NEIGHBOR CELL RELATION LIST INITIALIZATION

• US 20090047968A1
• Filed: 06/20/2008
• Published: 02/19/2009
• Est. Priority Date: 08/13/2007
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Gunnarsson, Fredrik, Frenger, Pal, Moe, Johan
• Granted Patent: US 8,165,590 B2
• Time in Patent Office: Days
• US Class Current: 455/446
• CPC Class Codes: H04W 36/0007 for multicast or broadcast services, e.g. MBMS multicast or broadcast application services H04W4/06; resource management for broadcast services H04W72/30; connection management for selective distribution or broadcast H04W76/40
• CPC Class Codes: H04W 36/30 by measured or perceived connection quality data
• CPC Class Codes: H04W 36/38 by fixed network equipment
• CPC Class Codes: H04W 4/06 Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
• CPC Class Codes: H04W 48/12 using downlink control channel
• CPC Class Codes: H04W 84/045 using private Base Stations, e.g. femto Base Stations, home Node B

Abstract

Neighbor cell relation lists are initialized and managed in various ways that are especially beneficial to closed subscriber group (CSG) cells served by CSG base stations. Typically, only a radio terminal belonging to the CSG is permitted to access and receive service from the CSG cell. As a result, information is provided to radio terminals in the cells neighboring the CSG cell that generally indicates that radio terminals are not to report to a respective serving base station signal quality measurements of a signal received from the CSG base station unless the radio terminal is a member of the closed subscriber group for the CSG cell. When a CSG cell is powered-up, it is determined whether the CSG cell has previously been powered-on in the same environment. If so, the neighbor cell relation information for the CSG cell is updated with other network node(s). If not, neighbor cell relations of the CSG cell are initialized. In one example, when a new neighbor cell relation has been added to its neighbor cell relation list, the CSG base station inherits neighbor cell relation list entries from the newly-added neighbor cell.

Claims

1. A method for managing neighbor cell relation lists of a closed subscriber group (CSG) cell served by a CSG base station, where only a radio terminal belonging to the CSG is permitted to access and receive service from the CSG cell, and where information is provided to radio terminals in the cells neighboring the CSG cell that generally indicates that radio terminals are not to report to a respective serving base station signal quality measurements of a signal received from the CSG base station unless the radio terminal is a member of the closed subscriber group for the CSG cell, the method comprising the steps of:

(a) powering-up the CSG cell;

(b) determining whether the CSG cell has previously been powered-on in a same environment;

(c) if the CSG cell is powered-on in the same environment, updating neighbor cell relation information for the CSG cell by comparing information with one or more other network nodes; and

(d) if the CSG cell is not powered-on in the same environment, initializing neighbor cell relation information for the CSG cell.

2. The method in claim 1, wherein the environment includes a location of the CSG cell.

3. The method in claim 1, wherein the environment includes network connectivity information associated with the CSG base station.

4. The method in claim 3, wherein the connectivity information includes CSG base station connection address information, such as an internet protocol address, internet protocol subnet information, or information about an internet service provider providing network connectivity to the CSG base station location.

5. The method in claim 1, wherein the CSG base station informs the central node that the environment has changed.

6. The method in claim 5, wherein the CSG base station includes means for permitting an owner or operator of the CSG base station to trigger a message to the central node informing that the CSG base station is in a new environment.

7. The method in claim 1, wherein the environment includes a cell network in which the CSG cell is a member and a different environment includes a change in neighbor cell relation information for one or more other cells in the cell network since a last time the CSG cell was powered-on.

8. A method for initializing a closed subscriber group (CSG) cell served by a CSG base station, where only a radio terminal belonging to the CSG is permitted to access and receive service from the CSG cell, and where information is provided to radio terminals in cells neighboring the CSG cell that generally indicates that radio terminals are not to report to a respective serving base station signal quality measurements of a signal received from the CSG base station unless the radio terminal is a member of the closed subscriber group for the CSG cell, the method comprising the following after the CSG cell powers-up:

informing the radio terminals in neighboring cells that if they receive a signal transmitted by the CSG base station at or above a predetermined signal quality, or if the received signal quality of a signal transmitted by the CSG base station is higher than the signal quality of a signal transmitted by the serving base station by a predetermined amount, then those radio terminals in neighboring cells may report signal quality measurements for the CSG cell to a respective serving cell even though one or more of the radio terminals in neighboring cells do not belong to the closed subscriber group of the CSG.

9. The method in claim 8, wherein the method is performed by the serving base station in the neighboring cells.

10. A method for initializing a closed subscriber group (CSG) cell served by a CSG base station, where in general only a radio terminal belonging to the CSG is permitted to access and receive service from the CSG cell, and where the CSG base station signals that the CSG cell is a forbidden cell over a broadcast channel of the CSG cell, the method comprising the following steps after the CSG cell powers-up:

(a) halting signaling that the CSG cell is a forbidden cell so that radio terminals served by neighboring cells can report signal quality measurements associated with the CSG cell to their serving cells; and

(b) when a predetermined number of neighbor cells are included in a neighbor cell list for the CSG cell, informing radio terminals that the CSG cell is a forbidden cell where only radio terminals belonging to the closed subscriber group of the CSG cell may report signal quality measurements for the CSG cell to their respective serving cells.

11. The method in claim 10, wherein steps (a) and (b) are performed by the CSG base station.

12. The method in claim 10, wherein steps (a) and (b) are performed if the CSG cell has been moved to a new location different from a location when the CSG cell was last powered-up or if a neighbor cell relation information for multiple cells in a cell network that the CSG cell belongs to has changed since a last time the CSG cell was powered-on.

13. The method in claim 10, wherein steps (a) and (b) are not preformed if the CSG cell has not been moved to a new location different from a location when the CSG cell was last powered-up or if a neighbor cell relation information for multiple cells in a cell network that the CSG cell belongs to has not changed since a last time the CSG cell was powered-on, in which case, neighbor cell information associated with the CSG cell is updated.

14. The method in claim 10, wherein after the CSG cell powers-up, the method further comprises:

identifying a first cell that is a neighboring cell to the CSG cell;

adding one or more neighbor cells associated with the first cell as one or more neighbor cells associated with the CSG cell until a predetermined number of neighbor cells is included in a neighbor cell relations list for the CSG cell.

15. The method in claim 14, wherein the neighbor cell relation list information of the first cell is signaled from a central node to the CSG base station serving the CSG cell.

16. The method in claim 14, wherein the neighbor cell relation list information of the first cell is signaled from the first base station serving the first cell to the CSG cell.

17. The method in claim 14, wherein the adding of one or more neighbors associated with the first cell is performed if the CSG cell has been moved to a new location different from a location when the CSG cell was last powered-up or if neighbor cell relation information for multiple cells in a cell network that the CSG cell belongs to has changed since a last time the CSG cell was powered-on.

18. A method for initializing a closed subscriber group (CSG) cell served by a CSG base station, where only a radio terminal belonging to the CSG is permitted to access and receive service from the CSG cell, the method comprising:

providing information to radio terminals served by the CSG cell to report to the CSG base station signal quality measurements of signals received from neighboring cell base stations if a received signal quality of a signal transmitted by a neighboring base station is within a reporting window relative to a received signal quality of a signal transmitted by the CSG base station,

wherein the CSG base station initially configures a relatively wide reporting window to increase a number of signal quality measurement reports associated with neighboring cells, and then reconfigures the reporting window to a narrower reporting window when a number of established neighbor relations in neighbor cell relation list for the CSG cell is at or above a predetermined threshold.

19. A base station for serving a cell and providing to served radio terminals information that generally indicates that radio terminals are not to report to the serving base station signal quality measurements of a signal received from the CSG base station unless the radio terminal is a member of the closed subscriber group, the CSG base station comprising:

radio transceiving circuitry, and

a data processing system including electronic circuitry configured to inform radio terminals via the radio transceiving circuitry that if they receive a signal transmitted by the CSG base station at or above a predetermined signal quality, then the radio terminals may report signal quality measurements for the CSG cell to the serving cell even though some of the radio terminals are not in the closed subscriber group of the CSG cell.

20. A closed subscriber group (CSG) base station for serving a CSG cell, where in general only a radio terminal belonging to the closed subscriber group is permitted to access and receive service from the CSG cell, and where the CSG base station signals that the CSG cell is forbidden over the broadcast channel of the CSG cell, the CSG base station comprising:

radio transceiving circuitry, and

a data processing system including electronic circuitry configured, when the CSG cell is powered-up, to perform the following tasks;

(a) initially inhibit signaling via the radio transceiving circuitry that the CSG cell is forbidden so that radio terminals served by neighboring cells can report a received signal quality associated with the CSG cell to their serving cells; and

(b) thereafter, when a predetermined number of neighbor cells are included in a neighbor cell list for the CSG cell, signaling, via the radio transceiving circuitry, that the CSG cell is a forbidden cell where only radio terminals belonging to the closed subscriber group of the CSG cell may report signal quality measurements for the CSG cell to their respective serving cells.

21. The CSG base station in claim 20, wherein tasks (a) and (b) are performed if the CSG cell has been moved to a new location different from a location when the CSG cell was last powered-up or a neighbor cell relation information for multiple cells in a cell network that the CSG cell belongs to has changed since a last time the CSG cell was powered-on.

22. The CSG base station in claim 20, wherein tasks (a) and (b) are not performed if the CSG cell has not been moved to a new location different from a location when the CSG cell was last powered-up or if a neighbor cell relation information for multiple cells in a cell network that the CSG cell belongs to has not changed since a last time the CSG cell was powered-on, and

wherein if the CSG cell has not been moved to a new location different from a location when the CSG cell was last powered-up or if a neighbor cell relation information for multiple cells in a cell network that the CSG cell belongs to has not changed since a last time the CSG cell was powered-on, neighbor cell information associated with the CSG cell is updated.

23. The CSG base station in claim 20, wherein the CSG base station includes means to permit a CSG base station owner or operator to trigger a message to a central node informing that the CSG base station is in a new environment.

24. The CSG base station in claim 20, wherein the CSG base station includes means to permit a CSG base station owner or operator to inhibit signaling via the radio transceiving circuitry that the CSG cell is forbidden so that radio terminals served by neighboring cells can report a received signal quality associated with the CSG cell to their respective serving cell.

25. The CSG base station in claim 20, wherein the CSG base station includes means to permit a CSG base station owner or operator to initiate signaling via the radio transceiving circuitry indicating that the CSG cell is a forbidden cell so that radio terminals served by neighboring cells are instructed not to report a received signal quality associated with the CSG cell to their respective serving cell.

26. A network node for use in a network including open base stations associated with open access cells and a closed subscriber group (CSG) base station serving a CSG cell in which only a radio terminal belonging to the CSG is permitted to access and receive service from the CSG cell, and where information is provided to radio terminals in cells neighboring the CSG cell that generally indicates that radio terminals are not to report to a respective serving base station signal quality measurements of a signal received from the CSG base station unless the radio terminal is a member of the closed subscriber group, the network node comprising:

a memory for storing CSG base station environment information

a controller configured to;

detecting the CSG base station environment information of a CSG cell recently powered-up for operation;

determine whether the CSG base station is in the same environment after being powered-up compared to the stored environment information from when the CSG base station was powered-up the last time; and

if the CSG cell is not powered-on in the same environment, initialize neighbor cell relation information for the CSG cell.

27. The network node in claim 26, wherein the network node is a central node coupled to the CSG and other base stations, and wherein the memory stores (i) a neighbor cell relation list for each open cell, (ii) a neighbor cell relation list for each CSG cell, and (iii) a CSG authorization list which, for each of multiple radio terminals, identifies all CSG cells that the radio terminal is authorized to access and receive service from.

28. The network node in claim 26, wherein the CSG base station informs the network node of a changed environment.

29. The network node in claim 26, wherein the network node is a base station.

30. A network node, comprising:

a memory for storing a neighbor cell relation list for each cell having an associated base station; and

a controller configured to;

determine that a cell recently powered-up for operation;

based on neighbor cell relation list information stored in the memory, identify a first cell that is a neighboring cell to the powered-up cell; and

add one or more neighbor cells associated with the first cell as neighbor cells associated with the powered-up cell until a predetermined number of neighbor cells are included in a neighbor cell list for the powered-up cell.

31. The network node in claim 30, wherein the network node is a central node configured to provide the neighbor cell relation list information of the first cell to a base station serving the first cell.

32. The network node in claim 30, wherein the first cell is a closed subscriber group (CSG) cell and the neighbor cell relation list information of the first cell is provided to a CSG base station serving the CSG cell by a first base station serving the first cell.

33. A radio terminal, comprising:

radio transceiving circuitry, and

a data processing system coupled to the radio transceiving circuitry including electronic circuitry configured to;

receive signals transmitted by neighboring base stations associated with neighboring cells and determine an associated signal quality;

identify those signals transmitted by neighboring base stations that exceed a predetermined signal quality threshold; and

determine whether a signal quality of a signal transmitted by a restricted access base station associated with a restricted access cell exceeds a signal quality of signals transmitted by non-restricted access base stations that exceed the predetermined signal quality threshold, and if so, to send a registration request to the restricted access base station.

34. The radio terminal in claim 33, wherein the electronic circuitry is configured, if the signal quality measurement corresponding to the CSG cell does not exceed a signal quality measurement corresponding to a non-CSG cell by a predetermined amount, to send a registration request to one of the non-CSG cells associated a signal quality measurement that exceeds the predetermined signal quality threshold.

35. The radio terminal in claim 33, wherein some of the identified signals correspond to restricted access cells, and wherein the electronic circuitry is configured to determine whether the radio terminal has access to at least one of those restricted access cells before attempting to send a registration request to the restricted access base station.

36. A radio terminal, comprising:

radio transceiving circuitry, and

a data processing system coupled to the radio transceiving circuitry including electronic circuitry configured to;

receive signals transmitted by neighboring base stations associated with neighboring cells and determine an associated signal quality;

identify those signals transmitted by neighboring base stations that exceed a predetermined signal quality threshold; and

determine whether a signal quality of a signal transmitted by a restricted access base station associated with a restricted access cell exceeds a signal quality of signals transmitted by non-restricted access base stations by a predetermined, and if so, to trigger a measurement report that is sent, via the radio transceiving circuitry, to the serving base station.

37. The radio terminal in claim 36, wherein the a reconfigured predetermined amount can be reconfigured, via the radio transceiver circuitry, by the serving base station.