Power adaptation for multihop networks with end-to-end BER requirements

With the requirement of average end-to-end bit error rate (BER) performance, we study power-adaptation problems for multihop ad hoc networks to minimize the power consumption in fading channels, considering two scenarios with regard to the knowledge of the channel-state information (CSI). One is that the transmitter for each hop knows the instantaneous CSI (ICSI) of its hop and all other hops (ICSI/ICSI), and the other is that the transmitter of each hop has only the knowledge of the ICSI of its hop and the average CSI (ACSI) of all other hops (ICSI/ACSI). The two power-adaptation problems (with ICSI/ICSI and ICSI/ACSI) are formulated into nonlinear programming problems, and corresponding power-adaptation solutions/schemes are obtained. Numerical examples are presented to compare the networks with the two proposed power-adaptation schemes and a distributed power-adaptation scheme, in which the transmitter of each individual hop adjusts its transmission power based on its own ICSI and a specified BER requirement for this hop. It is shown that the two proposed schemes have similar power consumptions, and both achieve a noticeable power saving over the distributed scheme.