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Research Publications (Engineering and Built Environment)

Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/215

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Author: search.filters.author.Patel, Sulaiman SaleemSubject: search.filters.subject.0805 Distributed Computing

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    Error performance of uncoded space time labelling diversity in spatially correlated Nakagami-q channels
    (Wiley, 2018-08) Patel, Sulaiman Saleem; Quazi, Tahmid; Xu, Hongjun
    Greater spectral efficiency has recently been achieved for Uncoded Space Time Labelling Diversity (USTLD) systems by increasing the number of antennas in the transmit antenna array. However, due to constrained physical space in hardware, the use of more antennas can lead to degradation in error performance due to correlation. Thus, this paper studies the effects of spatial correlation on the error performance of USTLD systems. The union bound approach, along with the Kronecker correlation model, is used to derive an analytical expression for the average bit error probability (ABEP) in the presence of Nakagami‐q fading. This expression is validated by the results of Monte Carlo simulations, which shows a tight fit in the high signal‐to‐noise ratio (SNR) region. The degradation in error performance due to transmit and receive antenna correlation is investigated independently. Results indicate that transmit antenna correlation in the USTLD systems investigated (3 × 3 8PSK, 2 × 4 16PSK, 2 × 4 16QAM, and 2 × 4 64QAM) causes a greater degradation in error performance than receive antenna correlation. It is also shown that 2 × 4 USTLD systems are more susceptible to correlation than comparable space‐time block coded systems for 8PSK, 16PSK, 16QAM, and 64QAM.
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    High-rate uncoded space-time labelling diversity with low-complexity detection
    (Wiley, 2020-09-25) Patel, Sulaiman Saleem; Quazi, Tahmid; Xu, Hongjun
    Uncoded space-time labelling diversity (USTLD) is a recent scheme that improved the error performance compared to conventional multiple-input, multiple-output systems. Thus far, USTLD has suffered from limited achievable data rates, as the original model uses only two transmit antennas. This motivates for the work in this paper, where the USTLD model is extended to allow for any desired number of transmit antennas. An analytical bound for the average bit error probability of this high-rate USTLD (HR-USTLD) system is derived. This expression is verified using the results of Monte Carlo simulations, which show a tight fit in the high signal-to-noise ratio region. The increased data rates associated with larger transmit antenna arrays in HRUSTLD systems come at the cost of increased detection complexity. Therefore, this paper studies the application of low-complexity detection algorithms based on the popular QR decomposition technique and proposes a new algorithm specifically designed for HR-USTLD systems. Analysis of this algorithm in terms of accuracy and computational complexity is also provided and benchmarked against maximum-likelihood detection (MLD). It is shown that the proposed algorithm achieves near-MLD accuracy, while reducing complexity by 79.75% and 92.53% for the respective 4 × 4 16QAM and 4 × 5 16PSK HR-USTLD systems investigated.
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    Performance analysis of M-APSK generalised spatial modulation with constellation reassignment
    (Wiley, 2020-09-25) Khalid, Ahmad; Quazi, Tahmid; Xu, Hongjun; Patel, Sulaiman Saleem
    Generalised spatial modulation (GSM) is a recently developed multiple-input multiple-output (MIMO) technique aimed at improving data rates over conventional spatial modulation (SM) systems. However, for identical antenna array size and configurations (AASC), the bit error rate (BER) of GSM systems in comparison with SM systems is degraded. Recently, a GSM system with constellation reassignment (GSM-CR) was proposed in order to improve the BER of traditional GSM systems. However, this study focused on M-ary quadrature amplitude modulation (M-QAM) schemes. The focus of this paper is the application of a circular constellations scheme, in particular, amplitude phase shift keying (APSK) modulation, to GSM and GSM-CR systems. An analytical bound for the average BER of the proposed M-APSK GSM and M-APSK GSMCR systems over fading channels is derived. The accuracy of this bound is verified using Monte Carlo simulation results. A 4 × 4 16-APSK GSM-CR system achieves a gain of 2.5 dB at BER of 10−5 over the traditional 16-APSK GSM system with similar AASC. Similarly, a 6 × 4 32-APSK GSM-CR system achieves a gain of 2 dB at BER of 10−5 over equivalent 32-APSK GSM system.