Transmit Diversity and Relay Selection Algorithms for Multirelay Cooperative MIMO Systems

The throughput of high-speed railway (HSR) communication systems is limited not only by frequency spectrum but also by high mobility. Under the HSR scenario, one of the promising solutions to improve the throughput is multi-stream beamforming. However, severe performance degradation occurs due to larger inter-beam interference (IBI) as the number of beams is constant. In order to maximize the throughput, a massive multiple input and multiple output (MIMO)-based adaptive multi-stream beamforming scheme is proposed, which utilizes an adaptive beam-selection proposal by exploiting the location information of the train. By adaptively selecting the optimal subset of beams, including active subset size and active receive antenna indices, with respect to the location of the train, the proposed scheme significantly outperforms single/dual-stream beamforming and conventional massive MIMO. We also find that the throughput is not proportional to, but a nonlinear function of, the number of active receive antennas in this scenario.

Section: Fig 2 Throughputs With Different Number Of Beamsmentioning

confidence: 99%

A massive MIMO-based adaptive multi-stream beamforming scheme for high-speed railway

Cui

Fang

2015

“…To further demonstrate the performance of the proposed schemes in cooperative relaying systems [5], we apply them to an AF cooperative DS-CDMA system detailed in Section 2. Figure 10 shows that the bidirectional scheme obtains performance benefits over the differential schemes during convergence but, as expected, the performance gap closes as steady-sate is reached.…”

Section: Cooperative Ds-cdmamentioning

confidence: 99%

“…Conventional adaptive schemes fulfill many of these requirements and have been a significant focus of the research literature [1][2][3][4][5][6][7][8]. However, in time-varying fading channels commonly associated with mobile systems, these adaptive techniques encounter tracking and convergence problems.…”

Section: Introductionmentioning

confidence: 99%

Bidirectional algorithms for interference suppression in multiuser systems

Clarke

Lamare

2015

Self Cite

This paper presents adaptive bidirectional minimum mean-square error parameter estimation algorithms for fast-fading channels. The time correlation between successive channel gains is exploited to improve the estimation and tracking capabilities of adaptive algorithms and provide robustness against time-varying channels. Bidirectional normalized least mean-square and conjugate gradient algorithms are devised along with adaptive mixing parameters that adjust to the time-varying channel correlation properties. An analysis of the proposed algorithms is provided along with a discussion of their performance advantages. Simulations for an application to interference suppression in multiuser DS-CDMA systems show the advantages of the proposed algorithms.

“…Cooperative multiple-input multiple-output (MIMO) systems can obtain diversity gains by providing copies of transmitted signals with the help of relays to improve the reliability of wireless communications [1][2][3][4][5] and in applications to spectrum sensing [6,7]. The idea behind cooperative relaying systems is to employ multiple relay nodes between the source node and the destination node to form a distributed antenna array, which can provide significant advantages in terms of diversity gains.…”

Section: Introductionmentioning

confidence: 99%

Delay-tolerant distributed space-time coding with feedback for cooperative MIMO relaying systems

Peng

Lamare

2018

Self Cite

An adaptive delay-tolerant distributed space-time coding (DSTC) scheme equipped with a feedback channel is proposed for two-hop cooperative multiple-input multiple-output (MIMO) networks. A maximum likelihood receiver and adjustable code matrices subject to a power constraint with a decode-and-forward cooperation strategy are considered with different DSTC antenna configurations. In the proposed delay-tolerant DSTC schemes, an adjustable code matrix is employed to transform the space-time coded matrices at the relay nodes. Stochastic gradient and least squares algorithms are also developed with reduced computational complexity. The proposed algorithms are then extended to a cooperative MIMO system using amplify-and-forward strategy and opportunistic relaying algorithms in order to develop a delay-tolerant coding scheme combined with optimal relay selection strategies. An upper bound on the pairwise error probability and a rank criterion analysis are derived which indicate the advantage of the proposed algorithms. Simulation results show that the proposed algorithms obtain significant performance gains and address the delay issue in cooperative MIMO systems as compared to existing DSTC schemes.