TCA-PCA based hybrid code assignment for enhancement and easy deployability of CDMA protocol

Code Division Multiple Access (CDMA) aims at the simultaneous transmissions among mobile stations using orthogonal spreading codes where the spatial reuse of the codes is considered for the reduction of code requirement. Code assignment should be such that the communication performance of the network is improved where no code assignment interference is allowed. There exists three code assignment techniques namely TCA, RCA and PCA, and several efficient methods for code assignment are published in literature. In this paper, we reinvestigated the TCA based code assignment scheme for easy deployment, non-existence of secondary interference, supporting easy implementability of RCA (being equivalent to TCA) etc. Since TCA requires Δ times number of codes over the Δ codes as required in PCA approximately, where Δ is the maximum degree of a CDMA network graph, we incorporate PCA with TCA in a systematic manner for completing interference-free code assignment and reducing the code requirement to only 2Δ+1 codes. The proposed technique may be called a TCA-PCA hybrid code assignment scheme, which is first time presented in this paper. The details of the scheme with its simulation using MATLAB is provided. The results show that the proposed technique outperforms the existing TCA-based techniques in one hand, and on the other hand, it not only eases the RCA implementation but also significantly simplifies the PCA scheme.