System and method for cooperative scheduling for co-located access points

1. A method of scheduling data for transmission from a first access point (AP) to a station in a system of multiple co-located APs, the method comprising:

determining whether the station is a cell edge station if, the station is able to receive transmitted data from said first AP and from at least one second AP of the multiple co-located APs other than the first AP, and

the signal to noise ratio (SNR) or signal to noise plus interference ratio (SINR) of the first AP is less than a first threshold, and

the ratio of signal to noise ratios (SNRs) or signal to interference plus noise ratios (SINRs) for the first AP and the second AP is less than a second threshold; and

if said determining is positive, only transmitting the data by the first AP after ascertaining that the first AP has permission to transmit the data to the station, wherein the second AP is prevented from transmitting while said first AP has permission to transmit to the station.

2. The method of claim 1 , wherein the determining comprises consulting a list of stations categorized as cell edge stations.

3. The method of claim 2 , comprising compiling said list of stations categorized as cell edge stations based on said determining.

4. The method of claim 1 , comprising, if said determination is negative, transmitting the data to the station from the first AP.

5. The method of claim 4 , comprising:

prior to transmitting the data to the station, ascertaining whether any other co-located AP of the multiple co-located APs operating on the same channel other than the first AP has exclusive permission to transmit data to another station that is able to receive data from the first AP and the other co-located AP; and

only transmitting the data to the station if no other co-located AP of the multiple co-located APs operating on the same channel other than the first AP has said exclusive permission.

6. The method of claim 5 , comprising:

if another co-located AP has said exclusive permission, performing one or more of the following operations prior to transmitting the data to the station from the first AP:

waiting for the exclusive permission to be revoked,

lowering transmit power, and

adjusting one or more transmission beams to reduce the signal interference of the first AP on the other station.

7. The method of claim 1 , comprising:

determining whether the first AP has been granted exclusive permission to transmit the data to the station; and

if the permission has not been granted moving the data to a queue to be transmitted at a later time, and

if the permission has been granted transmitting the data.

8. The method of claim 7 , comprising scheduling the data in the queue to have higher priority than other data to be transmitted to the station.

9. The method of claim 1 , wherein if said determining is positive, then further:

receiving an exclusive permission token by the first AP prior to transmitting the data to the station; and

relinquishing the exclusive permission token by the first AP after transmitting the data to the station.

10. A method of scheduling data for transmission from a first access point “AP” to a first station in a system of multiple co-located APs, the method comprising:

determining whether the first station is able to receive transmitted data from the first AP and another of the multiple co-located APs other than the first AP; and if said determining is negative,

ascertaining whether any other co-located AP of the multiple co-located APs operating on the same channel has exclusive permission to transmit data to a second station that is able to receive data from the first AP and the other co-located AP, and

if the other co-located AP has said exclusive permission to transmit to said second station, performing one or more of the following operations prior to transmitting the data from the first AP to the first station:

waiting until the other co-located AP no longer has the exclusive permission,

lowering transmit power, and

adjusting one or more transmission beams to reduce the signal interference of the first AP on the second station.

11. An access point (AP) for a wireless communication network comprising a system of multiple co-located APs, the AP comprising:

a receiver for receiving signals from stations in the network;

a transmitter for transmitting data to stations in the network; and

one or more processors for processing data, wherein the one or more processors are configured to:

receive data for transmission to a station in the network,

determine whether the station is a cell edge station if:

the station is able to receive transmitted data from said AP and from a second of the multiple co-located APs in the system of multiple co-located APs, and

the signal to noise ratio (SNR) or signal to noise plus interference ratio (SINR) of the first AP is less than a first threshold, and

the ratio of signal to noise ratios (SNRs) or signal to interference plus noise ratios (SINRs) for the first AP and the second AP is less than a second threshold; and

if said determining is positive, withhold transmission of the data unless exclusive permission to transmit the data to the station has been granted to the AP.

12. An access point according to claim 11 , further comprising a memory, wherein the one or more processors are further configured to compile a list to be stored in the memory of cell edge stations.

13. An access point according to claim 11 , further comprising a scheduler, wherein the one or more processors are configured to move the data to a queue in the scheduler if exclusive permission to transmit the data to the station has not been granted.

14. An access point according to claim 11 , wherein the one or more processors are further configured to allocate to data in the queue higher priority than other data to be transmitted to the station.

15. An access point according to claim 11 , wherein the one or more processors are further configured to:

ascertain whether any other co-located AP operating on the same channel has exclusive permission to transmit data to a station that is able to receive data from the AP and the other co-located AP, prior to transmitting said data; and

only transmit the data to the station if no AP has said exclusive permission.

16. An access point according to claim 15 configured to:

if another AP has said exclusive permission, perform one or more of the following operations prior to transmitting the data to the station:

wait for the exclusive permission to be revoked,

lower transmit power, and

adjust one or more transmission beams to reduce the signal interference of the AP on the station.

17. The access point of claim 11 , wherein the processor is further configured to perform the following steps if said determining is positive:

receive an exclusive permission token prior to transmitting the data to the station;

transmit the data to the station after receiving said exclusive permission token; and

relinquish the exclusive permission token after transmitting the data to the station.