Automated, dynamic minimization of inter-cell site interference in CDMA networks

Patent metadata

Field	Value
Publication number	US-10193650-B2
Application number	US-201415125392-A
Country	US
Kind code	B2
Filing date	Mar 14, 2014
Priority date	Mar 14, 2014
Publication date	Jan 29, 2019
Grant date	Jan 29, 2019

Abstract

Methods and apparatus for allocating scrambling codes to cells of a wireless network. In an example method, current scrambling code allocation information for a plurality of cells and network configuration information for a radio access network are received ( 310 ). A reallocation of scrambling codes to the plurality of cells is computed ( 320 ), based on the current scrambling code allocation information and the network configuration information, using a metaheuristic algorithm. A change in scrambling code for at least one of the plurality of cells is then triggered ( 330 ), based on the computed reallocation. In some embodiments, the metaheuristic algorithm is based on an objective function that comprises a summation of interference metrics for each of the plurality of cells, wherein the interference metrics depend on scrambling code allocations to the plurality of cells. In some embodiments, a simulated annealing metaheuristic is used.

First claim

What is claimed is:

1. A method, in a network node operatively connected to a wireless network, for detecting and correcting problems with scrambling code allocations among cells supported by a group of base stations in the wireless network, where each base station supports one or more of the cells, the method comprising
designating an initial one of the group of base stations as a source base station;
identifying a first set of scrambling codes, the first set of scrambling codes consisting of all scrambling codes allocated to cells supported by the source base station;
determining a second set of scrambling codes, the second set of scrambling codes comprising at least all scrambling codes allocated to cells neighboring any of the cells supported by the source base station;
comparing the first and second sets of scrambling codes to detect duplicate scrambling codes between the first and second sets;
upon detecting a duplicated scrambling code between the first and second sets, using location information for the cells corresponding to the duplicated scrambling code to determine whether interference between the cells is likely and, if interference is likely, changing the scrambling code for the cell that has the duplicated scrambling code and that is supported by a base station other than the source base station; and
selecting a next one of the base stations for designation as the source base station; and
repeating said identifying, determining, comparing, using, changing, and selecting operations until each one of the base stations has been designated as the source base station.

2. The method of claim 1 , further comprising first identifying one or more changes to be made to a current scrambling code allocation among the cells, wherein:
designating the initial one of the base stations as a source base station comprises designating one of those base stations affected by the one or more changes; and
the identified set of scrambling codes reflects the one or more changes to be made to the current scrambling code allocation.

3. The method of claim 2 , wherein designating the initial one of the base stations as a source base station comprises determining which of the one or more changes to be made to the current scrambling code allocation is expected to result in a highest improvement in inter-cell interference and designating the base station corresponding to that change as the source base station.

4. The method of claim 2 , wherein identifying one or more changes to be made to a current scrambling code allocation among the cells comprises:
receiving current scrambling code allocation information for the cells and receiving network configuration information for the group of base stations;
computing a reallocation of scrambling codes to the cells, based on the current scrambling code allocation information and the network configuration information, using a metaheuristic algorithm; and
identifying the one or more changes to be made based on the computed reallocation.

5. The method of claim 4 , wherein the metaheuristic algorithm is based on an objective function that comprises a summation of interference metrics for each of the cells, wherein the interference metrics depend on scrambling code allocations to the cells.

6. The method of claim 4 , wherein the metaheuristic algorithm employs a simulated annealing metaheuristic.

7. The method of claim 1 , further comprising using antenna orientation information for the cells corresponding to the duplicated scrambling codes to determine whether interference between the cells is likely.

8. The method of claim 1 , wherein determining the second set of scrambling codes comprises identifying scrambling codes allocated to cells neighboring any of the cells supported by the source base station using system-configured neighbor relations or using location data corresponding to the cells, or both.

9. The method of claim 1 , wherein determining the second set of scrambling codes comprises including in the second set a first subset comprising all scrambling codes allocated to cells neighboring any of the cells supported by the source base station and further including in the second set one or more scrambling codes identified as closely related to one or more of the scrambling codes in the first subset, wherein scrambling codes are identified as closely related based on predetermined relationships between scrambling codes.

10. The method of claim 1 , wherein using location information for the cells corresponding to the duplicated scrambling codes to determine whether interference between the cells is likely comprises comparing a distance between the cells to a cell radius for one or both of the cells to determine whether interference is likely.

11. The method of claim 1 , wherein the network node is a network-management node operatively connected to one or more base stations in the wireless network or to one or more radio network controllers in the wireless network, or to one or more of each.

12. The method of claim 1 , wherein the network node is a radio network controller controlling a plurality of the base stations.

13. A network node, comprising communications interface circuitry configured to communicate with one or more nodes in a radio access network and a processing circuit configured to control the communications interface circuitry and to:
designate an initial one of a group of base stations in the radio access network as a source base station;
identify a first set of scrambling codes, the first set of scrambling codes consisting of all scrambling codes allocated to cells supported by the source base station;
determine a second set of scrambling codes, the second set of scrambling codes comprising at least all scrambling codes allocated to cells neighboring any of the cells supported by the source base station;
compare the first and second sets of scrambling codes to detect duplicate scrambling codes between the first and second sets;
upon detecting a duplicated scrambling code between the first and second sets, use location information for the cells corresponding to the duplicated scrambling code to determine whether interference between the cells is likely and, if interference is likely, change the scrambling code for the cell that has the duplicated scrambling code and that is supported by a base station other than the source base station;
select a next one of the base stations for designation as the source base station; and
repeat said identifying, determining, comparing, using, changing, and selecting operations until each one of the base stations has been designated as the source base station.

14. The network node of claim 13 , wherein the processing circuit is configured to first identify one or more changes to be made to a current scrambling code allocation among the cells, and wherein the processing circuit is further configured to designate the initial one of the base stations as a source base station by designating one of those base stations affected by the one or more changes, and wherein the identified set of scrambling codes reflects the one or more changes to be made to the current scrambling code allocation.

15. The network node of claim 14 , wherein the processing circuit is configured to designate the initial one of the base stations as a source base station by determining which of the one or more changes to be made to the current scrambling code allocation is expected to result in a highest improvement in inter-cell interference and designating the base station corresponding to that change as the source base station.

16. The network

Assignees

• Ericsson Telefon Ab L M

Inventors

• Joshi Monil
• El Chebib Nader
• El-Najjar Jad

Classifications

• H04W72/541

  using the level of interference · CPC title

• H04L41/08

  Configuration management of networks or network elements (address allocation H04L61/50) · CPC title

• H04W88/08

  Access point devices · CPC title

• H04W72/082

  Electricity · mapped topic

• H04J11/005

  of intercell interference · CPC title