A Sphere Decoding Algorithm for Underdetermined OFDM/SDMA Uplink System with an Effective Radius Selection

Shahnaz, K. V.; Ali, C. K.

doi:10.1007/978-3-319-11218-3_17

Cited by 2 publications

(3 citation statements)

References 8 publications

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“…In Hassibi and Vikalo's study and Shahnaz and Ali's study, a value that lies between 0 and 1 ( λ = 0.01) was selected empirically which is suitable for MIMO channels. Since contribution from data errors and rounding errors are much less at good SNRs, too much regularization or damping given at high SNR will affect the residual of the LS problem adversely.…”

Section: R‐fsd Algorithm and Radius Selectionmentioning

confidence: 99%

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A signal power adaptive regularized sphere decoding algorithm based multiuser detection technique for underdetermined OFDM/SDMA uplink system

Shahnaz

Ali

2018

Int J Communication

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This work considers a regularized Fincke-Pohst Sphere Decoder (R-FSD) to detect the multiuser data of orthogonal frequency division multiplexing/space division multiple access (OFDM/SDMA) uplink system with underdetermined and rank-deficient channel. Rank-deficiency of the detected channel coefficients makes error-free multiuser detection (MUD) a difficult task. In literature, most of the papers deal with either a determined or over-determined full-rank system. The method proposed in this work transforms an original ill-posed least squares (LS) problem to a well-posed one at the receiver, by using the standard Tikhonov regularization method. This is an efficient, direct, and less complex approach where the channel is modified using a regularization parameter that adapts to the signal power at the receiver. The result obtained is compared with maximum likelihood (ML), zero forcing (ZF), minimum mean squared error (MMSE) and ordered successive interference cancellation (OSIC) based detection techniques.

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Section: R‐fsd Algorithm and Radius Selectionmentioning

confidence: 99%

“…Authors' previous work used a fixed value regularization parameter, λ . Radius selection was based on a deterministic method proposed by where the procedure is the same as ZF equalization in communication application.…”

Section: Introductionmentioning

confidence: 99%

A signal power adaptive regularized sphere decoding algorithm based multiuser detection technique for underdetermined OFDM/SDMA uplink system

Shahnaz

Ali

2018

Int J Communication

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“…Conversely, if d is very small, the number of candidates within the sphere will be less than the desired number of candidates, and the search will restart again with an increased radius, thereby repeating the computational effort. In [19] and [20], the ZF estimate is used to set the initial sphere center. The ZF solution gives the Babai point [21].…”

Section: Sphere Decoding Algorithm For a Dasmentioning

confidence: 99%

Sphere decoding algorithm for multiuser detection in a distributed antenna system

Khawaja¹,

Zaib²,

Khattak³

2017

Turk J Elec Eng & Comp Sci

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Abstract:In this paper, the impact of initial search radius on the complexity and performance of a sphere decoding algorithm is investigated for different user positions within a distributed antenna system. In a distributed antenna system, users can take up random positions within the cell clusters. The channel matrix can therefore take up infinitely different forms. In the presented work, a distributed antenna system with three different user positions in the cooperating cells is considered by employing different channel matrices. The effect on the complexity and performance of the sphere decoder due to the choice of the initial sphere radius is investigated for these user positions. It is shown that the signal lattice volume changes considerably for different user positions within the cells. A dynamic radius allocation algorithm is proposed in which the behavior is exploited by dynamically adjusting the initial sphere radius based on the knowledge of the channel path gain matrix. The simulation results show that the proposed algorithm results in a considerable reduction in the complexity of the sphere decoder in a distributed antenna system. Additionally, the performance of the sphere decoder in different coupling scenarios within the distributed antenna system has been investigated for a different number of candidates. It is shown that the performance of cell edge users can be considerably enhanced with high channel diversity, which otherwise could severely deteriorate the overall system performance.

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A Sphere Decoding Algorithm for Underdetermined OFDM/SDMA Uplink System with an Effective Radius Selection

Cited by 2 publications

References 8 publications

A signal power adaptive regularized sphere decoding algorithm based multiuser detection technique for underdetermined OFDM/SDMA uplink system

A signal power adaptive regularized sphere decoding algorithm based multiuser detection technique for underdetermined OFDM/SDMA uplink system

Sphere decoding algorithm for multiuser detection in a distributed antenna system

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