Collaborative beamforming for distributed wireless ad hoc sensor networks

Abstract

The performance of collaborative beamforming is analyzed using the theory of random arrays. The statistical average and distribution of the beampattern of randomly generated phased arrays is derived in the framework of wireless ad hoc sensor networks. Each sensor node is assumed to have a single isotropic antenna and nodes in the cluster collaboratively transmit the signal such that the signal in the target direction is coherently added in the far-field region. It is shown that with N sensor nodes uniformly distributed over a disk, the directivity can approach N , provided that the nodes are located sparsely enough. The distribution of the maximum sidelobe peak is also studied. With the application to ad hoc networks in mind, two scenarios, closed-loop and open-loop, are considered. Associated with these scenarios, the effects of phase jitter and location estimation errors on the average beampattern are also analyzed.

Radiating sensor selection for distributed beamforming in wireless sensor networks

“…The idea of collaborative beamforming has been recently proposed as an efficient method for achieving the required information dissemination [4], [5], [6]. In collaborative beamforming, the nodes are forming a distributed antenna array in order to direct the transmitted energy to the desired direction and minimize radiation in all other directions.…”

“…The key conclusion of completed studies so far is that the achieved radiation patterns are on average acceptable. However, the results of a typical realization may be far from ideal [6]. In addition, no specific design methodology has been provided on how to form an efficient distributed array for a particular realization and in the presence of localization and synchronization uncertainties.…”

Energy-efficient cellular network operation via base station cooperation

“…For the UEs inside a switched-off cell, the cooperative coverage extension scheme for both downlink and uplink is specified as follows: 1) Downlink: Since the channel state information is available at the BS side, the optimum cooperative transmission scheme is cooperative beamforming [17]. The resulting SNR at the UE (receiver) is given by: where P BS is the total transmit power of all the cooperating BSs, N UE is the noise power at the UE, and K is the number of cooperating BSs.…”

Opportunistic collaborative beamforming with one-bit feedback

“…More specifically, each source node must pre-compensate its any local carrier offset as well as any phase distortion caused by its channel such that the bandpass signals from all the nodes arrive at the receiver with identical phase. Without properly adjusting the phases of transmitted signals, collaborative beamforming may perform poorly due to pointing errors and mainbeam degradation [1]. Man-On Pun and H. Vincent Poor are with the Department of Electrical Engineering, Princeton University, Princeton, NJ 08544 (e-mail: mopun@princeton.edu; poor@princeton.edu).…”