Patent ID: 7991425

Claim:
A mobile terminal device for roaming from a current access point (AP) to an object access point according to communication environment parameters of a plurality of access points, comprising: a detecting module configured for detecting current communication environment parameters of each of the plurality of access points, and a roaming frequency and a packet retransmission rate of the mobile terminal device in a predetermined detection period; a roaming adjusting module configured for calculating a value of a radio quality index (RQI) according to the communication environment parameters of each of the plurality of access points, and the roaming frequency and the packet retransmission rate of the mobile terminal device, and adjusting a roaming threshold of the current access point according to the value of the RQI; a site detecting module configured for receiving the RQI from the roaming adjusting module, and calculating a value of a user movement index (UMI) according to the communication environment parameters of the access points, and the beacon loss rate and the packet loss rate of the mobile terminal device, and adjusting a frequency of the mobile terminal device for scanning object access points according to the value of the UMI and the value of the RQI; a roaming determining module configured for receiving the roaming threshold from the roaming adjusting module, and determining the object access point that has satisfied a roaming threshold; and a roaming executing module configured for receiving a roaming executing command from the roaming determining module, and ending the communication between the mobile terminal device and the current access point, and establishing a communication between the mobile terminal device and the object access point a processor for executing operations for the detecting module, the roaming adjusting module, the site detecting module, the roaming determining module, and the roaming executing module of the mobile terminal device.