Comparison of two interleaving techniques for CDMA radio communications systems

For code-division multiple access (CDMA) radio communications systems, orthogonal signaling with noncoherent detection has been proposed when a reference phase is not available. Orthogonal signaling using Hadamard signals is considered. Performance of the channel using error-correcting coding together with bit-by-bit interleaving or Hadamard word-by-word interleaving is investigated. It is found for the same M-ary orthogonal signaling, at a given bit error ratio, the second technique with complete soft decision decoding gives significant reduction in the required signal-to-interference ratio over the first technique with slightly added complexity in the decoder.<>