GSM channel tracking

• US 9,066,270 B2
• Filed: 03/15/2013
• Issued: 06/23/2015
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Raytheon Applied Signal Technology Incorporated (Rtx Corporation)
• Original Assignee: Raytheon Applied Signal Technology Incorporated (Rtx Corporation)
• Inventors: Cunningham, Daniel, Guastaferro, Peter
• Primary Examiner(s): Elhag, Magdi
• Application Number:
  US13/837,271
• Publication Number:
  US 20140274054A1
• Time in Patent Office: 830 Days
• Field of Search: 455/403, 455/404.1, 455/404.2, 455/405, 455/406, 455/408, 455/410, 455/414.1, 455/414.2, 455/415, 455418-420, 455/423, 455/424, 455/436, 455/450, 455/456.1, 455/456.2
• US Class Current: 1/1
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic
• CPC Class Codes: H04W 36/0066 of control information between different types of networks in order to establish a new radio link in the target network
• CPC Class Codes: H04W 36/08 Reselecting an access point

Abstract

A system and method for determining a correspondence between an Abis signaling channel and an air channel frequency designator. A monitoring instrument may be connected to multiple E1 circuits, monitoring messages sent on Abis signaling channels. By repeatedly observing channel activation messages (135) preceding channel assignment messages (145) of interest, or channel assignment messages (145) following channel activation messages (135) of interest, the instrument may infer a correspondence between an Abis signaling channel and an air channel frequency designator.

Claims

1. A monitoring instrument, comprising:

a processor; and

a memory, wherein the memory has stored thereon instructions that, when executed by the processor, cause the processor;

to determine a correspondence between a Global System for Mobile Communications (GSM) air channel frequency designator and an Abis signaling channel, by

detecting a first channel activation message on the Abis signaling channel;

detecting, during a first time interval following the first channel activation message, a first set of one or more frequency designators;

detecting a second channel activation message on the Abis signaling channel;

detecting, during a second time interval following the second channel activation message, a second set of one or more frequency designators; and

forming a list of candidate frequency designators comprising frequency designators included in both;

the first set of one or more frequency designators, and

the second set of one or more frequency designators; and

to use the correspondence established when the list of candidate frequency designators contains exactly one frequency designator to identify a post-handover Abis signaling channel corresponding to a post-handover frequency designator.

2. The instrument of claim 1, wherein the first set of one or more frequency designators and the second set of one or more frequency designators comprise one or more absolute radio frequency channel numbers (ARFCNs).

3. The instrument of claim 1, wherein the first set of one or more frequency designators and the second set of one or more frequency designators comprise one or more mobile allocation index offsets (MAIOs) and one or more hopping sequence numbers (HSNs).

4. The instrument of claim 1, wherein the Abis signaling channel is a channel on an E1 circuit.

5. The instrument of claim 1, wherein the length of each of the first time interval and the second time interval is more than 2 seconds and less than 10 seconds.

6. The instrument of claim 1, wherein:

the detecting of the first channel activation message on the Abis signaling channel comprises detecting a first channel activation message having a first air channel time slot;

the detecting, during a first time interval following the first channel activation message, of a first set of one or more frequency designators comprises detecting a set of one or more frequency designators associated in channel assignment messages with the first air channel time slot;

the detecting of a second channel activation message on the Abis signaling channel comprises detecting a second channel activation message having a second air channel time slot; and

the detecting, during a second time interval following the second channel activation message, of a second set of one or more frequency designators comprises detecting a set of one or more frequency designators associated in channel assignment messages with the second air channel time slot.

7. A method for monitoring a Global System for Mobile Communications (GSM) network, the method comprising:

determining a correspondence between an air channel frequency designator and an Abis signaling channel; and

using the correspondence to identify a post-handover Abis signaling channel corresponding to a post-handover frequency designator,

the determining comprising;

detecting a first channel activation message on the Abis signaling channel;

detecting, during a first time interval following the first channel activation message, a first set of one or more frequency designators;

detecting a second channel activation message on the Abis signaling channel;

detecting, during a second time interval following the second channel activation message, a second set of one or more frequency designators;

forming a list of candidate frequency designators comprising frequency designators included in both;

the first set of one or more frequency designators, and

the second set of one or more frequency designators; and

identifying the correspondence when the list of candidate frequency designators contains exactly one frequency designator.

8. The method of claim 7, wherein the first set of one or more frequency designators and the second set of one or more frequency designators comprise one or more absolute radio frequency channel numbers (ARFCNs).

9. The method of claim 7, wherein the first set of one or more frequency designators and the second set of one or more frequency designators comprise one or more mobile allocation index offsets (MAIOs) and one or more hopping sequence numbers (HSNs).

10. The method of claim 7, wherein the Abis signaling channel is a channel on an E1 circuit.

11. The method of claim 7, wherein the length of each of the first time interval and the second time interval is more than 2 seconds and less than 10 seconds.

12. A monitoring instrument, comprising:

a processor; and

a memory, wherein the memory has stored thereon instructions that, when executed by the processor, cause the processor;

to determine a correspondence between a Global System for Mobile Communications (GSM) air channel frequency designator and an Abis signaling channel, by

detecting a first channel assignment message containing a first air channel frequency designator;

detecting, during a first time interval preceding the first channel assignment message, a first set of one or more Abis signaling channel activation messages for activating a first set of one or more Abis signaling channels;

detecting a second channel assignment message containing the first air channel frequency designator;

detecting, during a second time interval preceding the second channel assignment message, a second set of one or more Abis signaling channel activation messages for activating a second set of one or more Abis signaling channels; and

forming a list of candidate Abis signaling channels comprising Abis signaling channels included in both;

the first set of one or more Abis signaling channels, and

the second set of one or more Abis signaling channels; and

to use the correspondence established when the list of candidate Abis signaling channels contains exactly one Abis signaling channel to identify a post-handover Abis signaling channel corresponding to a post-handover frequency designator.

13. The instrument of claim 12, wherein the frequency designator is an absolute radio frequency channel number (ARFCN).

14. The instrument of claim 12, wherein the frequency designator is a combination of a mobile allocation index offset and a hopping sequence number (HSN).

15. The instrument of claim 12, wherein the Abis signaling channel is a channel on an E1 circuit.

16. The instrument of claim 12, wherein the length of each of the first time interval and the second time interval is more than 2 seconds and less than 10 seconds.

17. The instrument of claim 12, wherein:

the detecting of the first channel assignment message containing a first air channel frequency designator comprises detecting a first channel assignment message containing a first air channel frequency designator and a first air channel time slot;

the detecting, during a first time interval preceding the first channel assignment message, a first set of one or more Abis signaling channel activation messages for activating a first set of one or more Abis signaling channels comprises detecting, during a first time interval preceding the first channel assignment message, a first set of one or more Abis signaling channel activation messages, having a first air channel time slot, for activating a first set of one or more Abis signaling channels;

the detecting of a second channel assignment message containing the first air channel frequency designator comprises detecting a second channel assignment message containing the first air channel frequency designator and a second air channel time slot; and

the detecting, during a second time interval preceding the second channel assignment message, of a second set of one or more Abis signaling channel activation messages for activating a second set of one or more Abis signaling channels comprises detecting, during a second time interval preceding the second channel assignment message, a second set of one or more Abis signaling channel activation messages, having a second air channel time slot, for activating a second set of one or more Abis signaling channels.