Spectral efficiency optimization in overlapping channels using TR-MISO systems

Traditionally, cellular radio communication systems define a spectrum mask to avoid inter-channel interference between services operated in adjacent frequency bands. In this paper, we intend to optimize the spectrum efficiency of wireless systems by frequency band reused, which is performed by partial channel overlapping of adjacent bands. The impact of interchannel interference is studied for both single and multicarrier modulations. Then time reversal (TR) with multiple-input-single-output (MISO) is applied to depress the inter-channel interference thanks to the TR focusing properties. The spectral efficiency of the system is evaluated according to the overlap ratio τ and the number of transmitting antennas. The optimal τ_max is identified and, as a result, channel overlapping is proved to be interesting at low SNR regime in a range depending on the number of antennas.