Coordinated access point time division multiple access
This disclosure provides methods, devices and systems for sharing time resources of a wireless medium. Particular implementations relate more specifically to coordinated AP (CAP) time-division-multiple-access (TDMA) techniques for sharing the time resources of a transmission opportunity (TXOP). According to such techniques, a coordinated AP that wins contention and gains access to the wireless medium for the duration of a TXOP may share its time resources with other coordinated APs. To share its time resources, the winning AP may partition the TXOP into multiple TXOP segments each including respective time resources representing a sub-duration of the TXOP. For example, the winning AP may assign, grant or allocate (hereinafter used interchangeably) itself one or more of the time resources and also allocate each of one or more remaining time resources to one or more other ones of the coordinated APs.
1. A method for wireless communication by a first wireless access point, the method comprising:
obtaining a transmission opportunity for wireless communication via a wireless channel;
selecting one or more other wireless access points to participate in the transmission opportunity;
wirelessly transmitting a first frame to the one or more selected access points that includes, for each selected access point of the selected access points, an indication of respective time resources, of a plurality of time resources of the transmission opportunity, allocated to the selected access point and usable by the selected access point to transmit data to, or receive data from, one or more respective wireless stations associated with the selected access point during the transmission opportunity; and
wirelessly transmitting data to, or receiving data from, one or more first wireless stations associated with the first wireless access point using first time resources allocated to the first wireless access point from the plurality of time resources, the first time resources not overlapping other time resources of the plurality of time resources that are allocated to the selected access points.
2. The method of claim 1 , further comprising:
wirelessly transmitting at least one second frame to a plurality of wireless access points that indicates that the plurality of time resources of the transmission opportunity can be shared by the first wireless access point; and
wirelessly receiving a third frame from each of one or more candidate access points of the plurality of wireless access points, each third frame indicating a desire to participate in the transmission opportunity;
wherein the one or more selected access points are selected from the one or more candidate access points.
3. The method of claim 2 , wherein the at least one second frame is configured to trigger the one or more candidate access points to transmit the respective third frames.
4. The method of claim 3 , wherein a destination address associated with the at least one second frame is set to a broadcast address.
5. The method of claim 2 , wherein one or more of the third frames includes an indication of a buffer status of the selected access point that transmitted the third frame, a duration of time resources requested by the selected access point that transmitted the third frame, or a bandwidth requested by the selected access point that transmitted the third frame, and wherein the one or more wireless access points selected to participate in the transmission opportunity are selected based on the indications of the buffer statuses, the desired durations of time resources, or the bandwidths.
6. The method of claim 2 , further comprising, in response to obtaining the transmission opportunity and prior to transmitting the at least one second frame, wirelessly transmitting a request-to-send (RTS) frame to a plurality of wireless stations associated with the first wireless access point that is configured to cause the plurality of wireless access points and the plurality of wireless stations to set their network allocation vectors (NAVs) for a duration of time indicated in the RTS frame, wherein the at least one second frame is configured to cause the one or more candidate access points to respond to the at least one second frame by transmitting their respective third frames regardless of their respective NAVs.
7. The method of claim 1 , further comprising determining the respective time resources allocated to each selected access point of the selected access points, the determination of the respective allocated time resources comprising dividing time resources of the transmission opportunity into a plurality of equal portions, the number of portions being equal to the number of wireless access points sharing the transmission opportunity, the wireless access points sharing the transmission opportunity consisting of the first wireless access point and the selected access points.
8. The method of claim 1 , further comprising determining the respective time resources allocated to each selected access point of the selected access points, the determination of the respective allocated time resources comprising partitioning the time resources of the transmission opportunity into a plurality of portions, wherein at least one of the portions includes more time resources than another of the portions.
9. The method of claim 1 , wherein the first frame includes a respective user information field for each selected access point of the selected access points that includes the indication of the respective time resources allocated to the selected access point, wherein each user information field includes a respective AP identifier (APID) of the respective selected access point associated with the user information field, and wherein each user information field includes, for the respective selected access point, an indication of a starting time of the respective allocated time resources or a duration of the respective allocated time resources.
10. The method of claim 1 , wherein a destination address associated with the first frame is set to a broadcast address.
11. The method of claim 1 , wherein the first frame is configured to trigger the selected access points to transmit, simultaneously, respective second frames to their respective basic service sets (BSSs) identifying their respective allocated time resources and indicating that their respective allocated time resources are allocated for use by the respective BSSs.
12. The method of claim 11 , wherein the second frames are identical, and wherein:
a source address associated with each of the second frames is set to a same multicast address,
a basic service set (BSS) Identifier (BSSID) associated with each of the second frames is set to a same BSSID of the first wireless access point,
a destination address associated with each of the second frames is set to a same broadcast address, or
a receiver address associated with each of the second frames is set to a same particular multicast address.
13. The method of claim 11 , wherein each of the second frames includes an information element (IE) for each of itself and the selected access points that includes an indication of a starting time of the respective allocated time resources or a duration of the respective allocated time resources.
14. The method of claim 11 , wherein each of the second frames is or includes a clear-to-send (CTS) frame.
15. The method of claim 1 , further comprising transmitting a trigger frame to the selected access points after transmitting the first frame, the trigger frame being configured to synchronize in time the selected access points with the first wireless access point.
16. The method of claim 1 , further comprising, immediately prior to the respective time resources of the transmission opportunity allocated to each selected access point, transmitting a trigger to the selected access point that indicates a start of the plurality of time resources of the transmission opportunity allocated to the selected access point.
17. The method of claim 16 , wherein the trigger comprises a null data packet (NDP) or a clear-to-send (CTS) frame.
18. A method for wireless communication by a first wireless access point, the method comprising:
wirelessly receiving a first frame from a second wireless access point that includes an indication of time resources of a plurality of time resources of a transmission opportunity obtained by the second wireless access point allocated to the first wireless access point and usable by the first wireless access point to transmit data to, or receive data from, one or more wireless stations associated with the first wireless access point during the transmission opportunity; and
wirelessly transmitting data to, or receiving data from, one or more wireless stations of the wireless stations associated with the first wireless access point using the time resources allocated to the first wireless access point from the plurality of time resources.
19. The method of claim 18 , further comprising:
wirelessly receiving a second frame from the second wireless access point that indicates that the plurality of time resources of the transmission opportunity obtained by the second wireless access point can be shared by the second wireless access point; and
wirelessly transmitting a third frame to the second wireless access point indicating a desire to participate in the transmission opportunity.
20. The method of claim 19 , wherein the second frame is configured to trigger the first wireless access point to transmit the third frame.
21. The method of claim 20 , wherein a destination address associated with the second frame is set to a broadcast address.
22. The method of claim 18 , wherein the third frame includes an indication of a buffer status of the first wireless access point, a duration of time resources requested by the first wireless access point, or a bandwidth requested by the first wireless access point.
23. The method of claim 18 , wherein the first frame includes a user information field for the first wireless access point that includes the indication of the time resources allocated to the first wireless access point, wherein the user information field includes an AP identifier (APID) of the first wireless access point, and wherein the user information field includes an indication of a starting time of the allocated time resources or a duration of the allocated time resources.
24. The method of claim 18 , further comprising wirelessly transmitting a second frame, based on receiving the first frame, to one or more wireless stations that identifies the allocated time resources and that indicates that the allocated time resources are allocated for use by the first wireless access point and the one or more wireless stations.
25. The method of claim 24 , wherein:
a destination address associated with the second frame is set to a broadcast address,
a source address associated with the second frame is set to a multicast address,
a basic service set (BSS) Identifier (BSSID) of the second frame is set to a BSSID of the first wireless access point,
a destination address associated with the second frame is set to a broadcast address, or
a receiver address associated with the second frame is set to a particular multicast address.
26. The method of claim 24 , wherein the second frame includes an information element (IE) that includes an indication of a starting time of the respective allocated time resources or a duration of the respective allocated time resources.
27. The method of claim 24 , wherein the fourth frame is or includes a clear-to-send (CTS) frame.
28. The method of claim 18 , further comprising, immediately prior to the plurality of time resources of the transmission opportunity allocated to the first wireless access point, receiving a trigger from the second wireless access point that indicates a start of the plurality of time resources of the transmission opportunity allocated to the first wireless access point.
29. A wireless communication device comprising:
at least one modem;
at least one processor communicatively coupled with the at least one modem; and
at least one memory communicatively coupled with the at least one processor and storing processor-readable code that, when executed by the at least one processor in conjunction with the at least one modem, is configured to cause the wireless communication device to:
obtain a transmission opportunity for wireless communication via a wireless channel;
select one or more other wireless access points to participate in the transmission opportunity;
wirelessly transmit a first frame to the one or more selected access points that includes, for each selected access point of the selected access points, an indication of respective time resources, of a plurality of time resources of the transmission opportunity, allocated to the selected access point and usable by the selected access point to transmit data to, or receive data from, one or more respective wireless stations associated with the selected access point during the transmission opportunity; and
wirelessly transmit data to, or receive data from, one or more first wireless stations associated with the first wireless access point using first time resources allocated to the first wireless access point from the plurality of time resources, the first time resources not overlapping other time resources of the plurality of time resources that are allocated to the selected access points.
30. A wireless communication device comprising:
at least one modem;
at least one processor communicatively coupled with the at least one modem; and
at least one memory communicatively coupled with the at least one processor and storing processor-readable code that, when executed by the at least one processor in conjunction with the at least one modem, is configured to cause the wireless communication device to:
wirelessly receive a first frame from a second wireless access point that includes an indication of time resources of a plurality of time resources of a transmission opportunity obtained by the second wireless access point allocated to the first wireless access point and usable by the first wireless access point to transmit data to, or receive data from, one or more wireless stations associated with the first wireless access point during the transmission opportunity; and
wirelessly transmit data to, or receive data from, one or more wireless stations of the wireless stations associated with the first wireless access point using the time resources allocated to the first wireless access point from the plurality of time resources.