Multi-tone Code Division Multiple Access System Research Articles

A novel bandwidth efficient channel coding scheme using super orthogonal code-based turbo code for S/P-Replica MT-CDMA system

In this paper, we analyze the bit error rate (BER) performance of a new modified structure of multitone code-division-multiple-access (MT-CDMA) system that is serial-to-parallel (S/P)-Replica MT-CDMA. It is shown that with the same bandwidth, the S/P-Replica MT-CDMA system outperforms the conventional system that we name it S/P MT-CDMA. We also propose a novel bandwidth-efficient-channel-coding-scheme (BECCS) based on super-orthogonal-code (SOC)-assisted serially concatenated turbo code (SCSOC) for S/P-Replica MT-CDMA system so that by using it, the coded system without extra bandwidth, significantly improves the performance of an uncoded system over fading channel.

The performance of MT-CDMA system in the presence of carrier frequency offset

In this letter, the sensitivity of an uplink Multi-Tone Code-Division Multiple Access (MT-CDMA) system to the Carrier Frequency Offset (CFO) is investigated. The analytical expression for the Bit Error Rate (BER) of uplink MT-CDMA in the presence of CFO is derived in a multipath Rayleigh fading channel which is verified through simulations. Both Maximal Ratio Combining (MRC) and Equal Gain Combining (EGC) are considered in combining multipath signals in the analysis. It is found that the BER performance can be improved with the number of multipath increasing in the presence of CFO.

Performance Analysis of MT-CDMA System with Antenna Array in a Multipath Fading Channel

In this paper, we propose a multitone code-division multiple-access (MT-CDMA) system employing antenna array at base station with quaternary phase shift keying modulation (QPSK) modulation. Based on the detailed analysis of interference characteristics the BER performance of the proposed MT-CDMA system is provided. With regard to spatial domain combining, the optimum and suboptimum combining weight is derived while the suboptimum set of weights is simplified on sense of that only the knowledge of array vector of desired user alone is sufficient for the optimum combining. Simulation results verify the analysis and show that better performance is achieved for the proposed antenna array system than single antenna MT-CDMA approach.

Noncoherent MT-CDMA system with post-detection diversity combining

This paper presents a theoretical analysis of a noncoherent multitone code division multiple access (MT-CDMA) system with diversity combining in terms of average bit error rate performance. The study is carried out for both slow Rayleigh and Ricean fading frequency-selective channels with differential binary phase-shift keying (DBPSK) modulation in the indoor environment. The investigation considers post-detection diversity with maximal ratio combining. Assuming a fixed bandwidth, bit rate and transmitter power, the effect of diversity order and number of tones on the systems performance is studied. Numerical results are presented to validate the analysis and to justify the approximations made.

Effect of fading, diversity and interference on the performance of multitone CDMA systems

AbstractThe performance of a multitone Code Division Multiple Access (CDMA) system is investigated in this paper by considering the effect of multipath fading, diversity and narrowband interference. The performance is evaluated in terms of the average bit error rate when both multiple access and partial band interference are present. Results are obtained by deriving the statistics of the receiver output parameters and then tested by numerical evaluation. The bit error rate performance is analyzed as a function of bit rate, bandwidth, delay range and different diversity techniques, while considering issues relevant to system implementation. Comparisons were made between conventional single‐tone CDMA systems and multitone CDMA systems. The effectiveness of multitone CDMA in suppressing interference compared to conventional CDMA system is analyzed. Results reveal considerable performance improvement of multitone CDMA system over conventional CDMA system. Copyright © 2002 John Wiley & Sons, Ltd.

Fractionally spaced linear joint detection for multitone CDMA systems

We consider a fractionally spaced linear joint detector (FS-LIJD) for multitone code-division multiple-access (CDMA) systems. We first derive the structure of the receiver for a minimum mean-squared error (MMSE) criterion. Then, we exactly evaluate the bit-error rate (BER) achieved by this detector for binary phase-shift keying (BPSK) modulation in steady-state conditions. We consider an asynchronous scenario, where the signal of each user propagates over a two-path channel. The resistance of the detector against timing errors is studied, and the resistance against a near-far scenario is also demonstrated.

Fractionally spaced decision feedback joint detection for multitone CDMA systems

We consider a fractionally spaced decision feedback joint detector (FS-DFJD) for multitone code division multiple access (CDMA) systems. We first derive the structure of the receiver for an minimum mean-squared error (MMSE) criterion. Then we investigate the bit-error rate (BER) performance achieved by this detector for binary phase-shift keying (BPSK) modulation in steady-state conditions. We consider an asynchronous scenario where the signal of each user propagates over a two-path channel. The resistance of the detector against timing errors is studied, and the resistance against a near-far scenario is also demonstrated.