Families of Four-Phase Quasi-Orthogonal Code Arrays

A method of construction is presented for rectangular quasi-ortogonal code arrays over the ring Z4. The proposed arrays are easy to generate: The four-phase linear recurring sequences constructed by Boztas et. al. are utilized to generate the arrays by modulo 4 substraction. The periodic auto-and cross-correlation properties of these arrays are then derived in a straightforward manner. The maximum off-peak correlation magnitude for these arrays is lower by a factor of /spl radic/2 when compared to the binary Gold code arrays constructed by Kuo and Rigas. The arrays can be used for 'add-on' data transmission, pattern synchronization, and code division image multiplexing.