One of the important means to improve the performance of spread spectrum communication system is to combine error-correcting with spread-spectrum.In this paper
we discuss the advantages of applying TCM to the orthogonal code spread spectrum systems
which increase the minimum free Euclidean distance between the transmitted sequences by expanding and partitioning of the signal sets.Analysis and computer simulation show that the performance of the system in the channel with additive white Gaussian noise and multiple-access interference is markedly improved.