METHODS AND APPARATUS FOR ACCESS POINT SCANNING IN VOIP SYSTEMS

• US 20100110949A1
• Filed: 10/31/2008
• Published: 05/06/2010
• Est. Priority Date: 10/31/2008
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Lundsgaard, Soren
• Granted Patent: US 8,270,304 B2
• Time in Patent Office: Days
• US Class Current: 370/311
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 52/0219 where the power saving management affects multiple terminals
• CPC Class Codes: H04W 8/005 Discovery of network devices, e.g. terminals
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A system is configured to scan for APs on DFS channels while maintaining VOIP traffic employing both passive and active scans. During passive scan mode, the APs are configured to listen only. During active scan mode, the STA sends a probe request, and the AP(s) send(s) probe responses. During power save mode, the STA tells the associated AP that it will be turning “off” to save power. The STA is then required to listen to beacons for traffic notifications. The power save mode enables the STA to move to other channels during periods in which the AP “thinks” it is asleep. An 802.11 “in-use” list is used to facilitate scanning.

Claims

1. A method for data and voice communication in a wireless local area network (WLAN) of the type including one or more access points and one or more mobile devices, the method comprising:

determining a main channel list associated with the plurality of access points and plurality of mobile devices; and

determining an in-use channel list that is a subset of the main channel list;

wherein, during a passive scan mode, the access points listen for beacons or probe responses;

wherein, during an active scan mode, the mobile devices send probe requests, and the access points send back probe responses; and

wherein, during a power save mode, the mobile devices instruct an associated one of the access points that it is entering a power save mode, during which the mobile device listens for beacons and may move to other channels;

wherein the APs and mobile devices may associate and provide data and voice communication over channels within the in-use channel list.

2. The method of claim 1, wherein the in-use channel list is an 802.11h in-use channel list.

3. The method of claim 1, wherein the channel list includes a plurality of dynamic frequency selection (DFS) channels.

4. The method of claim 3, wherein the DFS channels are subject to use restrictions under a predetermined set of conditions.

5. The method of claim 4, wherein the predetermined set of conditions comprises the existence of radar on one or more of the DFS channels.

6. A wireless local area network (WLAN) system comprising:

a plurality of access points coupled to the network and configured to listen for beacons or probe responses when in a passive scanning mode, and to send back probe responses in an active scanning mode;

a plurality of mobile devices coupled to the network and configured to send probe requests during the active scanning mode, wherein each mobile device is configured to instruct an associated one of the access points that it is entering a power save mode, during which the mobile device listens for beacons and may move to other channels;

a main channel list associated with the plurality of access points and the plurality of mobile devices, and

an in-use channel list that is a subset of the main channel list;

wherein, during a power save mode, the access points and mobile devices may associate and provide data and voice communication over channels within the in-use channel list.

7. The system of claim 6, wherein the in-use channel list is an 802.11h in-use channel list.

8. The system of claim 6, wherein the channel list includes a plurality of dynamic frequency selection (DFS) channels.

9. The system of claim 6, wherein the DFS channels are subject to use restrictions under a predetermined set of conditions.

10. The system of claim 9, wherein the predetermined set of conditions comprises the existence of radar on one or more of the DFS channels.