检索结果-内蒙古大学图书馆

Power-Efficient Tomlinson-Harashima precoding for the Downlink of Multi-User MISO Systems

IEEE TRANSACTIONS ON COMMUNICATIONS 2014年第6期62卷 1884-1896页

作者： Garcia-Rodriguez, Adrian Masouros, Christos UCL Dept Elect & Elect Engn London WC1E 7JE England

We propose a power-efficient Tomlinson-Harashima precoder (THP) in the downlink of multi-user multiple-input single-output (MU-MISO) systems, where a transmit power reduction is achieved by means of interference optimization. The adopted approach is based on adaptively scaling the symbols of a number of users whose received signal-to-noise ratio (SNR) thresholds are known to the transmitter. By doing this, the interference can be better aligned to the symbols of interest, thus reducing the power required to cancel it. The scaling is performed by forming a constrained optimization problem, solved with existing well-known techniques, which entails an increase in the computational complexity at the base station. To quantify this trade-off in performance and complexity, a study of the impact in the signal processing load is carried out by means of a power efficiency analysis. The presented analytical and simulation results in this paper confirm that the proposed technique increases the power efficiency up to 100% with respect to previous THP-based approaches while, at the same time, maintaining the same average performance.

关键词： Broadcast channel non-linear precoding multi-user multiple-input single-output (MU-MISO) Tomlinson-Harashima precoding (THP) power efficiency

来源：评论

学校读者我要写书评

暂无评论

Computationally Efficient Vector Perturbation precoding Using Thresholded Optimization

引用

IEEE TRANSACTIONS ON COMMUNICATIONS 2013年第5期61卷 1880-1890页

作者： Masouros, C. Sellathurai, M. Ratnarajah, T. UCL Dept Elect & Elect Eng London WC1E 7JE England Heriot Watt Univ Dept Elect Elect & Comp Eng Edinburgh Midlothian Scotland Univ Edinburgh Inst Digital Commun Edinburgh EH9 3JL Midlothian Scotland

We propose a low-complexity vector perturbation (VP) precoding scheme for the downlink of multi-user multiple input multiple output (MU-MIMO) systems. While conventional VP performs a computationally intensive sphere search through multiple candidate perturbation vectors to minimize the norm of the precoded signal, the proposed precoder applies a threshold to the desired norm to reduce the number of search nodes visited by the sphere encoder. This threshold is determined by the performance requirements of the mobile users. Once the threshold is met, the search for the perturbation vectors finishes thus saving significant computational burden at the transmitter. To evaluate the advantages of the proposed technique compared to VP, we further derive the computational complexity in terms of the volume of the associated search space and the resulting numerical operations. In addition, we use a new performance-complexity metric to study the relevant tradeoff and look at the power efficiency of the system, both of which metrics can be used to optimize the user-determined threshold accordingly. The presented analysis and results show that the proposed thresholded VP (TVP) offers a favorable tradeoff between performance and complexity where significant complexity reduction is attained while the user threshold performance is guaranteed.

关键词： Vector perturbation sphere encoding complexity reduction multi-user MIMO non-linear precoding

来源：评论

学校读者我要写书评

暂无评论

Reduction of Out-of-Band Radiation with Quantized precoding Using Gibbs Sampling in Massive MU-MIMO-OFDM

引用

IEICE TRANSACTIONS ON COMMUNICATIONS 2022年第10期E105B卷 1240-1248页

作者： Yamakado, Taichi Okawa, Riki Sanada, Yukitoshi Keio Univ Dept Elect & Elect Engn Yokohama 2238522 Japan

In this paper, a non-linear precoding algorithm with low out-of-band (OOB) radiation is proposed for massive multiple-input multiple-output (MIMO) systems. Massive MIMO sets more than one hundred antennas at each base station to achieve higher spectral efficiency and throughput. Full digital massive MIMO may constrain the resolution of digital-to-analog converters (DACs) since each DAC consumes a large amount of power. In massive MIMO systems with low resolution DACs, designing methods of DAC output signals by nonlinear processing are be-ing investigated. The conventional scheme focuses only on a sum rate or errors in the received signals and so triggers large OOB radiation. This paper proposes an optimization criterion that takes OOB radiation power into account. Gibbs sampling is used as an algorithm to find sub-optimal solutions given this criterion. Numerical results obtained through computer simulation show that the proposed criterion reduces mean OOB radiation power by a factor of 10 as compared with the conventional criterion. The proposed criterion also reduces OOB radiation while increasing the average sum rate by optimizing the weight factor for the OOB radiation. As a result, the proposed criterion achieves approximately 1.3 times higher average sum rates than an error-based criterion. On the other hand, as compared with a sum rate based criterion, the throughput on each subcarrier shows less vari-ation which reduces the number of link adaptation options needed although the average sum rate of the proposed criterion is smaller.

关键词： massive MIMO low resolution DACs gibbs sampling non-linear precoding

来源：评论

学校读者我要写书评

暂无评论

CONSTANT-ENVELOPE precoding FOR SATELLITE SYSTEMS

CONSTANT-ENVELOPE PRECODING FOR SATELLITE SYSTEMS

引用

IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： Tsinos, Christos G. Arora, Aakash Ottersten, Bjorn Univ Luxembourg SnT Interdisciplinary Ctr Secur Reliabil & Trust Luxembourg Luxembourg

ISBN: (纸本)9781509066315

In this paper, Constant-Envelope precoding techniques are presented for satellite-based communication systems. In the developed transmission technique the signals of the antennas are designed to be of constant amplitude, improving the robustness of the latter to the non-linear distortions on satellite systems, introduced by the employed on-board Traveling-Wave-Tube-Amplifiers. We consider the forward link of a multi-beam broadband satellite system where the aim is to design the signals at the gateway such that the desired symbols are transmitted to the intended user terminals and the transmitted signals from the satellite terminal are of constant amplitude. At first, the gateway signals are designed given that a fixed on-board beamformer is applied to the satellite terminal. Then, the case of an adaptive on-board beamformer is considered which is designed jointly with the gateway signals. The design of the gateway signals and the adaptive on-board beamformer, in the second case, requires solving difficult nonconvex problems. Efficient algorithmic solutions are developed based on the saddle point method. The effectiveness of the proposed approaches is verified via numerical results.

关键词： Constant Envelope precoding On-board Beamforming Ground-based precoding non-linear precoding Satellite Communications

来源：评论

学校读者我要写书评

暂无评论

An Extension of Tomlinson-Harashima precoding for Downlink Multi-User MIMO Systems 85

An Extension of Tomlinson-Harashima Precoding for Downlink M...

引用

IEEE 85th Vehicular Technology Conference (VTC Spring)

作者： Hoshino, Kenji Mikami, Manabu Maiti, Sourabh Yoshino, Hitoshi SoftBank Corp Div Res & Dev Koto Ku Telecom Ctr Bldg East Tower 13F2-5-10 Aomi Tokyo 1350064 Japan

ISBN: (纸本)9781509059324

non-linear precoding (NLP) for downlink multiuser multiple-input multiple-output (DL-MU-MIMO) transmission is receiving much attention as a promising technology to achieve high capacity within the limited bandwidths available to radio access systems. In order to minimize the required transmission power for DL-MU-MIMO and achieve high spectrum efficiency, Vector Perturbation (VP) was proposed as an optimal NLP scheme. Unfortunately, the original VP suffers from significant computation complexity in searching the optimal perturbation vector due to the infinite number of perturbation vector candidates. To achieve the complexity reduction with the transmission performance near to that of Sphere Encoding VP (SE-VP), several recent studies have investigated various efficient NLP schemes based on Tomlinson-Harashima precoding (THP) approach that applies successive pre-cancellation of inter-user interference (IUI) and offsets the transmission vector based on the modulo operation. This paper investigates transmission performance improvement of Lattice Reduction Aided THP (LRA THP), called Extended LRA THP, where the modulo operation is substituted by seaching perturbation vector and subtracting this perturbation vector from the transmit signal vector. This paper proposes an extension of LRA THP with Minimum Mean Square Error based successive IUI precancellation called Extended LRA MMSE-THP as a novel NLP scheme. Computer simulations quantitatively clarify that our proposed Extended LRA MMSE-THP achieves better transmission performance than the conventional NLP techniques while decreasing the number of searches required to determine the optimal perturbation vector.

关键词： multi-user MIMO non-linear precoding THP lattice reduction

来源：评论

学校读者我要写书评

暂无评论

Decentralized nonlinear precoding Algorithm for Multi-cell Coordinated Systems

Decentralized Nonlinear Precoding Algorithm for Multi-cell C...

引用

IEEE Global Communications Conference (GLOBECOM)

作者： Hu, Zhirui Feng, Chunyan Zhang, Tiankui Gao, Qiubin Sun, Shaohui Beijing Univ Posts & Telecommun Beijing Key Lab Network Syst Architecture & Conve Beijing Peoples R China State Key Lab Wireless Mobile Commun CATT Beijing Peoples R China

ISBN: (纸本)9781479935123

Multi-cell coordinated system is an attractive way of improving data rate, by serving one user through several base stations (BSs). BSs might share both data and their channel state information (CSI), but the demand on backhaul capacity makes it inflexible. In this paper, we consider the case with BSs sharing data dedicated to users but having only local CSI, and propose a decentralized nonlinear precoding algorithm for multi-cell coordinated system with multi-stream multi-antenna users. The proposed algorithm is designed to eliminate the inter-user interference and the inter-stream interference, and meanwhile to achieve equal performance for streams of each user. In the proposed algorithm, Tomlinson-Harashima precoding is applied to eliminate partial interference, and transmit space matrix is designed to eliminate the other interference. After the interference elimination, closed-form expression of the transmit and receive processing matrix are derived to maximize the minimum signal to interference plus noise ratio for streams of each user. Simulation results show that, compared with the decentralized linear precoding, the proposed algorithm achieves better performance.

关键词： multi-cell coordinated non-linear precoding decentralized precoding

来源：评论

学校读者我要写书评

暂无评论

Low Complexity Vector precoding for Fast Fading MIMO Downlinks

Low Complexity Vector Precoding for Fast Fading MIMO Downlin...

引用

IEEE Global Communications Conference (GLOBECOM)

作者： Masouros, Christos Sellathurai, Mathini Ratnarajah, Tharm UCL Dept Elect & Elect Engn London England Heriot Watt Univ Sch Engn & Phys Sci Edinburgh Midlothian Scotland Univ Edinburgh Sch Engn Edinburgh Midlothian Scotland

ISBN: (纸本)9781479913534

Vector precoding (VP) requires the feed-forwarding of the transmit scaling factor to the receiver for correct detection. This can be problematic in fast fading scenarios where the statistics of the scaling factor change frequently and in limited feedback scenarios where the feed-forwarding to the receiver is prone to quantization errors. In response to this, a new VP scheme is proposed for the downlink of multi-user multiple input multiple output (MU-MIMO) systems with limited feedback. The proposed VP circumvents the need for receive-scaling by constraining the search of perturbing vectors to the area in the symbol constellation which is constrictive to the information symbols, i.e. the area where the distances from the decision thresholds are increased with respect to a distance threshold. By doing this, the perturbation quantities need not be removed at the receiver and successful detection can be done without the use of the modulo operation and the scaling factor. In addition, instead of a computationally expensive sphere search used in conventional VP, the proposed scheme uses a MinMax Optimization to select the perturbation quantities. As illustrated by the analysis and results, the error floor encountered in conventional VP in limited feedback scenarios is avoided in the proposed scheme.

关键词： Terms Vector precoding limited feedback multi-user MIMO non-linear precoding

来源：评论

学校读者我要写书评

暂无评论

Limited Feedback Vector Perturbation precoding By MinMax Optimization

Limited Feedback Vector Perturbation Precoding By MinMax Opt...

引用

IEEE Global Communications Conference (GLOBECOM)

作者： Masouros, Christos Sellathurai, Mathini Ratnarajah, Tharmalingam UCL Dept Elect & Elect Engn London England Heriot Watt Univ Sch Engn & Phys Sci Edinburgh Midlothian Scotland Univ Edinburgh Sch Engn Edinburgh Midlothian Scotland

ISBN: (纸本)9781479935123

A vector perturbation (VP) scheme is proposed for the downlink of multi-user multiple input multiple output (MU-MIMO) systems with limited feedback. Instead of a computationally expensive sphere search used in conventional VP, the proposed scheme uses a MinMax Optimization to select the perturbation quantities. In addition, the proposed VP circumvents the need for receive-scaling by constraining the search of perturbing vectors to the area in the symbol constellation which is constrictive to the information symbols, i.e. the area where the distances from the decision thresholds are increased with respect to a distance threshold. Consequently, while conventional VP requires the feed-forwarding of the scaling factor to the receiver for correct detection, the proposed scheme does not require the scaling of the received symbols. This advantage is particularly pronounced in limited feedback scenarios where the scaling factors forwarded to the receiver are prone to quantization errors. As illustrated by the results, the error floor encountered in conventional VP in limited feedback scenarios is avoided in the proposed scheme.

关键词： Vector perturbation limited feedback multiuser MIMO non-linear precoding

来源：评论

学校读者我要写书评

暂无评论

nonlinear precoding for Quantized Outphasing RF Chains in Massive MIMO Systems 93

Nonlinear Precoding for Quantized Outphasing RF Chains in Ma...

引用

IEEE 93rd Vehicular Technology Conference (VTC-Spring)

作者： Upadhya, Karthik Wesemann, Stefan Nokia Bell Labs Espoo Finland Nokia Bell Labs Stuttgart Germany

ISBN: (纸本)9781728189642

Implementing large antenna arrays for massive multiple-input multiple-output (MIMO) base stations requires transmit radio frequency (RF) chains with low complexity and high power amplifier (PA) efficiency. One approach to achieve this goal is to relax PA linearity and to digitally compensate for some of the resulting non-linear effects such as an increased error vector magnitude (EVM) and adjacent channel leakage ratio (ACLR). The required compensation method can be implemented in a non-linear precoding module that exploits the large spatial degrees of freedom in a massive MIMO system. In this paper, we propose using outphasing RF chains with low-resolution phase shifters to generate constrained amplitude and phase-modulated signals with very low hardware complexity. To improve transmit power efficiency and to control the ACLR and EVM, we develop a novel non-linear precoding algorithm that incorporates the quantized phase-shift constraints in the outphasing RF chains. The achieved flexibility to trade-off EVM and ACLR in favor of a higher PA efficiency (and vice versa) is demonstrated by means of simulations.

关键词： massive MIMO outphasing non-linear precoding adjacent channel leakage quantized precoding

来源：评论

学校读者我要写书评

暂无评论

COMPLEXITY REDUCTION FOR VECTOR precoding USING QOS REQUIREMENTS

COMPLEXITY REDUCTION FOR VECTOR PRECODING USING QOS REQUIREM...

引用

IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： Masouros, Christos Ratnarajah, Tharm Sellathurai, Mathini UCL Dept Elect & Elect Eng London England Univ Edinburgh Sch Engn Edinburgh Midlothian Scotland Heriot Watt Univ Sch Engn & Phys Sci Edinburgh Midlothian Scotland

ISBN: (纸本)9781479903566

We propose a low-complexity vector precoding (VP) scheme for the downlink of multi-user multiple input multiple output (MU-MIMO) systems. Instead of performing a full sphere search to maximize the receive signal to noise ratio (SNR), the search for the perturbation vectors finishes once a threshold SNR value is reached, thus saving significant computational burden at the transmitter. This threshold is determined by the quality of service (QoS) requirements of the mobile users. To evaluate the advantages of the proposed technique compared to VP, we analytically calculate its computational complexity in terms of the volume of the associated search space. The results show that the proposed thresholded VP (TVP) offers a significantly reduced complexity compared to VP.

关键词： Vector precoding sphere encoding complexity reduction multi-user MIMO non-linear precoding

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：