GLOBAL VIRTUAL LOCAL AREA NETWORK FOR VOICE COMMUNICATION SESSIONS IN A WIRELESS LOCAL AREA NETWORK

• US 20080151868A1
• Filed: 12/22/2006
• Published: 06/26/2008
• Est. Priority Date: 12/22/2006
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: Kezys, Vytautas Robertas
• Granted Patent: US 8,194,605 B2
• Time in Patent Office: Days
• US Class Current: 370/352
• CPC Class Codes: H04L 12/4641 Virtual LANs, VLANs, e.g. virtual private networks [VPN] LAN interconnection over a bridge based backbone H04L12/462; encapsulation techniques H04L12/4633; routing of packets H04L45/00; packet switches H04L49/00; virtual private networks for security H04L63/0272
• CPC Class Codes: H04L 65/1083 In-session procedures
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04W 36/0011 for data sessions of end-to-end connection
• CPC Class Codes: H04W 36/0019 adapted for mobile IP [MIP]
• CPC Class Codes: H04W 8/087 for preserving data network PoA address despite hand-offs
• CPC Class Codes: H04W 8/26 Network addressing or numbering for mobility support
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A computer network which includes a wireless local area network; (WLAN) has at least first and second subnet segments and a router coupled between the first and the second subnet segments. The first subnet segment has a first IP subnet address range and the second subnet segment has a second IP subnet address range different, from the first IP subnet address range. At least a first wireless access point of the WLAN in the first subnet segment has both a local extended service set identifier (ESSID) and a global ESSID for mobile communication devices to associate with it. Similarly, at least a second wireless access point of the WLAN in the second subnet segment has both a local ESSID and the global ESSID for mobile communication devices to associate with it. The global ESSID is used for accessing a global virtual local area network (VLAN) which spans the entire network including the first and the second subnet segments. Initially, a mobile communication device associates with the first wireless access point using the local ESSID. Just prior to the establishment of a Voice over IP (VoIP) session, however, the mobile device reassociates with the first wireless access point using the global ESSID of the global VLAN. Thus, the VoIP session is established and maintained for the mobile device in the global VLAN. If a handoff to the second wireless access point in the second subnet segment is made during the VoIP session, the mobile device associates with the second wireless access point using the global ESSID of the global VLAN. After termination of the VoIP session, the mobile device associates with a wireless access point of the WLAN using the local ESSID Advantageously, no IP address reassignment for inter-subnet handoffs are needed during VoIP sessions, which improves the timeliness and reliability of such handoffs.

Claims

1. A method for use in a computer network which includes a wireless local area network (WLAN) for facilitating Voice over IP (VoIP) communication sessions for mobile communication devices, the computer network having at least first and second subnet segments and a router coupled between the first and the second subnet segments, the first subnet segment having a first IP subnet address range and the second subnet segment having a second IP subnet address range different from the first IP subnet address range, at least a first wireless access point in the first subnet segment having a local extended service set identifier (ESSID) and a global ESSID for mobile communication devices to associate with it, and at least a second wireless access point in the second subnet segment having a local ESSID and the global ESSID for mobile communication devices to associate with it, the global ESSID being used for accessing a global virtual local area network (VLAN) of the computer network which spans the first and the second subnet, segments, the method comprising the acts of:

causing an association to be made between a mobile communication device and the first, wireless access point in the first subnet segment with use of the local ESSID of the first wireless access point;

for a VoIP communication session with the mobile communication device in the WLAN;

prior to the VoIP communication session being established;

causing an association to be made between the mobile communication device and the first wireless access point of the first subnet segment with use of the global ESSID of the global VLAN;

maintaining the VoIP communication session for the mobile communication device in the global VLAN; and

if a handoff to the second wireless access point of the second subnet segment is made during the VoIP communication session;

causing an association to be made between the mobile communication device and the second wireless access point of the second subnet segment with use of the global ESSID of the global VLAN.

2. The method of claim 1, further comprising:

after termination of the VoIP communication session;

causing an association to be made between the mobile communication device and one of the first and the second wireless access points with use of the local ESSID.

3. The method of claim 1, further comprising:

prior to the VoIP communication session being established;

receiving an assignment of an IP address of the first subnet segment; and

after causing an association to be made with use of the global ESSID of the global VLAN;

receiving an assignment of an IP address in the global VLAN.

4. The method of claim 1, further comprising:

if the handoff to the second wireless access point of the second subnet segment is made during the VoIP communication session;

refraining from requesting an assignment of an IP address of the second subnet segment during the VoIP communication session for the mobile communication device.

5. The method of claim 1, further comprising:

after termination of the VoIP communication session;

causing an association to be made between the mobile communication device and the second wireless access point of the second subnet segment with use of the local ESSID of the second wireless access point; and

receiving an assignment of an IP address of the second subnet segment.

6. The method of claim 1, further comprising:

prior to the VoIP communication session being established;

identifying whether the mobile communication device is likely to require the handoff during the VoIP communication session; and

in response to identifying that the mobile communication device is likely to require the handoff during the VoIP communication session;

using the global ESSID and the global VLAN for the VoIP communication session.

7. The method of claim 1, which is performed by the computer network.

8. The method of claim 1, which is performed by the mobile communication device.

9. The method of claim 1, which is embodied in a computer program product which comprises a computer readable medium and computer instructions stored in the computer readable medium which are executable by one or more processors for performing the method.

10. A computer network having a wireless local area network (WLAN) adapted to provide wireless communications for a plurality of mobile communication devices, the computer network comprising:

at least first and second subnet segments;

the first subnet segment having a first IP subnet address range;

the second subnet segment having a second IP subnet address range different from the first IP subnet address range;

a router for coupling between the first and the second subnet segments;

a voice over IP (VoIP) server which is accessible in a global virtual local area network (VLAN) which spans the first and the second subnet segments;

at least a first wireless access point for coupling in the first subnet segment;

the at least first wireless access point having both a local extended service set identifier (ESSID) and a global ESSID of the global VLAN;

the at least first wireless access point being adapted to allow a mobile communication device to associate with it with use of the global ESSID of the global VLAN prior to a VoIP communication session involving the mobile communication device, and maintain such association with the mobile communication device using the global ESSID during the VoIP communication session;

at least a second wireless access point for coupling in the second subnet segment;

the at least second wireless access point having both a local ESSID and the global ESSID of the global VLAN; and

the at least second wireless access point being adapted to allow the mobile communication device to associate with it with use of the global ESSID of the global VLAN, and maintain such association with the mobile communication device using the global ESSID during the VoIP communication session.

11. The computer network of claim 10, further comprising;

the at least first, wireless access point being further adapted to associate with the mobile communication device with use of the local ESSID outside of any VoIP communication session; and

the at least second wireless access point being further adapted to associate with the mobile communication device with use of the local ESSID outside of any VoIP communication session.

12. The computer network of claim 10, further comprising:

at least one VLAN switch which is adapted to provide the global VLAN in the computer network.

13. The computer network of claim 10, further comprising:

the mobile communication device being adapted to cause an association to be made with one of the first and the second wireless access points using the local ESSID after termination of the VoIP communication session.

14. The computer network of claim 10, further comprising:

the mobile communication device being adapted to identify whether the mobile communication device is likely to require the handoff during the VoIP communication session, and use the global ESSID and the global VLAN for the VoIP communication session in response to identifying that the mobile communication device is likely to require the handoff during the VoIP communication session.

15. A mobile communication device which is adapted to operate in a computer network which includes a wireless local area network (WLAN), the computer network having at least first and second subnet segments and a router coupled between the first and the second subnet segments, the first subnet segment having a first IP subnet address range and the second subnet segment having a second IP subnet address range different from the first IP subnet address range, at least a first wireless access point in the first subnet segment having a local extended sendee set identifier (ESSID) and a global ESSID for mobile communication devices to associate with it, and at least a second wireless access point in the second subnet segment having a local ESSID and the global ESSID for mobile communication devices to associate with it, the global ESSID being used for accessing a global virtual local area network (VLAN) of the computer network which spans the first and the second subnet segments, the mobile communication device comprising:

one or more processors;

a wireless transceiver coupled to the one or more processors;

an antenna circuit coupled to the wireless transceiver;

the one or more processors being operative to;

cause an association to be made with the first wireless access point, with use of the wireless transceiver, using the local ESSID of the first wireless access point;

for a Voice over IP (VoIP) communication session in the WLAN;

prior to the VoIP communication session being established;

cause an association to be made with the first wireless access point, with use of the wireless transceiver, using the global ESSID of the global VLAN;

maintain the VoIP communication session in the global VLAN with use of the wireless transceiver; and

if a handoff to the second wireless access point of the second subnet segment is made during the VoIP communication session;

cause an association to be made with the second wireless access point, with use of the wireless transceiver, using the global ESSID of the global VLAN.

16. The mobile communication device of claim 15, wherein the one or more processors are further operative to:

after termination of the VoIP communication session;

cause an association to be made with one of the first and the second wireless access points, with use of the wireless transceiver, using the local ESSID.

17. The mobile communication device of claim 15, wherein the one or more processors are further operative to:

prior to the VoIP communication session being established;

receive an assignment of an IP address of the first subnet segment; and

after causing an association to be made with use of the global ESSID of the global VLAN;

requesting an assignment of an IP address of the global VLAN.

18. The mobile communication device of claim 15, wherein the one or more processors are further operative to:

if the handoff to the second wireless access point of the second subnet segment is made during the VoIP communication session;

refrain from requesting an assignment of an IP address of the second subnet segment during the VoIP communication session for the mobile communication device.

19. The mobile communication device of claim 15, wherein the one or more processors are further operative to:

after termination of the VoIP communication session;

cause an association to be made with the second wireless access point, with use of the wireless transceiver, using the local ESSID; and

receive an assignment of an IP address of the second subnet segment.

20. The mobile communication device of claim 15, wherein the one or more processors are further operative to:

prior to the VoIP communication session being established;

identify whether the mobile communication device is likely to require the handoff during the VoIP communication session; and

in response to identifying that the mobile communication device is likely to require the handoff during the VoIP communication session;

use the global ESSID and the global VLAN for the VoIP communication session.