Transmission Scheduling and Relay Assignment for Multiuser Uplink with Partial Channel Knowledge

We consider a wireless network where multiple nodes transmit to an access point (AP) with the assistance of relays. Nodes are assumed to be mobile, thus both relays and AP have only a partial knowledge of the channel on the links with nodes. Relays instead are fixed, so a perfect channel knowledge of AP-relays links can be assumed. Transmissions are organized in packets, with the use of hybrid automatic repeat request (HARQ) over many frames. At each frame we a) schedule transmission of nodes, and b) assign relays to nodes, i.e., decide which relay forwards data to the AP for each node. Both scheduling and assignment are made by computing the average capacity of the link between the nodes and the relays, based only on the knowledge of the second order statistics of the channel. The contribution of this paper is twofold. First, we derive analytically the constrained capacity for the correlated single input-multiple output (SIMO) channels. Then, we solve the allocation problem by a greedy approach.