| A high capacity in cellular systems can be achieved through an effective reuse of the allocated spectrum resources. However, tight spectrum reuse increases the co-channel interference and as a result the Quality of Service (QoS) experienced by users is degraded. To facilitate the reuse, and achieve high capacity without QoS degradations, the receivers used in cellular radios need to be designed so that they can tolerate a significant level of the co-channel interference. This can be achieved by using various interference reduction techniques.; The approach for interference reduction proposed and examined in this research combines two effective RF signal-processing techniques. The first one is diversity reception and the second one is the blind separation of the source signals. Diversity reception is used to generate multiple copies of the signal of interest and its co-channel interferers. Blind signal separation is accomplished through Independent Component Analysis (ICA), which separates signals on the basis of their mutual statistical independence.; In this dissertation, the problem of co-channel interference cancellation is formulated in a mathematical framework that allows application of the ICA. The framework provides a unified treatment of various linear and angle modulation schemes. For each of the examined modulation schemes, an ICA based receiver architecture is proposed. Through computer simulations, the performance of the proposed receiver architectures are evaluated in different types of propagation environment and for cases of single and multiple co-channel interferers. In all cases, the simulation results demonstrate that proposed techniques provide significant benefits to the performance of the receiver.; From a mathematical standpoint, co-channel interference from the frequency reuse in cellular systems is similar to the cross talk between I and Q branches of the QAM receiver, which occurs as a result of the amplitude and phase mismatch. This similarity is utilized to devise an effective ICA based QAM receiver architecture. The architecture does not need estimation of the carrier phase and can tolerate high levels of amplitude and phase mismatch between local oscillators in I and Q branches. |
