Roaming method and apparatus for VOIP handset

A method for operating a voice communication device in a wireless communication network, the method comprising:

• while the voice communication device is associated with a current access point (AP):
• transmitting, with the voice communication device, probe requests to scan for candidate APs during a plurality of scan intervals;
• identifying, with the voice communication device, a strength of communication with the current AP;
• setting, with the voice communication device, durations for the plurality of scan intervals based on the identified strength of communication;
• receiving, with the voice communication device, probe responses to the probe requests, the probe responses comprising information about the candidate APs;
• and
• storing, with the voice communication device, the information about the candidate APs in a scan table;
• and
• when a signal parameter for radio communication between the voice communication device and the current AP degrades to the degraded level, roaming, with the voice communication device, to one of the candidate APs based on the information stored in the scan table.

A mobile handset for voice communication with a wireless local area network (WLAN), the mobile handset comprising:

• a radio communication circuit to communicate a voice call with one or more remote access points (APs);
• a memory;
• and
• a controller coupled to the radio communication circuit to control transmission and reception of information with the one or more APs, the controller operable to associate with a current access point (AP);
• retrieve from the memory a last-measured received signal strength value during a call between the mobile handset and the current AP on a first radio channel;
• using the last-measured received signal strength value, determine a background scan interval;
• switch a radio channel on which the radio communication circuit communicates from a first channel to a second channel;
• during the background scan interval and while associated with the current AP:
• communicate a probe request to identify other APs available for voice communication with the mobile handset, and
• receive any probe responses to the probe requests;
• retrieve AP identification information from received probe requests;
• update a scan table stored in the memory with the retrieved AP identification information;
• and
• when the background scan interval expires, enter a power save state.