Abstract:

Deterministic Adaptive Priority Network Access Delay （DAP-NAD） provides prior access for network nodes by using token ring. The First Station Number （FSN） of this algorithm goes forward one by one with the step of 1， introducing many empty slots within each Network Access Period （NAP）， so that channel resources were wasted. DAP-NAD-R algorithm was proposed to solve the above problem. Firstly， FSN step was modified from 1 to R to jump over the nodes that had got prior network access in previous NAP. Secondly， B slot was introduced to meet the communication requirement of nodes being jumped over. In specific， those nodes were able to send an emergent short frame to stop the corresponding jump. Finally， the fact is that multicast communication is a typical application of combat network radio. To make prior access for multicast source node， DAP-NAD-R algorithm was further modified. In this way， the multicast source node was able to also send the emergent short frame in B slot， and after nodes of each station receiving the short frame， network access opportunity was transferred to the multicast source node at first. Simulation results show that compared with DAP-NAD-R algorithm， the modified algorithm for multicast decreases the End-To-End delay （ETE） and the lost rate of voice packet by 10% and 15%， respectively. DAP-NAD-R algorithm and its modified algorithm are suitable for combat network radio with simultaneous voice and data transmission， decreasing the delay for data packet with high priority and the lost rate of voice packet significantly， so as to increases the efficiency of multicast communications.

Key words: MIL-STD 188-220 protocol, multicast, Deterministic Adaptive Priority Network Access Delay (DAP-NAD), Medium Access Control (MAC), simultaneous voice and data transmission

摘要：

确定性自适应优先级网络接入延时（DAP-NAD）采用令牌环的方式为网络节点提供优先接入。该算法的首站号（FSN）以步长为1递进，每个网络接入周期（NAP）中会引入较多空闲时隙，造成信道资源的浪费。针对此问题，提出DAP-NAD-R算法。首先，把FSN的步长调整为R，从而跳过前一个NAP中已经被提供优先网络接入机会的节点；其次，为了兼顾被跨越节点的通信需求，即引入B时隙允许被跨越节点发送紧急短帧以阻止本次跨越；最后，多播通信是战斗无线电网的典型应用，而为了照顾多播源节点的优先接入，进一步改进DAP-NAD-R算法，从而允许多播源节点有高优先级信息时也可以在B时隙里发出紧急短帧，而各站点收到该短帧后，网络接入机会会先交给多播源节点。仿真实验结果表明，相较于DAP-NAD-R算法，多播改进算法的话音分组的端到端延时（ETE）和丢包率分别降低了10%和15%。DAP-NAD-R算法及其改进算法适用于数话同传的战斗无线电网，能显著降低高优先级数据分组的延时和话音分组的丢包率，从而提高多播的通信效率。

关键词: MIL-STD 188-220协议, 多播, 确定性自适应优先级网络接入延时, 媒体接入控制, 数话同传