Beijing University of Posts and Telecommunications

About: Beijing University of Posts and Telecommunications is a education organization based out in Beijing, Beijing, China. It is known for research contribution in the topics: MIMO & Quality of service. The organization has 39576 authors who have published 41525 publications receiving 403759 citations. The organization is also known as: BUPT.

Spatio-Temporal Wireless Traffic Prediction With Recurrent Neural Network

Abstract: Accurate prediction of user traffic in cellular networks is crucial to improve the system performance in terms of energy efficiency and resource utilization. However, existing work mainly considers the temporal traffic correlation within each cell while neglecting the spatial correlation across neighboring cells. In this letter, machine learning models that jointly explore the spatio-temporal correlations are proposed. Specifically, several recurrent neural network structures are utilized. Furthermore, a multi-task learning approach is adopted to explore the commonalities and differences across cells in improving the prediction performance. Base on real data, we demonstrate the benefits of joint learning over spatial and temporal dimensions.

Spreading and direction of Gaussian-Schell model beam through a non-Kolmogorov turbulence

Abstract: We show that the far-field beam spreading and direction of partially coherent Gaussian–Schell model (GSM) beams are independent on the spatial coherence of the source through non-Kolmogorov atmospheric turbulence, which has potential applications in long-distance free-space optical communication. The effects of spatial coherence, exponent value α, and inner scale and outer scale of atmospheric turbulence on beam spreading are studied in details. The GSM beam has greater spreading for smaller inner scale or bigger outer scale through non-Kolmogorov turbulent atmosphere.

Performance Analysis of Multiuser Diversity in MIMO Systems with Antenna Selection

Abstract: In this paper, a framework is presented to analyze the performance of multiuser diversity (MUD) in multiuser point-to-multipoint (PMP) MIMO systems with antenna selection. Based on this framework, the tight closed-form expressions of outage capacity and average symbol error rate are derived for the multiuser transmit antenna selection with maximal-ratio combining (TAS/MRC) system, by which we show how and with what characteristics antenna selection gains, MIMO antenna configurations and fading gains impact on the system performance, with an emphasis on the study of multiuser diversity influence. From both theoretical and simulation results, our study shows that in multiuser PMP TAS/MRC systems an diversity order equals to the product of the number of transmit antennas, number of receive antennas and number of users can be achieved; what's more, users plays a key role in the system performance and can be viewed as equivalent "virtual" transmit antennas, which is the source of the multiuser diversity inherent exists in the multiuser system. This kind of diversity can be efficiently extracted in the design of multiantenna systems.

Design and Implementation of LPWA-Based Air Quality Monitoring System

Abstract: Increasing attention has been paid to air quality monitoring with a rapid development in industry and transportation applications in the modern society. However, the existing air quality monitoring systems cannot provide satisfactory spatial and temporal resolutions of the air quality information with low costs in real time. In this paper, we propose a new method to implement the air quality monitoring system based on state-of-the-art Internet-of-Things (IoT) techniques. In this system, portable sensors collect the air quality information timely, which is transmitted through a low power wide area network. All air quality data are processed and analyzed in the IoT cloud. The completed air quality monitoring system, including both hardware and software, is developed and deployed successfully in urban environments. Experimental results show that the proposed system is reliable in sensing the air quality, which helps reveal the change patterns of air quality to some extent.

Dromion-like soliton interactions for nonlinear Schrödinger equation with variable coefficients in inhomogeneous optical fibers

Abstract: In this paper, a generalized nonlinear Schrodinger equation with variable coefficients is investigated. According to the analytic soliton solutions, the dromion-like structures between soliton interactions are revealed, and interaction properties are discussed. By changing the values of gain/loss, group velocity dispersion and self-phase modulation parameters, influences of them on interaction intensity and phase of solitons are presented. Besides, methods of controlling the path and spacing of solitons are suggested. Results of this paper may be potential valuable to the study of soliton interactions in inhomogeneous optical fibers and have applications in all-optical switches.