Exploiting Asynchronous Signaling for Multiuser Cooperative Networks with Analog Network Coding

In this paper, we present an asynchronous analog network coding (AANC) scheme for multiuser cooperative communications. In particular, we consider a relay network comprised of multiple sources and one relay. With conventional analog network coding, i.e., synchronous analog network coding (SANC), perfect timing synchronization is assumed. In contrast, in AANC, the signals from the sources arrive at the relay and destination with different time delays. Then the relay amplifies the received asynchronous combination of the transmitted signals and forwards it to the destination. We present a simple decoding strategy at the destination and examine the diversity order by investigating the asymptotic performance at a high signal to noise ratio. Our results show that AANC achieves a greater diversity order compared to that of SANC with the same linear decoding complexity. In addition, we present the Viterbi decoding for AANC and use simulations to compare its performance with that of SANC with maximum likelihhood decoding. We show that AANC has a better symbol error rate performance compared to that of SANC.