Antiphase Tones Across Transmitting Antennas: A Spectrum Sharing Technique for Cognitive CO-STFC MB-OFDM UWB System

摘要

This paper proposes a spectrum sharing technique for coexistence of multiband orthogonal frequency division multiplexing ultra wideband (UWB) system with other primary wireless services. Existing technique like tone nulling do not utilize subcarriers within victim band, hence affects the throughput of the system. The same nulling effect can be produced by applying antiphase tones across transmitting antennas and simultaneously utilizing the victim band to transmit the data. This scheme can be applied without any impact on the current specifications of the system. In this paper complex orthogonal space time frequency code is implemented to achieve diversity in multiple antenna system. UWB receiver processing is described for both victim and unprotected band. A less computationally complex active interference cancellation scheme is also applied to improve notch depth. The proposed scheme is implemented for fixed frequency interleaving operation and discussed for time frequency interleaving with special cases. The proposed scheme is very simple to implement and provide flexibility in terms of notch width and depth.