Title :
Broadband Channel Long Delay Cluster Measurements and Analysis at 2.4GHz in Subway Tunnels
Author :
He, Ruisi ; Zhong, Zhangdui ; Briso, Cesar
Author_Institution :
State Key Lab. of Rail Traffic Control & Safely, Beijing Jiaotong Univ., Beijing, China
Abstract :
The delay caused by the reflected ray in broadband communication has a great influence on the communications in subway tunnel. This paper presents measurements taken in subway tunnels at 2.4 GHz, with 5 MHz bandwidth. According to propagation characteristics of tunnel, the measurements were carried out with a frequency domain channel sounding technique, in three typical scenarios: line of sight (LOS), Non-line-of-sight (NLOS) and far line of sight (FLOS), which lead to different delay distributions. Firstly IFFT was chosen to get channel impulse response (CIR) h(t) from measured three-dimensional transfer functions. Power delay profile (PDP) was investigated to give an overview of broadband channel model. Thereafter, a long delay caused by the obturation of tunnel is observed and investigated in all the scenarios. The measurements show that the reflection can be greatly remained by the tunnel, which leads to long delay cluster where the reflection, but direct ray, makes the main contribution for radio wave propagation. Four important parameters: distribution of whole PDP power, first peak arriving time, reflection cluster duration and PDP power distribution of reflection cluster were studied to give a detailed description of long delay characteristic in tunnel. This can be used to ensure high capacity communication in tunnels.
Keywords :
UHF measurement; broadband networks; delays; electromagnetic wave reflection; frequency-domain analysis; radiowave propagation; transfer functions; transient response; tunnels; underground communication; PDP power distribution; bandwidth 5 MHz; broadband channel long delay cluster measurements; broadband communication; channel impulse response; delay distributions; frequency 2.4 GHz; frequency domain channel sounding technique; power delay profile; propagation characteristics; radio wave propagation; reflection cluster; subway tunnels; three-dimensional transfer functions; Antenna measurements; Broadband communication; Delay; Frequency measurement; Reflection; Three dimensional displays; Transmitters;
Conference_Titel :
Vehicular Technology Conference (VTC Spring), 2011 IEEE 73rd
Conference_Location :
Yokohama
Print_ISBN :
978-1-4244-8332-7
DOI :
10.1109/VETECS.2011.5956539