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Spatial Characteristics of Distortion Radiated From Antenna Arrays With Transceiver Nonlinearities

IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2018年第10期17卷 6663-6679页

作者： Mollen, Christopher Gustaysson, Ulf Eriksson, Thomas Larsson, Erik G. Linkoping Univ Dept Elect Engn ISY S-58183 Linkoping Sweden Ericsson AB Ericsson Res S-41756 Gothenburg Sweden Chalmers Univ Technol Dept Signals & Syst S-41296 Gothenburg Sweden

The distortion from massive multiple-input multiple-output base stations with nonlinear amplifiers is studied and its radiation pattern is derived. The distortion is analyzed both in-band and out-of-band. By using an orthogonal Hermite representation of the amplified signal, the spatial cross-correlation matrix of the nonlinear distortion is obtained. It shows that, if the input signal to the amplifiers has a dominant beam, the distortion is beamformed in the same way as that beam. When there are multiple beams without any one being dominant, it is shown that the distortion is practically isotropic. The derived theory is useful to predict how the nonlinear distortion will behave, to analyze the out-of-band radiation, to do reciprocity calibration, and to schedule users in the frequency plane to minimize the effect of in-band distortion.

关键词： Amplifiers distortion in-band distortion massive multiple-input multiple-output nonlinear out-of-band radiation reciprocity calibration spectral regrowth

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FDD-RT: A Simple CSI Acquisition Technique via Channel Reciprocity for FDD massive MIMO Downlink

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IEEE SYSTEMS JOURNAL 2018年第1期12卷 714-724页

作者： Liang, Han-Wen Chung, Wei-Ho Kuo, Sy-Yen Acad Sinica Res Ctr Informat Technol Innovat Taipei 11529 Taiwan Natl Taiwan Univ Dept Elect Engn Taipei 106 Taiwan

We propose a channel state information acquisition mechanism to reduce the training overhead in frequency-division duplexing (FDD) massive multiple-input multiple-output (MIMO) downlink (DL). While the massive MIMO has demonstrated the great potentials in many aspects, the carrier multiplexing designs in massive MIMO mostly adopt time-division duplexing (TDD) system, which stems from a stereotype that the uplink/DL channel reciprocity only holds for TDD. On the other hand, FDD massive MIMO is generally considered infeasible due to the unaffordable temporal overhead for sending training symbols at base station. Our proposed FDD with reverse training (FDD-RT) modifies the DL band training procedure in typical FDD system to reduce pilot overhead, where the DL band channel reciprocity is exploited in FDD-RT. FDD-RT contributes to providing a feasible and relatively low complexity method to implement massive MIMO in FDD system. Without FDD-RT, communication operators who currently use FDD system may be enforced to change to TDD system in the future to accommodate massive MIMO, where the cost is prohibitive. The most different property of FDD-RT from other solutions is that its training overhead does not scale with the number of antennas at base station. The detail analysis/comparison of FDD-RT will be given in this paper.

关键词： Channel reciprocity channel state information (CSI) acquisition frequency-division duplexing FDD with reverse training massive multiple-input multiple-output reverse training time-division duplexing

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Improved Scaling Law for Status Update Timeliness in massive IoT by Elastic Spatial multiplexing

Improved Scaling Law for Status Update Timeliness in Massive...

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IEEE Global Conference on Communications (GLOBECOM) / Workshop on Wireless Networking and Control for UAV

作者： Jiang, Zhiyuan Zhou, Sheng Niu, Zhisheng Tsinghua Univ Beijing Natl Res Ctr Informat Sci & Technol BNRis Beijing 100084 Peoples R China

ISBN: (纸本)9781538647271

In this paper, the wireless uplink is considered for status update with a large number of terminals. Thy key problem we address is that whether spatial multiplexing of multiple terminals, enabled by the massive multiple-input multiple-output technology, can help to improve the scaling law of age-of-information versus the number of terminals, on account of the mandatory pilot overhead. Based on a queuing theory analysis, we show that the proposed elastic spatial multiplexing scheme, which assigns an optimized pilot length that is smaller than the number of transmitting terminals on account of random packet arrivals, can indeed improve the scaling law compared with the optimal scaling law without spatial multiplexing, by a factor that is related to the packet lengths and arrival rates. Simulation results are provided to validate our findings.

关键词： Internet-of-Things age-of-information massive multiple-input multiple-output queuing theory

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Joint Direction-of-Departure and Two-Dimensional Direction-of-Arrival Estimation with Automatic Pairing in massive MIMO Systems 12th

Joint Direction-of-Departure and Two-Dimensional Direction-o...

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12th International Conference on Communications and Networking in China (CHINACOM)

作者： Zhou, Yuan Ji, Xiang Dai, Man Beijing Inst Technol Sch Informat & Elect RCDCT Beijing Peoples R China

ISBN: (纸本)9783319781303;9783319781297

In this paper, we focus on the problem of joint direction-of-departure (DOD) and two-dimensional (2D) direction-of-arrival (DOA) estimation in massive multiple-input multiple-output (MIMO) systems. A novel method for angle estimation is proposed with automatic pairing. The method transforms the element space into the beamspace by employing the property of conjugate centrosymmetric array, such that the angle estimation operates only on the real-valued computation. Then, we utilize the real-valued rotational invariance relationships in beamspace to estimate DOD and 2D DOA in a fresh fashion. Numerical results show that the proposed algorithm provides reduced computational complexity without the loss of estimation accuracy owing to real-valued processing, automatic pairing and computation dimension reduction in massive MIMO systems.

关键词： Two-dimensional direction-of-arrival (DOA) Direction-of-departure (DOD) Uniform rectangle array massive multiple-input multiple-output

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Energy-Efficient Downlink Transmission for Multicell massive DAS With Pilot Contamination

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2017年第2期66卷 1209-1221页

作者： Zuo, Jun Zhang, Jun Yuen, Chau Jiang, Wei Luo, Wu Peking Univ State Key Lab Adv Opt Commun Syst & Networks Sch Elect Engn & Comp Sci Beijing 100871 Peoples R China Nanjing Univ Posts & Telecommun Jiangsu Key Lab Wireless Commun Coll Telecommun & Informat Engn Nanjing 210003 Peoples R China Singapore Univ Technol & Design Singapore 487372 Singapore

In this paper, we study the energy efficiency (EE) of a downlink multicell massive distributed antenna system (DAS) in the presence of pilot contamination (PC), where the antennas are clustered on the remote radio heads (RRHs). We employ a practical power consumption model by considering the transmit power, the circuit power, and the backhaul power, in contrast to most of the existing works which focus on colocated antenna systems (CASs), where the backhaul power is negligible. For a given average user rate, we consider the problem of maximizing the EE with respect to the number of antennas of each RRH n, the number of RRHs M, and the number of users K and study the impact of system parameters on the optimal n, M, and K. Specifically, by applying random matrix theory, we derive the closed-form expressions of the optimal n and find the solution of the optimal M and K under a simplified channel model with maximum ratio transmission. From the results, we find that, to achieve the optimal EE, a large number of antennas is needed for a given user rate and PC. As the number of users increases, EE can be improved further by having more RRHs and antennas. Moreover, if the backhauling power is not large, a massive DAS can be more energy efficient than a massive CAS. These insights provide a useful guide to the practical deployment of massive DASs.

关键词： Distributed antenna system (DAS) energy efficiency (EE) massive multiple-input multiple-output multicell pilot contamination (PC)

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Joint Angle Estimation and Signal Reconstruction for Coherently Distributed Sources in massive MIMO Systems Based on 2-D Unitary ESPRIT

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IEEE ACCESS 2017年 5卷 9632-9646页

作者： Zhou, Yuan Fei, Zesong Yang, Shaoshi Kuang, Jingming Chen, Sheng Hanzo, Lajos Beijing Inst Technol Sch Informat & Elect Beijing 100081 Peoples R China Univ Southampton Sch Elect & Comp Sci Southampton SO17 1BJ Hants England King Abdulaziz Univ Jeddah 21589 Saudi Arabia

We consider the challenging problem of joint angle estimation and signal reconstruction for coherently distributed (CD) sources in massive multiple-input multiple-output (MIMO) systems employing uniform rectangular arrays. A simplified method inspired by the two-dimensional (2-D) unitary estimating signal parameters via rotational invariance technique (ESPRIT) is proposed to estimate both the central angle and the angular spread without the need for a spectrum peak search and covariance matrix matching process. We first approximate the 2-D generalized steering vector expressed as a Schur-Hadamard product by a pair of one-dimensional generalized steering vectors. Then, we obtain two approximate rotational invariance relationships with respect to the central angles of the CD sources using a linear approximation of the individual generalized steering vectors of the azimuth and elevation subarrays. With the aid of this approximate decomposition, a new unitary ESPRIT-inspired algorithm is conceived to automatically pair the 2-D central angle estimations and a novel method capable of bypassing the high-complexity search process is proposed for angular spread estimation. Furthermore, the closed-form approximate Cramer-Rao lower bounds are derived for the estimators of both the central angles and the angular spreads. The complexity of the proposed estimator is also analyzed. Additionally, the orthogonality of the generalized steering vectors is proved, which enables us to propose a low-complexity method to reconstruct the CD signal matrix by replacing the inversion operator with the conjugate transpose operator. The simulation results demonstrate the efficiency of our proposed approach.

关键词： massive multiple-input multiple-output two-dimensional array coherently distributed source direction-of-arrival angular spread signal reconstruction

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Phase-Only Zero Forcing for Secure Communication With multiple Antennas

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IEEE JOURNAL OF SELECTED TOPICS IN SIGNAL PROCESSING 2016年第8期10卷 1334-1345页

作者： Zhao, Wanyao Lee, Si-Hyeon Khisti, Ashish Univ Toronto Dept Elect & Comp Engn Toronto ON M5S 1A1 Canada Bank China Ltd Beijing 100094 Peoples R China

Artificial noise (AN) transmission can enhance the secrecy in multiantenna wireless channels by superimposing judiciously constructed synthetic noise signals over information signals during transmission. Motivated by the large-scale multiple-input multiple-output systems, we study AN transmission under a constraint that all elements (weights) in each beamforming vector must have a constant magnitude, but can have arbitrary phases. For the special case of one AN beamforming vector and one legitimate receiver, we derive a necessary and sufficient condition for finding a beamforming vector in the null space of the legitimate receiver's channel and provide a geometric interpretation. For the independent identically distributed Rayleigh fading channel, we derive an approximate expression for the probability of failing to find such a beamforming vector, and show that it decreases exponentially in the square of the number of transmit antennas. For the general case, we propose a numerical algorithm for obtaining a set of mutually orthogonal AN beamforming vectors in the null space of all the receivers. Our approach involves reducing the problem to an unconstrained nonlinear programming problem, which is then solved using the Gauss-Newton method. We show numerically that our proposed algorithm performs significantly better than a heuristic relaxation approach. Finally, for a multiantenna system with multiple RF chains, we show numerically that the secrecy rate achieved by our proposed approach is close to that achieved by the AN transmission with unconstrained beamforming, when the number of transmit antennas is sufficiently large.

关键词： Artificial noise transmission massive multiple-input multiple-output phase-only zero forcing physical layer security

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Iterative receiver based on the EGC for massive MIMO schemes using SC-FDE modulations

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ELECTRONICS LETTERS 2016年第11期52卷 972-973页

作者： Dinis, R. Montezuma, P. Univ Nova Lisboa Inst Telecomunicacoes P-1200 Lisbon Portugal Univ Nova Lisboa FCT P-1200 Lisbon Portugal Univ Nova Lisboa FCT UNINOVA DCS P-1200 Lisbon Portugal

This Letter considers the use of massive multiple-input, multiple-output (MIMO) combined with single-carrier with frequency-domain equalisation (SC-FDE) modulations. A low-complexity iterative frequency-domain receiver based on the equal gain combining (EGC) approach is proposed. This receiver does not require matrix inversions and has excellent performance, which can be very close to the matched filter bound after just a few iterations, even when the number of receive antennas is not very high.

关键词： MIMO communication diversity reception equalisers radio receivers EGC approach SC-FDE modulations equal gain combining approach low-complexity iterative frequency-domain receiver massive MIMO schemes massive multiple-input multiple-output matched filter matrix inversions single-carrier with frequency-domain equalisation modulations

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An optimized Interference Alignment Algorithm Based on Dynamic Power Allocation for MIMO System 11

An optimized Interference Alignment Algorithm Based on Dynam...

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11th International Symposium on Antennas, Propagation and EM Theory (ISAPE)

作者： Liu, Yun Yuan, Hongwei Li, Ning Zhai, Lijun China Elect Technol Grp Corp CETC54 Res Inst 54 Beijing Res & Dev Ctr Beijing 100070 Peoples R China China Elect Technol Grp Corp CETC54 Res Inst 54 CETC Key Lab Aerosp Informat Applicat Beijing 100070 Peoples R China

ISBN: (纸本)9781509047437

High density small cells with large number of simultaneously connected devices will be controlled by the macro cell in the future 5G wireless standards. In this context, interference management becomes critical in achieving high spectral efficiency. An approach called interference alignment (IA) technique has shown great promise in many theoretical studies. However, the performance improvement brought by IA in the MIMO interference network has not been investigated well when combined with power allocation. In this paper, we propose a joint IA and power allocation algorithm that designed to find the interference mitigation solution and allocate power among different data streams of the users with less computational cost. The proposed algorithm combines the maximum of total system signal interference noise ratio (Max-SINR) criterion and the maximum chord distance of channel matrix criterion not only maximize the distances between the interference subspace and the signal spanned, but also further reduce the interference between users by power allocation. Further, the algorithm in this paper which does not use iterative to get the precoding matrix or the mitigation matrix minimizes the complexity of the whole system and has better engineering applicability. Finally, simulation results show that the proposed method outperforms other known interference alignment algorithms in terms of throughput and the energy efficiency, which also accord with the green communications.

关键词： Green Communications multiple-input multiple-output Interference Alignment power allocation massive multiple-input multiple-output

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Adaptive Pilot-Duration and Resource Allocation in Virtualized Wireless Networks with massive MIMO

Adaptive Pilot-Duration and Resource Allocation in Virtualiz...

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IEEE Wireless Communications and Networking Conference

作者： Rajesh Dawadi Saeedeh Parsaeefard Mahsa Derakhshani Tho Le-Ngoc Department of Electrical & Computer Engineering McGill University Iran Telecommunication Research Center Department of Electrical & Electronic Engineering Imperial College

ISBN: (纸本)9781467398152

This paper investigates the resource allocation problem for a virtualized wireless network (VWN) in which each base station (BS) is equipped with a large number of antennas and due to the pilot contamination error, the perfect estimation of channel state information (CSI) is not available. In this case, the duration of pilot sequence transmission plays a critical role on the achieved VWN throughput. Therefore, we consider this parameter as a new optimization variable and propose a novel utility function for the resource allocation problem. The proposed optimization problem is non-convex with high computational complexity. To address this issue, by applying relaxation and variable transformation techniques, we propose a two-step iterative algorithm in which the allocation of power, sub-carrier and number of antennas is first established and then used to optimize the pilot duration. Simulation results reveal that proper pilot duration design improves the VWN performance.

关键词： massive multiple-input multiple-output Pilot contamination error Virtualized wireless networks

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