Joint Design of Routing and Power Control Over Unreliable Links in Multi-Hop Wireless Networks With Energy-Delay Tradeoff

Energy consumption and delay in end-to-end transmission, two significant cost metrics for guiding the design of routing protocols, are often relevant and even conflicting with each other. Therefore, it naturally becomes important to identify the tradeoff between them. In this paper, we investigate the joint design of routing and power control over unreliable communication links in multi-hop wireless networks with energy-delay tradeoff. Two popular retransmission schemes, hop-by-hop (HBH) scheme and end-to-end (E2E) scheme, are adopted to achieve the reliable transmissions over unreliable links. We model the process of packet transmission in HBH or E2E scheme as a random walk and then calculate the expected energy consumption and the expected delay needed to forward a packet. An expected cost function is defined to capture the tradeoff between energy consumption and delay. Due to the correlation between cost function and transmit power assigned on each link, power control technique is necessary to be integrated into the minimum expected cost routing (MECR) for each retransmission scheme. We prove that the optimal power assignment for each link in a candidate path, which minimizes the expected cost for packet transmission, uniquely exists. Then, the MECR algorithms are proposed for both HBH scheme and E2E scheme to find the optimal routing paths. Simulations illustrate that our proposed protocols not only attain the tradeoff between energy consumption and delay, but also outperform the existing protocols in terms of energy-efficiency and delay.