In this article, a dual-hop amplify-and-forward (AF) multiple-inputmultiple-output (MIMO) relay communication system is studied. With a splitting (PS) protocol, the relay node harvests the radio frequency (RF) energy...
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In this article, a dual-hop amplify-and-forward (AF) multiple-inputmultiple-output (MIMO) relay communication system is studied. With a splitting (PS) protocol, the relay node harvests the radio frequency (RF) energy in the signals sent by the source node and utilizes the harvested energy to forward signals from the source node to the destination node. We aim at maximizing the source-destination mutual information (MI) through a joint design of the source matrix, the relay matrix, and the PS ratios under the source node power constraint and the relay node harvested energy constraint. We consider a general sum energy constraint at the relay node with different PS ratios across relay antennas, which includes existing works based on uniform PS or per data stream energy constraint as special cases. Moreover, a practical nonlinear energy harvesting (EH) model is adopted, where the harvested energy is bounded as the incident RF signal power increases. We establish the structure of the source matrix and the relay matrix, which simplifies the complicated transceiver design problem with matrix variables to a power distribution problem with scalar variables. Three approaches are proposed to efficiently solve the optimal power distribution problem. In particular, the first proposed algorithm solves the original nonconvex power allocation problem using the sequential quadratic programming, while the other two algorithms convert the original problem to convex problems by exploiting a tight upper bound and a tight lower bound of the objective function, respectively. Numerical simulations demonstrate that when the EH circuit works in the linear region, the proposed algorithms have a larger system MI than existing PS and TS based MIMO AF relay systems. The peak harvest power constraint plays an important role in choosing the location of the relay node.
This paper studies the impact of a multiple-input-multiple-output (MIMO) relay on the K-user multiple-input-single-output (MISO) interference channel (IC) when the relay has delayed feedback (i.e., delayed channel sta...
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This paper studies the impact of a multiple-input-multiple-output (MIMO) relay on the K-user multiple-input-single-output (MISO) interference channel (IC) when the relay has delayed feedback (i.e., delayed channel state information (CSI) or delayed channel output feedback) from each receiver, yet each transmitter has no knowledge about CSI. We first develop a new relay-aided retrospective interference alignment (r-RIA) and characterize the optimal sum degrees of freedom (DoFs) for the K-user MISO IC with a MIMO relay by providing a new matching outer bound. It is shown that the sum DoF does not decrease, even in the absence of direct links between transmitters and receivers, as long asK is sufficiently large. We next show that a MIMO relay can provide a sum-DoF gain in the K-user MISO IC with delayed feedback to the relay in the absence of CSI at transmitter (CSIT), whereas relaying is shown to be not useful with instantaneous CSIT from the DoF perspective.
This paper focuses on linear precoding designs in multi-user multiple-inputmultiple-output block diagonalization (BD) relay systems with limited feedback. A base station employs spatial multiplexing transmission base...
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ISBN:
(纸本)9781509013289
This paper focuses on linear precoding designs in multi-user multiple-inputmultiple-output block diagonalization (BD) relay systems with limited feedback. A base station employs spatial multiplexing transmission based on quantized channel state information (CSI) obtained from a relay. Then the relay transmits the received signal to users equipped with multiple antennas. In this paper, we propose a BD precoding scheme based on minimum mean square error (MMSE) criterion, which results in a closed-form solution. We show that the proposed scheme is robust to both noise and channel uncertainties caused by quantization errors. Also, we extend the proposed scheme to the case with CSI feedback delays. Simulation results verify the effectiveness of our proposed schemes.
Parallel relay is an effective way to extend wireless communication distance. Employing multiple-inputmultiple-output (MIMO) relay can improve communication quality on a large scale, but the communication efficiency ...
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Parallel relay is an effective way to extend wireless communication distance. Employing multiple-inputmultiple-output (MIMO) relay can improve communication quality on a large scale, but the communication efficiency is reduced due to channel estimation. In this study, a mutual information-based estimate-and-forward scheme is proposed based on unitary space-time modulation in MIMO system. An equivalent transmission model is also constructed by regarding that the source signal is affected by a multiplicative factor and an additive noise. Based on this equivalent MIMO model, the generalized signal-to-noise ratio and global mutual information of the forwarding schemes are calculated. Error rate and mutual information analysis show that the proposed soft information forwarding can improve the reliability of parallel relaying system and has a better error rate performance than all the existing memory-less forwarding schemes.
Full-duplex amplify-and-forward multiple-input multiple-output relaying has been the focus of several recent studies, due to the potential for achieving a higher spectral efficiency and lower latency, together with in...
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Full-duplex amplify-and-forward multiple-input multiple-output relaying has been the focus of several recent studies, due to the potential for achieving a higher spectral efficiency and lower latency, together with inherent processing simplicity. However, when the impact of hardware distortions are considered, such relays suffer from a distortion-amplification loop, due to the inter-dependent nature of the relay transmit signal covariance and the residual self-interference covariance. The aforementioned behavior leads to a significant performance degradation for a system with a low or medium hardware accuracy. In this work, we analyze the relay transfer function as well as the mean squared-error performance of a full-duplex amplify-and-forward multiple-input multiple-output relaying communication, under the impact of collective sources of additive and multiplicative transmit and receive impairments. Building on the performed analysis, an optimization problem is devised to minimize the communication Mean Squared-Error and solved by employing the recently proposed penalty dual-decomposition framework. The proposed solution converges to a stationary point of the original problem via a sequence of convex quadratic programs, thereby enjoying an acceptable arithmetic complexity as the problem dimensions grow large. Numerical simulations verify the significance of the proposed distortion-aware design and analysis, compared to the common simplified approaches, as the hardware accuracy degrades.
This paper focuses on linear precoding designs in multi-user multiple-inputmultiple-output block diagonalization (BD) relay systems with limited feedback. A base station employs spatial multiplexing transmission base...
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ISBN:
(纸本)9781509013296
This paper focuses on linear precoding designs in multi-user multiple-inputmultiple-output block diagonalization (BD) relay systems with limited feedback. A base station employs spatial multiplexing transmission based on quantized channel state information (CSI) obtained from a relay. Then the relay transmits the received signal to users equipped with multiple antennas. In this paper, we propose a BD precoding scheme based on minimum mean square error (MMSE) criterion, which results in a closed-form solution. We show that the proposed scheme is robust to both noise and channel uncertainties caused by quantization errors. Also, we extend the proposed scheme to the case with CSI feedback delays. Simulation results verify the effectiveness of our proposed schemes.
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