Effects of Delay Constraints on Multihop Networks Using Rateless Codes

When a message is forwarded through a network, a node will have multiple opportunities to reliably receive the message and cooperate in transmission. However, the transmit power of each node in a network is limited and so is the transmission range. Therefore, multihop transmission is a potential technique to deliver the data over large distances. Rateless code properties ideally suit decode and forward based relaying strategies as it improves the outage and bandwidth efficiency. In decode and forward based multihop networks, the messages are decoded and relayed over sequential point-to-point communication links. In a conventional multihop network, the intermediate nodes will have to wait indefinitely to correctly decode the information. To quantify the impact of this unknown waiting time, this paper analyses the performance of a multihop network with strict delay constraints. The average packet loss for such a network is obtained as a function of the total delay. By optimizing the total delay based on the performance across each links, the average packet loss can be minimized.