Adaptive-Rate Transmission With Opportunistic Scheduling in Wireless Networks

In this paper, we propose an adaptive-rate transmission scheme with opportunistic scheduling in a two-hop relay network over a Rayleigh fading environment. We assume that only channel state information (CSI) at receivers is available in a decentralized network, where n source-to-destination pairs are completely independent and m half-duplex relays cooperate by exchanging their selected source IDs at the beginning of the two-hop transmission. In the limit of large n and fixed m, the system throughput of the scheme scales as (m/2)log log n. It is shown that this is the same achievable scaling even with perfect CSI assumptions at transmitters and full cooperation among nodes. Furthermore, it is shown that the optimal scaling of m is Θ(log n), under which a linear increase in throughput with m is obtained. A closed-form delay expression of the proposed scheme is also presented.