Pulse Shaping Considerations in Ds-cdma Systems with Long Spreading Sequences
نویسندگان
چکیده
In this work, we analyze the effect of different pulse shaping filters on the performance of the asynchronous DS-CDMA systems employing long spreading sequences over Rayleigh-fading channels. We numerically evaluated and compared the performance of rectangular pulse and square root raised cosine pulses with different rolloff factors for conventional receiver and multiuser detectors. Our work justifies the use of rectangular pulse when evaluating the receiver algorithms with computer simulations. Based on the simulation results, we also made some recommendations on how to choose RRC pulses in practical systems, e.g., the selection of rolloff factor, truncation length, etc..
منابع مشابه
Nonlinear Multiuser Receiver for Optimized Chaos-Based DS-CDMA Systems
Chaos based communications have drawn increasing attention over the past years. Chaotic signals are derived from non-linear dynamic systems. They are aperiodic, broadband and deterministic signals that appear random in the time domain. Because of these properties, chaotic signals have been proposed to generate spreading sequences for wide-band secure communication recently. Like conventional DS...
متن کاملError Probability Performance of Quadriphase DS-CDMA Wireless Communication Systems Based on Generalized Approach to Signal Processing
Probability of bit-error er P performance of asynchronous direct-sequence code-division multiple-access (DS-CDMA) wireless communication systems employing the generalized detector (GD) constructed based on the generalized approach to signal processing in noise is analyzed. The effects of pulse shaping, quadriphase or direct sequence quadriphase shift keying (DS-QPSK) spreading, aperiodic spread...
متن کاملThroughput Improvement of STS-Based MC DS-CDMA System with Variable Spreading Factor
The throughput enhancement of Space-Time Spreading (STS)-based Multicarrier Direct Sequence Code Division Multiple Access (MC DS-CDMA) system is investigated in this paper. Variable Spreading Factor (VSF) is utilized to improve the data throughput of the system. In this contribution, an analytical approach is proposed to compute a new expression for the Bit Error Rate (BER) performance of t...
متن کاملSome Results on Pulse Shaping in DS-CDMA Systems
DS-CDMA is evaluated for rectangular pulse shaping and square root raised cosine pulses with different roll off factors. Rectangular pulses are found to be better even with close adjacent channels. With synchronization error in the order of 10% of a chip interval, square root raised cosine pulses outperform the rectangular pulse.
متن کاملBinary Spreading Sequences with Negative Auto-Correlation Based on Chaos Theory and Gold Sequences for Application to Asynchronous DS/CDMA Communications
SUMMARY Spreading sequences with appropriate negative auto-correlation can reduce average multiple access interference (MAI) in asyn-chronous DS/CDMA systems compared with the conventional Gold Sequences generated by linear feedback shift registers (LFSRs). We design spreading sequences with negative auto-correlation based on Gold sequences and the chaos theory for the Bernoulli map. By compute...
متن کامل