Spectrum combining technique base on the extensible average phase algorithm for the frequency selective channels

In order to improve the performance of the received system for the frequency selective channel at low SNR, spectrum combining technique before symbol timing synchronization for a randomly distributed sensor array is proposed. Moreover, to meliorate adverse effect on the demodulation performance caused by the single channel´s nonlinear phase characteristic, a simple extensible average phase algorithm is demonstrated to converge the combining signal´s phase to the average phase instead of the value of the fixed branch. Finally the simulations show that the spectrum combining technique with extensible average phase algorithm can achieve a substantial performance improvement without the symbol timing synchronization. Therefore it may be regarded as a useful combining technique in the frequency selective channels at low SNR, especially when timing synchronization is difficult to realize.