| Summary: | 博士 === 義守大學 === 電機工程學系 === 100 === Without increasing the bandwidth or power budget, multiple-input-multiple-output (MIMO) scheme is one of the most efficient ways to answer the demand of ever increasing spectrum efficiency. Therefore, an integration of selection combining (SC) at the transmitter and maximum-ratio combining (MRC) at the receiver (labeled TAS/MRC) was proposed. The TAS/MRC scheme needs low-rate feedback transmission, and hence this scheme also offers a higher degree of robustness against channel estimation error as well as time variation of the channels.
In this dissertation, a concise closed-form approximation for the outage capacity of TAS/MRC scheme over i.i.d Nakagami-m fading channels is first derived while the fading index is a positive integer. When the Nakagami-m fading index is not an integer, the approximate outage capacity is derived as a single infinite series of Gamma function. In additions, the outage probability of multiuser diversity (MUD) in the TAS/MRC scheme is also obtained as an exact closed expression for an integer m and as a single infinite series of incomplete Gamma function for non-integer m. At high SNRs, the analytical results deduce that the multiuser TAS/MRC systems can achieve a full diversity order equal to the product of the fading parameter, number of users, number of transmit antennas, and number of receive antennas. The advantage of the total diversity gain becomes more pronounced on a severe fading channel. The achieved results provide an analytical framework for the assessment of multiuser TAS/MRC systems.
Moreover, we present unified formulas of the outage probability and the bit error rate (BER) for MUD with different MIMO schemes, including: 1) transmit selective/receive selective (SC/SC); 2) transmit selective/receive maximum ratio combining (SC/MRC or TAS/MRC); and 3) space-time block codes (STBC) on Nakagami-m fading channels. The exact closed-form expressions can be derived for the outage probability with arbitrary m and for the BER with integer m. For a non-integer fading parameter, the BER is expressible as a single infinite series of Gamma function. We also achieve simplified calculations for the performance at high SNR to gain insights regarding the factors determining the performance in fading. It is shown that the multiuser MIMO systems can achieve a full diversity order. The achieved results provide an analytical framework for the assessment of multiuser MIMO systems. All the analytical results are verified by Monte Carlo simulations.
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