卫星物联网中ZigZag-IRSA随机接入方案

ZigZag-IRSA random access scheme in IoT-oriented satellite networks

针对高负载下卫星物联网中随机接入碰撞环路的急剧增加而引起的吞吐量严重恶化问题,提出了基于之字形译码的分段非规则重复时隙ALOHA随机接入协议。在该协议中,通过调制编码技术缩短数据包分组的长度,并设计基于分段的帧结构,从而形成时隙内不同的分组映射模式。在接收端,当数据包级的连续干扰消除过程结束后,通过将用户分组副本视为重传,以进行用户分组段级的之字形译码来消除碰撞环路中分组的子段,同时组合成功译码的子段来恢复碰撞环路中的用户分组。采用密度演化对性能进行了分析。相对于传统的随机接入协议,度分布优化后的所提协议在丢包率和吞吐量均有显著提升,尤其吞吐量相比非规则重复时隙ALOHA提升了270%,能有效地解决高负载下的碰撞冲突问题,因此可以工作于大容量设备的卫星物联网中。

The throughput performance of random access(RA)in internet of things(IoT)-oriented satellite networks deteriorates seriously under a high traffic load as collision loops radically increase.To further improve the throughput,a ZigZag decoding based segmented irregular slotted ALOHA(IRSA)RA protocol is proposed.In this protocol,we shorten the length of the packet by utilizing modulation and coding techniques and design segment-level based frame format;thus,the different packet mapping modes are formed in the same timeslot.At the receiver,after the packet-level successive interference cancellation,by considering replicas as retransmitted packets,collided segments of collision loops are cancelled by the segment-level ZigZag decoder and the whole packet can be recovered by combining the successfully decoded segments.The performance of the proposed scheme is analyzed through the density evolution analysis.Compared with traditional RA protocols,the proposed protocol optimized by degree distribution has significantly improved the packet loss rate and throughput,and especially the throughput is 270%better than that of the IRSA.The proposed protocol can effectively solve the collision problem under a high traffic load,so it can work effectively in the IoT-oriented satellite networks with massive IoT devices.