METHODS AND APPARATUS FOR USE IN INITIATING VERTICAL HANDOVER BASED ON COMPARATIVE EVALUATION OF WLAN AND WWAN SIGNAL QUALITIES

摘要

Techniques in a mobile device for use in initiating vertical handover ofa voice or a data call between a wireless local area network (WLAN) and awide area wireless network (WWAN) are described. The mobile deviceperforms communication operations for maintaining the voice or the data callvia the WLAN or the WWAN. During the voice or the data call, the mobiledevice identifies a WLAN signal quality value of signals with the WLAN, aswell as a WWAN signal quality value of signals with the WWAN. The mobiledevice then performs a comparative evaluation of the WLAN and the WWANsignal quality values, and initiates a vertical handover of the voice or thedata call between the WLAN and the WWAN based on the comparativeevaluation of the WLAN and WWAN signal quality values. The comparativeevaluation may involve calculating a signal indicator value which is based ona ratio of the WLAN and the WWAN signal quality values. Alternatively, thecomparative evaluation may involve comparing or finding the differencebetween the WLAN and the WWAN signal quality values.