Code Combining Diversity Reception and Its Application to Broadband Wireless

In this paper, we propose the utilization of code combining (CC) diversity branch combining scheme for diversity reception in mobile communications. The bit-error-rate (BER) performance of CC scheme is investigated by computer simulation at various conditions of transmission systems and channels, and compared with that of the counterpart systems using conventional maximal ratio combining (MRC) scheme. The simulation results show that CC scheme can directly improve the BER performance of the transmission systems by increasing the error correcting capability of the error control code after diversity branch combining, therefore, is effective to combat not only frequency flat fading, but also frequency selective fading, co-channel interference, and so on. Furthermore, the system implementation of CC scheme is as simple as that of conventional selection combining (CC) scheme. Applying the idea of CC to broadband wireless communications, we also propose a low-complexity RAKE W-CDMA reception scheme using code combining space and RAKE path diversity reception. Computer simulation has confirmed that proposed RAKE receiver has better BER performance with much lower implementation complexity than the conventional coherent RAKE receiver, and is very attractive especially for mobile units.