WiFi performance analysis in high-speed railway communication

In High-Speed Railways(HSRs),the Train Control and Management System(TCMS)plays a crucial role.However,as the demand for train networks grows,the limitations of traditional wired connections have become apparent.This paper designs and implements a Wireless Train Communication Network(WTCN)to enhance the existing train network infrastructure.To address the challenges that wireless communication technology faces in the unique environment of high-speed rail,this study first analyzes various onboard environments and simulates several typical scenarios in the laboratory.Integrating the specific application scenarios and service characteristics of the high-speed train control network,we conduct measurements and validations of WiFi performance,exploring the specific impacts of different factors on throughput and delay.

A general communication performance evaluation model based on routing path decomposition

The network-on-chip (NoC) architecture is a main factor affecting the system performance of complicated multi-processor systems-on-chips (MPSoCs).To evaluate the effects of the NoC architectures on communication efficiency,several kinds of techniques have been developed,including various simulators and analytical models.The simulators are accurate but time consuming,especially in large space explorations of diverse network configurations;in contrast,the analytical models are fast and flexible,providing alternative methods for performance evaluation.In this paper,we propose a general analytical model to esti-mate the communication performance for arbitrary NoCs with wormhole routing and virtual channel flow control.To resolve the inherent dependency of successive links occupied by one packet in wormhole routing,we propose the routing path decomposition approach to generating a series of ordered link categories.Then we use the traditional queuing system to derive the fine-grained transmission latency for each network component.According to our experiments,the proposed analytical model provides a good approximation of the average packet latency to the simulation results,and estimates the network throughput precisely under various NoC configurations and workloads.Also,the analytical model runs about 10 5 times faster than the cycle-accurate NoC simulator.Practical applications of the model including bottleneck detection and virtual channel allocation are also presented.

Air turbulence effects on performance of optical wireless communication with crosstalk in server backplane

Free space optical interconnections（FSOIs） are anticipated to become a prevalent technology for short-range high-speed communication. FSOIs use lasers in board-to-board and rack-to-rack communication to achieve improved performance in next generation servers and are expected to help meet the growing demand for massive amounts of inter-card data communication. An array of transmitters and receivers arranged to create an optical bus for inter-card and card-to-backplane communication could be the solution. However, both chip heating and cooling fans produce temperature gradients and hot air flow that results in air turbulence inside the server, which induces signal fading and, hence, influences the communication performance. In addition, the proximity between neighboring transmitters and receivers in the array leads to crosstalk in the received signal, which further contributes to signal degradation. In this Letter, the primary objective is to experimentally examine the off-axis crosstalk between links in the presence of turbulence inside a server chassis. The effects of geometrical and inter-chassis turbulence characteristics are investigated and first-and second-order statistics are derived.