To maintain high quality of service （QoS）of global system for mobile communications for railways（GSM-R）under the situation of high bit error rate （BER）during the connection of network, a probability of satisfied communication （PoSC) model was proposed based on the data mining of GSM-R drive test data. Three key factors were considered: received signal strength, cochannel interference, and velocity of train. Then the handoff decision algorithm based on PoSC model was designed, in order to reduce the number of handoffs and maintain high QoS.Numerical results demonstrate the feasibility of the proposed algorithm. Besides the satisfied communication, the number of handoffs can be as small as 1, the handoff delay is low, and the handoff location is near the center of the two base stations. Comparison with the traditional strength-based handoff algorithm shows that the proposed system performs less handoffs at the same handoff distance.
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