Network Beamforming Using Relays With Perfect Channel Information

By Yindi Jing, Hamid Jafarkhani. IEEE Transactions on Information Theory, 2008

561 citations recorded by the source corpus.

This paper deals with beamforming in wireless relay networks with perfect channel information at the relays, receiver, and transmitter if there is a direct link between the transmitter and receiver. It is assumed that every node in the network has its own power constraint. A two-step amplify-and-forward protocol is used, in which the transmitter and relays not only use match filters to form a beam at the receiver but also adaptively adjust their transmit powers according to the channel strength information. For networks with no direct link, an algorithm is proposed to analytically find the exact solution with linear (in network size) complexity. It is shown that the transmitter should always use its maximal power while the optimal power of a relay ca.n take any value between zero and its maxima. Also, this value depends on the quality of all other channels in addition to the relay's own. Despite this coupling fact, distributive strategies are proposed in which, with the aid of a low-rate receiver broadcast, a relay needs only its own channel information to implement the optimal power control. Then, beamforming in networks with a direct link is considered. When the direct link exists during the first step only, the optimal power control is the same as that of networks with no direct link. For networks with a direct link during the second step only and both steps, recursive numerical algorithms are proposed. Simulation shows that network beamforming achieves the maximal diversity order and outperforms other existing schemes.

Subfields: Computer Networks and Communications, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/b4265ae18f6750b130be3142f3ebad354e9771a1

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Citations in the corpus

Optimal Distributed Beamforming for Two-Way Relay Networks (2010, background): “Recently, distributed beamforming algorithms have been developed for relaying schemes where the relays retransmit amplified and phase-adjusted versions of their received signals [7]–[10].”
Single and multiple relay selection schemes and their achievable diversity orders (2009, background): “In our network beamforming paper [36], a relay ordering is proposed, based on which we can find the relays that use their full power sequentially.”
Distributed Beamforming for Relay Networks Based on Second-Order Statistics of the Channel State Information (2008, background): “While assuming that the power of each individual relay is limited, it is assumed in [17] that each relay knows the instantaneous CSI for both backward (transmitter to the relay) and forward (relay to the receiver) links.”