A Link Distance Division Based Time Division Multiple Access Protocol for Directional Aeronautical Relay Networks

定向航空中继网络中一种基于链路距离分环的多址接入协议

School of Electronics and Information, Northwestern Polytechnical University, Xi'an 710072, China

Received: 12 January 2019

Abstract

In directional aeronautical relay networks, the airplane relay explores the advantages of the directional antenna, in terms of long transmission distance, low transmission power, small interference range and so on, to help the ground nodes transmitting data. However, data transmission delay extension problem occurs when the distance of the transmission link extends, where the wireless signal transmission time approximates the data transmission time such that the wireless signal transmission time cannot be omitted. To address the data transmission delay extension problem, a link distance division based time division multiple access protocol, LDD-TDMA, is proposed in this paper. Different from the traditional TDMA protocol, where the time slots are equal and are determined by the longest transmission link, the length of the time slots are different and are determined by different transmission links. Furthermore, the concept of communication coverage ring is proposed where the nodes located in the same ring communicate with the relay utilizing the same time slot length. The relationships between the number of rings, the ring radius and the transmission range of the LDD-TDMA are modelled and derived as a closed formula, where the ring radius are optimized such that the gain is maximized. Simulation results show that LDD-TDMA outperforms TDMA by 13.37% when the transmission range is 200 km and the ring number is 4.

摘要

在定向航空中继网络中，中继飞机利用定向天线通信距离远、发射功率小、无线信号干扰范围小等优点，辅助地面节点克服地形遮挡、信号衰弱大、通信距离受限等缺点，以较少的跳数进行通信，有效降低端到端数据传输时延、提高网络吞吐量。针对定向航空中继网络中由于通信链路长、无线信号传播时延与数据传输时延相近，所引起的通信时延扩展、多址接入协议效率低等问题，提出了一种基于通信链路距离进行分环的时分多址接入协议（link distance division based time division multiple access protocol，LDD-TDMA）。与传统的TDMA多址接入协议中所有链路均使用相同的时隙长度不同，LDD-TDMA根据通信链路的距离远近使用不同的时隙长度。进一步为了简化协议实现，提出通信覆盖范围分环的概念，使得处于同一个环内链路距离相近的节点使用相同的时隙长度。接着，建模分析并推导出了最大化多址接入效率的分环的个数、分环半径与节点最大通信距离之间的闭合表达式。最后，仿真结果表明，当中继飞机最大通信距离为200 km、分环个数为4时，LDD-TDMA的多址接入效率相较于传统的TDMA可提高13.37%。