A novel iterative detection method for time-varying MIMO system

In centralized massive multiple-input multiple-output (MIMO) systems, the channel hardening phenomenon can occur, in which the channel behaves as almost fully deterministic as the number of antennas increases. Nevertheless, in a cell-free massive MIMO system, the channel is less deterministic. In this paper, we propose using instantaneous channel state information (CSI) instead of statistical CSI to obtain the power control coefficient in cell-free massive MIMO. Access points (APs) and user equipment (UE) have sufficient time to obtain instantaneous CSI in a slowly time-varying channel environment. We derive the achievable downlink rate under instantaneous CSI for frequency division duplex (FDD) cell-free massive MIMO systems and apply the results to the power control coefficients. For FDD systems, quantized channel coefficients are proposed to reduce feedback overhead. The simulation results show that the spectral efficiency performance when using instantaneous CSI is approximately three times higher than that achieved using statistical CSI.

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The Achievable Rate of the Training-Based MIMO System over Time-Varying Fading Channels: A BCRB Perspective on Channel Tracking

2011 IEEE International Conference on Communications (ICC) ◽

10.1109/icc.2011.5963514 ◽

2011 ◽

Cited By ~ 1

Author(s):

Lin-Kai Chiu ◽

Sau-Hsuan Wu

Keyword(s):

Fading Channels ◽

Mimo System ◽

Achievable Rate ◽

Time Varying ◽

Channel Tracking ◽

Over Time

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Adaptable Channel Decomposition for Time-Varying MIMO System with QoS Constraints

2008 4th International Conference on Wireless Communications, Networking and Mobile Computing ◽

10.1109/wicom.2008.526 ◽

2008 ◽

Cited By ~ 1

Author(s):

Jie Hu ◽

Xianzhong Xie ◽

Suili Feng ◽

Jianqiang Lu

Keyword(s):

Mimo System ◽

Time Varying ◽

Channel Decomposition

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Measurement-Based Evaluation of a Multiuser MIMO System in an Indoor Time-Varying Environment

2010 IEEE 72nd Vehicular Technology Conference - Fall ◽

10.1109/vetecf.2010.5594155 ◽

2010 ◽

Cited By ~ 2

Author(s):

Huu Phu Bui ◽

Yasutaka Ogawa ◽

Toshihiko Nishimura ◽

Takeo Ohgane

Keyword(s):

Mimo System ◽

Time Varying ◽

Multiuser Mimo ◽

Time Varying Environment ◽

Varying Environment

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Precise detection of the size of monodisperse droplets considering the fluctuations induced by the droplet generation process

10.21203/rs.3.rs-626018/v1 ◽

2021 ◽

Author(s):

Wen Zeng ◽

Hai Fu

Keyword(s):

Droplet Size ◽

Detection Method ◽

Droplet Microfluidics ◽

Generation Process ◽

Time Varying ◽

Electrical Detection ◽

Flow Focusing ◽

Wide Range ◽

Droplet Production ◽

Monodisperse Droplets

Abstract For droplet microfluidics, the electrical-detection method which can precisely detect the size of monodisperse droplets is demonstrated in this paper. In a Flow-focusing microdroplet generator, three pairs of the microelectrodes are allocated along the microchannel, and during the passing-by process of each droplet, both the length, the velocity and the production speed of the droplets can be obtained from the experimental measurements of the time-varying capacitance between each pair of the microelectrodes. Particularly, for different geometries of the Flow-focusing microchannel, the method of the electrical-detection is validated experimentally over a wide range of the typical conditions of monodisperse droplet production. In addition, the droplet size measured by the electrical-detection method is compared with that by the method of image processing, and the detection precision of the electrical-detection method is verified experimentally. Most importantly, by calculating the root-mean-square value of the droplet lengths for three pairs of the microelectrodes, the detection precision of the droplet size can be increased drastically.

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Dynamic Traffic Detection and Modeling for Beidou Satellite Networks

Journal of Sensors ◽

10.1155/2020/4575721 ◽

2020 ◽

Vol 2020 ◽

pp. 1-11

Author(s):

Yanyu Qu ◽

Fangling Pu ◽

Jianguo Yin ◽

Lingzi Liu ◽

Xin Xu

Keyword(s):

Network Traffic ◽

Spatial Information ◽

Detection Method ◽

Data Communication ◽

Traffic Monitoring ◽

Integrated System ◽

Time Varying ◽

Dynamic Traffic ◽

Ground Station ◽

Traffic Detection

Beidou navigation system (BDS) has been developed as an integrated system. The third BDS, BSD-3, will be capable of providing not only global positioning and navigation but also data communication. When the volume of data transmitted through BDS-3 continues to increase, BDS-3 will encounter network traffic congestion, unbalanced resource usage, or security attacks as terrestrial networks. The network traffic monitoring is essential for automatic management and safety assurance of BDS-3. A dynamic traffic detection method including traffic prediction by Long Short-Term Memory (LSTM) and a dynamically adjusting polling strategy is proposed to unevenly sample the traffic of each link. A distributed traffic detection architecture is designed for collection of the detected traffic and its related temporal and spatial information with low delay. A time-varying graph (TVG) model is introduced to represent the dynamic topology, the time-varying link, and its traffic. The BDS-3 network is simulated by STK. The WIDE dataset is used to simulate the traffic between the satellite and ground station. Simulation results show that the dynamic traffic detection method can follow the variation of the traffic of each link with uneven sampling. The detected traffic can be transmitted to the ground station in near real time through the distributed traffic detection architecture. The traffic and its related information are stored by using Neo4j in terms of the TVG model. The nodes, edges, and traffic of BDS-3 can be quickly queried through Neo4j. The presented dynamic traffic detection and representation schemes will support BDS-3 to establish automatic management and security system and develop business.

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