi-hop scenarios can improve the data transmission performance.2)Considering external interference and to-pology changes,adjusting the access strategy of the protocols according to the environmental changes,and more fully utilizing the prioritized channel resources.