Many wireless devices are capable of communicating with wireless networks on more than one frequency band. Wireless networks in different countries or regions often have different frequency bands available for wireless communication services. In particular, North American systems typically have 850 MHz band and/or 1900 MHz band and European systems typically have 900 MHz band and/or 1800 MHz band. Devices that are capable of communicating on more than one frequency band require a mechanism and method for scanning supported frequency bands and selecting a suitable network.
One option is to perform an exhaustive network scan to search for suitable networks on all frequency bands supported by the device. This process is typically performed by many wireless devices upon power cycle and/or radio cycle; however scanning all frequency bands exhaustively is expensive in terms of battery power. A device sometime loses coverage on one frequency band and needs to re-establish a connection with a wireless network as quickly and efficiently as possible. In these circumstances, an exhaustive network scan consumes time and battery power.
Accordingly, some devices base their search for active frequency bands upon the country in which the device was most recently connected. For example, if the device had established communications on a 900 MHz band, it may choose to assume it is located in a country supporting the European network frequency plan. Therefore, it may assume that the frequency bands that will be available are the usual 900 MHz and/or 1800 MHz bands. Thus, the device may limit its search for suitable networks to these two likely co-existing frequency bands, if these two bands are supported by the device.
There are some circumstances in which this technique fails to locate the available networks unless a power cycle or radio cycle is performed. In some countries or regions suitable networks may be available on frequency bands associated with both network frequency plans. For example, in the border regions of some countries a device may be capable of connecting to wireless providers in either of two countries, each of which may be on a different network frequency plan. Therefore, the device may have available to it suitable networks providing, for example, 850 MHz, 900 MHz, and 1800 MHz bands. It would be advantageous to have a method and system for efficiently locating suitable networks on available supported frequency bands in such a situation.