Center for Railway Engineering

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Browsing Center for Railway Engineering by Subject "AA-LRT Railway"

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    Alternative Wireless Communication System Design for AA-LRT Railway Tunnels at Piassa
    (Addis Ababa University, 2015-04) Mehari, Belete; Yalemzewd, Negash (PhD)
    Railway transport is effective and reliable only if it has best communication and signaling system with safety, reliability and good quality of service which are maintained by railway management and communication system. By implementing latest technologies for railway communication railway transportation can be made safer, efficient, and more accessible. This research work focuses on the study of Ultra wide band (UWB) radio based wireless communication system as an auxiliary or alternative communication system for Addis Ababa Light rail transit (AA-LRT) tunnel at piassa (Gyorgis), whose main task is to maintain an uninterrupted data transmission between train driver to wayside controller. The much larger bandwidth of ultra-wideband allows a very high data rate (up to maximum 480 Mbps), which is beneficial in case of emergency in railway networks. This research studied the rectangular shaped railway tunnel environment as wireless channel by considering ray theory model of wave propagation (modal analysis and ray tracing) and the effect of the curvature of the tunnel on the wave propagation. In this thesis work the frequency response, channel impulse response and path loss for different distances between transmitter and receiver and also the effect of fading over the channel is evaluated. The evaluations have been used to model the effects of tunnel propagation, including curves inside the tunnel. Then three standard wave shapes has been tested with the modelled channel to observe the phase shift and time delay provided by the considered channel model which behaves as a multipath fading channel with additive white Gaussian noise. Lastly to check the quality of reception bit error rate performance has been evaluated for BPSK and OOK modulation techniques. Finally, a complete propagation model combining both modal analysis and ray tracing has been applied to predict the propagation loss inside the tunnel. So to maintain the continuity of communication it needs to install ultra-wideband trans-receiver over the specific interval.