Method for adaptive formation of cell clusters for cellular wireless networks with coordinated transmission and reception
View Patent ↗The present invention provides a method of forming clusters of cells in a wireless communication system. The method includes accessing information generated by measuring channel conditions for at least one mobile unit and a plurality of cells in the wireless communication system. The method also includes adding more than one of the plurality of cells to at least one cell cluster based on the accessed information and coordinating communication between the cells in each cell cluster and the mobile unit(s).
1. A method of forming clusters of cells in a wireless communication system, comprising:
accessing information generated by measuring a plurality of channel conditions for at least one mobile unit and a plurality of cells in the wireless communication system;
adding more than one of the plurality of cells to at least one cell cluster based on the accessed information;
establishing at least one interface to exchange information between the cells in said at least one cell cluster;
synchronizing communication between the cells in said at least one cell cluster and said at least one mobile unit using timing reference signals transmitted between the cells over said at least one interface; and
updating the cells in the at least one cell cluster by establishing or tearing down interfaces between pairs of cells based on measured values of channel conditions, wherein said updates are performed on a time scale determined by a coherence distance of multipath fading in the wireless communication system.
2. The method of claim 1 , wherein accessing the information generated by measuring a plurality of channel conditions comprises accessing information indicating strengths of a plurality of signals received by said at least one mobile unit or the plurality of cells.
3. The method of claim 2 , wherein accessing the information indicating the strengths of the plurality of signals comprises accessing a plurality of instantaneous signal strengths.
4. The method of claim 3 , wherein accessing the information indicating the plurality of instantaneous signal strengths comprises accessing information indicating at least one of a distance-dependent path loss, shadow fading, or multipath fading between said at least one mobile unit and the plurality of cells.
5. The method of claim 2 , wherein accessing the information indicating the plurality of strengths of the plurality of signals comprises accessing a plurality of local-average signal strengths.
6. The method of claim 5 , wherein accessing the plurality of local-average signal strengths comprises accessing information indicating at least one of a distance-dependent path loss or shadow fading.
7. The method of claim 2 , wherein accessing the information generated by measuring the plurality of channel conditions comprises measuring a level of interference at the plurality of cells.
8. The method of claim 7 , wherein accessing the information generated by measuring the plurality of channel conditions comprises accessing a plurality of signal-to-interference-plus-noise ratios measured at the plurality of cells.
9. The method of claim 8 , wherein adding more than one cell to said at least one cell cluster comprises adding a first cell to said at least one cell cluster, the first cell having a value of the signal-to-interference-plus-noise ratio that exceeds the values of the signal-to-interference-plus-noise ratios of the other cells.
10. The method of claim 9 , wherein adding more than one cell to said at least one cell cluster comprises adding at least one second cell to said at least one cell cluster, said at least one second cell having a value of the signal-to-interference-plus-noise ratio that exceeds a threshold value of the signal-to-interference-plus-noise ratio.
11. The method of claim 10 , wherein the threshold is dependent on the signal-to-interference-plus-noise ratio of said first cell.
12. The method of claim 1 , wherein establishing said at least one interface between the cells in said at least one cell cluster comprises establishing communication channels between the cells using a backhaul network that interconnects the cells.
13. The method of claim 12 , comprising transmitting the timing reference signals over said communication channels of said at least one interface.
14. The method of claim 1 , wherein accessing the information generated by measuring the plurality of channel conditions comprises accessing information generated by measuring a plurality of uplink channel conditions, and wherein adding the cells to said at least one cell cluster comprises adding the cells to an uplink cell cluster, and wherein coordinating communication comprises coordinating communication over the uplink.
15. The method of claim 14 , comprising measuring the uplink channel conditions.
16. The method of claim 1 , wherein accessing the information generated by measuring the plurality of channel conditions comprises accessing information generated by measuring a plurality of downlink channel conditions, and wherein adding the cells to said at least one cell cluster comprises adding the cells to an downlink cell cluster, and wherein coordinating communication comprises coordinating communication over the downlink.
17. The method of claim 16 , wherein accessing the information generated by measuring the plurality of downlink channel conditions comprises receiving feedback from said at least one of mobile unit indicating the information generated by measuring the plurality of downlink channel conditions.
18. The method of claim 16 , wherein accessing the information generated by measuring the plurality of downlink channel conditions comprises accessing information generated by measuring a plurality of uplink channel conditions in a time multiplexed system.
19. A method of forming clusters of cells in a wireless communication system, comprising:
establishing interfaces to exchange information between a plurality of cells in at least one cell cluster associated with a mobile unit, wherein cells are added to said at least one cell cluster in response to the mobile unit measuring a value of a channel condition for the cells that is above a threshold;
synchronizing communication between the cells in said at least one cell cluster and the mobile unit using timing reference signals transmitted between the cells over the interfaces; and
updating the cells in the at least one cell cluster by establishing or tearing down interfaces between pairs of cells based on measured values of channel conditions, wherein said updates are performed on a time scale determined by a coherence distance of multipath fading in the wireless communication system.
20. The method of claim 19 , comprising tearing down at least one of the interfaces between a pair of cells in response to the mobile unit determining that the value of the channel condition for at least one of the pair of cells has fallen below the threshold.
21. The method of claim 19 , wherein updating the cells in said at least one cell cluster on the time scale determined by the coherence distance comprises updating the cells in said at least one cell cluster on a time scale that ranges from milliseconds to tens of milliseconds.
22. The method of claim 19 , wherein establishing said at least one interface between the cells in said at least one cell cluster comprises establishing communication channels between the cells using a backhaul network that interconnects the cells.
23. The method of claim 22 , comprising transmitting the timing reference signals over the communication channels between the cells.