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Title: The application of spatial complementary code keying in point-to-point MIMO wireless communications systems
Author: Kh Shati, Ibrahim Ali
ISNI:       0000 0004 7964 5062
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2018
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Due to the increasing data speeds of wireless communications, there is a considerable concern about the means of sending data with lower costs and less complexity including by applying advanced coding mechanisms. Current solutions based on techniques such as Spatial Modulation, while achieving low complexity, suffer from limited spectral efficiency. This arises from the use of restricted code sets that limit the data rate. A spatial coding-modulation scheme based on complementary code keying (CCK) sequences with non-conventional phases in the spatial domain applied to MIMO-OFDM systems has been previously presented. Spatial CCK modulation is presented in this study where CCK is processed as a coded modulation technique applied in the spatial domain. Spatial CCK modulation is implemented for various Wi-Fi configurations of Multiple Input Multiple Output (MIMO) systems. CCK codes can achieve higher spectral efficiencies through the deployment of larger code sets. These codes improve BER performance based on the number of codeword pairs in any CCK set with large Euclidean distance. This means that low complexity detection scheme can be used effectively. The previous research, which explored spectral efficiencies of 2, 4 and8 bit/s/Hz with CCK codes, which also has limited spectral efficiency, is defined in this thesis as an enhanced spatial CCK system. This work extends the previous work to 11 bit/s/Hz with length 16 CCK codewords and tests this system with different detectors: zero forcing (ZF) and minimum mean square error (MMSE) and the optimal maximum likelihood detection (ML). This research proposes spatial CCK modulation with conventional QPSK modulation phase order in CCK codewords of lengths 2, 4, 8 and16 with wideband Rayleigh and Rician IEEE channels MIMO-OFDM system model. The Exponential Kronecker correlation is applied as a mathematical model of correlation between antenna channels in both transmit and receive antennas, which provides more realistic channel scenarios. The 4-phase spatial CCK system is extended to an 8-phase spatial CCK system, which is novel. This is done by applying 8-PSK modulation phases to increase the number of codewords to exploit the salient property of CCK codes in the spatial domain, such codes have many codewords with large Euclidean distances. This leads to higher spectral efficiencies in the cases of length 2, 4, 8 and 16 CCK codewords compared with the 4-phase case. An analytical framework has been developed to evaluate the system using the CCK modulation with length 2, 4, 8 and 16 CCK codewords by constructing an analytical model of 4-phase CCK, modified CCK and 8-phase CCK under narrowband uncorrelated and correlated wireless fading channels with the optimal detection (ML) scheme .The performance of SCCK was compared with the state of the art such as spatial modulation (SM) and spatial multiplexing (SMX) with the same detector and channel conditions. Finally, for the first time, the performance of SCCK is tested in an analytical model, whereby the performance improvement in the case of spectral efficiency compared with SM system and BER performance of SCCK principle compared with both SM and SMX schemes is validated.
Supervisor: O'Farrell, Timothy ; Benaissa, Mohammed Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available