In this study, exact closed-form expressions for the second-order statistics of the signal-to-noise ratio at a maximum ratio combiner (MRC) output for a Nakagami fading channel are derived. Using the joint characteristic function for the MRC output and its time derivative, the level crossing rate, average fading duration and autocorrelation function expressions are derived for the case of independent but unbalanced diversity branches, with unequal fading parameters and an arbitrary number of diversity branches. The analytical results are validated by simulations.

The second-order statistics of the time varying signal to noise ratio at the output of a multiple-input-multiple-output(MIMO) system with maximal ratio combining (MRC) are analyzed. Exact closed-form expressions for the level crossing rate and the average fade duration are derived for the Ricean propagation and arbitrary channel matrix dimensions. Novel expressions are compared with the special case of MRC receive diversity. The analytical results are validated by simulation.

An analytical method for the performance evaluation of adaptive multiple-input-multiple-output (MIMO) system employing maximal ratio combining (MRC) by a Markov model is developed. The finite state Markov channel model parameters were determined by a new exact expression for level crossing rate of the signal to noise ratio at the output of MIMO-MRC with imperfect channel state information, derived for the Rayleigh propagation and arbitrary channel matrix dimensions. The analytical results are validated by computer simulation.

It is shown that the optimal frame synchronization markers for channels with memory, considering the widely used postdetection maintenance and the minimum average rule, are not the ones optimized for an AWGN channel. A method for obtaining the optimal marker using the channel state diagram and the corresponding trellis is presented.>

A novel criterion for digital synchronous communication system efficiency estimation is defined. All system attributes such as bit error probability, coding efficiency, initial system synchronization time, efficiency of detection of timing anomalies and system sync recovery, reliability of the lock indication, and the amount of redundancy insertion in the data stream for synchronization and error-correcting coding purposes are included in a single parameter called "system efficiency." The expression for this parameter is derived under the assumption of signal ergodicity and steady-state system operation. In its final form, this parameter seems obvious almost by inspection. Even so, until now, it has not been used in the analysis of communication system efficiency. The analysis of this parameter for several different systems is presented as an illustration.