There are many active mobile users today in trains, especially during the rush hour, hence the potential for mobile communication traffic in trains to rocket in the near future; as applications become diversified and communication tariffs becomes cheaper due to flat rate pricing. The increase in such traffic within a train will mean a mass of accessing users, moving along the railway tracks. In CDMA systems, the signal-to-noise ratio (SNR) of users in the train is greatly influenced by the fluctuation in the number of users accessing the base station. With this in mind, we propose a cell planning scheme using integer linear programming and taking account of the movement of a train containing many accessing users. The scheme minimizes the number of base stations, ensuring the SNR of a user within a target train remains equivalent to or exceeds the required SNR. Finally, simulations using the proposed scheme verify that the SNR of a user in a train for all areas calculated based on optimally-sited base stations reaches a constant value when the interference from other accessing users in a train is much larger than that of those outside the train
['Shinobu Nanba', 'Xiaoqiu Wang', 'Hajime Nakamura']
A cell planning scheme along railway tracks in CDMA systems