Performance improvement of uplink of analog wireless communication systems employing spatial diversity

Signal attenuation is one of the most important problems in wireless communication systems. The message conveyed by the transmitted waveform will not be recovered correctly if this attenuation is such that the SNR in the receiver is less than a specific threshold. Channel fading which results from receiving many non-coherent reflected versions of transmitted signal in the receiver, is one of the sources of this signal degradation. Fading may result in severe changes in the strength of the received signal in short time intervals. Diversity techniques are the most powerful tools to combat degrading effects of wireless fading, by using two or more independent communication channels. Diversity techniques are mainly designed for digital communications, therefore employing them in analog systems such as FM radios is a challenging issue. In this study, spatial diversity in receiver is proposed in order to making the current VHF wireless systems smart against channel fading. Based on this idea, three different applicable methods have been proposed for traditional analog FM repeating systems which can be implemented with little changes in the current hardware system. Simulation results show the improvement in reliability and performance of the systems using these methods.