Class of blind maximal ratio combining methods for digital communication systems

Simple iterative methods for blind maximal ratio combining based on a maximum likelihood principle and finite alphabet properties inherent in digital communication systems are presented. These methods can provide accurate estimates of channel parameters even with a small subset of data. The channel parameters and the data sequence are estimated simultaneously. Two methods, the joint combining and data sequence estimation method and the pre-combining and blind phase estimation method, are presented. Efficient initialisation schemes that can assure the convergence to the global optimum are presented. Simulation results demonstrate the performance of the two methods in terms of the symbol error rate and the estimated accuracy of the channel parameters