A practical method of estimation of train mobile radio coverage in the 320 MHz band

Once the train leaves station, there is no communication between the running train and the station or controller. Hence, in case of failures or in emergencies in between stations immediate information cannot be given and a particular problem will escalate with valuable time lost. Hence, the introduction of a train radio communication system will not only improve the level of safety of Indian Railways (IR) but will also improve efficiency of train operations. Further, due to interference and other problems with copper cable in electrified territory, IR have decided to replace open wire lines by optical fibre cables along the electrified routes. The usage of optical fibre cables does not lend itself for presiding trackside communication as in the case of copper cable, which can be tapped at regular intervals along the track. Hence, another transmission medium is necessary for communication outside the station limits with drivers, guards, maintenance gangs, gateman etc. Obviously the medium of choice for such communication is wireless. With increasing speed and train density, adoption of train control methods such as automatic warning system, (AWS) or, automatic train stop (ATS), or positive train separation (PTS) is a must. Even though, these methods traditionally pick up their signals from track based beacons, radio based systems are emerging and are ideally suited for Indian conditions due to theft and vandalism of ground based equipment. Hence, the increasing demand for different applications of radio communication on railways, makes it necessary to provide a good basis for designing the coverage of radio system.