Scrambling Code Planning in TD-SCDMA Cellular Systems

Scrambling code planning (SCP) for time-division synchronous code-division multiple-access (TD-SCDMA) systems is a challenging issue due to the poor cross correlations between the spreading codes generated by cell-specific scrambling codes. In this paper, a novel SCP algorithm is proposed. Intercell interference is modeled as a function not only of the cross correlations between spreading codes but of the radio propagation conditions and traffic distributions as well. The cross correlation of spreading codes is analyzed, and the concept of the scrambling code family is proposed to simplify the code planning process. The proposed algorithm facilitates the assignment and selection of scrambling codes. Numerical results shows that the proposed algorithm can achieve a much lower intercell interference than the existing SCP algorithms.