I/Q Column-Wise Complementary Codes for Interference-Resistant CDMA Communication Systems

Motivated by growing demand for high-speed wireless communications, we proposed to implement code division multiple access systems based on orthogonal complementary codes (OCC-CDMA). While an OCC-CDMA system indeed offers ideal correlation properties, its capacity is strictly constrained by the number of element codes each user may use. In this paper, we suggest to use in-phase/quadrature (I/Q) column-wise complementary (IQCC) codes to implement a CDMA system to support 2M users, where M stands for the number of element codes in a flock of IQCC codes assigned to a user. The IQCC codes were designed to fit quadrature phase-shift keying modulation, where odd and even chips can be transmitted via I and Q carriers. We analyze correlation properties of the IQCC codes and introduce a CDMA system design based on the codes. The analytical results show that out-of-phase autocorrelation and cross-correlation functions are zero for any relative time shifts. Thus, a CDMA system implemented by the IQCC codes has an inherent capability to mitigate multiple access interference and multipath interference.