Efficient Multiple Access Using Received Signal Strength and Local Channel Information

Contention-based multiple access is a crucial component of many wireless systems. It is known that using interference cancellation techniques to receive and decode multiple packets that arrive simultaneously can improve the efficiency of multiple access. However, such multi-packet reception (MPR) schemes proposed in the literature require complex receivers capable of performing advanced signal processing over significant amounts of soft undecodable information received over multiple contention steps. In this paper, we show that local channel knowledge and elementary received signal strength measurements, which are made by many receivers today, can actively facilitate multi-packet reception and even simplify the interference canceling receiver´s design. We introduce a simple algorithm called turbo-dual power multiple access (turbo-DPMA) that uses local channel knowledge to limit the receive power levels to two discrete values that are carefully chosen to facilitate successive interference cancellation. As we shall see, limiting the receive power in such a manner not only facilitates the simultaneous reception of up to two packets, but it also enables the receiver to derive additional useful information about the contending users from its received signal strength indicator. The resulting receiver structure is markedly simpler, as it needs to process only the immediate received signal, without having to store and process signals received previously. Even more remarkably, the turbo-DPMA is stable for packet arrival rates as high as 0.793 packets/slot, which is significantly better than all the contention algorithms known to date.