NETWORK-WIDE INTER-CELL INTERFERENCE MINIMIZATION VIA COORDINATED MULTIPOINT CELL SCHEDULING COORDINATION

• US 20100323712A1
• Filed: 06/17/2009
• Published: 12/23/2010
• Est. Priority Date: 06/17/2009
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Guey, Jiann-Ching, Hoymann, Christian
• Granted Patent: US 8,442,545 B2
• Time in Patent Office: Days
• US Class Current: 455/452.2
• CPC Class Codes: H04L 5/0041 Frequency-non-contiguous
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04W 72/20 Control channels or signalling for resource management
• CPC Class Codes: H04W 72/54 based on quality criteria

Abstract

Network-wide inter-cell interference is reduced by aggregating cells (herein, sub-cells) into Coordinated MultiPoint (CoMP) cells, each having a controller. The CoMP cells are divided into sets, similar to a frequency reuse plan. Scheduling information regarding transmissions scheduled to and from UEs in one set of CoMP cells is transmitted to controllers in sets of neighboring CoMP cells, in advance of the transmissions. Controllers in the receiving sets of CoMP cells schedule transmission to minimize both inter-sub-cell interference and interference with the set of CoMP cells that transmitted the scheduling information, and assuming no interference from other CoMP cells. They then transmit scheduling information to subsequent set(s) of CoMP cells. The order of scheduling information transmission between sets of CoMP cells may be rotated for fairness. The scheduling information may range from bare threshold data indicating at least one transmission, to detailed information such as estimated path gains to each UE.

Claims

1. A method of reducing interference in a wireless communication network comprising a plurality of sub-cells, the sub-cells grouped into two or more Coordinated MultiPoint (CoMP) cells wherein each CoMP cell comprises a plurality of contiguous sub-cells and a controller operative to manage transmissions within the sub-cells of the CoMP cell to minimize intra-CoMP cell interference, the method comprising the steps of:

scheduling, by a first CoMP cell controller, transmissions to and from user equipments (UEs) within a first CoMP cell;

transmitting, from the first CoMP cell controller to a second controller of a neighboring second CoMP cell, scheduling information regarding transmissions scheduled to and from UEs in sub-cells at the border of the first CoMP cell, in advance of the transmissions; and

scheduling, by the second CoMP cell controller, transmissions to and from UEs within the second CoMP cell utilizing the scheduling information transmitted by the first CoMP cell controller to minimize inter-CoMP cell interference between the first and second CoMP cells.

2. The method of claim 1 wherein the scheduling information comprises an indication whether any transmission is scheduled to and from any UE in each border sub-cell.

3. The method of claim 1 wherein the first CoMP cell belongs to a first set of non-contiguous CoMP cells and the second CoMP cell belongs to a second set of non-contiguous CoMP cells, the CoMP cells of each set distributed through the network such that no transmissions from any CoMP cell within a particular set cause interference to any other CoMP cell in that set.

4. The method of claim 2 wherein the indication comprises a single bit per border sub-cell.

5. The method of claim 1 wherein the scheduling information comprises an estimate of the path gain to a UE of a transmission scheduled to or from that UE.

6. The method of claim 5 wherein the scheduling information further comprises an estimate of the path gain to a UE of a transmission scheduled to or from a different UE.

7. The method of claim 6 wherein the scheduling information comprises the path gain estimates that exceed a predetermined threshold.

8. The method of claim 6 wherein the path gain estimates are in the form of an m×

n matrix where m is an index identifying UEs and n is an index identifying sub-cells.

9. The method of claim 1 wherein the scheduling information comprises information regarding transmissions scheduled to occur during a future predefined transmission duration.

10. The method of claim 1 further comprising:

receiving, at the first CoMP cell controller, from the second CoMP cell controller, scheduling information regarding transmissions scheduled to and from UEs in sub-cells of the second CoMP cell, in advance of the transmissions.

11. The method of claim 10 wherein the scheduling information comprises information regarding transmissions scheduled to occur during a future predefined duration other than a duration for which the first CoMP cell controller transmitted scheduling information regarding transmissions scheduled to and from UEs in sub-cells at the border of the first CoMP cell.

12. The method of claim 11 further comprising:

scheduling, by the first CoMP cell controller, transmissions to and from UEs in the first CoMP cell, considering the received scheduling information, so as to minimize interference to UEs in the second CoMP cell, during the predefined duration to which the received information about the second CoMP cell pertains.

24. The method according to claim 1, further comprising the steps of:

passing scheduling information from each of the CoMP cells in the second subset to neighboring CoMP cells in all other subsets except the first subset; and

scheduling transmissions to and from UEs in the sub-cells of the CoMP cells in a third subset, wherein transmissions in the third subset are scheduled to minimize intra-CoMP-cell interference among the sub-cells within the CoMP cells in the third subset, and wherein transmissions in the third subset are also scheduled utilizing the scheduling information received from the first and second subsets to minimize inter-CoMP-cell interference with CoMP cells in the first and second subsets.

13. A Coordinated MultiPoint (CoMP) cell controller communicatively linked to a plurality of network transceivers, each transceiver providing radio communications to User Equipments (UEs) in a sub-cell of the CoMP cell, comprising:

a scheduler for scheduling transmissions with UEs in sub-cells of the CoMP cell to minimize inter-sub-cell interference within the CoMP cell, wherein the scheduler generates scheduling information; and

a communication interface for transmitting to one or more controllers of neighboring CoMP cells, scheduling information generated by the scheduler regarding transmissions scheduled to and from UEs in sub-cells at the border of the CoMP cell, in advance of the transmissions.

14. The CoMP cell controller of claim 13 wherein the controller includes means for receiving over the communication interface, scheduling information regarding transmissions scheduled to and from UEs in sub-cells at the border of one or more neighboring CoMP cells, in advance of the transmissions, and wherein the scheduler utilizes the received scheduling information to schedule transmissions with UEs in sub-cells of the CoMP cell to minimize interference with UEs in the one or more neighboring CoMP cells.

15. The CoMP cell controller of claim 14 wherein the relative order in which the controller transmits or receives scheduling information, changes for each predefined transmission duration according to a predetermined protocol.

16. The CoMP cell controller of claim 13 wherein the scheduling information comprises an indication whether any transmission is scheduled to or from any UE in each border sub-cell.

17. The CoMP cell controller of claim 16 wherein the indication comprises a single bit per border sub-cell.

18. The CoMP cell controller of claim 13 wherein the scheduling information comprises an estimate of the path gain to a UE of a transmission scheduled to or from that UE.

19. The CoMP cell controller of claim 18 wherein the scheduling information further comprises an estimate of the path gain to a UE of a transmission scheduled to or from a different UE.

20. The CoMP cell controller of claim 18 wherein the scheduling information comprises the path gain estimates that exceed a predetermined threshold.

21. The CoMP cell controller of claim 19 wherein the path gain estimates are in the form of an m×

n matrix where m is an index identifying UEs and n is an index identifying sub-cells.

22. (canceled)

23. A method of reducing inter-cell interference within a Coordinated Multi-Point (CoMP) cellular network architecture having a plurality of CoMP cells, wherein each CoMP cell includes a plurality of sub-cells in which radio transmissions are made to and from User Equipments (UEs), said method comprising the steps of:

grouping the plurality of CoMP cells into a number of mutually exclusive subsets, wherein the CoMP cells in each subset are sufficiently separated from each other geographically so that no inter-CoMP-cell interference occurs among the CoMP cells in any given subset;

scheduling transmissions to and from UEs in the sub-cells of the CoMP cells in a first subset to minimize intra-CoMP-cell interference among the sub-cells within the CoMP cells in the first subset;

passing scheduling information from each of the CoMP cells in the first subset to neighboring CoMP cells in all other subsets; and

scheduling transmissions to and from UEs in the sub-cells of the CoMP cells in a second subset, wherein transmissions in the second subset are scheduled to minimize intra-CoMP-cell interference among the sub-cells within the CoMP cells in the second subset, and wherein transmissions in the second subset are also scheduled utilizing the scheduling information received from the first subset to minimize inter-CoMP-cell interference with CoMP cells in the first subset.

25. A system in a cellular communication network for minimizing inter-cell interference among Coordinated MultiPoint (CoMP) cells, the system comprising:

a first CoMP cell controller communicatively linked to a first plurality of network transceivers, each transceiver providing radio communications to User Equipments (UEs) in a sub-cell of the CoMP cell;

a second CoMP cell controller communicatively linked to a second plurality of network transceivers neighboring the first plurality of network transceivers;

wherein the first and second CoMP cell controllers include;

a scheduler for scheduling transmissions with UEs in sub-cells of the first and second CoMP cells, respectively, to minimize inter-sub-cell interference within the first and second CoMP cell, wherein the schedulers generate scheduling information; and

a communication interface for transmitting from the first CoMP cell controller to the second CoMP cell controller, scheduling information generated by the scheduler of the first CoMP cell controller regarding transmissions scheduled to and from UEs in sub-cells at the border of the first CoMP cell, in advance of the transmissions;

wherein the scheduler of the second CoMP cell controller includes means for utilizing the scheduling information transmitted by the first CoMP cell controller to schedule transmission to and from UEs in the in sub-cells at the border of the second CoMP cell so as to minimize inter-CoMP cell interference between the first CoMP cell and the second CoMP cell.