Comparison of BER performance of WCDMA/TDD based optimum combining and beamforming in angular spread channel

We compare the BER performance of WCDMA/TDD based optimum combining and beamforming in different angular spread environments. In previous studies, the received signals at the array antenna are independent by separating the antenna distance and applied MMSE, MSINR, MRC to compare the performance under CCI (cochannel interference). In addition they theoretically and experimently proved the results they have simulated. With the premise of the results they suggested we perform a simulation to compare the BER performance of optimum combining and beamforming in using the MMSE algorithm under different users (intracell interference) and E_b/N_o. For the simulation, we chose the WCDMA/TDD standard. Through the simulation results, the uncorrelated receive signals at the array antenna can fight the fading for the sacrifice of the beamforming to the wanted signal direction. In simulation, two types of array structures were assumed. One is λ/2 and the other is 10λ. Also, the MMSE and MRC beamforming algorithms are compared under different angular spread channel environments. For the BER performance it is shown that the beamforming effect of maximum directivity to the wanted user is less than that of the space diversity effect. Therefore, there are two factors of the antenna distance and channel environment to get the receive signals uncorrelated. In WCDMA/TDD mode the cell is small (rich scattering environment) and the users are restricted so the optimum combining method is suggested as an effective method.