Compressive sensing based asynchronous random access for wireless networks

The theory of compressive sensing has shown that with a small number of samples from random projections of a sparse signal, one can recover the original signal under certain conditions. In this paper, we use compressive sensing to design a random access protocol for requesting uplink data channels. A wireless node transmits a pseudo-random sequence to an access point (AP) when it requires an uplink channel. The AP receives multiple sequences in a random access shared channel. Due to different propagation delays, the received signals from different wireless nodes are not synchronized at the receiver. Assume that the number of sequence transmissions is substantially less than the number of wireless nodes in the system. Under such circumstances, we design an asynchronous compressive sensing based decoder to recover the original signals in a random access setting. The key difference between our proposed decoder and those presented in the literature is that we do not require any synchronization before sequence transmission which makes our approach practical. Simulation results show the throughput improvement of our proposed scheme compared to two other random access protocols.