Distributed subchannel assignment in a two-hop network

This paper studies distributed subchannel allocation in a two-hop network comprising multiple source nodes, one multi-channel relay node and one destination node. The underlying subchannel allocation problem in a relay network, when posed as a centralized allocation problem, is formulated as a three-dimensional assignment problem. Distributed subchannel allocation is studied using noncooperative game theory. A sequential game model is formulated where in first stage source nodes opportunistically select their transmission resources after which in second stage a channel-aware relay node assigns the resources in a way that maximizes the sum of utilities at the destination node. The subchannel allocation game is a potential game, possessing an implicit joint objective (potential) of the players. Numerical examples illustrate the performance of opportunistic channel allocation in an OFDMA system. Using the sequential scheme, noncooperative allocation in first link implies performance similar to that obtained by solving two consecutive assignment problems, first optimizing the allocation of subchannels in source-relay link and second in relay-destination link. Auction-based solutions to noncooperative subchannel allocation, both with fixed and variable transmit power, are presented to obtain approximate solutions to the underlying centralized resource optimization problems.