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A diversity guarantee and SNR performance for unitary limited feedback MIMO systems

EURASIP JOURNAL ON ADVANCES IN SIGNAL PROCESSING 2008年第unknown期2008卷 594928-1-594928-15-0页

作者： Mondal, Bishwarup Heath, Robert W., Jr. Univ Texas Austin Dept Elect & Comp Engn Austin TX 78712 USA

A multiple-input multiple-output (MIMO) wireless channel formed by antenna arrays at the transmitter and at the receiver offers high capacity and significant diversity. Linear precoding may be used, along with spatial multiplexing (SM) or space-time block coding (STBC), to realize these gains with low-complexity receivers. In the absence of perfect channel knowledge at the transmitter, the precoding matrices may be quantized at the receiver and informed to the transmitter using a feedback channel, constituting a limited feedback system. This can possibly lead to a performance degradation, both in terms of diversity and array gain, due to the mismatch between the quantized precoder and the downlink channel. In this paper, it is proven that if the feedback per channel realization is greater than a threshold, then there is no loss of diversity due to quantization. The threshold is completely determined by the number of transmit antennas and the number of transmitted symbol streams. This result applies to both SM and STBC with unitary precoding and confirms some conjectures made about antenna subset selection with linear receivers. A closed form characterization of the loss in SNR (transmit array gain) due to precoder quantization is presented that applies to a precoded orthogonal STBC system and generalizes earlier results for single-stream beamforming. Copyright (C) 2008 B. Mondal and R. W. Heath, Jr.

关键词： transmitting antennas Feedback degradation of performance Transmitter prediction coding Unitary multiple input multiple output systems Samarium Antenna arrays space time block coding Receivers feedback channel signal to noise ratios

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Fully Pipelined Implementation of Tree-Search Algorithms for Vector Precoding

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INTERNATIONAL JOURNAL OF RECONFIGURABLE COMPUTING 2013年第unknown期2013卷 496013-496013页

作者： Barrenechea, Maitane Mendicute, Mikel Arruti, Egoitz Univ Mondragon Dept Elect & Comp Sci Arrasate Mondragon 20500 Spain

The nonlinear vector precoding (VP) technique has been proven to achieve close-to-capacity performance in multiuser multiple input multiple-output (MIMO) downlink channels. The performance benefit with respect to its linear counterparts stems from the incorporation of a perturbation signal that reduces the power of the precoded signal. The computation of this perturbation element, which is known to belong in the class of NP-hard problems, is the main aspect that hinders the hardware implementation of VP systems. To this respect, several tree-search algorithms have been proposed for the closest-point lattice search problem in VP systems hitherto. Nevertheless, the optimality of these algorithms has been assessed mainly in terms of error-rate performance and computational complexity, leaving the hardware cost of their implementation an open issue. The parallel data-processing capabilities of field-programmable gate arrays (FPGA) and the loopless nature of the proposed tree-search algorithms have enabled an efficient hardware implementation of a VP system that provides a very high data-processing throughput.

关键词： perturbation Nondeterministic polynomial-time hard complexity classes algorithms SEARCHING ALGORITHM Field programmable gate arrays prediction coding Throughput Computer hardware multiple input multiple output systems

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Orthogonal superimposed training design for doubly selective channel estimation using basis expansion models

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TRANSACTIONS ON EMERGING TELECOMMUNICATIONS TECHNOLOGIES 2017年第8期28卷 n/a-n/a页

作者： Dou, Gaoqi He, Xianwen Deng, Ren Li, Lihua Gao, Jun Naval Univ Engn Dept Commun Engn Wuhan 430033 Hubei Peoples R China

In this paper, we consider channel estimation for single-carrier block transmission over doubly selective fading channel, where basis expansion models are used to describe the time-varying channel. The affine precoding model is used as the transmission strategy, wherein the training sequence is added on the top of the precoded data prior to transmission. By enforcing a special form of orthogonality between training sequence and precoded matrix, we propose orthogonal superimposed training design for doubly selective channel that makes channel estimation decouple from symbol detection, and then the affine precoding model based on orthogonal polyphase sequence set is designed under the orthogonal conditions. To further improve the estimation performance, we exploited a joint iterative approach is used, where the detected symbols, to enhance the estimation performance. Simulations results show that the proposed scheme can yield better detection performance than the data-dependent superimposed training and can be competitive with time-multiplexed training scheme with higher bandwidth efficiency.

关键词： Orthogonal orthogonality doubly selective channel channel estimation prediction coding training sequence Frequency-selective fading channels transmission strategies bandwidth efficiency

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An Algorithm for Simple Differential Speech coding Based on Backward Adaptation Technique

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Informatica 2019年第3期29卷 539-553页

作者： Tomić, Stefan S. Perić, Zoran H. Nikolić, Jelena R.

This paper presents a simple differential speech signal coding algorithm, based on backward adaptation. The considered algorithm is executed in frame by frame manner, by implementing predictive and adaptive quantization techniques. Both prediction and adaptation are performed backward, based on thepreviously quantized input signal frame. This enables us to obtain high quality output signal, without increasing the bit rate. This research puts emphasis on the quantizer design, with the optimal support limit determination, and theoretical performance evaluation. Objective quality of the output signal is evaluated through signal to quantization noise ratio (SQNR). We perform theoretical and experimental analysis of the algorithm performance and provide comparative results of implementing speech signal coding techniques with similar complexity. Experimental results show that our simple differential speech coding algorithm satisfies the G.712 Recommendation for high-quality speech coding at the bit rate of 6 bits per sample. This indicates that the algorithm can be successfully implemented in high quality speech signal coding.

关键词： speech coding algorithm backward adaptive technique prediction coding differential coding

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Partial Joint Processing with Efficient Backhauling in Coordinated MultiPoint Networks

Partial Joint Processing with Efficient Backhauling in Coord...

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IEEE Vehicular Technology Conference

作者： Tilak Rajesh Lakshmana Carmen Botella Tommy Svensson Signals and Systems Chalmers University of Technology Gothenburg Sweden Institute of Robotics and Information & Communication Technologies (IRTIC) Universitat de València València Spain

ISBN: (纸本)9781467309899

Joint processing between base stations is a promising technique to improve the quality of service to users at the cell edge, but this technique poses tremendous requirements on the backhaul signaling capabilities. Partial joint processing is a technique aimed to reduce feedback load, in one approach the users feed back the channel state information of the best links based on a channel gain threshold mechanism. However, it has been shown in the literature that the reduction in the feedback load is not reflected in an equivalent backhaul reduction, unless additional scheduling or precoding techniques are applied. The reason is that reduced feedback from users yields sparse channel state information at the Central Coordination Node. Under these conditions, existing linear precoding techniques fail to remove the interference and reduce backhaul, simultaneously, unless constraints are imposed on scheduling. In this paper, a partial joint processing scheme with efficient backhauling is proposed, based on a stochastic optimization algorithm called particle swarm optimization. The use of particle swarm optimization in the design of the precoder promises efficient backhauling with improved sum rate.

关键词： Joint Processing Zero Forcing Backhaul load reduction Particle Swarm Optimization Stochastic Optimization Particle swarm optimization return stroke Channel state information Consumers Feedback Joints Joints Optimization algorithms prediction coding BASE STATION

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Gradient-based solution for hybrid precoding in MIMO systems

Gradient-based solution for hybrid precoding in MIMO systems

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IEEE International Conference on Acoustics, Speech and Signal Processing

作者： Negin Bakhshi Zanjani Seyran Khademi Geert Leus Faculty of Electrical Engineering Mathematics and Computer Science TU Delft The Netherlands

ISBN: (纸本)9781509041183

The combination of baseband and analog precoding for multiple-input multiple-output (MIMO) systems is considered in this paper which is referred to as hybrid precoding. The system capacity, as a design criterion, is maximized subject to unit modulus constraints on the elements of the analog precoder (phase shifters), and a total power constraint. This is a non-convex problem due to the product of the analog and baseband precoder variables. The proposed technique suggests computing non-trivial complex derivatives of the objective and constraints, analytically, in order to develop an iterative gradient-based sequential optimization algorithm to solve the non-convex problem. Promising simulation results show that the solution of the proposed algorithm is sufficiently close to the optimal (full-baseband) precoder solution, regardless of the channel characteristics.

关键词： multiple-input multiple-output (MIMO) hybrid precoding nonlinear optimization sequential quadratic programming sequential quadratic programming multiple input multiple output systems prediction coding system capacity Baseband Non-Convex DESIGN CRITERIA Analog HYBRID aggregate capacity Solutions

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Energy-efficient precoding matrix design for relay-aided multiuser downlink networks

Energy-efficient precoding matrix design for relay-aided mul...

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IEEE International Conference on Acoustics, Speech and Signal Processing

作者： W. C. Li R. Y. Chang K. Y. Wang C. Y. Chi Dept. of Electr. Eng. Nat. Tsing Hua Univ. Hsinchu Taiwan

ISBN: (纸本)9781467369985

This paper considers the energy-efficient precoding matrix design for relay-aided multiuser downlink multiple-input single-output wireless systems. The precoders of the base station (BS) and the relay station (RS) are designed to maximize the transmit energy efficiency, defined as the ratio between the system sum rate and the total power consumption, under the quality-of-service constraints of the users and the transmit power constraints on the BS and the RS. In view of the fact that this precoder design problem is a nonconvex fractional programming, a successive Dinkelbach and convex approximation (SDCA) algorithm is proposed to handle this problem. Simulation results are provided to demonstrate the effectiveness of the proposed SDCA algorithm, and significant EE improvement as the number of antennas at the BS and the RS increases.

关键词： Convex optimization beamforming designs energy efficiency fractional programming relay-aided communications mathematical programming Energy efficiency Bahamas communication aid design problems Convex function prediction coding Downlink Transmitter power

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Multiuser MIMO Capacity with Limited Feedback Trellis Exploration Based Precoder

Multiuser MIMO Capacity with Limited Feedback Trellis Explor...

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International Conference on Computing, Networking and Communications

作者： Sayak Bose Dalin Zhu Balasubramaniam Natarajan WiCom Group Department of Electrical and Computer Engineering Kansas State University Associate Wireless Researcher NEC Labs China (NLC)

ISBN: (纸本)9781467300087

In this paper, a linear trellis based precoder technique is proposed for maximizing multiuser MIMO capacity. We consider MIMO multiple access channel with inter symbol interference (ISI). We use the trellis exploration algorithm to form a precoding matrix that minimizes the interference from other users by allocating power in the appropriate eigen modes for each user. Employing a finite number of phases, the precoder matrix for each user is first custom designed at the receiver. Then a bit sequence indicating the phase indices of the optimized precoding matrix for the corresponding user is fed back to the transmitter. We show that under limited feedback, the sum rate capacity achieved is comparable to the optimal sum-rate capacity employing the well-known water filling solution with complete channel knowledge at the transmitter for spatio-temporal vector coding (STVC). Our simulations for various multiuser MIMO cases, show that the per user precoding strategy achieves desirable performance gain with limited feedback and equal user power allocation in terms of ergodic capacity.

关键词： multiple input multiple output systems Multiple Access Channel rated capacity Feedback Transmitters eigen mode prediction coding bit sequence power splitting Exploration Consumers

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Rate-Boosting Using Strong Crosstalk in Next Generation Wireline Systems

Rate-Boosting Using Strong Crosstalk in Next Generation Wire...

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IEEE Global Communications Conference

作者： Yezi Huang Thomas Magesacher Eduardo Medeiros Chenguang Lu Per-Erik Eriksson Per Odling Department of Electrical and Information Technology Lund University Ericsson Research

ISBN: (纸本)9781479959532

Next-generation wireline systems may exploit frequencies up to several hundred MHz on short lines. Strong crosstalk coupling, comparable to the direct paths, is one of the main channel characteristics at high frequencies. Instead of fully canceling all crosstalk, we utilize strong crosstalk paths to boost data-rate for active users. Two linear precoding schemes, based on maximum ratio combining and convex optimization respectively, are proposed and applied to a common network topology. The precoding schemes exploit constructive crosstalk signals on unused lines or in unused parts of the spectrum on neighboring lines to boost data-rate while still complying with the regulated spectral power limits per line. More than 500 Mbps throughput gain per active user can be achieved compared to state-of-the-art linear precoding.

关键词： crosstalk diversity reception prediction coding Network topology Data transfer rates direct path Convex function Spectra

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GSVD Based Multi-user Multi-stream MIMO Linear Precoding with Limited Feedback

GSVD Based Multi-user Multi-stream MIMO Linear Precoding wit...

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IEEE 23rd International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： Park, Jaehyun Um, Jung-Sun Park, Yunju Jeong, Byung Jang Elect & Telecommun Res Inst Broadcasting & Telecommun Convergence Res Lab Taejon 305606 South Korea Korea Adv Inst Sci & Technol Korea Sci Acad Busan South Korea

ISBN: (纸本)9781467325691

We present a generalized singular value decomposition (GSVD) based multi-user (MU) multi-stream multiple-input multiple-output (MIMO) precoding scheme with limited feedback. Our precoding scheme maximizes the signal to leakage and noise ratio (SLNR), so that it does not require any iterations to obtain precoding matrices. However, in MU-MIMO system, the precoding matrix should be computed at transmit side, because the precoding matrix of a user affects those of other users. Accordingly, full channel state information (CSI) for all users is required at the transmitter, which prevents MU-MIMO precoding implementable. To overcome this problem, an efficient limited feedback algorithm optimized to the GSVD based MU-MIMO precoding is proposed. Here, by extracting the parameters to be utilized in GSVD based precoding from the full CSI, the amount of feedback information is reduced. Furthermore, by analyzing their statistical properties, the parameters are efficiently quantized according to their probability densities. Finally, we develop a modified GSVD based precoding considering the channel quantization errors due to the limited feedback.

关键词： GSVD Based Linear Precoding Limited Feedback prediction coding feedback information multiple input multiple output systems Feedback Consumers based

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