Coordinating a transition of a roaming client between wireless access points using another client in physical proximity

• US 8,102,813 B2
• Filed: 04/28/2006
• Issued: 01/24/2012
• Est. Priority Date: 04/28/2006
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Abhishek, Abhishek, Chen, Yue, Shen, Hui, Ruan, Jiandong, Mandhana, Taroon, Lu, Yi
• Primary Examiner(s): Pérez-Gutiérrez, Rafael
• Assistant Examiner(s): AREVALO, JOSEPH
• Application Number:
  US11/414,571
• Publication Number:
  US 20070253369A1
• Time in Patent Office: 2,097 Days
• Field of Search: 370/328, 370/352, 370/465, 370/363, 370/349, 370/313, 370/227, 370/338, 370/347, 370/329, 370/278, 370/389, 370/331, 370/310, 455/456.1, 455/457, 455/436, 455/404.2, 455/450, 455/434, 455/432, 455/552.1, 713/138
• US Class Current: 370/331
• CPC Class Codes: H04W 36/0055 Transmission or use of information for re-establishing the radio link
• CPC Class Codes: H04W 88/04 adapted for relaying to or from another terminal or user

Abstract

Systems and methods for handling a transition of a roaming mobile user device (i.e., a roaming client) from one access point (AP) to a target AP, referred to herein as soft inter-AP handoff. This technique involves a second mobile user device that is already connected with the target AP, called a roaming coordinator, assisting in handoff coordination between the APs. This coordination includes assisting the roaming client in establishing a client-to-client connection to relay data traffic during the handoff, while the roaming client establishes a connection with the target AP using traditional techniques. Soft inter-AP handoff allows a faster hand-off between APs than traditional techniques, and may reduce jitter in communications with the roaming device during the transition.

Claims

1. A method of a roaming mobile user device transitioning from a first wireless access point to a second wireless access point, comprising:

(a) when the roaming mobile user device is within range of the second wireless access point, the roaming mobile user device initiating a transition from the first wireless access point to the second wireless access point, the transition including a handoff of the roaming mobile user device from the first wireless access point to the second wireless access point, the handoff including terminating a connection between the roaming mobile user device and the first wireless access point, and establishing a new connection between the roaming mobile user device and the second wireless access point;

(b) during the transition, the roaming mobile user device transmitting and receiving communications with the second wireless access point through a second mobile user device in physical proximity to the roaming mobile user device, the second mobile user device having a connection to the second wireless access point, the transmitting and receiving of communications with the second wireless access point through the second mobile user device being performed in parallel with and during the handoff of the roaming mobile user device from the first wireless access point to the second wireless access point, and being performed after the connection to the first wireless access point has been terminated and before the new connection to the second wireless access point has been established, wherein the act (b) comprises encrypting and/or decrypting data using one or more data encryption keys negotiated prior to the transition and wherein the act (b) comprises transmitting and receiving data with the second wireless access point through the second mobile user device during the transition; and

(c) after completion of the transition from the first wireless access point to the second wireless access point, the roaming mobile user device terminating communications with the second wireless access point through the second mobile user device.

2. The method of claim 1, further comprising an act of:

(d) communicating with the second mobile user device prior to the transition.

3. The method of claim 2, wherein the act (d) comprises discovering one or more mobile user devices in the physical proximity of the roaming mobile user device, the one or more mobile user devices including the second mobile user device.

4. The method of claim 3, wherein the act (d) comprises exchanging one or more data encryption keys with at least one of the one or more mobile user devices, the at least one mobile user device including the second mobile user device.

5. The method of claim 1, further comprising:

(d) prior to the act (b), selecting the second mobile user device from a list of candidate mobile user devices.

6. The method of claim 1, further comprising:

(d) establishing a client-to-client connection with the second mobile user device over which to exchange communications with the second mobile user device during the transition; and

(e) after the transition is complete, terminating the connection.

7. A system for transitioning a roaming mobile user device from a first wireless access point to a second wireless access point, the system comprising:

a transition module to initiate a transition from the first wireless access point to the second wireless access point when the roaming mobile user device is within range of the second wireless access point, the transition including a handoff of the roaming mobile user device from the first wireless access point to the second wireless access point, the handoff including terminating a connection between the roaming mobile user device and the first wireless access point, and establishing a new connection between the roaming mobile user device and the second wireless access point, to transmit and receive, during the transition, communications with the second wireless access point through a second mobile user device in physical proximity to the roaming mobile user device, the second mobile user device having a connection to the second wireless access point, the transmitting and receiving of communications with the second wireless access point through the second mobile user device being performed in parallel with and during the handoff of the roaming mobile user device from the first wireless access point to the second wireless access point, and being performed after the connection to the first wireless access point has been terminated and before the new connection to the second wireless access point has been established and, after completion of the transition from the first wireless access point to the second wireless access point, to terminate communications with the second wireless access point through the second mobile user device, wherein the transition module is operative to encrypt and/or decrypt data using one or more data encryption keys negotiated prior to the transition and wherein the act (b) comprises transmitting and receiving data with the second wireless access point through the second mobile user device during the transition.

8. The system of claim 7, further comprising a discovery module operative to discover one or more mobile user devices in the physical proximity of the roaming mobile user device, the one or more mobile user devices including the second mobile user device.

9. The system of claim 8, wherein the discovery module is operative to exchange one or more data encryption keys with at least one of the one or more mobile user devices, the at least one mobile user device including the second mobile user device.

10. The system of claim 7, wherein the transition module is operative to select the second mobile user device from a list of candidate mobile user devices.

11. The system of claim 7, wherein the transition module is operative to establish a client-to-client connection with the second mobile user device over which to exchange communications with the second mobile user device during the transition, and to terminate the connection after the transition is complete.

12. A computer program product comprising:

a non-transitory computer-readable storage medium encoded with computer-executable instructions that, as a result of being executed by a computer, control the computer to perform a method of a roaming mobile user device transitioning from a first wireless access point to a second wireless access point, the method comprising acts of;

(a) communicating with a second mobile user device in physical proximity to the roaming mobile user device prior to transitioning from the first wireless access point to the second wireless access point;

(b) when the roaming mobile user device is within range of the second wireless access point, the roaming mobile user device initiating a transition from the first wireless access point to the second wireless access point, the transition including a handoff of the roaming mobile user device from the first wireless access point to the second wireless access point, the handoff including terminating a connection between the roaming mobile user device and the first wireless access point, and establishing a new connection between the roaming mobile user device and the second wireless access point;

(c) during the transition, the roaming mobile user device transmitting and receiving communications with the second wireless access point through the second mobile user device, the second mobile user device having a connection to the second wireless access point, the transmitting and receiving of communications with the second wireless access point through the second mobile user device being performed in parallel with and during the handoff of the roaming mobile user device from the first wireless access point to the second wireless access point, and being performed after the connection to the first wireless access point has been terminated and before the new connection to the second wireless access point has been established, wherein the act (c) comprises encrypting and/or decrypting data using one or more data encryption keys negotiated prior to the transition; and

(d) after completion of the transition from the first wireless access point to the second wireless access point, the roaming mobile user device terminating communications with the second wireless access point through the second mobile user device.

13. The computer program product of claim 12, wherein the act (a) comprises discovering one or more mobile user devices in the physical proximity of the roaming mobile user device, the one or more mobile user devices including the second mobile user device.

14. The computer program product of claim 12, wherein the act (a) comprises exchanging one or more data encryption keys with at least one of the one or more mobile user devices, the at least one mobile user device including the second mobile user device.

15. The computer program product of claim 12, wherein the method further comprises acts of:

(e) establishing a client-to-client connection with the second mobile user device over which to exchange communications with the second mobile user device during the transition; and

(f) after the transition is complete, terminating the connection.