The authors present a cooperative transmit beamforming (CTBF) technique for the uplink of multiusermultiple-inputmultiple-output (MIMO) systems. To maximise MIMO channel capacity, the proposed technique embeds a par...
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The authors present a cooperative transmit beamforming (CTBF) technique for the uplink of multiusermultiple-inputmultiple-output (MIMO) systems. To maximise MIMO channel capacity, the proposed technique embeds a parallel update (PU) mechanism into the particle swarm optimisation (PSO) scheme to concurrently search and refine each user's CTBF weights at every iteration in the PSO, thus named the embedded PU/PSO. Moreover, a reduced complexity and yet effective scheme is also proposed, which cascades the conventional PSO with the PU mechanism, thus called the cascaded PU/PSO. Simulation results demonstrate that the proposed CTBF schemes overcome the bit-error-rate floor phenomenon problem at higher signal-to-noise ratios, which appears in the existing works, at the expense of moderately higher complexity if the cascaded PU/PSO is used.
This study examines the uplink performance of large-constellation multi-user massive multiple-inputmultiple-outputsystems with low-resolution analogue-to-digital converters (ADCs) in the presence of channel correlat...
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This study examines the uplink performance of large-constellation multi-user massive multiple-inputmultiple-outputsystems with low-resolution analogue-to-digital converters (ADCs) in the presence of channel correlation and imperfect channel state information (CSI). The base station (BS) employs a large number of antennas for multiplexing and demultiplexing co-channel users with each antenna element having a dedicated radio frequency chain and two low-resolution ADCs. While such ADCs cause data loss due to coarse quantisation, the large number of antennas can be exploited not only to alleviate such a problem but also to make it possible to utilise large-constellation modulation schemes. The results provide an insight into the trade-off between various performance metrics and the number of quantisation bits under a wide range of realistic conditions. It will be shown that 1-bit quantisation provides sufficient resolution with 100 BS antennas to communicate with ten user equipments using quadrature phase shift keying, but the number of quantisation bits must be increased for larger constellations particularly to overcome CSI mismatch and channel correlation. The results also consider the trade-off between average mutual information and power consumption of the low-resolution ADCs. It will be shown that 16-quantum amplitude modulation with 2-bit quantisation may provide a good compromise between energy efficiency and average mutual information.
Using an opportunistic transmission protocol in which users contend for transmission to a base station under equal-correlated generalised-Rician fading, new single-integral selection combiner output cumulative distrib...
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Using an opportunistic transmission protocol in which users contend for transmission to a base station under equal-correlated generalised-Rician fading, new single-integral selection combiner output cumulative distribution functions (cdfs) of multivariate equal-correlated generalised-Rician fading for multiuser multiple-input multiple-output systems, and even degrees of freedom with multiple transmit and receive antennas per user are obtained in this study. Corresponding infinite-summation cdfs of multivariate equal-correlated generalised-Rician fading are obtained. Cross-verification is mathematically performed to validate the proposed findings. The new findings provide a useful mathematical framework to assess performance of wireless networks under equal-correlated generalised-Rician fading environments. The effectiveness of the new findings is exemplified by computing average bit error rates for the binary phase-shift keying scheme under equal-correlated generalised-Rician fading, and plotted against (i) a common average branch normalised signal-to-noise ratio, (ii) line-of-sight power, (iii) an even number of independently and identically distributed underlying Gaussian random variables, (iv) a total number of transmit antennas, and (v) a total number of receive antennas. Simulation results are shown to exactly match numerical simulation. Detailed discussions are given.
In this paper, we propose two efficient and practical resource allocation algorithms to maximize the weighted sum-rate of coordinated multipoint (CoMP) transmission with joint processing in multiusermultiple-input mu...
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ISBN:
(纸本)9781479935130
In this paper, we propose two efficient and practical resource allocation algorithms to maximize the weighted sum-rate of coordinated multipoint (CoMP) transmission with joint processing in multiusermultiple-inputmultiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) systems subject to per-antenna power constraints. We first propose a continuous-rate algorithm that utilizes successive convex approximation (SCA) to dynamically allocate the transmit powers of multiple CoMP base stations (BSs) transmitting to multiple co-channel user terminals (UTs). Next, we propose a discrete-rate algorithm that takes the continuous-rate result as a starting point and redistributes the transmit powers to obtain a discrete solution. Simulation results are provided to benchmark our continuous-rate algorithm with two alternative approaches: iterative waterfilling (IWF), and zero-forcing beamforming (ZFB). Results show that SCA provides significant sum-rate improvements over IWF in medium to high interference scenarios, and outperforms ZFB in low to medium interference scenarios. Moreover, our proposed discrete rate algorithm produces a higher discrete sum-rate with much lower computational complexity compared to existing algorithms.
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