3,236 research outputs found

    An Analytical Design: Performance Comparison of MMSE and ZF Detector

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    By using multiple antennas at transmitter and receiver sides, the performance of the system can be enhanced in terms of high data rates by applying the concept of multiplexing and diversity as compared to single antenna systems. In this article we will study and compare the performance of BLAST architecture with different detectors like Zero Forcing (ZF), Minimum Mean Square Error (MMSE). Furthermore, we introduced OSIC schemes to improve the independent coded BLAST system and to combat the error propagation. We have also analyzed the BER performance of these MIMO schemes in Rayleigh and Rician fading channel. Finally we observed that the performance of BPSK and QPSK modulation techniques is almost same in BLAST architecture, while using the given detection techniques in both the channels and 16-QAM modulation technique gives the worst result. Keywords: Binary Phase Shift Key (BPSK), Bit Error Rate (BER), Multiple input multiple output (MIMO),Maximum Likelihood (ML), Minimum mean square error (MMSE), Zero Forcing (ZF), Ordered Successive Interference Cancellation (OSIC), Quardrature Phase Shift Keying (QPSK), Quadrature Amplitude Modulation (QAM), Independent identically distributed (i.i.d), Bell Laboratories Layered Space-Time (BLAST)  

    Parallel QR decomposition in LTE-A systems

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    The QR Decomposition (QRD) of communication channel matrices is a fundamental prerequisite to several detection schemes in Multiple-Input Multiple-Output (MIMO) communication systems. Herein, the main feature of the QRD is to transform the non-causal system into a causal system, where consequently efficient detection algorithms based on the Successive Interference Cancellation (SIC) or Sphere Decoder (SD) become possible. Also, QRD can be used as a light but efficient antenna selection scheme. In this paper, we address the study of the QRD methods and compare their efficiency in terms of computational complexity and error rate performance. Moreover, a particular attention is paid to the parallelism of the QRD algorithms since it reduces the latency of the matrix factorization.Comment: The eleventh IEEE International Workshop on Signal Processing Advances for Wireless Communications, 5 pages, 4 figures, 4 algorithms, 1 tabl

    Dual-Polarized Massive MIMO-RSMA Networks: Tackling Imperfect SIC

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    The polarization domain provides an extra degree of freedom (DoF) for improving the performance of multiple-input multiple-output (MIMO) systems. This paper takes advantage of this additional DoF to alleviate practical issues of successive interference cancellation (SIC) in rate-splitting multiple access (RSMA) schemes. Specifically, we propose three dual-polarized downlink transmission approaches for a massive MIMO-RSMA network under the effects of polarization interference and residual errors of imperfect SIC. The first approach implements polarization multiplexing for transmitting the users' data messages, which removes the need to execute SIC in the reception. The second approach transmits replicas of users' messages in the two polarizations, which enables users to exploit diversity through the polarization domain. The third approach, in its turn, employs the original SIC-based RSMA technique per polarization, and this allows the BS to transmit two independent superimposed data streams simultaneously. An in-depth theoretical analysis is carried out, in which we derive tight closed-form approximations for the outage probabilities of the three proposed approaches. Accurate approximations for the ergodic sum-rates of the two first schemes are also derived. Simulation results validate the theoretical analysis and confirm the effectiveness of the proposed schemes. For instance, under low to moderate cross-polar interference, the results show that, even under high levels of residual SIC error, our dual-polarized MIMO-RSMA strategies outperform the conventional single-polarized MIMO-RSMA counterpart. It is also shown that the performance of all RSMA schemes is impressively higher than that of single and dual-polarized massive MIMO systems employing non-orthogonal multiple access (NOMA) and orthogonal multiple access (OMA) techniques

    On the Throughput of Large-but-Finite MIMO Networks using Schedulers

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    This paper studies the sum throughput of the {multi-user} multiple-input-single-output (MISO) networks in the cases with large but finite number of transmit antennas and users. Considering continuous and bursty communication scenarios with different users' data request probabilities, we derive quasi-closed-form expressions for the maximum achievable throughput of the networks using optimal schedulers. The results are obtained in various cases with different levels of interference cancellation. Also, we develop an efficient scheduling scheme using genetic algorithms (GAs), and evaluate the effect of different parameters, such as channel/precoding models, number of antennas/users, scheduling costs and power amplifiers' efficiency, on the system performance. Finally, we use the recent results on the achievable rates of finite block-length codes to analyze the system performance in the cases with short packets. As demonstrated, the proposed GA-based scheduler reaches (almost) the same throughput as in the exhaustive search-based optimal scheduler, with substantially less implementation complexity. Moreover, the power amplifiers' inefficiency and the scheduling delay affect the performance of the scheduling-based systems significantly
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