Current book is organized over three sub-topics, related to the physical- and MAC layers of advanced wireless networks. The first one deals with the analytic error analysis of M-QAM and M-PSK modulation techniques, providing analytic calculation solutions for the SER and BER, by considering different fading models and stochastic interference scenarios. The second part contains radio resource management solutions for OFDMA- and OFDMA-MIMO-based digital transmission. A fairness-increasing solution is provided for OFDMA, and further methods are shown towards increasing the spectral efficiency of the OFDMA-MIMO transmission, considering realistic propagation conditions. The third topic deals with the effects of the imperfect estimation of the channel state information (CSI) during OFDMA-MIMO based transmissions. CSI knowledge imperfections can result a significant degradation in the system performance. Error models are defined for the CSI estimation. The spectral efficiency of MIMO can be increased by the pre-coding operation. An error model is provided for the feedback of pre-coding information, and the performance degradation caused by the imperfect feedback has been investigated.