Mitigating multiple access interference and intersymbol interference in uncoded CDMA systems with chip-level interleaving

Mahadevappa, R.; Proakis, J.G.

doi:10.1109/twc.2002.804163

Cited by 146 publications

(90 citation statements)

References 15 publications

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“…In particular, we construct such sequences to mitigate multiple access interferences (MAIs) for overloaded PS-CDMA. By analyzing extrinsic information transfer (EXIT) charts and trajectories, we show that PS-CDMA using the proposed scrambling sequences has faster iterative decoding convergence and better bit error rate (BER) performance, when compare to that using random-phase scrambling sequences and IDMA [7,8]. Finally, we remark that our scrambling sequence design can be also easily adapted to any multiple access system with different number of users and various spreading factors.…”

Section: Introductionmentioning

confidence: 91%

“…Motivated by the above, authors of [3] proposed codespread CDMA (CS-CDMA) by making use of a class of lowrate convolutional codes [4], followed by ideal interleavers, user-specific pseudorandom scrambling sequences and harddecision decoding combined with interference cancellation. Recently, a chip-interleaved CDMA was proposed in [7], which admits a transmitter structure similar to that of CS-CDMA, but with user-specific interleavers to distinguish users. At the receiver, a joint soft-input soft-output (SISO) iterative multiuser decoding was adopted.…”

Section: Introductionmentioning

confidence: 99%

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Algebraic-phase scrambling sequences for code-spread code-division multiple-access

Hong

Shlomo

Viterbo

2008

2008 IEEE International Symposium on Information Theory

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Abstract-In this paper, we first present a modified codespread code-division multiple-access (CS-CDMA) scheme, named phase-scrambling CDMA (PS-CDMA), for a Gaussian multiple access channel (MAC). In PS-CDMA, we realize the codespreading using a low-rate serially concatenated code consisting of a convolutional code and a repetition code. Then, we use complex user-specific algebraic-phase scrambling sequences to distinguish users. The receiver is based on the iterative multiuser decoding suggested in [5,8]. Next, we design complex algebraicphase scrambling sequences to mitigate multiple access interferences for overloaded PS-CDMA, i.e., the number of users is greater than the spreading factor. By analyzing extrinsic information transfer (EXIT) curves and the trajectories, we demonstrate that PS-CDMA using the proposed scrambling sequences has faster iterative decoding convergency and better system performance, when compared to the PS-CDMA using random-phase scrambling sequences and some previously known multiple access schemes.

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Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Algebraic-phase scrambling sequences for code-spread code-division multiple-access

Hong

Shlomo

Viterbo

2008

2008 IEEE International Symposium on Information Theory

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“…Instead, the PN despreader is either replaced with a low-rate iteratively decoded turbo code [9] or iterative turbo decoding is invoked only after the independent PN despreading operation [10]. Our approach has a greater resemblance to chip-interleaved Code Division Multiple Access (CDMA) schemes [11], which employ iterative despreading and MultiUser Detection (MUD) [12].…”

Section: Augmented Phymentioning

confidence: 99%

Iterative Decoding for Redistributing Energy Consumption in Wireless Sensor Networks

Maunder

Weddell

Merrett

et al. 2008

2008 Proceedings of 17th International Conference on Computer Communications and Networks

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Abstract-In this paper, we propose a method for desirably redistributing a wireless sensor network's energy consumption from its sensor nodes (which may have scarce energy resources obtained through energy harvesting, for example) to its central node (which often has an abundant energy resource, such as the mains). At the cost of increasing the central node's decoding complexity, our method facilitates (1) a significant reduction in the number of times the sensor nodes are required to retransmit data owing to transmission errors and/or (2) a reduction of up to 3.99 dB in the sensor node's total transmit energy consumption. We show that our approach can reduce the overall energy consumption of transmitting sensor nodes by more than 20% in practice.

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“…In the context of IDMA systems, it is assumed that this interleaving process is employed randomly and independently [4,6]. The authors in [7] also presented chip-interleaved CDMA to combat ISI and MAI. The spreading process is carried out before interleaving in the transmitter part of IDMA.…”

Section: Introductionmentioning

confidence: 99%

Effect of repetition coding on the BER performance of interleave-division multiple access systems

Bilim

Kapucu²,

Develı³

2016

Turk J Elec Eng & Comp Sci

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This paper investigates the bit error rate (BER) performance of interleave-division multiple access (IDMA) schemes to show the effect of repetition coding on the system performance. The considered system is tested in the presence of repetition coding by varying system parameters such as number of simultaneous users, data length, spread length, iteration number, and code rate over additive white Gaussian noise channels. In addition, the performance of the considered system is also illustrated in Rayleigh flat fading channels for a more realistic scenario. Our simulation resultsshow that the BER performance of IDMA systems with repetition coding can achieve significant performance gains over existing uncoded IDMA schemes.

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Mitigating multiple access interference and intersymbol interference in uncoded CDMA systems with chip-level interleaving

Cited by 146 publications

References 15 publications

Algebraic-phase scrambling sequences for code-spread code-division multiple-access

Algebraic-phase scrambling sequences for code-spread code-division multiple-access

Iterative Decoding for Redistributing Energy Consumption in Wireless Sensor Networks

Effect of repetition coding on the BER performance of interleave-division multiple access systems

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