User performance variability in DS-CDMA systems-long vs. short spreading sequences

The uplink performance in a cellular DS-CDMA systems using long and short spreading sequences is compared in terms of the distribution of the bit error probability, both with and without forward error correction. Two different receiver types are considered, conventional and MMSE, both with and without forward error correction. The short code system has a slightly higher performance variability among the user population than the corresponding long code system, which requires attention when designing a short code system. Code hopping as a technique to mitigate this is investigated