  Filter bank multiple access (FBMA) without subbands orthogonality has been
proposed as a new candidate waveform to better meet the requirements of future
wireless communication systems and scenarios. It has the ability to process
directly the complex symbols without any fancy preprocessing. Along with the
usage of cyclic prefix (CP) and wide-banded subband design, CP-FBMA can further
improve the peak-to-average power ratio and bit error rate performance while
reducing the length of filters. However, the potential gain of removing the
orthogonality constraint on the subband filters in the system has not been
fully exploited from the perspective of waveform design, which inspires us to
optimize the subband filters for CP-FBMA system to maximizing the achievable
rate. Besides, we propose a joint optimization algorithm to optimize both the
waveform and the covariance matrices iteratively. Furthermore, the joint
optimization algorithm can meet the requirements of filter design in practical
applications in which the available spectrum consists of several isolated
bandwidth parts. Both general framework and detailed derivation of the
algorithms are presented. Simulation results show that the algorithms converge
after only a few iterations and can improve the sum rate dramatically while
reducing the transmission delay of information symbols.
