Method and apparatus for initiating channel sounding with unassociated access points
A system and method are disclosed that may allow a STA to request one or more non-associated APs to initiate channel sounding operations with the STA. In response to the request, a number of the non-associated APs may send one or more NDPs to the STA. The STA may use the received NDPs to determine a goodput value for each of the number of non-associated APs. The STA may then use the determined goodput values to select one of the number of non-associated APs with which to associate. Thereafter, the STA may initiate an association operation with the selected AP.
1. A method performed by a mobile station (STA) for selecting an access point (AP) with which to associate, the method comprising:
broadcasting a probe request that includes a request for one or more non-associated APs to initiate a channel sounding operation with the STA;
receiving, from each of a number of the non-associated APs, a null data packet (NDP), wherein the probe request includes a schedule indicating an order in which the number of non-associated APs are to send the NDPs to the STA;
determining, for each of the number of non-associated APs, a goodput value based, at least in part, on a corresponding one of the received NDPs; and
selecting one of the number of non-associated APs for an association operation with the STA based, at least in part, on the determined goodput values of the number of non-associated APs.
2. The method of claim 1 , wherein the NDP is embedded within an action no-acknowledgement (NO-ACK) frame.
3. The method of claim 1 , further comprising:
receiving, from each of the number of non-associated APs, a null data packet announcement (NDPA) indicating that the corresponding non-associated AP is to send one or more NDPs to the STA.
4. The method of claim 3 , wherein the NDPA includes an association identification (AID) value set to 0.
5. The method of claim 3 , wherein the NDPA is embedded within a probe response.
6. The method of claim 3 , wherein the NDPA is embedded within an action no-acknowledgement (NO-ACK) frame.
7. The method of claim 1 , further comprising:
estimating channel state information for at least one of the non-associated APs based, at least in part, on the received NDPs; and
sending the estimated channel state information to the at least one non-associated AP.
8. The method of claim 1 , wherein the number of non-associated APs includes at least a first non-associated AP and a second non-associated AP, wherein the selecting comprises:
comparing the goodput value of the first non-associated AP with the goodput value of the second non-associated AP;
selecting the first non-associated AP for the association operation if the goodput value of the first non-associated AP is greater than the goodput value of the second non-associated AP; and
selecting the second non-associated AP for the association operation if the goodput value of the second non-associated AP is greater than the goodput value of the first non-associated AP.
9. A mobile station (STA) configured to select an access point (AP) with which to associate, the STA comprising:
a transceiver to exchange wireless signals with one or more APs;
one or more processors; and
a memory storing instructions that, when executed by the one or more processors, cause the STA to:
broadcast a probe request that includes a request for one or more non-associated APs to initiate a channel sounding operation with the STA;
receive, from each of a number of the non-associated APs, a null data packet (NDP), wherein the probe request includes a schedule indicating an order in which the number of non-associated APs are to send the NDPs to the STA;
determine, for each of the number of non-associated APs, a goodput value based, at least in part, on a corresponding one of the received NDPs; and
select one of the number of non-associated APs for an association operation with the STA based, at least in part, on the determined goodput values of the number of non-associated APs.
10. The mobile station of claim 9 , wherein the NDP is embedded within an action no-acknowledgement (NO-ACK) frame.
11. The mobile station of claim 9 , wherein execution of the instructions causes the STA to further:
receive, from each of the number of non-associated APs, a null data packet announcement (NDPA) indicating that the corresponding non-associated AP is to send one or more NDPs to the STA.
12. The mobile station of claim 11 , wherein the NDPA includes an association identification (AID) value set to 0.
13. The mobile station of claim 11 , wherein the NDPA is embedded within a probe response.
14. The mobile station of claim 11 , wherein the NDPA is embedded within an action no-acknowledgement (NO-ACK) frame.
15. The mobile station of claim 9 , wherein execution of the instructions causes the STA to further:
estimate channel state information for at least one of the non-associated APs based, at least in part, on the received NDPs; and
send the estimated channel state information to the at least one non-associated AP.
16. The mobile station of claim 9 , wherein the number of non-associated APs includes at least a first non-associated AP and a second non-associated AP, wherein execution of the instructions to select one of the number of non-associated APs for the association operation causes the STA to:
compare the goodput value of the first non-associated AP with the goodput value of the second non-associated AP;
select the first non-associated AP for the association operation if the goodput value of the first non-associated AP is greater than the goodput value of the second non-associated AP; and
select the second non-associated AP for the association operation if the goodput value of the second non-associated AP is greater than the goodput value of the first non-associated AP.
17. A non-transitory computer-readable medium storing instructions that, when executed by one or more processors of a mobile station (STA), cause the STA to select an access point (AP) with which to associate by performing operations comprising:
broadcasting a probe request that includes a request for one or more non-associated APs to initiate a channel sounding operation with the STA;
receiving, from each of a number of the non-associated APs, a null data packet (NDP) wherein the probe request includes a schedule indicating an order in which the number of non-associated APs are to send the NDPs to the STA;
determining, for each of the number of non-associated APs, a goodput value based, at least in part, on a corresponding one of the received NDPs; and
selecting one of the number of non-associated APs for an association operation with the STA based, at least in part, on the determined goodput values of the number of non-associated APs.
18. The non-transitory computer-readable medium of claim 17 , wherein the NDP is embedded within an action no-acknowledgement (NO-ACK) frame.
19. The non-transitory computer-readable medium of claim 17 , wherein execution of the instructions causes the STA to perform operations further comprising:
receiving, from each of the number of non-associated APs, a null data packet announcement (NDPA) indicating that the corresponding non-associated AP is to send one or more NDPs to the STA.
20. The non-transitory computer-readable medium of claim 19 , wherein the NDPA includes an association identification (AID) value set to 0.
21. The non-transitory computer-readable medium of claim 19 , wherein the NDPA is embedded within a probe response.
22. The non-transitory computer-readable medium of claim 19 , wherein the NDPA is embedded within an action no-acknowledgement (NO-ACK) frame.
23. The non-transitory computer-readable medium of claim 17 , wherein execution of the instructions causes the STA to perform operations further comprising:
estimating channel state information for at least one of the non-associated APs based, at least in part, on the received NDPs; and
sending the estimated channel state information to the at least one non-associated AP.
24. The non-transitory computer-readable medium of claim 17 , wherein the number of non-associated APs includes at least a first non-associated AP and a second non-associated AP, wherein execution of the instructions to select one of the number of non-associated APs for the association operation causes the STA to perform operations further comprising:
comparing the goodput value of the first non-associated AP with the goodput value of the second non-associated AP;
selecting the first non-associated AP for the association operation if the goodput value of the first non-associated AP is greater than the goodput value of the second non-associated AP; and
selecting the second non-associated AP for the association operation if the goodput value of the second non-associated AP is greater than the goodput value of the first non-associated AP.
25. A mobile station (STA) configured to select an access point (AP) with which to associate, the STA comprising:
means for broadcasting a probe request that includes a request for one or more non-associated APs to initiate a channel sounding operation with the STA;
means for receiving, from each of a number of the non-associated APs, a null data packet (NDP), wherein the probe request includes a schedule indicating an order in which the number of non-associated APs are to send the NDPs to the STA;
means for determining, for each of the number of non-associated APs, a goodput value based, at least in part, on a corresponding one of the received NDPs; and
means for selecting one of the number of non-associated APs for an association operation with the STA based, at least in part, on the determined goodput values of the number of non-associated APs.
26. The mobile station of claim 25 , wherein the NDP is embedded within an action no-acknowledgement (NO-ACK) frame.
27. The mobile station of claim 26 , further comprising:
means for receiving, from each of the number of non-associated APs, a null data packet announcement (NDPA), wherein the NDPA is embedded in the action NO-ACK frame.