An expert system approach for cellular CDMA

Ulloa, J.A.; Taylor, D.P.; Poehlman, W.F.S.

doi:10.1109/25.350280

Cited by 12 publications

(4 citation statements)

References 7 publications

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“…Depending on the type of CDMA technique, different codes can be used. In a synchronous system, orthogonal codes like (orthogonal variable spreading factor (OVSF) codes and hadamard codes) have been used, while pseudo-random codes or Gold codes have been used [6], [7].…”

Section: Issn: 2502-4752 mentioning

confidence: 99%

Enhancement of code division multiple access system performance using raptor codes

Farhan

Zaghar

Abdullah

2022

IJEECS

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Some kinds of communication systems work in very low signal-to-noise (LSNR) environments. For these systems to function reliably, <span>specific techniques and methodologies have to be used to mitigate the degrading effects of the channel. The channel coding method is the key element in most LSNR communication systems, but emphasizing the code division multiple access (CDMA) is a new transmission technique in these channels. To enhance the CDMA scheme's system capacity and reach unprecedented ranges of LSNR values in wireless sensor network. This paper suggests combining CDMA with certain types of channel coding algorithms, such as the raptor codes. The raptor channel encoding technique has improved the CDMA system's performance when using binary phase-shift keying (BPSK) modulation in additive white gaussian noise (AWGN) channels. It has achieved a low bit error rate in range of 10-7 at Eb/No value of (-3) dB and about 10-6 at shannon's limit. The Raptor-coded CDMA scheme works well for channel signal to noise ration (SNR) values of greater than -9 dB, showing an improvement of about 7 dB compared with turbo/convolutional channel coding methods used with the CDMA system bit error rate (BER) and throughput. On the other hand, it has been shown that the convolutional encoder presents the weakest performance compared to both the turbo and raptor codes.</span>

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Section: Issn: 2502-4752 mentioning

confidence: 99%

Enhancement of code division multiple access system performance using raptor codes

Farhan

Zaghar

Abdullah

2022

IJEECS

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“…The system's main characteristics were reliability, security, robustness, and flexibility. This technique is also influenced by other aspects like transmission power, bandwidth, and overall system efficiency [5] [6]. In DS-CDMA technology, each user is assigned a unique code, and the code assigned to the user is essential for modulating the signal since the overall system performance depends on it.…”

Section: Introductionmentioning

confidence: 99%

“…Depending on the type of CDMA technique, different codes can be used. In a synchronous system, the orthogonal codes like (OVSF codes, Hadamard codes) have been used, while in an asynchronous system, pseudo -random codes or Gold codes have been used [6] [7] .Channel coding can minimize multi-access interference (MAI) by decreasing the transmitted power at the expense of increasing the transmitted signal bandwidth through the redundant codes. Specific techniques can be used to improve the DS-CDMA system effectiveness and performance.…”

Section: Introductionmentioning

confidence: 99%

Performance Improvement of CDMA Wireless Sensor Networks in Low SNR Channels Based on Raptor Codes

Mahmoud

Zaghar

Abdullah

2023

Wireless Pers Commun

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Some kinds of communication systems work in very low signal to noise power ratio (SNR) environments. For these systems to function reliably, certain techniques and methodologies have to be used to mitigate the degrading effects of the channel.The channel coding method is the key element in most low SNR communication systems with emphasis on the Code Division Multiple Access (CDMA) as a recommended transmission technique in these channels. To enhance the system capacity of the CDMA scheme and reach to unprecedented ranges of low SNR values in systems like the Wireless Sensor Network (WSN), this paper suggests a technique for combining CDMA with certain types of channel coding algorithms such as the Raptor codes. The Raptor channel encoding technique has shown an improved performance for the CDMA system when using BPSK digital modulation in AWGNchannels. It has achieved a low bit error rate in the range of 10 -6 at Eb/No value of -2 dB and 10 -7 at Eb/No value of -3 dB for code rates 1/2 and 1/3 resprctively. The Raptor-coded CDMA scheme showing an improvement of about 6 dB when compared with some other channel coding methods used with the CDMA system for the same BER.

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“…It is well known that CDMA system is characterized as being interference-limited and reducing the interference results in increased capacity [2]. The evaluation of CDMA system is carried out in asynchronous manner because the perfect synchronism between users rarely occurs.…”

Section: Introductionmentioning

confidence: 99%

An interference cancellation scheme using dynamic space code multiple access (DSCMA) system

Ali

Khatun

et al. 2007

2007 IEEE International Conference on Telecommunications and Malaysia International Conference on Communications

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Non-uniform traffics can severely degrade the performance of code division multiple access (CDMA) and space division multiple access (SDMA) cellular systems. In this paper, we propose a novel interference cancellation scheme by using the joint multiple access system from the merge of CDMA and SDMA systems to form dynamic space code multiple access (DSCMA). This multiple access system uses a modified version of large area synchronous (LAS) sequence called LAS even-ternary (LAS-ET) sequence to increase its duty ratio. This sequence also exhibits a region called interference free window (IFW) near zero delay time offset. In order to ensure that all the signal components drop within the IFW, a narrow beam with higher directivity smart antenna system is exploited. The size of IFW is adapted to the smart antenna half-power beamwidth using DSC algorithm. By using this algorithm the spectrum efficiency is further increased. Finally, all the interferences induced in non-uniform traffics can be dramatically reduced in DSCMA system and thus resulting in a higher system capacity.Index Terms -CDMA, SDMA. Interference Cancellation.

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An expert system approach for cellular CDMA

Cited by 12 publications

References 7 publications

Enhancement of code division multiple access system performance using raptor codes

Enhancement of code division multiple access system performance using raptor codes

Performance Improvement of CDMA Wireless Sensor Networks in Low SNR Channels Based on Raptor Codes

An interference cancellation scheme using dynamic space code multiple access (DSCMA) system

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