A Novel Code Assignment Scheme for Broadband OFCDM Systems

To provide high speed mobile services, multi-code transmission is employed in the orthogonal frequency and code division multiplexing (OFCDM) system. However, the code channel orthogonality is distorted by the broadband wireless channel, and multi-code interference (MCI) is caused. The amount of the MCI is dependent on which codes to be used. This paper investigates the code assignment in the multi-code OFCDM system, aiming to mitigate the MCI at the receiver. In terms of the code distance defined in this paper, a novel code assignment scheme is proposed. It has been shown that the system performance can be improved significantly by the proposed scheme under various channel conditions, especially when a low to medium system load is assumed