Highly reliable data transmission using concatenated coding and hybrid-type I ARQ in DS-CDMA systems

Highly reliable data transmission using Reed-Solomon(RS)/convolutional concatenated coding in conjunction with hybrid type-I automatic retransmission request (ARQ) is investigated. The study is based on an analysis of the tradeoff between error correction and error detection capabilities of RS codes for the direct-sequence code-division multiple-access (DS-CDMA) systems. Two RS decoding schemes are considered: error-only decoding (decoding without side information) and error-and-erasure (EE) decoding. In the EE scheme, the inner code is decoded with a modified Viterbi algorithm, which produces reliable information along with the decoded output. Numerical results illustrate the importance of properly selecting the design parameters for the purpose of maximizing spectral efficiency. The results also show that an E_b/N₀ gain of 0.1 to 0.5 dB can be obtained by using EE decoding, depending on the selected parameters