Multiuser PSK-Chirp-BOK Communication System Under Co-Channel Interference

A chirp binary orthogonal keying (BOK) system normally transmits 1 bit per symbol and requires two correlators at the receiver. This brief presents a chirp-BOK system incorporating phase shift keying (PSK) modulation, viz. , PSK-chirp-BOK system, to double the transmission rate while using only two correlators. Design of a set of orthogonal chirps is presented to minimize the performance degradation due to non-orthogonality between up-chirps and down-chirps in a PSK-chirp-BOK multiuser system. In an effort to reduce the required total system bandwidth while maintaining the same number of chirps for a multiuser system, a time domain multiplexing of orthogonal chirp sets with filtering using fractional Fourier transform is proposed. Symbol error rate performance of the proposed PSK-chirp-BOK system in a multiuser environment under Nakagami- $m$ fading with the effect of co-channel interference is analyzed. Benefits of the proposed scheme over the existing ones are also outlined.