Distributed space-time filtering for cooperative wireless networks

Significant performance gains can be leveraged in wireless networks by allowing the different nodes to cooperate. Cooperative transmission strategies attempt to realize the performance gains possible in multi-input multi-output (MIMO) fading channels by modeling the cooperating nodes as virtual antennas. However, in contrast to the point-to-point MIMO scenario, efficient cooperative schemes must address the distributed implementation challenge. For example, individual cooperating nodes may not be aware of their partners. We formulate the problem of maximizing the diversity advantage subject to the constraint of unknown message state information at the cooperating transmitter(s). We argue that our formulation can be used to model different relevant scenarios in wireless networks (e.g., fault tolerant applications, energy efficient sensor networks). In this setting, we propose a novel space-time filtering (STF) approach that achieves the optimal tradeoff between diversity advantage and receiver complexity. We further compare this approach with existing space-time coding approaches, highlighting the benefits of STF in the distributed implementation setting. Our arguments are supported by simulation results that demonstrate the performance gains possible with the proposed scheme in certain representative scenarios.