Reliable hybrid ARQ data transmission with optimal signal-to-interference ratio assignment in CDMA PCS

Combined error correction and detection techniques, or hybrid automatic-repeat-request (ARQ) schemes with negative acknowledgment are considered for highly reliable reverse link data transmission in direct sequence code division multiple access (DS-CDMA) personal communication systems. In this paper a coherent link using OQPSK and continuous pilot signal assisted radio channel estimation is analyzed. The proposed selective repeat hybrid ARQ scheme employs an inner convolutional code for error correction and an outer shortened BCH code for error detection. Accepted packet error rate and throughput are derived as a function of the error correction encoded frame error rate. An optimum signal-to-interference ratio (SIR) assignment maximizing the system´s capacity is also found. Analysis and simulations show that by applying the proposed type I hybrid ARQ scheme with properly selected system parameters, virtually error free and highly efficient data transmission in CDMA personal communication systems is possible