Pre-emptive roaming mechanism allowing for enhanced QoS in wireless network environments
First Claim
Patent Images
1. A wireless client, comprising:
- a wireless network interface for communicating with one or more access elements;
a processor;
a memory;
a wireless network interface driver application, stored in the memory, comprising instructions operable to cause the processor and the wireless network interface to;
receive, from a first access element, a roaming list identifying at least one candidate access element of one or more candidate access elements other than the first access element, the roaming list is appended to an association response transmitted from the first access element to the wireless client in response to an association request transmitted from the wireless client;
monitor, during an associated state with the first access element, one or more radio frequency signals transmitted by the first access element relative to a signal attribute; and
when the wireless client determines that the monitored signal attribute crosses below a threshold value, then alternate betweena pre-emptive scanning mode to actively scan for one or more candidate access elements identified in the roaming list with which to associate by sending directed probes to the one or more candidate access elements identified in the roaming list, anda traffic mode to communicate with the first access element to transmit or receive wireless frames; and
when a second access element of the one or more candidate access elements having a value of the monitored signal attribute greater than the value of the monitored signal attribute of the first access element by at least a predetermined margin is identified during a scan for candidate access elements while in the pre-emptive scanning mode;
select the second access element; and
associate with the selected second access element;
the instructions are operable to cause the processor and the wireless network interface to alternate between the pre-emptive scanning mode and the traffic mode at least a plurality of times before selecting the second access element identified during the pre-emptive scanning mode.
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Abstract
A preemptive roaming mechanism in wireless network environments. In one implementation, the present invention provides a wireless client that implements a preemptive roaming mode that, when an attribute of the signal (e.g., Signal to Noise Ratio (SNR), etc.) between the access point with which the client is currently associated crosses a threshold, scans for other access points with which to associate. In one implementation, the client switches between the scanning mode and a traffic mode to allow data to be transferred between the client and the current access point. The pre-emptive roaming functionality can be configured to support desired data rates or other QoS levels.
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Citations
34 Claims
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1. A wireless client, comprising:
- a wireless network interface for communicating with one or more access elements;
a processor; a memory; a wireless network interface driver application, stored in the memory, comprising instructions operable to cause the processor and the wireless network interface to; receive, from a first access element, a roaming list identifying at least one candidate access element of one or more candidate access elements other than the first access element, the roaming list is appended to an association response transmitted from the first access element to the wireless client in response to an association request transmitted from the wireless client; monitor, during an associated state with the first access element, one or more radio frequency signals transmitted by the first access element relative to a signal attribute; and when the wireless client determines that the monitored signal attribute crosses below a threshold value, then alternate between a pre-emptive scanning mode to actively scan for one or more candidate access elements identified in the roaming list with which to associate by sending directed probes to the one or more candidate access elements identified in the roaming list, and a traffic mode to communicate with the first access element to transmit or receive wireless frames; and when a second access element of the one or more candidate access elements having a value of the monitored signal attribute greater than the value of the monitored signal attribute of the first access element by at least a predetermined margin is identified during a scan for candidate access elements while in the pre-emptive scanning mode; select the second access element; and associate with the selected second access element; the instructions are operable to cause the processor and the wireless network interface to alternate between the pre-emptive scanning mode and the traffic mode at least a plurality of times before selecting the second access element identified during the pre-emptive scanning mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 29, 30, 31, 32, 33)
- a wireless network interface for communicating with one or more access elements;
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9. A method comprising:
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receiving from a first access element, by a wireless client device, a roaming list identifying at least one candidate access element of one or more candidate access elements other than the first access element, the roaming list is appended to an association response transmitted from the first access element to the wireless client in response to an association request transmitted from the wireless client device; monitoring, by the wireless client device, during an associated state with the first access element, one or more radio frequency signals transmitted by the first access element relative to a signal attribute; and when it is determined by the wireless client that the monitored signal attribute crosses below a threshold value, then alternate between a pre-emptive scanning mode to actively scan for one or more candidate access elements identified in the roaming list with which to associate by sending directed probes to the one or more candidate access elements identified in the roaming list, and a traffic mode to communicate with the first access element to transmit or receive wireless frames; and when a second access element of the one or more candidate access elements having a value of the monitored signal attribute greater than the value of the monitored signal attribute of the first access element by at least a predetermined margin is identified during a scan for candidate access elements while in the pre-emptive scanning mode; selecting, by the wireless client device, the second access element; and associating, by the wireless client device, with the selected second access element; the wireless client device is configured to alternate between the pre-emptive scanning mode and the traffic mode at least a plurality of times before selecting the second access element identified during the pre-emptive scanning mode. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. An apparatus, comprising:
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means for wirelessly communicating with one or more access elements; means for receiving from a first access element a roaming list identifying at least one candidate access element of one or more candidate access elements other than the first access element, the roaming list is appended to an association response transmitted from the first access element to the wireless client in response to an association request transmitted from the apparatus; means for monitoring, during an associated state with the first access element, one or more radio frequency signals transmitted by the first access element relative to a signal attribute; and means for alternating, when the signal attribute crosses below a threshold value, between a pre-emptive scanning mode to actively scan for one or more candidate access elements identified in the roaming list with which to associate by sending directed probes to the one or more candidate access elements identified in the roaming list, and a traffic mode to communicate with the first access element to transmit or receive wireless frames; and when a second access element of the one or more candidate access elements having a value of the monitored signal attribute greater than the value of the monitored signal attribute of the first access element by at least a predetermined margin is identified during a scan for candidate access elements while in the pre-emptive scanning mode; means for selecting the second access element; and means for associating with the selected second access element; the apparatus is configured to alternate between the pre-emptive scanning mode and the traffic mode at least a plurality of times before selecting the second access element identified during the pre-emptive scanning mode.
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17. A wireless network access device, comprising:
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a wireless network interface for communicating with one or more wireless clients; a processor; a memory; and a wireless network access application, stored in the memory, comprising instructions operable to cause the processor and the wireless network interface to; receive an association request from a wireless client, the association request identifies one or more other wireless network access devices discovered by the wireless client; generate a roaming list for the wireless client in response to the association request, the roaming list identifies at least one candidate wireless network access device among the one or more other wireless network access devices identified in the association request; append the roaming list to an association response; and transmit the association response with the roaming list to the wireless client the wireless client is configured to; receive the roaming list from the wireless network access device; monitor, during an associated state with the wireless network access device, one or more radio frequency signals transmitted by the wireless network access device relative to a signal attribute; and when the wireless client determines that the monitored signal attribute crosses below a threshold value, then alternate between; a pre-emptive scanning mode to actively scan for one or more candidate wireless network access devices identified in the roaming list with which to associate by sending directed probes to the one or more candidate wireless network access devices identified in the roaming list, and a traffic mode to communicate with the wireless network access device from which the wireless client received the roaming list to transmit or receive wireless frames; and when a second wireless network access device of the one or more candidate wireless network access devices having a value of the monitored signal attribute greater than the value of the monitored signal attribute of the wireless network access device from which the wireless client received the roaming list by at least a predetermined margin is identified during a scan for candidate wireless network access devices while in the pre-emptive scanning mode; select the second wireless network access device; and associate with the selected second wireless network access device; the wireless client is configured to alternate between the pre-emptive scanning mode and the traffic mode at least a plurality of times before selecting the second wireless network access device identified during the pre-emptive scanning mode. - View Dependent Claims (18, 19, 20, 21, 28)
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22. A method, comprising:
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receiving, by a wireless network access device, an association request from a wireless client, the association request identifies one or more other wireless network access devices discovered by the wireless client; generating, by the wireless network access device, a roaming list for the wireless client in response to the association request, the roaming list identifies at least one candidate wireless network access device among the one or more other wireless network access devices identified in the association request; appending, by the wireless network access device, the roaming list to an association response; and transmitting the association response with the roaming list to the wireless client; the wireless client is configured to; receive the roaming list from the wireless network access device; monitor, during an associated state with the wireless network access device, one or more radio frequency signals transmitted by the wireless network access device relative to a signal attribute; and when the wireless client determines that the monitored signal attribute crosses below a threshold value, then alternate between; a pre-emptive scanning mode to actively scan for one or more candidate wireless network access devices identified in the roaming list with which to associate by sending directed probes to the one or more candidate wireless network access devices identified in the roaming list, and a traffic mode to communicate with the wireless network access device from which the wireless client received the roaming list to transmit or receive wireless frames; and when a second wireless network access device of the one or more candidate wireless network access devices having a value of the monitored signal attribute greater than the value of the monitored signal attribute of the wireless network access device from which the wireless client received the roaming list by at least a predetermined margin is identified during a scan for candidate wireless network access devices while in the pre-emptive scanning mode; select the second wireless network access device; and associate with the selected second wireless network access device; the wireless client is configured to alternate between the pre-emptive scanning mode and the traffic mode at least a plurality of times before selecting the second wireless network access device identified during the pre-emptive scanning mode. - View Dependent Claims (23, 24)
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25. A wireless network access device, comprising:
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means for wirelessly communicating with a wireless client; means for receiving an association request from the wireless client, the association request identifies one or more other wireless network access devices discovered by the wireless client; means for generating a roaming list for the wireless client in response to the association request, the roaming list identifies at least one candidate wireless network access device among the one or more other wireless network access devices identified in the association request; means for appending the roaming list to an association response; and means for transmitting the association response with the roaming list to the wireless client; the wireless client is configured to; receive the roaming list from the wireless network access device; monitor, during an associated state with the wireless network access device, one or more radio frequency signals transmitted by the wireless network access device relative to a signal attribute; and when the wireless client determines that the monitored signal attribute crosses below a threshold value, then alternate between; a pre-emptive scanning mode to actively scan for one or more candidate wireless network access devices identified in the roaming list with which to associate by sending directed probes to the one or more candidate wireless network access devices identified in the roaming list, and a traffic mode to communicate with the wireless network access device from which the wireless client received the roaming list to transmit or receive wireless frames; and when a second wireless network access device of the one or more candidate wireless network access devices having a value of the monitored signal attribute greater than the value of the monitored signal attribute of the wireless network access device from which the wireless client received the roaming list by at least a predetermined margin is identified during a scan for candidate wireless network access devices while in the pre-emptive scanning mode; select the second wireless network access device; and associate with the selected second wireless network access device; the wireless client is configured to alternate between the pre-emptive scanning mode and the traffic mode at least a plurality of times before selecting the second wireless network access device identified during the pre-emptive scanning mode.
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26. A wireless network system, comprising:
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a plurality of access elements each operative to wirelessly communicate with at least one wireless client and to communicate with a respective central control element, the access elements are each operative to; establish and maintain, in connection with a respective central control element, one or more wireless connections with one or more respective wireless clients; transmit wireless frames received from the one or more respective wireless clients to the respective central control element; and at least one central control element for supervising the plurality of access elements, wherein the central control element is operative to; manage one or more wireless connections between one or more of the plurality of access elements and one or more respective wireless clients, and receive, through a first one of the plurality of access elements, an association request from a first one of the one or more respective wireless clients associated with the first one of the plurality of access elements, the association request identifies one or more other access elements of the plurality of access elements discovered by the first one of the wireless clients; determine a roaming list for the first one of the wireless clients in response to the association request, the roaming list identifies at least one candidate access element among the one or more other access elements identified in the association request; append the roaming list to an association response; and transmit, through the first one of the access elements, the association response with the roaming list to the first one of the wireless clients; the first one of the wireless clients is configured to; receive the roaming list from the first one of the access elements; monitor, during an associated state with the first one of the access elements, one or more radio frequency signals transmitted by the first one of the access elements relative to a signal attribute; and when the first one of the wireless clients determines that the monitored signal attribute crosses below a threshold value, then alternate between; a pre-emptive scanning mode to actively scan for one or more candidate access elements identified in the roaming list with which to associate by sending directed probes to the one or more candidate access elements identified in the roaming list, and a traffic mode to communicate with the first one of the access elements to transmit or receive wireless frames; and when a second one of the access elements of the one or more candidate access elements having a value of the monitored signal attribute greater than the value of the monitored signal attribute of the first one of the access elements by at least a predetermined margin is identified during a scan for candidate access elements while in the pre-emptive scanning mode; select the second one of the access elements; and associate with the selected second one of the access elements; the first one of the wireless clients is configured to alternate between the pre-emptive scanning mode and the traffic mode at least a plurality of times before selecting the second one of the access elements identified during the pre-emptive scanning mode. - View Dependent Claims (27)
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34. A wireless network system, comprising:
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one or more access points, each of the access points is operative to service one or more wireless clients for their wireless communications; and one or more control elements, each of the control elements is operative to manage one or more of the access points for their connections with the wireless clients, during associations with the wireless clients, between each one of the access points and a particular one of the control elements that manages the access point; the access point is operative to; receive an association request from a wireless client, the association request comprises one or more of the access points discovered by the wireless client; and forward the association request to the control element; and the control element is operative to; receive the association request from the access point; exchange and synchronize information regarding the wireless client with the other ones of the control elements; store the information regarding the wireless client; construct a roaming list based at least in part on the access points in the association request and the information regarding the wireless client; and transmit an association response to the wireless client, the association response comprises the roaming list the wireless client is configured to; receive the roaming list from the access point; monitor, during an associated state with the access point, one or more radio frequency signals transmitted by the access point relative to a signal attribute; and when the wireless client determines that the monitored signal attribute crosses below a threshold value, then alternate between;
a pre-emptive scanning mode to actively scan for one or more candidate access points identified in the roaming list with which to associate by sending directed probes to the one or more candidate access points identified in the roaming list, and
a traffic mode to communicate with the access point from which the wireless client received the roaming list to transmit or receive wireless frames; andwhen a second access point of the one or more candidate access points having a value of the monitored signal attribute greater than the value of the monitored signal attribute of the access point from which the wireless client received the roaming list by at least a predetermined margin is identified during a scan for candidate access points while in the pre-emptive scanning mode;
select the second access point; and
associate with the selected second access point;the wireless client is configured to alternate between the pre-emptive scanning mode and the traffic mode at least a plurality of times before selecting the second access point identified during the pre-emptive scanning mode.
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Specification