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Fixed-Complexity sphere encoder for Multi-User MIMO Systems

JOURNAL OF COMMUNICATIONS AND NETWORKS 2011年第1期13卷 63-69页

作者： Mohaisen, Manar Chang, KyungHi Inha Univ Grad Sch Informat Technol & Telecommun Inchon South Korea

In this paper, we propose a fixed-complexity sphere encoder (FSE) for multi-user multi-input multi-output (MU-MIMO) systems. The proposed FSE accomplishes a scalable tradeoff between performance and complexity. Also, because it has a parallel tree-search structure, the proposed encoder can be easily pipelined, leading to a tremendous reduction in the precoding latency. The complexity of the proposed encoder is also analyzed, and we propose two techniques that reduce it. Simulation and analytical results demonstrate that in a 4 x 4 MU-MIMO system, the proposed FSE requires only 11.5% of the computational complexity needed by the conventional QR decomposition with M-algorithm encoder (QRDM-E). Also, the encoding throughput of the proposed encoder is 7.5 times that of the QRDM-E with tolerable degradation in the BER performance, while achieving the optimum diversity order.

关键词： Multi-user multi-input multi-output (MU-MIMO) systems precoding QR decomposition with M-algorithm encoder (QRDM-E) sphere encoder Tomlinson-Harashima precoder (THP)

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Evolutionary Random Walk Aided Stochastic sphere encoder for Broadband ***

Evolutionary Random Walk Aided Stochastic Sphere Encoder for...

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IEEE International Conference on Communications (ICC)

作者： Zhang, Yangyishi Zhang, Jiankang Al Rawi, Anas British Telecommun PLC Appl Res Ipswich England Bournemouth Univ Dept Comp Sci Bournemouth England Univ Cambridge Dept Phys Cambridge England

ISBN: (数字)9781538683477

ISBN: (纸本)9781538683477

The next generation digital subscriber line (DSL) standard *** introduces far stronger co-channel interference termed as far-end crosstalk (FEXT) than the existing ones. Given perfect transmitter-side channel state information (CSIT), it is well known that the lattice-reduction-aided K-best sphere encoder (LR-KBSE) is a near-optimal transmit precoding (TPC) technique compared to the classic (LR-) depth-first sphere encoder (DFSE), albeit having significantly lower complexity than the latter. However, the decision feedback precoding (DFP) structure and the Schnorr-Euchner enumeration procedure, both perceived as state-of-the-art in the literature, are not provably optimal for solving the closest vector problem (CVP) embedded in sphere encoding. As a counterexample, this paper proposes a stochastic sphere encoder (SSE) relying on differential evolution aided random walk over lattices. The parallel processing complexity, memory efficiency and signal to noise ratio (SNR) improvement of the proposed SSE are all shown to be superior to the LR-KBSE for *** systems.

关键词： Differential evolution digital subscriber line G.mgfast far-end crosstalk transmit precoding lattice reduction sphere encoder random walk

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Parallel QRD-M encoder for multi-user MIMO systems

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TELECOMMUNICATION SYSTEMS 2014年第3期57卷 261-270页

作者： Mohaisen, Manar Mohaisen, Abedelaziz Debbah, Merouane Korea Univ Technol & Educ KoreaTech Dept EEC Engn Cheonan 303708 South Korea Univ Minnesota Minneapolis MN 55455 USA SupElec Paris France

In the context of multi-user precoding, the idea behind vector perturbation (VP) lies in adding an integer vector to the data vector such that the overall transmit power is reduced, where the performance at the users end is consequently improved. In the literature, several techniques have been proposed to find a quasi-optimum perturbing vector, where this process was represented as an integer lattice search problem. In this paper, we propose a parallel QRD-M encoder (PQRDME) that, besides attaining a quasi-optimum diversity order, leads to tremendous reduction in the latency of the vector perturbation stage. Based on the set grouping, the proposed encoder transforms the full tree-search of the conventional QRDME into partial trees that can be pipelined to increase the encoding throughput. We evaluate the proposed algorithm under several scenarios with both perfect channel state information (PCSI) and imperfect CSI (ICSI) at the transmitter side, where simulation results show robust performance when compared to the optimum encoder.

关键词： MU-MIMO precoding Vector perturbation QRD-M encoder sphere encoder

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Far-End Crosstalk Mitigation for Future Wireline Networks Beyond ***: A Survey and an Outlook

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IEEE ACCESS 2020年 8卷 9998-10039页

作者： Zhang, Yangyishi Zhang, Rong Zhang, Jiankang Bai, Tong Al Rawi, Anas F. Moonen, Marc Hanzo, Lajos BT Grp Plc Res & Design Dept Ipswich IP5 3RE Suffolk England Univ Southampton Dept Elect & Comp Sci Southampton SO17 1BJ Hants England Queen Mary Univ London London E1 4NS England Katholieke Univ Leuven Elect Engn Dept B-3001 Leuven Belgium

With the escalating demand for high speed, high reliability, low latency, low cost and ubiquitous connectivity, the telecommunications industry is entering a new era where the ultimate optimality of the current wireline-wireless access network has to be achieved. Regarding the current wireline network paradigm, dominated by the copper-based digital subscriber lines (DSL) technology, multi-Gigabit data rate is the ambitious design objective at the customer end for the forthcoming ITU-T *** standard. In order to prepare for the new challenges in the era of total network convergence, both the wireline and the wireless community must be able to think beyond their respective conventions and learn from each other if necessary. Overall, the current DSL-based wireline network architecture is prone to the mutual interference resulting in far-end crosstalk (FEXT). The newly expanded 424/848 MHz spectrum of the ambitious *** project introduces far higher FEXT than that over the current 212/30 MHz ***/VDSL2 band. Additionally, the coexistence of multiple standards will also cause & x2018;alien & x2019;FEXT. In these cases, using the plain zero forcing precoding (ZFP) will no longer attain a sufficiently high performance. However, as shown in the field of wireless communications, using lattice reduction as a signal space remapping technique significantly improves the performance of traditional multi-user detectors (MUD) and of the respective multi-user precoders (MUP). These promising techniques have largely remained unexploited in commercial wireless communications, due to their complexity in the face of the rapidly fluctuating wireless channels. In this survey, we present an overview of the state-of-the-art in wireline access network and an outlook for recent technological advances in the holistic & x2018;wireline & x002B;wireless & x2019;access network in the context of network convergence, focusing on the dominant challenge of FEXT mitigation in future DSL netwo

关键词： Wireline access network network convergence fibre-to-the-X G fast G mgfast far-end crosstalk multi-user precoding zero forcing Tomlinson-Harashima lattice reduction vector perturbation sphere encoder dynamic spectrum management

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Vector Perturbation Channel Inversion for SWIPT MU-MISO Systems

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IEEE WIRELESS COMMUNICATIONS LETTERS 2022年第11期11卷 2370-2374页

作者： Krikidis, Ioannis Psomas, Constantinos Chatzinotas, Symeon Univ Cyprus Dept Elect & Comp Engn CY-1678 Nicosia Cyprus Univ Luxembourg Interdisciplinary Ctr Secur Reliabil & Trust L-1855 Luxembourg Luxembourg

This letter investigates the employment of vector-perturbation (VP) precoding to convey simultaneously information and energy in multiple-user multiple-input single-output (MU-MISO) downlink channel. We show that the conventional VP in addition to the information capacity benefits that provides to linear channel inversion techniques, it enhances the harvested energy at the receivers due to the extended symbol constellation. To further boost harvesting performance, the proposed modified VP technique (named VP-EH) designs the VP integer offsets in order to maximize the delivered power. The proposed scheme incorporates an integer least square problem to find the closest lattice point to a point which is given by a Rayleigh quotient optimization problem. Finally, a convex combination between conventional VP and VP-EH is proposed to achieve a trade-off between maximizing information or energy. Theoretical and simulations results validate that VP is a promising technique to simultaneously convey information and energy in MU-MISO systems.

关键词： Perturbation methods Lattices Symbols Receivers Precoding Optimization Eigenvalues and eigenfunctions Vector perturbation wireless power transfer SWIPT sphere encoder average harvested power

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Fixed-complexity Vector Perturbation with Block Diagonalization for MU-MIMO Systems

Fixed-complexity Vector Perturbation with Block Diagonalizat...

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9th IEEE Malaysia International Conference on Communications

作者： Mohaisen, Manar Hui, Bing Chang, KyungHi Ji, Seunghwan Joung, Jinsoup Inha Univ Grad Sch IT&T Inchon 402751 South Korea Innowireless Co Seongnam South Korea

ISBN: (纸本)9781424455324

Block diagonalization (BD) is an attractive technique that transforms the multi-user multiple-input multiple-output (MU-MIMO) channel into parallel single-user MIMO (SU-MIMO) channels with zero inter-user interference (IUI). In this paper, we combine the BD technique with two deterministic vector perturbation (VP) algorithms that reduce the transmit power in MU-MIMO systems with linear precoding. These techniques are the fixed-complexity sphere encoder (FSE) and the QR-decomposition with M-algorithm encoder (QRDM-E). In contrast to the conventional BD VP technique, which is based on the sphere encoder (SE), the proposed techniques have fixed complexity and a tradeoff between performance and complexity can be achieved by controlling the size of the set of candidates for the perturbation vector. Simulation results and analysis demonstrate the properness of the proposed techniques for the next generation mobile communications systems which are latency and computational complexity limited. In MU-MIMO system with 4 users each equipped with 2 receive antennas, simulation results show that the proposed BD-FSE and BD-QRDM-E outperforms the conventional BD-THP (Tomlinson Harashima precoding) by 5.5 and 7.4dB, respectively, at a target BER of 10(-4).

关键词： Multi-user MIMO Vector Perturbation Block Diagonalization sphere encoder QRD-M encoder

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Near-capacity MIMO multiuser precoding with QRD-M algorithm

Near-capacity MIMO multiuser precoding with QRD-M algorithm

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39th Asilomar Conference on Signals, Systems and Computers

作者： Zhang, Jianzhong (Charlie) Kim, Kyeong Jin Nokia Res Ctr Irving TX 75039 USA

ISBN: (纸本)1424401313

In this paper, we propose two extensions to the vector perturbation based Multiple Transmit Multiple Receive (MIMO) Multiuser (MU) precoder originally proposed in [1]. First, we propose a suboptimal QRDM (QR Decomposition-M) algorithm to solve the closest lattice point search problem in the vector perturbation based method. The QRD-M algorithm not only avoids the random complexity of the sphere encoder in [1], but also provides flexible tradeoff between performance and complexity. Second, we propose to jointly optimize the linear prefilters and nonlinear perturbation vectors by taking into account the impact of perturbation in the optimization process. In contrast, the prefilters used in [1] and [2] are optimized for the linear precoding structure, not the nonlinear vector perturbation structure. Finally, we verify the proposed QRD-M algorithm and the joint optimization algorithm with numerical simulations.

关键词： MIMO BC MU DPC QRD-M TH precoding sphere encoder vector perturbation

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Studies in multiple -antenna wireless communications

Studies in multiple -antenna wireless communications

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作者： Peel, Christian B. Brigham Young University

学位级别：Ph.D.

Wireless communications systems are used today in a variety of milieux, with a recurring theme: users and applications regularly require higher throughput. Frequency bandwidth is a limited resource; multiple antennas enable higher through-put and/or more robust performance than single-antenna communications, with no increase in power or bandwidth. Systems are required which achieve the full potential of this “space-time” communication channel under the significant challenges of time-varying fading, multiple users, and the choice of appropriate coding schemes. This dissertation is focused on solutions to these problems. For the single-user case, there are many well-known coding techniques available; in the first part of this dissertation, the performance of two of these methods are analyzed. In the second part the focus is on multi-user systems for which capacity-approaching coding schemes were not previously available. In addition to analyzing current modulation schemes, new capacity-approaching multi-user coding techniques are developed. Trained and differential modulation are simple coding techniques for single-user time-varying channels. The performance of these coding methods is characterized for a channel having a constant specular component plus a time-varying diffuse component. A first-order auto-regressive model is used to characterize diffuse channel coefficients that vary from symbol to symbol, and is shown to lead to an effective SNR that decreases with time. The effective SNR of differential modulation is shown to be higher than that of trained techniques. Pairwise probability of error expressions are derived which accurately describe performance for unitary modulation over a Rician channel. A lower bound on the capacity of trained modulation is found for the specular/diffuse channel. This bound is maximized over the training length, training frequency, training signal, and training power. Trained modulation is shown to have higher capacity than differen

关键词： multiple-user wireless sphere encoder integer least-squares differential modulation training period effective SNR capacity lower bound

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A vector-perturbation technique for near-capacity multiantenna multiuser communication - Part II: Perturbation

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IEEE TRANSACTIONS ON COMMUNICATIONS 2005年第3期53卷 537-544页

作者： Hochwald, BM Peel, CB Swindlehurst, AL Bell Labs Math Commun Res Dept Murray Hill NJ 07974 USA Swiss Fed Inst Technol Commun Technol Lab CH-8092 Zurich Switzerland Brigham Young Univ Dept Elect & Comp Engn Provo UT 84602 USA

Recent theoretical results describing the sum-capacity when using multiple antennas to communicate with multiple users in a known rich scattering environment have not yet been followed with practical transmission schemes that achieve this capacity. We introduce a simple encoding algorithm that achieves near-capacity at sum-rates of tens of bits/channel use. The algorithm is a variation on channel inversion that regularizes the inverse and uses a "sphere encoder" to perturb the data to reduce the energy of the transmitted signal. The paper is comprised of two parts. In this second part, we show that, after the regularization of the channel inverse introduced in the first part, a certain perturbation of the data using a "sphere encoder" can be chosen to further reduce the energy of the transmitted signal. The performance difference with and without this perturbation is shown to be dramatic. With the perturbation, we achieve excellent performance at all signal-to-noise ratios. The results of both uncoded and turbo-coded simulations are presented.

关键词： broadcast channel dirty-paper coding multiple-antenna multiple-user wireless multiple-input multiple-output (MIMO) spatial equalization sphere encoder Tomlinson-Harashima precoding

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Fixed-complexity Vector Perturbation with Block Diagonalization for MU-MIMO Systems

Fixed-complexity Vector Perturbation with Block Diagonalizat...

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IEEE Malaysia International Conference on Communications

作者： Manar Mohaisen Bing Hui KyungHi Chang Seunghwan Ji Jinsoup Joung Inha University Graduate school of IT & T Innowireless Company

ISBN: (纸本)9781424455317;9781424455324

关键词： Multi-user MIMO Vector Perturbation Block Diagonalization sphere encoder QRD-M encoder multiple input multiple output systems diagonalization encoder perturbation Transmitter power prediction coding multi-user

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