PERFORMANCE OF LOW-RATE ORTHOGONAL CONVOLUTIONAL-CODES IN DS-CDMA APPLICATIONS

Low-rate orthogonal convolutional codes (LROCC), originally proposed b y A. J. Viterbi, can be used in a direct-sequence code-division multip le access (DS-CDMA) system to achieve both spreading of the data and p roviding coding gain, The implementation of this type of multiplexing in a practical DS-CDMA system is presented, and the theoretical perfor mance of the proposed system under ''other-user'' noise, additive whit e Gaussian noise (AWGN), intercell interference, and thermal noise is established using a computer simulation. The improvement in system per formance, gained through the use of a nonspreading randomizing sequenc e on the encoded output symbols, is also studied, Performance curves f or a rate 1/64 orthogonal convolutional code are shown, and the impact of code rate, quantization methods, and constraint length on the over all system performance are discussed.