Energy Efficiency in Multihop Wireless Networks with Unreliable Links

Due to the increasing number of wireless devices, the issue of energy efficiency that requires high data rate with reliability has spawned tremendous research interests in recent years. In wireless networks, a major problem that needs to be addressed is that multihop transmission, though requiring lower transmit power, incurs more circuit energy consumption than that of single-hop transmission and leads to more bit errors. Thus we are motivated to study the energy efficiency of multihop wireless networks with unreliable links, where such a problem is even more serious. Specifically, with a flat Rayleigh fading channel, our network model jointly considers the transmit energy and circuit energy, and characterizes the unreliability caused by the wireless nature with the assumption of probabilistic links. Based on that, we formulate our problems of energy consumption normalized by the source-destination (S-D) path loss, and derive the optimal set of signal-to-noise ratios in each hop to minimize the normalized energy consumption. In addition, our theoretical results exhibit a clear relation between the normalized energy consumption and the delay constraint, and meanwhile disclose the crucial impact that the circuit energy has on the monotonicity of the normalized energy consumption. More specifically, we find that the normalized total energy consumption with the delay constraint decreases as the number of hops increases when the number of hops is small, and increases as the number of hops increases when it is large. Extensive simulations confirm the theoretical results. Our findings shed light on the design, implementation, and operation of real-world energy-efficient multihop wireless networks.