A dynamic multiple-input-multiple-output (MIMO) system with carrier selection (CS) at the transmitter side and single-carrier frequency domain equalization (SCFDE) at the receiver side over dispersive Nakagami-m fading channels is examined. The estimation algorithm of the single-carrier spatially multiplexed data streams is proposed. Estimate the number of transmit diversity as the input information of the SCFDE, and then process the received data adaptively. Operationally, a unique word embedded with pseudo-noise codes has been used not only for stopping error propagation but also for identifying how many transmit antennae at the receiver side at the expense of little complexity. Simulation results reveal our proposed scheme is quite robust and very close to the perfect diversity estimation in dynamic MIMO systems.

The expectation-maximization-based (EM-based) receiver provides a decent solution for conquering the delay problem of estimating the channel side information (CSI) via detecting data sequence iteratively at the expense of increasing the processing time. To accelerate the processing time, an α-expectation-conditional-maximization (ECM) design for direct-sequence (DS) code-division multiple access (CDMA) systems over frequency-selective fading channels is studied. Simulation results reveal that the adaptive α-ECM receiver can speed up the convergence speed of joint estimation and detection under severe Doppler shifts when the value of α is increasing. Furthermore, the BER performance of the adaptive α-ECM-based DS-CDMA receiver for joint channel estimation and symbol detection under single-user and multiuser systems is also scrutinized.

Noncoherent and coherent multicode direct-sequence code-division multiple access (DS-CDMA) systems with successive interference cancellation (SIC) for multimedia reverse links over frequency-selective fading channels are studied. Followed by a RAKE receiver, the SIC scheme is applied for combating the multiple access interference. The bit error rate (BER) using the SIC technique over Nakagami-mfading channels is derived. Simulation results show that the multicode DS-CDMA system with SIC has demonstrated better performance than that without SIC under the multipath fading environment, while their corresponding numerical results from performance analyses are also provided for verifications. Furthermore, the coherent receiver could achieve a more satisfactory BER than the noncoherent counterpart at the expense of synchronization.

The performance of a noncoherent digital delay-lock loop (DDLL) with a RAKE scheme for direct-sequence spread-spectrum code division multiple access (DS/SS-CDMA) signals over frequency-selective Rayleigh fading channels is discussed. Closed-form expressions for the transition timing error probability density function (PDF) of the Chapman-Kolmogorov (C-K) equations of the first- and second-order loops are derived for driving analytical expressions of the steady-state timing error PDF. Furthermore, the statistics of the tracking error are scrutinized and verified via computer simulations, such as the mean square tracking error (MSTE) and Cramer-Rao lower bound (CRLB).

Statistical analyses of a non-coherent digital delay- lock loop (DDLL) for direct-sequence spread-spectrum signals over Nakagami-m fading channels are discussed. Analytical expressions to the characteristics, such as Cramer-Rao lower bound (CRLB), of the timing tracking errors have been proposed based upon the timing error probability density function (PDF) of the Chapman-Kolmogorov (C-K) equation of the first- and second-order loops. Furthermore, mean square tracking errors (MSTEs) against distinct parameters are also simulated, while their corresponding numerical results with CRLBs are confirmed by time-domain computer calculations.