Abstract
We treat the problem of cooperative multiple beamforming in wireless ad hoc networks. The basic scenario is that a cluster of source nodes cooperatively forms multiple data-carrying beams toward multiple destination nodes. To resolve the hidden node problem, we impose a link constraint on the receive power at each unintended destination node. Then the problem becomes to optimize the transmit powers and beam weights at the source cluster subject to the maximal transmit power constraint, the minimal receive signal-to-interference-plus-noise ratio (SINR) constraints at the destination nodes, and the minimal receive power constraints at the unintended destination nodes. We first propose an iterative transmit power allocation algorithm under fixed beamformers subject to the maximal transmit power constraint, as well as the minimal receive SINR and receive power constraints. We then develop a joint optimization algorithm to iteratively optimize the powers and the beamformers based on the duality analysis. Since channel state information (CSI) is required by the sources to perform the above optimization, we further propose a cooperative scheme to implement a simple CSI estimation and feedback mechanism based on the subspace tracking principle. Simulation results are provided to demonstrate the performance of the proposed algorithms.
Highlights
A new approach of achieving spatial diversity gain in relay networks, namely, cooperative diversity or user cooperation diversity, has received considerable interests [1,2,3,4,5]
Cooperative diversity comes from the fact that multiple nodes in an ad hoc network can cooperatively form a virtual antenna array providing the potential of realizing spatial diversity
We have analyzed the problem of cooperative multiple beamforming in wireless ad hoc networks
Summary
A new approach of achieving spatial diversity gain in relay networks, namely, cooperative diversity or user cooperation diversity, has received considerable interests [1,2,3,4,5]. From the viewpoint of power consumption, this assumption is reasonable in the sense that the overhead requested by intracluster information sharing is relatively small due to the short distances among intracluster nodes Another key issue is the synchronization among multiple cooperative nodes [12], for example, carrier frequency, phase, and timing synchronization. Instead of considering the beamforming problem that a cluster of nodes cooperatively forms one beam toward one destination node (e.g., [13, 14, 18]), we treat the problem of simultaneously forming multiple beams for multiple concurrent data transmissions in wireless ad hoc networks. The cooperative multiple beamforming problem can be formulated as a multiuser beamforming problem with extra receive power constraints for unintended destination nodes.
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