Spatial modulation (SM) is a multiple input multiple output wireless communication system that gives better spectral efficiency. This scheme uses antenna indices and a conventional signal set to convey information. A drawback in SM is its low spectral efficiency. A recently proposed extension (or generalization) of SM, termed generalized spatial modulation (GSM), allows multiple transmit antennas to be active simultaneously. By choosing a combination of total number of transmit antenna elements and number of transmit RF chains, GSM can achieve higher spectral efficiencies than SM. In this paper we are using Maximum Ratio Combining scheme i.e. MRC scheme and ML detection scheme and thus analyzing there BER and reduction in complexity for GSM. We provide an exact BER analysis for Maximum Ratio combining and imperfect channel estimation at the receiver. The BER characteristic of various transmitting and receiving antennas are simulated in MATLAB tool box. It shows that MRC based receiver is best choice for removing ISI and for minimizing the total noise power. ML decoding scheme in the SM system involves joint detection of transmit antenna index and the transmitted symbol. Sphere Decoding becomes essential in order to achieve ML performance while keeping decoding complexity at its minimum. Thus ML performance gives reduced complexity and MRC scheme reduces the BER as the antenna configuration is increased.
Keywords : MRC, ML, SM, GSM, MIMO.