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A fast handoff algorithm with high reliability and efficiency for CBTC systems

Successful handoff plays an indispensable role in wireless communications. Running through the large wireless networks with numerous APs in urban mass transit, a train equipped with CBTC systems inevitably encounters the problems of handoff. Against the possibly negative phenomena such as ping-pong effect, handoff delay, packet loss and so on, a new handoff algorithm with frequency combination has been employed. The algorithm is mostly, when the current field intensity is lower than the given threshold, to establish buffers between triggered handoff processes to ensure the quality of channel against stochastic source jamming and time-varying channel and choose the precise handoff time in whole networks when handoff is engaged. The simulation results show that the algorithm can accurately grasp handoff opportunities, reduce handoff delay and eliminate packet loss, and is simple and reliable as well.