BER Performance of Modified Walsh Hadamard Codes in a DS-CDMA and Cognitive Underlay System
Walsh Hadamard codes are widely used as signature codes in the current CDMA technologies due to their orthogonal property and simplicity of implementation. In this paper, modified set of Walsh Hadamard codes are used as signature codes for spreading. They are generated by modifying the basis sequences in any one stage of Kronecker product recursion of the original Walsh code generation. Hence these codes can be generated by reconfiguring the original Walsh Hadamard code generator. These codes also offer better correlation properties and their BER performance is comparable with Walsh codes in an AWGN and Rayleigh flat fading channels in a DS-CDMA system.