Collaborative Beam Forming of Base Transceiver stations for Reducing Interference in a Wireless Multi-Cell Network

• US 20080096546A1
• Filed: 03/23/2007
• Published: 04/24/2008
• Est. Priority Date: 10/24/2006
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Navini Networks, Inc. (Cisco Systems, Inc.)
• Inventors: Guo, Li, Jin, Hang
• Granted Patent: US 7,519,366 B2
• Time in Patent Office: Days
• US Class Current: 455/424
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: H04W 36/00692 using simultaneous multiple data streams, e.g. cooperative multipoint [CoMP], carrier aggregation [CA] or multiple input multiple output [MIMO] allocation of physical resources in CoMP or in CA H04L5/0035
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 36/20 for optimising the interference level

Abstract

A method of signal transmission and reception for a cellular wireless network includes steps of detecting signal strength of signals transmitted or received between a mobile station and a plurality of base transceiver stations; selecting a plurality of candidate serving base transceiver stations based on the detected signal strength; selecting a first group of serving base transceiver stations from the candidate serving base transceiver stations; and sending signals between the mobile station and the first group of serving base transceiver stations using beam forming technology to reduce interference received by the mobile station.

Claims

1. A method of signal transmission and reception for a cellular wireless network, comprising:

detecting signal strength of signals transmitted or received between a mobile station and a plurality of base transceiver stations;

selecting a plurality of candidate serving base transceiver stations based on the detected signal strength;

selecting a first group of serving base transceiver stations from the candidate serving base transceiver stations; and

sending signals between the mobile station and the first group of serving base transceiver stations using beam forming technology to reduce interference received by the mobile station.

2. The method of claim 1 wherein the candidate serving base transceiver stations are selected if their signal strength is greater than a predetermined threshold.

3. The method of claim 1 wherein the candidate serving base transceiver stations are selected if the candidate serving base transceiver stations have a combined signal to noise ratio greater than a predetermined threshold.

4. The method of claim 1 wherein the signal strength is associated with downlink signals received by the mobile station from the plurality of base transceiver stations.

5. The method of claim 4 further comprising transmitting signals containing information indicating the candidate serving base transceiver stations from the mobile station to current uplink serving base transceiver stations.

6. The method of claim 5 further comprising forwarding the indicating signals from the current uplink serving base transceiver stations to an element management server.

7. The method of claim 6 further comprising determining beam forming weighing factors for the first group of serving base transceiver stations, using the element management server.

8. The method of claim 7 further comprising transmitting a command signal containing information regarding the first group of base transceiver stations and the beam forming weighing factors from the element management server to the first group of serving base transceiver stations and current downlink serving base transceiver stations.

9. The method of claim 8 further comprising deactivating a first subset of base transceiver stations of the current downlink serving base transceiver stations from forming downlinks with the mobile station if the first subset of base transceiver stations do not belong to the first group of serving base transceiver stations.

10. The method of claim 9 further comprising activating a second subset of base transceiver stations of the first group of serving base transceiver stations to form downlinks with the mobile station if the second subset of base transceiver stations do not belong to the current downlink base transceiver stations.

11. The method of claim 10 further comprising sending a confirmation signal indicating whether beam forming among a plurality of base transceiver stations is performed.

12. The method of claim 1 wherein the signal strength is associated with uplink signals received by the plurality of base transceiver stations from the mobile station.

13. The method of claim 12 further comprising transmitting an uplink signal strength report from current uplink serving base transceiver stations to the element management server.

14. The method of claim 13 further comprising transmitting a command signal containing information regarding the first group of base transceiver stations from the element management server to the first group of serving base transceiver stations and the current uplink serving base transceiver stations.

15. The method of claim 14 further comprising deactivating a first subset of base transceiver stations of the current uplink serving base transceiver stations from forming uplinks with the mobile station if the first subset of base transceiver stations do not belong to the first group of serving base transceiver stations.

16. The method of claim 15 further comprising activating a second subset of base transceiver stations of the first group of base transceiver stations to form uplinks with the mobile station if the second subset of base transceiver stations do not belong to the current uplink base transceiver stations.

17. An element management server for controlling a plurality of base transceiver stations for transmitting downlink signals to at least one mobile station in a cellular wireless network, comprising:

means for selecting a first group of serving base transceiver stations from a plurality of candidate serving base transceiver stations provided by a mobile station based on signal strength received by the mobile station from a plurality of base transceiver stations; and

means for transmitting a command signal containing information regarding the first group of serving base transceiver stations to the first group of serving base transceiver stations and current downlink serving base transceiver stations for deactivating a first subset of base transceiver stations of the current downlink serving base transceiver stations from forming downlinks with the mobile station if the first subset of base transceiver stations do not belong to the first group of serving base transceiver stations, and for activating a second subset of base transceiver stations of the first group of serving base transceiver stations to form downlinks with the mobile station if the second subset of base transceiver stations do not belong to the current downlink base transceiver stations,

wherein the first group of serving base transceiver stations transmit downlink signals to the mobile station using a beam forming technology.

18. The element management server of claim 17 wherein the candidate serving base transceiver stations are selected if their signal strength is greater than a predetermined threshold.

19. The element management server of claim 17 wherein the candidate serving base transceiver stations are selected if the candidate serving base transceiver stations have a combined signal to noise ratio greater than a predetermined threshold.

20. An element management server for controlling a plurality of base transceiver stations for receiving downlink signals from at least one mobile station in a cellular wireless network, comprising:

means for selecting a first group of serving base transceiver stations from a plurality of candidate serving base transceiver stations provided by current uplink base transceiver stations based on signal strength received by the current uplink base transceiver stations from the mobile station; and

means for transmitting a command signal containing information regarding the first group of serving base transceiver stations to the first group of serving base transceiver stations and current uplink serving base transceiver stations for deactivating a first subset of base transceiver stations of the current uplink serving base transceiver stations from forming uplinks with the mobile station if the first subset of base transceiver stations do not belong to the first group of serving base transceiver stations, and for activating a second subset of base transceiver stations of the first group of serving base transceiver stations to form uplinks with the mobile station if the second subset of base transceiver stations do not belong to the current uplink base transceiver stations.

21. The element management server of claim 20 wherein the candidate serving base transceiver stations are selected if their signal strength is greater than a predetermined threshold.

22. The element management server of claim 20 wherein the candidate serving base transceiver stations are selected if the candidate serving base transceiver stations have a combined signal to noise ratio greater than a predetermined threshold.