SEAMLESS HANDOFF SCHEME FOR MULTI-RADIO WIRELESS MESH NETWORK

• US 20100260146A1
• Filed: 06/22/2010
• Published: 10/14/2010
• Est. Priority Date: 05/21/2007
• Status: Active Grant

• Current Assignee: Arrowspan Incorporated
• Original Assignee: Arrowspan Incorporated
• Inventors: Lu, Wenchen
• Granted Patent: US 8,451,752 B2
• Time in Patent Office: Days
• US Class Current: 370/331
• CPC Class Codes: H04L 12/4633 Interconnection of networks using encapsulation techniques, e.g. tunneling
• 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: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 40/36 due to handover
• CPC Class Codes: H04W 80/04 Network layer protocols, e.g. mobile IP [Internet Protocol]

Abstract

A mobile device communicates with a first mesh access point (AP) via a first radio frequency (RF) interface of the mobile device over a first wireless connection, where the first mesh AP is one of mesh APs of a first mesh cell of the wireless mesh network. It is detected that signal quality of the first wireless connection drops below a predetermined threshold as the mobile device moves from the first mesh cell towards a second mesh cell. In response to the detection, it is established via a second RF interface of the mobile device a second wireless connection with a second mesh AP of a second mesh cell of the wireless mesh network, while concurrently maintaining the first wireless connection with the first mesh AP via the first RF interface.

Claims

1. A method performed by a mobile device in a wireless mesh network, the method comprising:

communicating with a first mesh access point (AP) via a first radio frequency (RF) interface of the mobile device over a first wireless connection, the first mesh AP being one of a plurality of mesh APs of a first mesh cell of the wireless mesh network;

detecting that signal quality of the first wireless connection drops below a predetermined threshold as the mobile device moves from the first mesh cell towards a second mesh cell; and

in response to the detection, establishing via a second RF interface of the mobile device a second wireless connection with a second mesh AP of a second mesh cell of the wireless mesh network, while concurrently maintaining the first wireless connection with the first mesh AP via the first RF interface, such that the mobile device maintains communications with the wireless mesh network via at least one of the first and second wireless connections while roaming from the first mesh cell to the second mesh cell.

2. The method of claim 1, further comprising:

upon successfully establishing the second wireless network, switching network traffic between the mobile device and the wireless mesh network from the first wireless connection to the second wireless connection; and

terminating the first wireless connection once the network traffic has been switched over to the second wireless connection.

3. The method of claim 2, wherein the first RF interface is associated with a first media control access (MAC) address and the second RF interface is associated with a second MAC address that is different than the first MAC address.

4. The method of claim 3, wherein the first wireless connection is established based on the first MAC address and the second wireless connection is established based on the second MAC address.

5. The method of claim 4, wherein packets exchanged over the first wireless connection and the second wireless connection are originated from an end-user device coupled to a network port of the mobile device, and wherein the mobile device operates in a wireless distribution system (WDS) mode in which packets associated with the end-user device are passed through the mobile device using layer-2 routing while preserving a MAC address of the end-user device.

6. A mobile device, comprising:

a processor;

a first radio frequency (RF) interface card having a first network address to communicate with a mesh access point (AP) of a first mesh cell over a first wireless connection that has been established based on the first network address, the first mesh AP being one of a plurality of mesh APs in the first mesh cell of a wireless mesh network; and

a second RF interface card having a second network address that is different than the first network address,

wherein the processor is configured to detect that signal quality of the first wireless connection drops below a predetermined threshold as the mobile device moves from the first mesh cell towards to a second mesh cell of the wireless mesh network,

wherein in response to the detection, the processor is configured to establish a second wireless connection with a second mesh AP of the second mesh cell via the second RF interface card based on the second network address, while concurrently maintaining the first wireless connection with the first mesh AP via the first RF interface card, the second mesh AP being one of a plurality of mesh APs in the second mesh cell, such that the mobile device maintains communications with the wireless mesh network via at least one of the first and second wireless connections while roaming from the first mesh cell to the second mesh cell

7. The device of claim 6, wherein upon successfully establishing the second wireless network, network traffic between the mobile device and the wireless mesh network is switched from the first wireless connection to the second wireless connection, and wherein the first wireless connection is terminated once the network traffic has been switched over to the second wireless connection.

8. The device of claim 6, wherein the first network address is a first media control access (MAC) address and the second network address is a second MAC address that is different than the first MAC address.

9. The device of claim 8, wherein the first wireless connection is established based on the first MAC address and the second wireless connection is established based on the second MAC address.

10. The device of claim 9, further comprising a network port to be coupled to an end-user device, wherein packets exchanged over the first wireless connection and the second wireless connection are originated from the end-user device, and wherein the mobile device operates in a wireless distribution system (WDS) mode in which packets associated with the end-user device are passed through the mobile device using layer-2 routing while preserving a MAC address of the end-user device.

11. A method performed by a mesh access point (AP) of a wireless mesh network, comprising:

receive a first packet originated from a mobile device via a downlink interface of the mesh AP, the first packet being destined to a destination node of an external network, which is communicatively coupled to the wireless mesh network via a mobile mesh server (MMS), wherein the first packet is received via layer-2 routing from the mobile device based on a media access control (MAC) address of the mobile device and a MAC address of the mesh AP;

examining the first packet to determine whether the packet contains a predetermined virtual local area network (VLAN) ID;

generating within the mesh AP a second packet by encapsulating the first packet as a payload of the second packet if the first packet contains the predetermined VLAN ID, wherein the second packet includes an IP address of the mesh AP as a source IP address and an IP address of the MMS as a destination IP address; and

transmitting the second packet from the mesh AP to the MMS over a layer-3 tunnel that has been established based on the IP address of the mesh AP and the IP address of the MMS, in order to access the destination node of the external network, wherein when the MMS receives the second packet, the MMS is configured to strip off a layer-3 header from the second packet to reveal the first packet as part of the payload and to route the first packet to the external network.

12. The method of claim 11, wherein the mesh AP is configured as a mobile mesh manager (MMM) selected from a plurality of mesh APs that form a mesh cell, and wherein all traffic from the rest of the mesh APs are routed by the MMM to the MMS, or vice versa.

13. The method of claim 12, wherein the layer-3 tunnel between the MMM and the MMS is constantly maintained based on the IP addresses of the MMM and the MMS, such that the mobile device does not have to obtain a local IP address in order to access the MMS while roaming from one of the mesh APs to another one of the mesh AP within the mesh cell.

14. The method of claim 13, further comprising:

receiving, at the mesh AP, a third packet from the MMS over the layer-3 tunnel, wherein the third packet includes the IP address of the MMS as a source IP address, and wherein the third packet includes the IP address of the mesh AP as a destination IP address;

examining the third packet to determine whether the third packet includes a predetermined IP port number;

stripping off a layer-3 header from the third packet to reveal a payload of the third packet if the third packet contains the predetermined IP port number; and

transmitting a fourth packet containing the payload of the third packet to the mobile device using layer-2 routing based on the MAC address of the mesh AP and the MAC address of the mobile device.

15. The method of claim 14, wherein the MMS is communicatively coupled to a plurality of MMMs, each corresponding to a particular mesh cell, and wherein the MMS is configured to communicate with each of the MMMs over a different layer-3 tunnel, respectively.

16. A wireless mesh network system, comprising:

a mobile mesh server (MMS) having a first Ethernet interface and a second Ethernet interface, the first Ethernet interface to be coupled to the Internet;

a first mesh cell communicatively coupled to the second Ethernet interface of the MMS over a first layer-3 tunnel, the first mesh cell having a plurality of first mesh access points (APs) and a first mobile mesh manager (MMM) managing the first mesh APs, wherein in response to packets received from at least one of the first mesh APs, the first MMM is configured to transmit the packets via the first layer-3 tunnel to the MMS which routes the packets to the Internet;

a second mesh cell communicatively coupled to the second Ethernet interface of the MMS over a second layer-3 tunnel, the second mesh cell having a plurality of second APs and a second MMM managing the second mesh APs, wherein in response to packets received from at least one of the second mesh APs, the second MMM is configured to transmit the packets via the second layer-3 tunnel to the MMS which routes the packets to the Internet; and

a mobile device having a first radio frequency (RF) interface card having a first media access control (MAC) address and a second RF interface card having a second MAC address that is different than the first MAC address, the mobile device being communicatively coupled to the first mesh cell via at least one of the first mesh APs over a first wireless connection established via the first RF interface card based on the first MAC address,

wherein when the mobile device detects that signal quality of the first wireless connection drops below a predetermined threshold as the mobile device roams from the first mesh cell to the second mesh cell, the mobile device is configured to establish, via the second RF interface card, a second wireless connection with at least one of the second mesh APs based on the second MAC address, while currently maintaining the first wireless connection via the first RF interface card, such that the mobile device maintains communications with the MMS via at least one of the first and second wireless connections while roaming from the first mesh cell to the second mesh cell.

17. The system of claim 16, wherein the mobile device transmits a first packet to the first MMM using layer-2 routing via the first wireless connection, wherein the first MMM generates a second packet by encapsulating the first packet as a payload, using an IP address of the first MMM as a source IP address, and using an IP address of the MMS as a destination IP address, and wherein the first MMM transmits the second packet to the MMS via the first layer-3 tunnel.

18. The system of claim 17, wherein the mobile device transmits a third packet to the second MMM using layer-2 routing via the second wireless connection, wherein the second MMM generates a fourth packet by encapsulating the third packet as a payload, using an IP address of the second MMM as a source IP address, and using an IP address of the MMS as a destination IP address, and wherein the second MMM transmits the fourth packet to the MMS via the second layer-3 tunnel.

19. The system of claim 18, wherein in response to the second packet received from the first MMM, the MMS strips off a layer-3 header of the second packet to reveal the first packet and transmits the first packet to a destination node of the Internet, and wherein in response to a fifth packet received from destination node of the Internet responding to the first packet, the MMS generates a sixth packet as an IP packet by encapsulating the fifth packet and transmits the sixth packet to the first MMM via the first layer-3 tunnel, which recovers the fifth packet from the sixth packet and forwards the fifth packet to the mobile device using layer-2 routing.

20. The system of claim 19, wherein in response to the fourth packet received from the second MMM, the MMS strips off a layer-3 header of the fourth packet to reveal the third packet and transmits the third packet to the destination node of the Internet, and wherein in response to a seventh packet received from destination node of the Internet responding to the third packet, the MMS generates an eighth packet as an IP packet by encapsulating the seventh packet and transmits the eighth packet to the second MMM via the second layer-3 tunnel, which recovers the seventh packet from the eighth packet and forwards the seventh packet to the mobile device using layer-2 routing.