Multistage detection in asynchronous code-division multiple-access communications

Varanasi, Mahesh K.; Aazhang, Behnaam

doi:10.1109/26.52662

Cited by 1,180 publications

(433 citation statements)

References 15 publications

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“…Since the cost function is convex in its variable, this problem has a unique minimum (5) Taking the sign of the solution vector yields the well-known decorrelating detector [3]. Note that, due to the sign operation, the detector is insensitive to signal amplitudes, i.e., the bit estimate resulting from is the same as that of .…”

Section: Decorrelatormentioning

confidence: 99%

“…Multi-stage receivers are familiar in multiuser detection. In [5], hard decision bit estimates are used to reconstruct and subtract the interference for each user. The receiver is implemented in a parallel fashion as in (10) and is not convergent.…”

Section: Proof-lemmamentioning

confidence: 99%

“…Both detectors are optimum when no noise is present. Decision-directed nonlinear detectors that generally result in lower bit error rates (BERs) have been proposed in [5] and [6]. The decorrelating decision feedback detector [6] cancels the interference from the users that have already been decoded, and suppresses interference from users that have not yet been decoded, to obtain the decision statistic for the current user.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

CDMA multiuser detection: a nonlinear programming approach

Yener

Yates

Ulukuş

2002

IEEE Trans. Commun.

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Abstract-The optimum receiver to detect the bits of multiple code-divison multiple access (CDMA) users has exponential complexity in the number of active users in the system. Consequently, many suboptimum receivers have been developed to achieve good performance with less complexity. In this paper, we take the approach of approximating the solution of the optimum multiuser detection problem (OMUD) using nonlinear programming relaxations. First, we observe that some popular suboptimum receivers indeed correspond to relaxations of the optimal detection problem. In particular, one proposed approximation method yields to iterative solutions which correspond to previously proposed heuristic nonlinear detectors. Using a nonlinear programming approach, we identify the convergence properties of these iterative detectors. Secondly, we propose a relaxation that yields a receiver which we call the generalized minimum mean squared error detector. We give a simple iterative implementation of the detector. Its performance is evaluated and comparisons to other suboptimum detection schemes are given.

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Section: Decorrelatormentioning

confidence: 99%

Section: Proof-lemmamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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CDMA multiuser detection: a nonlinear programming approach

Yener

Yates

Ulukuş

2002

IEEE Trans. Commun.

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“…The matched filter receiver is not optimal in the scope of multi-user communications. More involved systems (multi-user receivers) may be developped to lower the BER, like in CDMA communications or, alternatively, error control codes may be developed [19][20][21]. Another key point is the Doppler effect which may be encountered in practice in our multi-band (that is multi-carrier) system.…”

Section: Resultsmentioning

confidence: 99%

“…The BER has been computed from equation (17), using the cross-correlation expression (20) above, for different SNR and β values. As may be expected, the results obtained for two identical MGF orders (m = n) are unsatisfactory: the BER remains always greater than 10 −3 , even at higher SNR values.…”

Section: Several Users In the Same Sub-bandmentioning

confidence: 99%

Performance Evaluation of a Multi-band UWB Location and Communication System Based on Modified Gegenbauer Functions

Lamari

Elbahhar

Rivenq

et al. 2008

Wireless Pers Commun

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Ultra Wide Band (UWB) may offer very effecient solutions for various communication and sensing applications. Two approaches have emerged, which meet all the communication requirements: impulse and multi-band systems. The first system operates between 3.1 to 10.6 GHz in a single frequency band. The second one exploits the division of the bandwidth into sub-bands (each sub-band width being up to around 500 MHz wide). The present work is concerned in the second approach. So, we propose to use orthogonal functions called Modified Gegenbauer Functions (MGF) in the multi-band UWB system. Different scenarios are studied and compared in the scope of a system offering communication and location capabilities for subway trains. In order to evaluate the performance of the proposed system, the Bit Error Rate (BER) values are calculated and analyzed in the presence of multi-user interference, assuming asynchonous users. It is shown that Gegenbauer functions offer the performance required for our multi-band UWB communication and location system.

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The Use of Programmable DSPs in Antenna Array Processing

Bromberg

Brown

2001

The Application of Programmable DSPs in Mobile Communications

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Multistage detection in asynchronous code-division multiple-access communications

Cited by 1,180 publications

References 15 publications

CDMA multiuser detection: a nonlinear programming approach

CDMA multiuser detection: a nonlinear programming approach

Performance Evaluation of a Multi-band UWB Location and Communication System Based on Modified Gegenbauer Functions

The Use of Programmable DSPs in Antenna Array Processing

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