Performance analysis of multi-hop token relay strategy in HF networks

High frequency (HF) tactical link is one of the most widely used types of long-range telecommunication. Media access control (MAC) protocols play a pivotal role in HF network management by affecting data transmission. STANAG 5066 in its 3rd edition recommends HF wireless token ring protocol (HFWTRP) as a MAC protocol with some features dedicated to HF networks. To deal with temporary link interruption as a natural specification in the HF channel, relay strategy in HFWTRP is proposed to provide better throughput under this situation. Even though one-hop relay is considered in STANAG, multi-hop relay can retain throughput in more link outages when there are mobile nodes or variable environment like weather changes. Based on the algorithm of the relay in STANAG, a loop in multi-hop relay should be found which can be a detrimental effect on the network and can be solved by adding some bits as relay controller in management frame of HFWTRP. This paper presents a proper evaluation on effect of one-hope relay in the quality of service of HF networks. Additionally, two-hope relay in the HFWTRP based on the proposed solution for loop creation are simulated and analysed too. The results obtained by NS3 simulator show that two-hop relay in long duration of link outages like 90% probability of disconnection gives 700 bps more throughput with acceptable mean delay vs one-hop relay.