Suboptimum multiuser receivers for convolutionally coded asynchronous DS-CDMA systems

Giallorenzi, T.R.; Wilson, Stephen G.

doi:10.1109/26.536924

Cited by 94 publications

(39 citation statements)

References 24 publications

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“…Relating (10) and (37) to results applying statistical mechanics to CDMA detection [28], [17], we can show that the performance of the iterative canceler for low and moderate loads is essentially identical to that of (uncoded) individually optimal detection (APP detection). Using [28,Eqns.…”

Section: Equal Power and Equal Rate Usersmentioning

confidence: 87%

Optimal Power/Rate Allocation and Code Selection for Iterative Joint Detection of Coded Random CDMA

Schlegel

Shi

Burnashev

2006

IEEE Trans. Inform. Theory

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Abstract-Iterative interference cancellation of coded CDMA using random spreading with linear cancellation is analyzed. If users are grouped into power classes and Shannon-bound approaching codes are used, a geometric power distribution achieves the AWGN channel Shannon bound as the numbers of classes becomes large. The optimal distribution of the size of these classes is shown to be uniform. If users are grouped into different rate classes with equal powers among equal rate users, the Shannon bound for AWGN channels can be achieved with an arbitrary distribution of the classes sizes, provided that the size of the largest rate class obeys the mild condition that its ratio of size to processing gain is much smaller than the inverse of the signal-to-noise ratio.The case of equal powers and equal rates among all users is addressed as a "worst case" scenario. It is argued that simple repetition codes provide for a larger achievable capacity than stronger codes. It is shown that this capacity monotonically increases as the rate of the code decreases. A density evolution analysis is used to show that the achievable rates exceed those of a minimum-mean square error filter applied to the uncoded signals. This lower bound is tight for small ratios of bit energy to noise power, and otherwise the iterative cancellation receiver provides an appreciably larger capacity. Relating to recent result from the application of statistical mechanics it is shown that the repetition-coded system with iterative cancellation achieves the performance of an equivalent optimal joint detector for uncoded transmission.

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Section: Equal Power and Equal Rate Usersmentioning

confidence: 87%

Optimal Power/Rate Allocation and Code Selection for Iterative Joint Detection of Coded Random CDMA

Schlegel

Shi

Burnashev

2006

IEEE Trans. Inform. Theory

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“…The most trivial multi-user detector is that based on HIC [15]. The receiver for each user is composed by a SISO SUD, a SISO decoder, an encoder and a modulator.…”

Section: ) Hic-based Receivermentioning

confidence: 99%

“…In (16) p(r J |α (ℓ)J ) and p(r J ) are probability density functions according to the auxiliary channel model (15), while the statistical average is with respect to the input and the output sequences evaluated according to the actual channel model (6). Both p(r J |α (ℓ)J ) and p(r J ) can be evaluated recursively through the forward recursion of the MAP detection algorithm matched to the auxiliary channel model [30].…”

Section: Spectral Efficiencymentioning

confidence: 99%

“…Because the complexity of the optimal multi-user receiver grows exponentially with the number of users, suboptimal detection schemes are required. We consider different multi-user detectors, based on hard interference cancellation (HIC) [15], soft interference cancellation (SIC) [16], extended to frequency division multiplexed CPM-based systems in [17], and an algorithm derived in [17] by using factor graphs (FGs) and the sum-product algorithm (SPA) framework [18].…”

Section: Introductionmentioning

confidence: 99%

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CPM-based spread spectrum systems for multi-user communications

Mazzali

Colavolpe

Buzzi

2012

2012 IEEE International Conference on Communications (ICC)

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Abstract-We propose a new spread spectrum (SS) system based on continuous-phase modulations (CPMs). The main idea is to exploit the sequence of modulation indices of a multi-h CPM as a frequency-hopping (FH) sequence. Spectral spreading, flatness and smoothness can be easily achieved by an appropriate choice of the maximum value of the modulation index and of the length of the index sequence. We will show that the proposed CPM-based spread spectrum system achieves an overall spectral efficiency larger than that of a single-user single-h CPM transmission even when a single-user detector is employed at the receiver. It also outperforms other solutions in the literature. In addition, we will also derive some suboptimal multi-user detectors.

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“…Specifically, we separate the multiuser detection and the space-time decoding into two stages, as is done in [13] for the case of (single-antenna) convolutionally coded CDMA channels. At the first stage of the partitioned receiver, multiuser detection is performed.…”

Section: Joint ML Multiuser Detection and Decoding For Space-time Codmentioning

confidence: 99%

Low Complexity Receiver Structures for Space-Time Coded Multiple-Access Systems

Jayaweera

Poor

2002

EURASIP J. Adv. Signal Process.

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Multiuser detection for space-time coded synchronous multiple-access systems in the presence of independent Rayleigh fading is considered. Under the assumption of quasi-static fading, it is shown that optimal (full diversity-achieving) space-time codes designed for single-user channels, can still provide full diversity in the multiuser channel. The joint optimal maximum likelihood multiuser detector, which can be implemented with a Viterbi-type algorithm, is derived for such space-time coded systems. Low complexity, partitioned detector structures that separate the multiuser detection and space-time decoding into two stages are also developed. Both linear and nonlinear multiuser detection schemes are considered for the first stage of these partitioned spacetime multiuser receivers. Simulation results show that these latter methods achieve performance competitive with the single-user bound for space-time coded systems.

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Suboptimum multiuser receivers for convolutionally coded asynchronous DS-CDMA systems

Cited by 94 publications

References 24 publications

Optimal Power/Rate Allocation and Code Selection for Iterative Joint Detection of Coded Random CDMA

Optimal Power/Rate Allocation and Code Selection for Iterative Joint Detection of Coded Random CDMA

CPM-based spread spectrum systems for multi-user communications

Low Complexity Receiver Structures for Space-Time Coded Multiple-Access Systems

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