METHOD FOR COORDINATED MULTI-CELL TRANSMISSION, CENTRAL CONTROLLER AND USER EQUIPMENT

• US 20110034163A1
• Filed: 07/20/2010
• Published: 02/10/2011
• Est. Priority Date: 08/05/2009
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Chen, Lan, She, Xiaoming, Zhu, Jianchi, Yun, Xiang
• Granted Patent: US 8,254,938 B2
• Time in Patent Office: Days
• US Class Current: 455/422.1
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04L 5/0035 Resource allocation in a cooperative multipoint environment
• CPC Class Codes: H04L 5/0091 Signaling for the administration of the divided path

Abstract

Embodiments of the present invention disclose a method for coordinated multi-cell transmission, a central controller and a User Equipment (UE). In one embodiment, the method includes: determining, by a central controller, at least one candidate cooperating set in a super-cell, wherein each cell in the super-cell belongs to at least one candidate cooperating set, and broadcasting information of the at least one candidate cooperating set determined to all UEs in the super-cell; selecting, by each UE, a candidate cooperating set from the at least one candidate cooperating set as a cooperating set of the UE, and feeding back information of the cooperating set selected to the central controller; and determining, by the central controller, all cooperating sets in the super-cell and UEs participating in cooperation in each cooperating set according to the information of the selected cooperating set fed back by each UE.

Claims

1. A method for coordinated multi-cell transmission, comprising:

determining, by a central controller, at least one candidate cooperating set in a super-cell, wherein each cell in the super-cell belongs to at least one candidate cooperating set, and broadcasting information of the at least one candidate cooperating set determined to all User Equipments (UEs) in the super-cell;

selecting, by each of the UEs, a candidate cooperating set from the at least one candidate cooperating set as a cooperating set of the UE; and

feeding back information of the cooperating set to the central controller; and

determining, by the central controller, all cooperating sets in the super-cell and UEs participating in cooperation in each cooperating set according to the information of the cooperating set fed back by each of the UEs.

2. The method of claim 1, wherein selecting by each of the UEs the cooperating set from the at least one candidate cooperating set as the cooperating set of the UE comprises:

selecting, by each of the UEs, the candidate cooperating set where the UE is located as the cooperating set of the UE according to a geographical location of the UE.

3. The method of claim 1, wherein selecting by each of the UEs the cooperating set from the at least one candidate cooperating set as the cooperating set of the UE comprises:

measuring, by each of the UEs, the at least one candidate cooperating set, selecting the candidate cooperating set from the at least one candidate cooperating set as the cooperating set of the UE according to channel information obtained by measurement.

4. The method of claim 3, wherein the channel information comprises:

long-term channel statistics or instant channel information;

wherein selecting the candidate cooperating set from the at least one candidate cooperating set as the cooperating set of the UE according to the channel information obtained by measurement comprises;

selecting a candidate cooperating set with a largest signal-to-noise ratio as the cooperating set of the UE.

5. The method of claim 1, wherein determining the cooperating sets in the super-cell and the UEs participating in the cooperation in each cooperating set comprises:

scheduling among all the UEs in each candidate cooperating set according to the information of the cooperating set selected by each UE and the channel information fed back by each UE, and determining the UEs participating in the cooperation in each cooperating set to maximize throughput or weighted throughput of the UEs participating in the cooperation in each cooperating set;

taking a group consisting of all candidate cooperating sets as a first group;

a1) selecting a candidate cooperating set with a highest priority from the first group as a cooperating set of the super-cell, and adding the selected cooperating set into a second group;

removing, from the first group, all candidate cooperating sets that are non-orthogonal with the candidate cooperating set added into the second group, returning to operational) until the first group is null.

6. The method of claim 1, wherein determining the cooperating sets in the super-cell and the UEs participating in the cooperation in each cooperating set comprises:

dividing all candidate cooperating sets in the super-cell into at least two groups, wherein it is guaranteed that all candidate cooperating sets in each group are orthogonal, and taking each group of candidate cooperating sets as a coordinated transmission mode;

multiplexing the at least two coordinated transmission modes in a time division multiplexing manner;

allocating a downlink slot for each coordinated transmission mode; and

performing, during a slot corresponding to one coordinated transmission mode, the scheduling among all the UEs in each candidate cooperating set in the coordinated transmission mode according to the information of the cooperating sets selected by all the UEs and the channel information fed back by all the UEs to maximize throughput or weighted throughput of the UEs scheduled in each candidate cooperating set.

7. The method of claim 1, wherein determining the cooperating sets in the super-cell and the UEs participating in the cooperation in each cooperating set comprises:

dividing all candidate cooperating sets in the super-cell into at least two groups, wherein it is guaranteed that all candidate cooperating sets in each group are orthogonal, and taking each group of candidate cooperating sets as a coordinated transmission mode;

multiplexing the at least two coordinated transmission modes in a frequency division multiplexing manner;

allocating a downlink frequency band for each coordinated transmission mode; and

performing, during a downlink frequency band corresponding to one coordinated transmission mode, the scheduling among all the UEs in each candidate cooperating set in the coordinated transmission mode according to the information of the cooperating sets selected by all the UEs and the channel information fed back by all the UEs to maximize throughput or weighted throughput of the UEs scheduled in each candidate cooperating set.

8. A method for coordinated multi-cell transmission, comprising:

determining, by a central controller, at least one candidate cooperating set in a super-cell, wherein each cell in the super-cell belongs to at least one candidate cooperating set, and broadcasting information of the at least one candidate cooperating set to all User Equipments (UEs) in the super-cell;

measuring, by each of all the UE, the at least one candidate cooperating set, and feeding back channel information obtained by measurement to the central controller; and

selecting, by the central controller, a cooperating set from the at least one candidate cooperating set for each of the UEs according to the channel information fed back by each of the UEs, and determining all cooperating sets in the super-cell and UEs participating in cooperation in each cooperating set according to the cooperating set selected for each of the UEs.

9. The method of claim 8, wherein the channel information comprises:

long-term channel statistics or instant channel information;

wherein selecting by the central controller the candidate cooperating set from the at least one candidate cooperating set for each of the UEs according to the channel information fed back by each of the UEs comprises;

selecting a candidate cooperating set with a largest signal-to-noise ratio for each of the UEs as the cooperating set of each of the UEs.

10. The method of claim 8, wherein determining the cooperating sets in the super-cell and the UEs participating in the cooperation in each cooperating set comprises:

scheduling among all the UEs in each candidate cooperating set according to the information of the cooperating set selected by each UE and the channel information fed back by each UE, and determining the UEs participating in the cooperation in each cooperating set to maximize throughput or weighted throughput of the UEs participating in the cooperation in each cooperating set;

taking a group consisting of all candidate cooperating sets as a first group;

a1) selecting a candidate cooperating set with a highest priority from the first group as a cooperating set of the super-cell, and adding the selected cooperating set into a second group;

removing, from the first group, all candidate cooperating sets that are non-orthogonal with the candidate cooperating set added into the second group, returning to the step a1) until the first group is null.

11. The method of claim 10, wherein the priority is throughput or weighted throughput of the candidate cooperating set.

12. The method of claim 8, wherein determining the cooperating sets in the super-cell and the UEs participating in the cooperation in each cooperating set comprises:

dividing all candidate cooperating sets in the super-cell into at least two groups, wherein it is guaranteed that all candidate cooperating sets in each group are orthogonal, and taking each group of candidate cooperating sets as a coordinated transmission mode;

multiplexing the at least two coordinated transmission modes in a time division multiplexing manner;

allocating a downlink slot for each coordinated transmission mode; and

performing, during a slot corresponding to one coordinated transmission mode, the scheduling among all the UEs in each candidate cooperating set in the coordinated transmission mode according to the information of the cooperating sets selected by all the UEs and the channel information fed back by all the UEs to maximize throughput or weighted throughput of the UEs scheduled in each candidate cooperating set.

13. The method of claim 8, wherein determining the cooperating sets in the super-cell and the UEs participating in the cooperation in each cooperating set comprises:

dividing all candidate cooperating sets in the super-cell into at least two groups, wherein it is guaranteed that all candidate cooperating sets in each group are orthogonal, and taking each group of candidate cooperating sets as a coordinated transmission mode;

multiplexing the at least two coordinated transmission modes in a frequency division multiplexing manner;

allocating a downlink frequency band for each coordinated transmission mode; and

performing, during a downlink frequency band corresponding to one coordinated transmission mode, the scheduling among all the UEs in each candidate cooperating set in the coordinated transmission mode according to the information of the cooperating sets selected by all the UEs and the channel information fed back by all the UEs to maximize throughput or weighted throughput of the UEs scheduled in each candidate cooperating set.

14. A central controller of a super-cell, comprising:

a candidate cooperating set determining unit to determine at least one candidate cooperating set in a super-cell, wherein each cell in the super-cell belongs to at least one candidate cooperating set; and

adapted to broadcast information of the at least one candidate cooperating set determined to all UEs in the super-cell;

a cooperating set information obtaining unit to receive information of a cooperating set of a UE fed back by the UE; and

a scheduling unit to determine all cooperating sets in the super-cell and UEs participating in cooperation in each cooperating set according to information of the cooperating sets selected by all the UEs.

15. The central controller of claim 14, wherein the scheduling unit comprises:

a UE scheduling module to schedule among all the UEs in each candidate cooperating set according to the information of the cooperating set selected by each of the UEs and the channel information fed back by each of the UEs, determine the UEs participating in the cooperation in each candidate cooperating set to maximize weighted throughput of the UEs participating in the cooperation in each candidate cooperating set; and

a cooperating set selecting module to take a group consisting of all the candidate cooperating sets as a first group, select a candidate cooperating set with a highest priority from the first group as a cooperating set of the super-cell, and add the selected candidate cooperating set into a second group;

remove all candidate cooperating sets which are non-orthogonal with the candidate cooperating set added into the second group from the first group, and return to the step of selecting the candidate cooperating set with the highest priority from the first group until the first group is null.

16. The central controller of claim 14, wherein the scheduling unit comprises:

a coordinated transmission mode dividing module to divide all candidate cooperating sets in the super-cell into at least two groups, wherein it is guaranteed that all candidate cooperating sets in each group are orthogonal, and take each group of candidate cooperating sets as a coordinated transmission mode; and

a UE scheduling module to allocate a downlink slot for each coordinated transmission mode, and perform, during a slot corresponding to one coordinated transmission mode, scheduling among all the UEs in each candidate cooperating set in the coordinated transmission mode according to information of the cooperating sets selected by all the UEs and the channel information fed back by all the UEs to maximize weighted throughput of all the UEs scheduled in each candidate cooperating set.

17. The central controller of claim 14, wherein the scheduling module comprises:

a coordinated transmission mode dividing module to divide all candidate cooperating sets in the super-cell into at least two groups, wherein it is guaranteed that all candidate cooperating sets in each group are orthogonal, and take each group of candidate cooperating sets as a coordinated transmission mode; and

a UE scheduling module to allocate a downlink frequency band for each coordinated transmission mode, and perform, within a downlink frequency band corresponding to one coordinated transmission mode, scheduling among all the UEs in each candidate cooperating set in the coordinated transmission mode according to information of the cooperating sets selected by all the UEs and the channel information fed back by all the UEs to maximize weighted throughput of all the UEs scheduled in each candidate cooperating set.

18. A central controller of a super-cell, comprising:

a candidate cooperating set determining unit to determine at least one candidate cooperating set in the super-cell, wherein each cell in the super-cell belongs to at least one candidate cooperating set; and

adapted to broadcast information of the at least one candidate cooperating set determined to all UEs in the super-cell;

a channel information obtaining unit to receive channel information fed back by each of the UEs;

a cooperating set selecting unit to select for each of the UEs a cooperating set from the at least one candidate cooperating set according to the channel information fed back by each of the UEs; and

a scheduling unit to determine all cooperating sets in the super-cell and UEs participating in cooperation in each cooperating set according to information of the cooperating set selected by each of the UEs.

19. The central controller of claim 18, wherein the scheduling unit comprises:

a UE scheduling module to schedule among all the UEs in each candidate cooperating set according to the information of the cooperating set selected by each of the UEs and the channel information fed back by each of the UEs, determine the UEs participating in the cooperation in each candidate cooperating set to maximize weighted throughput of the UEs participating in the cooperation in each candidate cooperating set; and

a cooperating set selecting module to take a group consisting of all the candidate cooperating sets as a first group, select a candidate cooperating set with a highest priority from the first group as a cooperating set of the super-cell, and add the selected candidate cooperating set into a second group;

remove all candidate cooperating sets which are non-orthogonal with the candidate cooperating set added into the second group from the first group, and return to the step of selecting the candidate cooperating set with the highest priority from the first group until the first group is null.

20. The central controller of claim 18, wherein the scheduling unit comprises:

a coordinated transmission mode dividing module to divide all candidate cooperating sets in the super-cell into at least two groups, wherein it is guaranteed that all candidate cooperating sets in each group are orthogonal, and take each group of candidate cooperating sets as a coordinated transmission mode; and

a UE scheduling module to allocate a downlink slot for each coordinated transmission mode, and perform, during a slot corresponding to one coordinated transmission mode, scheduling among all the UEs in each candidate cooperating set in the coordinated transmission mode according to information of the cooperating sets selected by all the UEs and the channel information fed back by all the UEs to maximize weighted throughput of all the UEs scheduled in each candidate cooperating set.

21. The central controller of claim 18, wherein the scheduling module comprises:

a coordinated transmission mode dividing module to divide all candidate cooperating sets in the super-cell into at least two groups, wherein it is guaranteed that all candidate cooperating sets in each group are orthogonal, and take each group of candidate cooperating sets as a coordinated transmission mode; and

a UE scheduling module to allocate a downlink frequency band for each coordinated transmission mode, and perform, within a downlink frequency band corresponding to one coordinated transmission mode, scheduling among all the UEs in each candidate cooperating set in the coordinated transmission mode according to information of the cooperating sets selected by all the UEs and the channel information fed back by all the UEs to maximize weighted throughput of all the UEs scheduled in each candidate cooperating set.

22. A User Equipment (UE), comprising:

a cooperating set selecting unit to select a cooperating set from all candidate cooperating sets broadcasted by a central controller of a super-cell as a cooperating set of the UE; and

a cooperating set information feedback unit to feed back information of the cooperating set selected to the central controller of the super-cell.

23. The UE of claim 22, further comprising:

a channel information feedback unit to dynamically measure a channel condition of the UE, and feed back channel information obtained by measurement to the central controller.

24. A User Equipment (UE), comprising:

a candidate cooperating set information receiving unit to receive information of all candidate cooperating sets broadcasted by a central controller of a super-cell;

a measuring unit to measure all the candidate cooperating sets; and

a channel information feedback unit to feed back channel information obtained by measurement to the central controller.