Dynamic scheduling of non-interfering clusters in a distributed diversity communications system

1. A cellular wireless communications network comprising one or more clusters, each cluster comprising:

a plurality of cells; and

a cluster-level controller that dynamically divides the cluster into a set of non-interfering sub-clusters for a resource allocation unit, wherein:

each sub-cluster comprises one or more cells that transmit to a single user in the cluster for the resource allocation unit;

at least one sub-cluster comprises at least two cells that transmit to a corresponding single user in the cluster for the resource allocation unit;

the controller dynamically divides the cluster into the set of non-interfering sub-clusters based on a cluster-level ranking of users in the cluster;

each user in the cluster is connected to only one serving cell in the cluster; and

for a highest-rank user in the ranking, the controller defines a sub-cluster for the highest-rank user, wherein:

if the controller determines that the highest-rank user has one or more potentially interfering, non-server cells in the cluster, then the controller includes in the sub-cluster for the highest-rank user (i) the one or more potentially interfering, non-serving cells and (ii) the serving cell for the highest-rank user; and

if the controller determines that the highest-rank user has no potentially interfering, non-server cells in the cluster, then the controller includes in the sub-cluster for the highest-rank user only the serving cell for the highest-rank user.

2. The invention of claim 1 , wherein the controller dynamically divides the cluster into the set of non-interfering sub-clusters for the resource allocation unit based on channel conditions in the cluster.

3. The invention of claim 1 , where the resource allocation unit corresponds to at least one time symbol and at least one frequency subcarrier.

4. The invention of claim 1 , wherein the controller determines that a non-serving cell in the cluster is a potentially interfering, non-serving cell for the highest-rank user when a measured power level at the highest-rank user from the non-serving cell is less than a specified threshold value below a measured power level at the highest-rank user from the serving cell for the highest-rank user.

5. The invention of claim 1 , wherein, after defining the sub-cluster for the highest-rank user:

the controller updates a list of available cells in the cluster by removing the cells in the sub-cluster;

the controller updates the ranking of users by removing the highest-rank user and any other users connected to any of the cells in the sub-cluster; and

if both of (i) the updated list of available cells and (ii) the updated ranking of users are not empty, then the controller attempts to schedule transmission to a highest-rank user in the updated ranking.

6. The invention of claim 1 , wherein, if the highest-rank user is susceptible to interference from a cell that has already been scheduled for the resource allocation unit, then the highest-rank user is removed from the ranking without scheduling any transmission to the highest-rank user for the resource allocation unit.

7. The invention of claim 1 , wherein:

each cell ranks its own users and determines its cell-level highest-rank user;

one or more cells identify their cell-level highest-rank users to the controller; and

the controller generates the cluster-level ranking based on the identified cell-level highest-rank users.

8. The invention of claim 7 , wherein:

each cell determines whether or not its cell-level highest-rank user is susceptible to interference from another cell in the cluster;

each cell that determines that its cell-level highest-rank user is not susceptible to interference schedules its cell-level highest-rank user for the resource allocation unit; and

each cell that determines that its cell-level highest-rank user is susceptible to interference identifies its cell-level highest-rank user to the controller for the resource allocation unit.

9. The invention of claim 1 , wherein the at least two cells in the at least one sub-cluster transmit to the corresponding single user using (i) a distributed diversity mode of communication in which the at least two cells share a single transmission code or (ii) other coordinated multipoint (COMP) scheme.

10. The invention of claim 9 , wherein:

the shared transmission code is a block code; and

each cell in the at least one sub-cluster is assigned a different subset of one or more columns of the block code.

11. The invention of claim 1 , wherein:

the controller dynamically divides the cluster into a corresponding set of non-interfering sub-clusters independently for each of multiple, different resource allocation units; and

the corresponding sets of non-interfering sub-clusters are different for at least two of the resource allocation units.

12. The invention of claim 1 , wherein:

one or more of the cells have a remote radio head (RRH), but no dedicated baseband unit (BBU); and

the cluster comprises a shared BBU for all of the cells in the cluster, wherein the shared BBU implements the controller.

13. The invention of claim 12 , wherein the plurality of cells further comprises a master cell having the shared BBU.

14. The invention of claim 13 , wherein:

none of the cells in the cluster has a BBU; and

the shared BBU is cloud-implemented.

15. The invention of claim 1 , wherein the communications network is an LTE communications network.

16. The invention of claim 1 , wherein the network further comprises one or more other clusters, wherein:

each other cluster has a plurality of other cells; and

each other cluster comprises an other cluster-level controller that dynamically divides the other cluster into an other set of non-interfering sub-clusters, each sub-cluster comprising one or more other cells that transmit to a single user in the other cluster.

17. A cluster-level controller for the network of claim 1 .

18. A cell for the network of claim 1 .

19. A cellular wireless communications network comprising one or more clusters, each cluster comprising:

a plurality of cells; and

a cluster-level controller that dynamically divides the cluster into a set of non-interfering sub-clusters for a resource allocation unit, wherein:

each sub-cluster comprises one or more cells that transmit to a single user in the cluster for the resource allocation unit;

at least one sub-cluster comprises at least two cells that transmit to a corresponding single user in the cluster for the resource allocation unit;

the controller dynamically divides the cluster into the set of non-interfering sub-clusters based on a cluster-level ranking of users in the cluster;

each cell ranks its own users and determines its cell-level highest-rank user;

one or more cells identify their cell-level highest-rank users to the controller; and

the controller generates the cluster-level ranking based on the identified cell-level highest-rank users.

20. The invention of claim 19 , wherein:

each cell determines whether or not its cell-level highest-rank user is susceptible to interference from another cell in the cluster;

each cell that determines that its cell-level highest-rank user is not susceptible to interference schedules its cell-level highest-rank user for the resource allocation unit; and

each cell that determines that its cell-level highest-rank user is susceptible to interference identifies its cell-level highest-rank user to the controller for the resource allocation unit.

21. A cluster-level controller for the network of claim 19 .

22. A cell for the network of claim 19 .

23. A cellular wireless communications network comprising one or more clusters, each cluster comprising:

a plurality of cells; and

a cluster-level controller that dynamically divides the cluster into a set of non-interfering sub-clusters for a resource allocation unit, wherein:

each sub-cluster comprises one or more cells that transmit to a single user in the cluster for the resource allocation unit;

at least one sub-cluster comprises at least two cells that transmit to a corresponding single user in the cluster for the resource allocation unit;

the controller dynamically divides the cluster into a corresponding set of non-interfering sub-clusters independently for each of multiple, different resource allocation units; and

the corresponding sets of non-interfering sub-clusters are different for at least two of the resource allocation units.

24. A cluster-level controller for the network of claim 23 .

25. A cellular wireless communications network comprising one or more clusters, each cluster comprising:

a plurality of cells; and

a cluster-level controller that dynamically divides the cluster into a set of non-interfering sub-clusters for a resource allocation unit, wherein:

each sub-cluster comprises one or more cells that transmit to a single user in the cluster for the resource allocation unit;

at least one sub-cluster comprises at least two cells that transmit to a corresponding single user in the cluster for the resource allocation unit;

one or more of the cells have a remote radio head (RRH), but no dedicated baseband unit (BBU); and

the cluster comprises a shared BBU for all of the cells in the cluster, wherein the shared BBU implements the controller.

26. The invention of claim 25 , wherein the plurality of cells further comprises a master cell having the shared BBU.

27. The invention of claim 26 , wherein:

none of the cells in the cluster has a BBU; and

the shared BBU is cloud-implemented.