Abstract
We propose techniques for optimizing transmit beamforming in a full-duplex multiple-input-multiple-output wireless-powered communication system, which consists of two phases. In the first phase, the wireless-powered mobile station (MS) harvests energy using signals from the base station (BS), whereas in the second phase, both MS and BS communicate to each other in a full-duplex mode. When complete instantaneous channel state information (CSI) is available, the BS beamformer and the time-splitting (TS) parameter of energy harvesting are jointly optimized in order to obtain the BS–MS rate region. The joint optimization problem is non-convex, however, a computationally efficient optimum technique, based upon semidefinite relaxation and line-search, is proposed to solve the problem. A sub-optimum zero-forcing approach is also proposed, in which a closed-form solution of TS parameter is obtained. When only the second-order statistics of transmit CSI is available, we propose to maximize the ergodic information rate at the MS while maintaining the outage probability at the BS below a certain threshold. An upper bound for the outage probability is also derived and an approximate convex optimization framework is proposed for efficiently solving the underlying non-convex problem. Simulations demonstrate the advantages of the proposed methods over the sub-optimum and half-duplex ones.
Highlights
P ROLIFERATION of communication devices, systems, and networks has considerably increased the demand for wireless spectrum, driving the interest to design systems withManuscript received December 21, 2016; revised April 1, 2017 and May 4, 2017; accepted May 8, 2017
Using the upper bound of the outage probability, we maximize the ergodic information rate at the mobile station (MS)
The joint optimization of transmit beamforming and TS parameter was considered for a wireless-powered bidirectional FD communication system
Summary
P ROLIFERATION of communication devices, systems, and networks has considerably increased the demand for wireless spectrum, driving the interest to design systems with. Manuscript received December 21, 2016; revised April 1, 2017 and May 4, 2017; accepted May 8, 2017. Date of publication June 1, 2017; date of current version September 14, 2017. Part of this work was presented at the IEEE SPAWC’16, Edinburgh, U.K., in 2016.The associate editor coordinating the review of this paper and approving it for publication was Y.
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