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Non-stationarities in extra-large scale massive MIMO

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arXiv 2019年

作者： de Carvalho, Elisabeth Ali, Anum Amiri, Abolfazl Angjelichinoski, Marko Heath, Robert W. Department of Elec-tronic Systems Aalborg University Aalborg9220 Denmark Department of Electrical and Computer Engineering Duke University DurhamNC27708 United States Wireless Networking and Communications Group Department of Electrical and Computer Engineering University of Texas at Austin AustinTX78712 United States

Massive MIMO, a key technology for increasing area spectral efficiency in cellular systems, was developed assuming moderately sized apertures. In this paper, we argue that massive MIMO systems behave differently in large-scale regimes due to spatial non-stationarity. In the large-scale regime, with arrays of around fifty wavelengths, the terminals see the whole array but non-stationarities occur because different regions of the array see different propagation paths. At even larger dimensions, which we call the extra-large scale regime, terminals see a portion of the array and inside the first type of non-stationarities might occur. We show that the non-stationarity properties of the massive MIMO channel change several important MIMO design aspects. In simulations, we demonstrate how non-stationarity is a curse when neglected but a blessing when embraced in terms of computational load and multi-user transceiver design. Copyright © 2019, The Authors. All rights reserved.

关键词： MIMO systems

Wideband Bandpass Filters Using a Novel Thick Metallization Technology

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arXiv 2019年

作者： Gomez-Molina, Celia Pons-Abenza, Alejandro Do, James Quesada-Pereira, Fernando Liu, Xiaoguang Gomez-Diaz, Juan Sebastian Alvarez-Melcon, Alejandro Department of Information Technologies and Communications Universidad Politécnica de Cartagena Cartagena30202 Spain Department of Electrical and Computer Engineering University of California Davis United States

—A new class of wideband bandpass filters based on using thick metallic bars as microwave resonators, instead of common microstrip lines, is presented. These bars provide a series of advantages over fully planar printed technologies, including higher coupling levels between resonators, better unloaded quality factors QU, and larger bandwidths, implemented with more compact structures. Moreover, thick bar resonators can easily be coupled to an additional resonance excited in a box used for shielding, allowing to realize transversal topologies able to implement transmission zeros at desired frequencies. To illustrate the capabilities of this technology, two microwave filters with different bandwidths and one transmission zero have been designed. One of the filters has been manufactured and tested using copper bars inside an aluminum housing partially filled with Teflon. Measured data demonstrates a fractional bandwidth about FBW = 32%, spurious free range SFR > 50%, unloaded quality factor of QU = 1180 and return losses over 20 dB without requiring any post-tuning on the prototype, confirming the exciting performance of the proposed technology. Copyright © 2019, The Authors. All rights reserved.

关键词： Microwave filters

Non-Linear Diode Rectifier Analysis for Multi-Tone Wireless Power Harvesting

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Non-Linear Diode Rectifier Analysis for Multi-Tone Wireless ...

IEEE International Conference on Microwaves, communications, Antennas and Electronic Systems, COMCAS

作者： Ana López-Yela Alberto López-Yela Daniel Segovia-Vargas Zoya Popović Department of Signal Theory and Communications University Carlos III of Madrid Leganés Spain Department of Electrical Computer and Energy Engineering University of Colorado Boulder Colorado USA

This paper presents an analysis of the non-linear performance of a zero-bias Schottky diode under multi-tone excitation for wireless power harvesting applications. At low incident power levels, it has been shown that multi-tone inputs increase RF-DC conversion efficiency. Here we extend the theoretical analysis to include a more practical diode model which includes series resistance essential for determining efficiency. We show that the more complex theory approximates the real diode IV curve more accurately at low input power levels than previous models which neglect the series resistance.

关键词： Schottky diodes Resistance Energy harvesting Microwave antennas Taylor series Wireless communication Microwave communication

Optimized deployment of millimeter wave networks for in-venue regions with stochastic users' orientation

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arXiv 2019年

作者： Soorki, Mehdi Naderi Saad, Walid Bennis, Mehdi Wireless-VT Bradley Department of Electrical and Computer Engineering Virginia Tech BlacksburgVA United States Centre for Wireless Communications University of Oulu Finland

Millimeter wave (mmW) communication is a promising solution for providing high-capacity wireless network access. However, the benefits of mmW are limited by the fact that the channel between a mmW access point and the user equipment can stochastically change due to severe blockage of mmW links by obstacles such as the human body. Thus, one main challenge of mmW network coverage is to enable directional line-of-sight links between access points and mobile devices. In this paper, a novel framework is proposed for optimizing mmW network coverage within hotspots and in-venue regions, while being cognizant of the body blockage of the network's users. In the studied model, the locations of potential access points and users are assumed as predefined parameters while the orientation of the users is assumed to be stochastic. Hence, a joint stochastic access point placement and beam steering problem subjected to stochastic users' body blockage is formulated, under desired network coverage constraints. Then, a greedy algorithm is introduced to find an approximation solution for the joint deployment and assignment problem using a new "size constrained weighted set cover" approach. A closed-form expression for the ratio between the optimal solution and approximate one (resulting from the greedy algorithm) is analytically derived. The proposed algorithm is simulated for three in-venue regions: the meeting room in the Alumni Assembly Hall of Virginia Tech, an airport gate, and one side of a stadium football. Simulation results show that, in order to guarantee network coverage for different in-venue regions, the greedy algorithm uses at most three more access points (APs) compared to the optimal solution. The results also show that, due to the use of the additional APs, the greedy algorithm will yield a network coverage up to 11:7% better than the optimal, AP-minimizing solution. Copyright © 2019, The Authors. All rights reserved.

关键词： Stochastic systems

A regression approach to certain information transmission problems

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arXiv 2019年

作者： Zhang, Wenyi Wang, Yizhu Shen, Cong Liang, Ning CAS Key Laboratory of Wireless-Optical Communications University of Science and Technology of China China Department of Electrical and Computer Engineering University of Virginia United States

A general information transmission model, under independent and identically distributed Gaussian codebook and nearest neighbor decoding rule with processed channel output, is investigated using the performance metric of generalized mutual information. When the encoder and the decoder know the statistical channel model, it is found that the optimal channel output processing function is the conditional expectation operator, thus hinting a potential role of regression, a classical topic in machine learning, for this model. Without utilizing the statistical channel model, a problem formulation inspired by machine learning principles is established, with suitable performance metrics introduced. A data-driven inference algorithm is proposed to solve the problem, and the effectiveness of the algorithm is validated via numerical experiments. Extensions to more general information transmission models are also discussed. Copyright © 2019, The Authors. All rights reserved.

关键词： Regression analysis

New Construction of Optimal Type-II Binary Z-Complementary Pairs

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arXiv 2020年

作者： Gu, Zhi Zhou, Zhengchun Wang, Qi Fan, Pingzhi School of Information Science and Technology Southwest Jiaotong University Chengdu611756 China School of Mathematics Southwest Jiaotong University Chengdu611756 China Department of Computer Science and Engineering Southern University of Science and Technology Shenzhen518055 China Institute of Mobile Communications Southwest Jiaotong University Chengdu611756 China

A pair of sequences is called a Z-complementary pair (ZCP) if it has zero aperiodic autocorrelation sums at each of the non-zero time-shifts within a certain region, called the zero correlation zone (ZCZ). ZCPs are categorised into two types: Type-I ZCPs and Type-II ZCPs. Type-I ZCPs have the ZCZ around the in-phase position and Type-II ZCPs have the ZCZ around the end-shift position. Till now only a few constructions of Type-II ZCPs are reported in the literature, and all have lengths of the form 2m±1 or N + 1 where N = 2a10b26c and a, b, c are non-negative integers. In this paper, we propose a recursive construction of ZCPs based on concatenation of sequences. Inspired by Turyn’s construction of Golay complementary pairs, we also propose a construction of Type-II ZCPs from known ones. The proposed constructions can generate optimal Type-II ZCPs with new flexible parameters and Z-optimal Type-II ZCPs with any odd length. In addition, we give upper bounds for the PMEPR of the proposed ZCPs. It turns out that our constructions lead to ZCPs with low PMEPR. Copyright © 2020, The Authors. All rights reserved.

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Statistical Shipping Noise Characterization and Mitigation for Underwater Acoustic communications

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Statistical Shipping Noise Characterization and Mitigation f...

OCEANS - Europe

作者： Lazar Atanackovic Ruoyu Zhang Lutz Lampe Roee Diamant Department of Electrical and Computer Engineering University of British Columbia Canada Communications Research Center Harbin Institute of Technology China Department of Marine Technologies University of Haifa Israel

Achieving high data rate robust communication in shallow and harbour underwater acoustic (UA) environments can be a demanding challenge in the presence of shipping noise. Noise generated from nearby passing ships can lead to impulsive agitations which impair UA communication systems. Utilizing the assumption that impulse noise exhibits sparsity, we realize a compressed sensing (CS) based framework for noise estimation exploiting the pilot sub-carriers of UA orthogonal frequency-division modulation systems. Under the CS framework, we propose the use of a empirical Bayesian approach which first characterizes the statistical properties of shipping noise prior to conceiving an estimate. In addition, we invoke the K-SVD algorithm for dictionary learning. K-SVD iteratively forms a sparse representation for the class of shipping noise signals, which is later used for noise estimation. Numerical results show that the empirical Bayesian based signal recovery algorithm yields the best performance for interference estimation.

关键词： Interference OFDM Estimation Marine vehicles Acoustics Sonar equipment Discrete Fourier transforms

Training Sequence Based Doppler Shift Estimation for Vehicular Communication

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Training Sequence Based Doppler Shift Estimation for Vehicul...

IEEE Conference on Wireless communications and Networking

作者： Qingpeng Ma Gang Qiu Qixun Zhang Huiqing Sun Zhiyong Feng Zhu Han Key Laboratory of Universal Wireless Communications Ministry of Education Beijing University of Posts and Telecommunications Beijing P.R.China ZTE Corporation LTE & 5G Wireless Research Institute Shenzhen P.R.China Electrical and Computer Engineering Department University of Houston Houston TX

ISBN: (数字)9781728131061

ISBN: (纸本)9781728131078

To guarantee the safety requirements of autonomous driving vehicles, the efficient and robust sensing information sharing among vehicles is crucial to overcome the environment sensing limitations beyond a single sensor or vehicle. The millimeter wave (mmWave) technology is considered as one of the potential mobile broadband communication solutions to solve high data rate sensing information sharing problem among vehicles with the low latency constraint. However, the Doppler shift effect is much more severe, which will deteriorate the performance of vehicular communication links, especially in a high speed vehicle communication scenario in the mmWave frequency band. Therefore, we propose a training sequence based estimator (TSBE) by designing a hybrid structure combining the fixed section and the repeated sequences, aiming to achieve a fast and accurate Doppler shift estimation (DSE) in the mmWave vehicular scenario. The fixed section provides a fast estimation, and the accuracy of DSE can be effectively improved by the random correlation selection of repeated sequences. Furthermore, the key performances of our proposed DSE algorithm are evaluated by both the link-level simulation and the hardware testbed results. Results prove that the mean-squared error of our proposed TSBE algorithm outperforms other conventional algorithms under various signal to noise ratio values. The hardware testbed shows a remarkable performance improvement on the error vector magnitude and the bit error rate using our proposed TSBE and compensation algorithm.

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Design of a Long-Short Range Soil Monitoring Wireless Sensor Network for Medium-Scale Deployment

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Design of a Long-Short Range Soil Monitoring Wireless Sensor...

2018 IEEE Region 10 Conference, TENCON 2018

作者： Co, Jerelyn Tiausas, Francis Jerome Aldrin Domer, Prince Guico, Maria Leonora Claro Monje, Jose Oppus, Carlos Department of Information Systems and Computer Science Ateneo de Manila University Quezon City1108 Philippines Department of Electronics Computer and Communications Engineering Ateneo de Manila University Quezon City1108 Philippines

ISBN: (纸本)9781538654576

This paper presents the design and development of the hardware and software components of a soil monitoring Wireless Sensor Network (WSN) for medium-scale deployments. It is composed of multiple remote sensing and transmitting devices for autonomous monitoring of soil and several surrounding environmental conditions. Using commercially-available sensor probes, it can gather soil parameters such as air and soil temperature, sunlight, moisture, humidity, and soil pH. The proposed system, subdivided into three node classes, namely sensor, relay, and aggregator nodes, has wireless communication capabilities enabled by short-range packet radio, and long-range/low-power radio (LoRa) modules which can attend to telemetry-related challenges imposed by large area coverage, vegetation density, and location remoteness. © 2018 IEEE.

关键词： Soils