Roaming techniques for high speed client device
First Claim
Patent Images
1. A method comprising:
- at a wireless client device configured to connect with access points (APs) over wireless channels of the APs and route traffic between multiple devices served by the wireless client device and the connected APs;
receiving a neighbor list from an access point (AP) to which the wireless client device is currently connected over a wireless channel, wherein the neighbor list identifies neighbor APs and wireless operating channels thereof, including Dynamic Frequency Selection (DFS) channels that have been determined to be clear of interfering radar events, in a vicinity of the AP;
if a link quality of the wireless connection falls below a roam threshold, attempting to roam to a neighbor AP on the neighbor list, wherein the attempting to roam includes;
actively scanning the wireless operating channels in the neighbor list, including actively scanning the DFS channels without passively scanning the DFS channels;
determining a best neighbor AP on the neighbor list to which to roam based on results of the active scanning; and
if a best neighbor AP is determined, roaming to the best neighbor AP; and
if the attempting to roam to a best neighbor AP on the neighbor list has failed, deleting the received neighbor list and roaming to an AP based on a full scanning procedure that includes passive and active scanning of wireless channels identified in a preconfigured list of wireless channels and associated APs;
sending a request for a neighbor list to the best neighbor AP to which the wireless client device has roamed;
if a neighbor list is not received responsive to the request, resending the request;
if a neighbor list is received responsive to the resent request, storing the received neighbor list for subsequent attempts to roam;
if a neighbor list is not received responsive to the resent request, deleting all previous neighbor lists; and
for subsequent roaming in an absence of the neighbor lists, performing full scanning of the preconfigured list of wireless channels and associated APs, including passive scanning followed by active scanning of the wireless channels on the preconfigured list.
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Abstract
Access points and a wireless client device, such as a workgroup bridge, are configured to optimize a roaming algorithm of the client device for a high-speed vehicle scenario, such as a high-speed train. A static/dynamic neighbor list is generated and used to improve scanning efficiency. An improved parent access point selection procedure, metrics, and thresholds are provided to optimize client roaming along the vehicle'"'"'s path, e.g., the train track.
26 Citations
22 Claims
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1. A method comprising:
at a wireless client device configured to connect with access points (APs) over wireless channels of the APs and route traffic between multiple devices served by the wireless client device and the connected APs; receiving a neighbor list from an access point (AP) to which the wireless client device is currently connected over a wireless channel, wherein the neighbor list identifies neighbor APs and wireless operating channels thereof, including Dynamic Frequency Selection (DFS) channels that have been determined to be clear of interfering radar events, in a vicinity of the AP; if a link quality of the wireless connection falls below a roam threshold, attempting to roam to a neighbor AP on the neighbor list, wherein the attempting to roam includes; actively scanning the wireless operating channels in the neighbor list, including actively scanning the DFS channels without passively scanning the DFS channels; determining a best neighbor AP on the neighbor list to which to roam based on results of the active scanning; and if a best neighbor AP is determined, roaming to the best neighbor AP; and if the attempting to roam to a best neighbor AP on the neighbor list has failed, deleting the received neighbor list and roaming to an AP based on a full scanning procedure that includes passive and active scanning of wireless channels identified in a preconfigured list of wireless channels and associated APs; sending a request for a neighbor list to the best neighbor AP to which the wireless client device has roamed; if a neighbor list is not received responsive to the request, resending the request; if a neighbor list is received responsive to the resent request, storing the received neighbor list for subsequent attempts to roam; if a neighbor list is not received responsive to the resent request, deleting all previous neighbor lists; and for subsequent roaming in an absence of the neighbor lists, performing full scanning of the preconfigured list of wireless channels and associated APs, including passive scanning followed by active scanning of the wireless channels on the preconfigured list. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus comprising:
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one or more radios to connect wirelessly with access points (APs) over wireless channels of the APs and multiple devices served by the apparatus; a processor, coupled to the one or more radios, and configured to route traffic between the multiple devices and the connected APs, the processor further configured to; receive a neighbor list from an access point (AP) to which the wireless client device is currently connected over a wireless channel, wherein the neighbor list identifies neighbor APs and wireless operating channels thereof, including Dynamic Frequency Selection (DFS) channels that have been determined to be clear of interfering radar events, in a vicinity of the AP; if a link quality of the wireless connection falls below a roam threshold, attempt to roam to a neighbor AP on the neighbor list, wherein the processor is further configured to; active scan the wireless operating channels in the neighbor list, wherein the active scan includes an active scan of the DFS channels without performing a passive scan of the DFS channels; determine a best neighbor AP on the neighbor list to which to roam based on results of the active scan; and if a best neighbor AP is determined, roam to the best neighbor AP; and if the attempt to roam to a best neighbor AP on the neighbor list has failed, delete the received neighbor list and roam to an AP based on a full scanning procedure that includes passive and active scanning of wireless channels identified in a preconfigured list of wireless channels and associated APs; send a request for a neighbor list to the best neighbor AP to which the wireless client device has roamed; if a neighbor list is not received responsive to the request, resend the request; if a neighbor list is received responsive to the resent request, store the received neighbor list for subsequent attempts to roam; if a neighbor list is not received responsive to the resent request, delete all previous neighbor lists; and for subsequent roaming in an absence of the neighbor lists, perform full scanning of the preconfigured list of wireless channels and associated APs, including passive scanning followed by active scanning of the wireless channels on the preconfigured list. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A non-transitory computer readable medium encoded with instruction that, when executed by a processor of a wireless client device configured to connect with access points (APs) over wireless channels of the APs and route traffic between multiple devices served by the wireless client device and the connected APs, cause the processor to perform:
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receiving a neighbor list from an access point (AP) to which the wireless client device is currently connected over a wireless channel, wherein the neighbor list identifies neighbor APs and wireless operating channels thereof, including Dynamic Frequency Selection (DFS) channels that have been determined to be clear of interfering radar events, in a vicinity of the AP; if a link quality of the wireless connection falls below a roam threshold, attempting to roam to a neighbor AP on the neighbor list, wherein the attempting to roam includes; actively scanning the wireless operating channels in the neighbor list, including actively scanning the DFS channels without passively scanning the DFS channels; determining a best neighbor AP on the neighbor list to which to roam based on results of the active scanning; and if a best neighbor AP is determined, roaming to the best neighbor AP; and if the attempting to roam to a best neighbor AP on the neighbor list has failed, deleting the received neighbor list and roaming to an AP based on a full scanning procedure that includes passive and active scanning of wireless channels identified in a preconfigured list of wireless channels and associated APs; sending a request for a neighbor list to the best neighbor AP to which the wireless client device has roamed; if a neighbor list is not received responsive to the request, resending the request; if a neighbor list is received responsive to the resent request, storing the received neighbor list for subsequent attempts to roam; if a neighbor list is not received responsive to the resent request, deleting all previous neighbor lists; and for subsequent roaming in an absence of the neighbor lists, performing full scanning of the preconfigured list of wireless channels and associated APs, including passive scanning followed by active scanning of the wireless channels on the preconfigured list. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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Specification