Forward link performance simulation of a fixed-point CDMA2000-1x mobile demodulator

Designing a limited word length fixed-point CDMA 2000-1X modem chip is essential for reduced die size and power consumption which leads to a cheaper and a higher performance handset. In this paper, we present the performance degradation due to the finite word length implementations of the pilot and traffic channels with various A/D quantizers for CDMA2000-1x mobile station (MS) demodulator. The performance results are also compared to that of a floating point implementation. The 4-bit, 5- bit and infinite resolution A/Ds are used in some simulation runs to compare their impact on performance. 4Viterbi decoder and a 4-bit turbo decoders are used in all the fixed point simulations. The frame error rate (FER) performance with 4- bit A/D with fixed-word length traffic and pilot symbols seems sufficiently close (maximum difference of 0.5 dB) to that of the floating point implementation.