Increasing CDMA capacity using multiple orthogonal spreading sequence sets and successive interference cancellation

Vanhaverbeke, F.; Moeneclaey, Marc; Sari, Hikmet

doi:10.1109/icc.2002.997103

Cited by 36 publications

(23 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The major drawback of this type of technique is that if one of the bits of LoDR is wrongly estimated, then it can effect 'q' number of HDR bits. Error propagation can be minimized if hard decision is replaced by soft decision of received data bits [7,10,17]. In the last stage of iteration, the final decision is made by hard detector, Mukherjee…”

Section: Decoding Of B 1 Usersmentioning

confidence: 99%

“…The BER performance of Sub-PIC improves significantly by taking soft estimation of the interfering users. In soft decision Sub-PIC (SDSub-PIC), the estimation of the received data is performed by taking soft decisions using non-linear function [17]. The soft decision of X k is given bỹ…”

Section: Againẑmentioning

confidence: 99%

“…Suboptimum multiuser detection [16] for overloaded systems has been proposed, but with very specific constraints on the signal set. Multistage iterative interference cancellation has been found suitable in overloaded system [17][18][19]. Recently, iterative multiuser detection with soft IC for multirate MC-CDMA has been proposed in [20].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A novel code-based iterative PIC scheme for multirate CI/MC-CDMA communication

Mukherjee

Kumar

2011

J Wireless Com Network

View full text Add to dashboard Cite

This paper introduces a novel code-based iterative parallel interference cancellation technique (Code-PIC) for the multirate carrier interferometry/multicarrier code division multiple-access (CI/MC-CDMA) system, which supports simultaneous transmission of high and low data rate users. In Code-PIC scheme, multiple-access interference (MAI) for the desired user is estimated based on the projection of subcarrier and subsequent removal of interference from the received signal depending on specific high or low data rate users. Carrier interferometry (CI) codes are used to minimize the cross-correlation between users, which significantly reduces the multiple-access interference (MAI) for the desired user. The effect of MAI in CI/MC-CDMA is reduced by giving proper phase shift to different set of users. Improved estimation of MAI in Code-PIC results in lower residual interference after interference cancellation. Simulation results show that Code-PIC scheme offers improved BER performance over AWGN and Rayleigh fading channels compared to Block-PIC and Sub-PIC with reduced latency and complexity.

show abstract

Section: Decoding Of B 1 Usersmentioning

confidence: 99%

Section: Againẑmentioning

confidence: 99%

See 1 more Smart Citation

A novel code-based iterative PIC scheme for multirate CI/MC-CDMA communication

Mukherjee

Kumar

2011

J Wireless Com Network

View full text Add to dashboard Cite

show abstract

“…In order to compare the performance of Cu systems with low TSAC sequences to WBE sequences of Sa systems, we make use of a turbo detector [8], where in each iteration, the data of the users are detected successively, taking account of an estimate of the interference, caused by the other users. In each iteration I we cancel the interference on user k caused by the other users, based on the most recently estimated values of the data symbols of the interfering users.…”

Section: Cancellationmentioning

confidence: 99%

Capacity Improvement through Signature Displacement in CDMA Systems

Vanhaverbeke

Moeneclaey

2006

2006 IEEE Ninth International Symposium on Spread Spectrum Techniques and Applications

View full text Add to dashboard Cite

Abstract-We evaluate the potential increase in critical load with interference cancellation and (downlink) user capacity by intentionally displacing the signatures of a CDMA system with respect to each other. It turns out that a huge capacity increase, both in terms of user capacity and critical load, is achievable as compared to conventional CDMA systems where all signatures are aligned in time. In addition, we introduce new achievable user capacity bounds that can serve as benchmarks for the evaluation of CDMA systems.

show abstract

“…Most of the research in the overloaded case is related to code design and multi-access interference (MAI) cancelation in order to decrease the probability of error. Examples of these types of codes are pseudo random spreading [9,10], Welsh Bound Equality (WBE) codes with minimal total square correlation (TSC) [11][12][13][14], OCDMA [15][16][17], Multiple-OCDMA [18], and PN/ OCDMA [19] signature sets. None of the above codes guarantee errorless transmission in the absence of channel noise for overloaded CDMA systems.…”

mentioning

confidence: 99%

A review on synchronous CDMA systems: optimum overloaded codes, channel capacity, and power control

Hosseini

Javidbakht

Pad

et al. 2011

J Wireless Com Network

View full text Add to dashboard Cite

This paper is a tutorial review on important issues related to code-division multiple-access (CDMA) systems such as channel capacity, power control, and optimum codes; specifically, we consider optimum overloaded codes that achieve errorless transmission in the absence of noise for the binary and nonbinary cases. A survey of lower and upper bounds for the sum channel capacity of such systems is given in the presence and absence of channel noise. The asymptotic results for the channel capacity are also investigated. The channel capacity, errorless transmission codes, and power estimation for near-far effects are also explored. The emphasis of this tutorial review is on the overloaded CDMA systems.Keywords: Code Division Multiple Access (CDMA), Optimum codes, channel capacity bounds, near-far effects, power control I Introductioncode-division multiple access (CDMA) has been the most important multiple access technology for the 3rd generation GSM and American Cellular systems [1]. Optical CDMA systems have become an alternative multiple access for fiber optics and optical wireless systems [2][3][4].In CDMA systems, each user is assigned a unique code signature that consists of a number of chips. The signature length (also called chip rate) is defined as the number of chips in each signature code. Each user signature is multiplied by the respective data, and the transmitted vectors are added up in the common channel. The resultant vector is then observed at the received user end. In order to decode the received signal, the detector of the received user should know its own unique signature. These codes should be designed such that the cross-correlations between the code of the desired user and the codes of the other users are minimal.For the wireless case, the most well-known binary (Endnote a) code for the synchronous case is Hadamard orthogonal code that is appropriate for fully and underloaded CDMA systems. (Endnote b) But because of bandwidth limitation in the communication systems, we are interested in finding codes that can support more users than the chip rate (overloaded case). In the overloaded case, we cannot use Hadamard codes; Even random codes create interference that cannot be eliminated completely [5][6][7]. Optical orthogonal codes (OOC) [3,8] are not really orthogonal; however, using interference cancelation, we can remove interference completely. Most of the research in the overloaded case is related to code design and multi-access interference (MAI) cancelation in order to decrease the probability of error. Examples of these types of codes are pseudo random spreading [9,10], Welsh Bound Equality (WBE) codes with minimal total square correlation (TSC) [11][12][13][14], OCDMA [15][16][17], Multiple-OCDMA [18], and PN/ OCDMA [19] signature sets. None of the above codes guarantee errorless transmission in the absence of channel noise for overloaded CDMA systems. There are also some codes that are not designed upon cross-correlation and are designed such that they can provide one-to-one transfor...

show abstract

Increasing CDMA capacity using multiple orthogonal spreading sequence sets and successive interference cancellation

Cited by 36 publications

References 7 publications

A novel code-based iterative PIC scheme for multirate CI/MC-CDMA communication

A novel code-based iterative PIC scheme for multirate CI/MC-CDMA communication

Capacity Improvement through Signature Displacement in CDMA Systems

A review on synchronous CDMA systems: optimum overloaded codes, channel capacity, and power control

Contact Info

Product

Resources

About