A multiple-access interference suppression technique employing orthogonal/random spreading sequences and a novel decentralized receiver for B-CDMA forward link systems in multipath channels

For suppressing multiple access interference (MAI) in a CDMA communication system, complementary sequence sets are employed as spreading sequences in such system. In this paper, we present a method for constructing a family of quaternary periodic complementary sequence sets, which arises from the conversion of the existing binary periodic complementary sequence sets with odd period of sub-sequences. The period of sub-sequences in the proposed sequence sets is twice as long as the one of the binary sequence sets employed, which is a drawback in the proposed method. Finally, some examples are given in order to illuminate the validity of the new method.

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On distributions of multiple access interference for spread spectrum communication systems using M-phase spreading sequences of Markov chains

2004 IEEE International Symposium on Circuits and Systems (IEEE Cat. No.04CH37512) ◽

10.1109/iscas.2004.1329077 ◽

2004 ◽

Author(s):

H. Fujisaki

Keyword(s):

Markov Chains ◽

Spread Spectrum ◽

Communication Systems ◽

Multiple Access ◽

Multiple Access Interference ◽

Spread Spectrum Communication ◽

M Phase ◽

Spreading Sequences

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Suitable Spreading Sequences for Asynchronous MC-CDMA Systems

Journal of Telecommunications and Information Technology ◽

10.26636/jtit.2018.118217 ◽

2018 ◽

Vol 3 ◽

pp. 9-13 ◽

Cited By ~ 1

Author(s):

Mouad Addad ◽

Ali Djebbari

Keyword(s):

Communication Systems ◽

Multiple Access ◽

Signal To Noise Ratio ◽

Multiple Access Interference ◽

High Data ◽

Research Areas ◽

Rate Transmission ◽

Cdma Systems ◽

Code Division Multiple ◽

Spreading Sequences

In order to meet the demand of high data rate transmission with good quality maintained, the multi-carrier code division multiple access (MC-CDMA) technology is considered for the next generation wireless communication systems. However, their high crest factor (CF) is one of the major drawbacks of multi-carrier transmission systems. Thus, CF reduction is one of the most important research areas in MC-CDMA systems. In addition, asynchronous MC-CDMA suﬀers from the eﬀect of multiple access interference (MAI), caused by all users active in the system. Degradation of the system’s bit error rate (BER) caused by MAI must be taken into consideration as well. The aim of this paper is to provide a comparative study on the enhancement of performance of an MC-CDMA system. The spreading sequences used in CDMA play an important role in CF and interference reduction. Hence, spreading sequences should be selected to simultaneously ensure low CF and low BER values. Therefore, the eﬀect that correlation properties of sequences exert on CF values is investigated in this study. Furthermore, a numerical BER evaluation, as a function of the signal-to-noise ratio (SNR) and the number of users, is provided. The results obtained indicate that a trade-oﬀ between the two criteria is necessary to ensure good performance. It was concluded that zero correlation zone (ZCZ) sequences are the most suitable spreading sequences as far as the satisfaction of the above criteria is concerned.

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