System and method to facilitate inter-frequency handoff of mobile terminals in a wireless communication network
View Patent ↗A system and method for facilitating inter-frequency handoff of a mobile node ( 102 ) in a wireless communication network ( 100 ). The system and method permit a mobile node ( 102 ), equipped with a single receiver, to perform handoffs seamlessly from one infrastructure node ( 106 - 1 ) to another infrastructure node ( 106 - 2 ) without having to scan through multiple frequencies and without having to interrupt the active communication session.
1. A method for changing association of a mobile node in a wireless communication network from a first access point to a second access point, the method comprising:
within the mobile node:
communicating at a first frequency with the first access point with which the mobile node is associated;
determining that it is to associate with the second access point;
initiating a handoff process in response to determining the association of the mobile node with the second access point by sending a request message including a quality of service requirement at a second frequency at which the second access point communicates for receipt by the second access point; and
changing its communication frequency back to the first frequency after sending the request message, thereby continuing communication with the first access point;
within the second access point:
receiving the request message including the quality of service requirement;
determining if it can meet the quality of service requirement; and
sending a reply message indicating if the second access point can meet the quality of service requirement to the mobile node via the first access point; and
within the mobile node:
receiving the reply message sent by the second access point in response to the request message, wherein the reply message includes a performance characteristic of the second access point, wherein the performance characteristic relates to a quality of service desired by the mobile node; and
when the performance characteristic meets a desired criteria, operating the mobile node to change its frequency to the second frequency and become associated with the second access point.
2. A method as claimed in claim 1 , wherein:
the first access point and the second access point communicate within a communication medium, and wherein the communication medium is selected from a group comprising a local area network and a wide area network.
3. A method as claimed in claim 1 , further comprising:
within the first access point:
forwarding the reply message to the mobile node at the first frequency.
4. A method as claimed in claim 1 , further comprising:
within the mobile node:
receiving the reply message from the second access point via the first access point, wherein the reply message includes one or more information; and
determining an identity of the second access point based on the information.
5. A method as claimed in claim 1 , wherein the request message is sent from the mobile node to the second access point via at least one other node.
6. A method as claimed in claim 1 , further comprising:
within operating the mobile node:
reviewing characteristics of other access points to select the second access point, by performing the following steps for each of the other access points:
changing its communication frequency to a frequency at which the other access point communicates, and sending another request message at the frequency at which the other access point communicates for receipt by the other access point; and
changing its communication frequency back to the first frequency after sending the another request message and before sending any additional message; and
selecting one of the other access points as the second access point based on one or more respective reply messages received from the respective other access points including respective information pertaining to the respective other access points.
7. A method for changing association of a mobile node in a wireless communication network from a first access point to a second access point, the method comprising:
within the mobile node:
communicating at a first frequency with the first access point with which the mobile node is associated;
periodically receiving one or more information associated with a list of neighboring access points from the first access point, wherein the one or more information includes one or more information selected from a group of information comprising an identity, an operating frequency and a quality of service level;
determining to handoff from the first access point to another access point;
selecting the second access point from the list of neighboring access points;
initiating a handoff process in response to selecting the second access point by sending a request message at a second frequency at which the second access point communicates for receipt by the second access point; and
changing its communication frequency back to the first frequency after sending the request message, thereby continuing communication with the first access point; and
within the second access point:
receiving the request message, wherein the request message includes a communication requirement; and
sending a reply message indicating if the second access point can meet the communication requirement to the mobile node via the first access point.
8. A method as claimed in claim 7 , wherein the one or more information associated with a list of neighboring access points comprises a quality of service level associated with each of the neighboring access points, and further wherein the selecting step comprises selecting the second access point based on the quality of service level.
9. A method for changing association of a mobile node in a wireless communication network from a first access point to a second access point, the method comprising:
within the mobile node:
communicating at a first frequency with the first access point with which the mobile node is associated;
determining to handoff from the first access point to another access point;
receiving contention period from the first access point, the contention period corresponding to a plurality of access points;
within the first access point:
determining quality of service provided and time slot availability based upon a MAC algorithm from the plurality of access points; and
selecting the second access point from the plurality of access points for the mobile node to transmit a handoff request message to the second access point; and
within the second access point:
receiving a handoff request message from the mobile node, wherein the handoff request message includes a communication requirement; and
sending a reply message indicating if the second access point can meet the communication requirement to the mobile node via the first access point.