Signal Quality Determination Methods And Apparatus Suitable For Use In WLAN-To-WWAN Transitioning

A mobile terminal adapted to operate in a wireless local area network (WLAN) and a wireless wide area network (WWAN), the mobile terminal comprising:

• a WLAN transceiver portion which is adapted for communicating via a WLAN;
• a WWAN transceiver portion which is adapted for communicating via a WWAN;
• one or more processors coupled to the WLAN and WWAN transceiver portions;
• the one or more processors being adapted to:
• perform communication operations using the WLAN transceiver portion for maintaining a voice or data call via a wireless access point (AP) of the WLAN;
• identify a received signal strength indicator (RSSI) value of a radio frequency (RF) signal of the wireless AP;
• identify a signal-to-noise ratio (SNR) value of the RF signal;
• when the RSSI value is less than a predetermined RSSI value, but the SNR value is greater than a predetermined SNR value, provide an indication to maintain the communication operations in the WLAN using the WLAN transceiver portion;
• and
• when the RSSI value is less than the predetermined RSSI value, and the SNR value is less than the predetermined SNR value, provide an indication to switch the communication operations from the WLAN to the WWAN.

A signal processing apparatus for use in a mobile terminal for switching communication operations for a voice or data call from a wireless local area network (WLAN) to a wireless wide area network (WWAN), comprising:

• a received signal strength indicator (RSSI) processing module, the RSSI processing module being adapted to identify an RSSI value of a radio frequency (RF) signal of a wireless access point (AP) of the WLAN and to provide, at its output, one of a plurality of discrete quality indicators based on the RSSI value;
• a signal-to-noise ratio (SNR) processing module, the SNR processing module being adapted to identify a SNR value of the RF signal of the wireless AP and to provide, at its output, one of the plurality of discrete quality indicators based on the SNR value;
• a range extension module having a first input coupled to the output of the RSSI processing module, a second input coupled to the output of the SNR processing module, and an output;
• the range extension module being adapted to provide, at its output, the discrete quality indicator from the RSSI processing module when the RSSI value is greater than a predetermined RSSI value;
• the range extension module being adapted to provide, at its output, the discrete quality indicator from the SNR processing module when the RSSI value is less than the predetermined RSSI value;
• a signal quality determination module having an input coupled to an output of the range extension module;
• the signal quality determination module being adapted to provide an indication to maintain the communication operations in the WLAN when the discrete quality indicator from the range extension module is a first discrete quality indicator;
• and
• the signal quality determination module being further adapted to provide an indication to switch the communication operations from the WLAN to the WWAN when the discrete quality indication from the range extension module is a second discrete quality indicator.