Transmitter and receiver diversity techniques in adaptively equalized offset-QAM cellular systems

Channel equalization used in conjunction with diversity techniques can combat effectively both the frequency non-selective and frequency selective fading that characterize mobile radio environments. In this paper the performance of offset 4 and 16-QAM outdoor mobile radio systems that use diversity and adaptive channel equalization techniques are analyzed. Various transmission and reception diversity techniques are investigated and the necessity of adaptively equalizing the radio channel has been stated in typical urban (TU) environments. Transmission diversity used jointly with a RLS-DFE equalizer has proved to be useful for low bit rate systems, taking advantage of the intersymbol interference induced on the received signal and improving the system performance without increasing the receiver complexity. Diversity reception, and in particular, equal gain combining diversity is a good choice for base stations where higher complexity can be assumed.