FEMTO-BTS RF ACCESS MECHANISM

• US 20120258711A1
• Filed: 06/21/2012
• Published: 10/11/2012
• Est. Priority Date: 08/22/2007
• Status: Active Grant

• Current Assignee: Cellco Partnership, Inc. (Verizon Communications Inc.)
• Original Assignee: Cellco Partnership, Inc. (Verizon Communications Inc.)
• Inventors: Bao, Derek Hongwei, Chiang, David
• Granted Patent: US 8,363,621 B2
• Time in Patent Office: Days
• US Class Current: 455/434
• CPC Class Codes: H04W 48/12 using downlink control channel
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 84/045 using private Base Stations, e.g. femto Base Stations, home Node B

Abstract

Femto cells that extend mobile network coverage into customer premises operate in a frequency band typically assigned to a macro network. To facilitate system discovery and registrations of mobile stations with femto cells, a carrier designates one the channels within the band as a primary channel for its femto cells. For example, neighbor list messages transmitted by macro network base stations can provide frequency and PN code information directing mobile stations to search the primary channel for a PN code of the femto cells. The mobile station preferred roaming list (PRL) may identify femto cells by SID/NID. The SID is that of the carrier'"'"'s macro network, whereas the NID may be a NID of the macro network or one specifically assigned to femto cell operations. The PRL uses frequency acquisition information for the femto cells that is the same as or similar to that for one of the macro networks.

Claims

1. A method comprising:

receiving, in a mobile station operable through base stations of a macro wireless communication network operated by a carrier and through at least one of a plurality of customer premises femto cells, a transmission of a neighbor list message from a base station of the carrier'"'"'s macro network, the neighbor list message containing information for use in searching at a particular frequency for and selecting a femto cell base transceiver system (BTS),

wherein the information for use in searching for and selecting a femto cell comprises an identification of a primary frequency channel designated for use by all femto cell BTSs of the carrier'"'"'s customers in a region served by the carrier'"'"'s macro network, from among a plurality of channels available for femto cell communication, and a code designated for use by femto cell BTSs of the carrier'"'"'s customers in the region communicating on the primary frequency channel;

searching for a system with which to register the mobile station for handoff, the search including searching the primary frequency channel for communications of a femto cell BTS using the code; and

upon detecting a condition for handoff, initiating a procedure to register the mobile station with one of the femto cell BTSs, based on the search detecting use of the code on the primary frequency channel.

2. The method of claim 1, wherein the identification of the primary frequency channel identifies a designated one of a plurality of frequency channels of a frequency band assigned for mobile communications via a macro network.

3. The method of claim 1, wherein the neighbor list message is a general neighbor list message (GNLM).

4. The method of claim 1, wherein:

the code designated for use by femto cell BTSs comprises a pseudorandom noise (PN) code for a pilot on the primary frequency channel, and

the PN code for the pilot on the primary frequency channel is the same PN code for all femto cell BTSs in the region.

5. The method of claim 1, wherein the code comprises a pseudorandom noise (PN) code for traffic communication service on the primary frequency channel.

6. The method of claim 1, wherein:

the code included in the information for use in searching for and selecting a femto cell is a pseudorandom noise (PN) code for a pilot on the primary frequency channel; and

the information for use in searching for and selecting a femto cell further includes a PN code for traffic communication service on the primary frequency channel.

7. The method of claim 1, wherein the code designated for use by femto cell BTSs comprises a plurality of pseudorandom noise (PN) codes for pilots on the primary frequency channel in the region.

8. The method of claim 1, wherein the neighbor list message comprises, for each region of a plurality of regions served by the carrier'"'"'s macro network, identification of a primary frequency channel designated for use by all femto cell BTSs of the carrier'"'"'s customers in a respective region.

9. The method of claim 1, wherein the step of initiating a procedure to register the mobile station with one of the femto cell BTSs comprises:

performing a hash, using data obtained from a pilot of the one femto cell BTS on the primary frequency channel, to identify a frequency channel designated for traffic communications with the one femto cell BTS; and

registering the mobile station with the one femto cell BTS using the identified frequency channel.

10. A mobile station comprising:

a communication interface configured to enable the mobile station to operate through a plurality of base stations and a plurality of femto cells of a macro wireless communication network,

wherein the macro wireless communication network is operated by a carrier and comprises the plurality of base stations and the plurality of femto cells installed in premises of a plurality of the carrier'"'"'s customers; and

a processor configured to enable the mobile station to perform functions to enable handoff to one of the plurality of femto cells, including functions to;

receive a transmission of a neighbor list message from a base station of the carrier'"'"'s macro network, the neighbor list message containing information for use in searching at a particular frequency for and selecting a femto cell base transceiver system (BTS),

wherein the information for use in searching for and selecting a femto cell comprises an identification of a primary frequency channel designated for use by all femto cell BTSs of the carrier'"'"'s customers in a region served by the carrier'"'"'s macro network, from among a plurality of channels available for femto cell communication, and a code designated for use by femto cell BTSs of the carrier'"'"'s customers in the region communicating on the primary frequency channel;

search for a system with which to register the mobile station for handoff, the search including searching the primary frequency channel for communications of a femto cell BTS using the code; and

upon detecting a condition for handoff, initiate a procedure to register the mobile station with one of the femto cell BTSs, based on the search detecting use of the code on the primary frequency channel.

11. The mobile station of claim 10, wherein the identification of the primary frequency channel identifies a designated one of a plurality of frequency channels of a frequency band assigned for mobile communications via a macro network.

12. The mobile station of claim 10, wherein the neighbor list message is a general neighbor list message (GNLM).

13. The mobile station of claim 10, wherein:

the code designated for use by femto cell BTSs comprises a pseudorandom noise (PN) code for a pilot on the primary frequency channel, and

the PN code for the pilot on the primary frequency channel is the same PN code for all femto cell BTSs in the region.

14. The mobile station of claim 10, wherein the code comprises a pseudorandom noise (PN) code for traffic communication service on the primary frequency channel.

15. The mobile station of claim 10, wherein:

the code included in the information for use in searching for and selecting a femto cell is a pseudorandom noise (PN) code for a pilot on the primary frequency channel; and

the information for use in searching for and selecting a femto cell further includes a PN code for traffic communication service on the primary frequency channel.

16. The mobile station of claim 10, wherein the code designated for use by femto cell BTSs comprises a plurality of pseudorandom noise (PN) codes for pilots on the primary frequency channel in the region.

17. The mobile station of claim 10, wherein the neighbor list message comprises, for each region of a plurality of regions served by the carrier'"'"'s macro network, identification of a primary frequency channel designated for use by all femto cell BTSs of the carrier'"'"'s customers in a respective region.

18. The mobile station of claim 10, wherein the function to initiate a procedure to register the mobile station with one of the femto cell BTSs comprises:

performing a hash, using data obtained from a pilot of the one femto cell BTS on the primary frequency channel, to identify a frequency channel designated for traffic communications with the one femto cell BTS; and

registering the mobile station with the one femto cell BTS using the identified frequency channel.