Research on switching strategy of 3G/WiFi combined wireless data transmission

Because of the complexity of the track traffic station environments, single data transmission method was unable to satisfy the request of wireless communication. In this paper, a 3G/WiFi combined wireless network data transmission method based on the loosely-coupled mode for the characteristic of track traffic station is introduced. According to the examination of correspondence signal strength in the traffic station, it can realize free switching among the heterogeneous network,and then makes superiority supplementary between 3G and WiFi technical. In order to realize smooth switching, some optimal strategy and algorithms based on the vertical switch are considered in the paper, which take consideration of three fators of signal strength, the hysteresis and the beacon union. According to the simulation, the throughput is lower than 3 bit/s, the packet dropout falls to 0.6 packet/ms, and the transmission delay is about 0.6s, which has effectively avoid the delay, the loss of data packet as well as the ping-pang phenomenon during the switching, and finally help the workers solve kinds of problems in the track traffic station.