Transmitting to Colocated Users in Wireless Ad Hoc and Sensor Networks

We consider wireless ad hoc networks and sensor networks where a remotely located source is transmitting information to a destined user embedded within a group of K densely packed physically colocated users enjoying favorable signal-to-noise ratio (SNR) conditions among themselves, but suffering from quasi-static flat Rayleigh fading with respect to the source. Stringent delay constraints require that information, once available, be transmitted immediately and delivered reliably to its destination during a period of one fading block, precluding waiting until the destined user enjoys favorable fading conditions with respect to the source. A cooperative transmission strategy is proposed for this scenario and its expected throughput is investigated. The strategy exhibits a substantial gain in throughput, especially when the colocation gain factor is high. In addition, a broadcast approach is incorporated into the transmission strategy suggesting further throughput benefits.