This paper considers the impact of incomplete information on incentives for node cooperation in parallel relay networks with one source node, one destination node, and multiple relay nodes. All nodes are selfish and strategic, interested in maximizing their own profit instead of the social welfare. The paper considers the practical situation where the channel state on any given relay path is not observable to the source or to the other relays. Different bargaining relationships between the source and the relays are considered, and a framework for studying the efficiency loss induced by incomplete information is proposed. The source of the efficiency loss is analyzed, and the amount of inefficiency which results is quantified.

In this paper, a distributed power control algorithm is proposed for wireless relay networks in interference-limited environments. The objective is to minimize the total transmission power while satisfying the signal-to-interference-plus-noise ratio (SINR) requirements. Two forwarding techniques, i.e., decode- and-forward (DF) and amplify-and-forward (AF), are considered. The proposed algorithm only requires locally measured SINR on the relay nodes (RNs) and the destination nodes (DNs), based on which each cooperation unit (defined as one source node (SN) and DN pair with the RN associated to it) iteratively updates the transmission power of the SN and the RN by solving a local optimization problem. We prove that the convergence is guaranteed when the parameters adopted in the algorithm are sufficiently large, and then a parameter adjusting method is also designed. Simulation results indicate that the proposed algorithm converges fast and leads to only 7% more power consumption than the optimal power allocation in the considered scenarios. It is also shown that even in interference-limited environments, relaying can still improve system performance substantially in terms of outage and power consumption.

The increasing density of WLAN devices induces severe inter-cell interference problem in nowadays WLAN system. The traditional distributed coordination function (DCF) mechanism in IEEE 802.11 protocol was designed for the avoidance of intra-cell collision, but the inter-cell interference cannot be alleviated by merely increasing the backoff time. Multi-cell scheduling mechanism allocates orthogonal resource to the clients interfering with each other and can efficiently alleviate the interference problem. However, most of the current scheduling schemes are formulated as an optimization problem, the implementation of which requires abundant inter-cell information exchange and the scalability cannot be guaranteed. In this paper, three completely distributed interference-aware multi-cell scheduling schemes are proposed, where the packet loss due to interference is utilized as the scheduling criterion. A stochastic approximation method is utilized to guarantee the system fairness also in the distributed manner. Simulation results show that the proposed scheduling schemes can significantly enhance the overall throughput while guarantee the fairness of the high density WLAN systems.