Analysis of neighbouring cells in cellular telecommunications systems

• US 6,192,244 B1
• Filed: 07/27/1998
• Issued: 02/20/2001
• Est. Priority Date: 07/29/1997
• Status: Expired due to Fees

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Hewlett Packard Company (HP Inc.)
• Inventors: Abbadessa, Daniele
• Primary Examiner(s): TROST IV, WILLIAM GEORGE
• Application Number:
  US09/123,032
• Time in Patent Office: 939 Days
• Field of Search: 455/423-425, 455/446-447, 455/436-437, 455/509, 455/514
• US Class Current: 455/436
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic

Abstract

A method is disclosed of analyzing lists of neighboring cells in a cellular telecommunications system comprising a plurality of active mobile stations and a static network, the static network having a first cell and a plurality of cells neighboring the first cell, each of the cells having a base station. The method is applicable to GSM and GSM-like systems. In the case of a GSM system, the analyzing method may comprise the steps of: extracting from the static network the GSM MEAS RES produced by the mobile stations in said first cell and producing a reporting list including, for each position in the GSM BA(SACCH) list, the number of times that any of the base station identifiers has been reported for that position; extracting from the static network GSM HANDO CMD messages for handovers from said first cell, and producing a handover list of the GSM BCCHs and corresponding GSM BSICs in the extracted handover messages; correlating the reporting list and the handover list with respect to the BCCHs; and analyzing the correlated lists to determine whether any of the control channels is affected by bad frequency planning.

Claims

1. A method of analysing lists of neighbouring cells in a cellular telecommunications system comprising a plurality of active mobile stations and a static network, the static network having a first cell and a plurality of cells neighbouring the first cell, some of the neighbouring cells being determined by an operator of the system as planned neighbouring cells, each containing the cells having a base station, wherein:

each base station transmits, on a control channel, a signal including a base station identifier of that base station;

each mobile station in the first cell is provided with an ordered control channel list of control channel frequencies to be detected by that mobile station; and

each mobile station in said first cell reports messages to the static network indicating the base station identifiers of control channels detected by that mobile station and the position in the control channel list of the respective control channel;

the method comprising the steps of;

extracting from the static network such reporting messages for said first cell and producing a reporting list including, for each position in the control channel list, the number of times that any of the base station identifiers has been reported for that position;

obtaining a planned neighbour list of the control channels and respective base station identifiers of the planned neighbouring cells;

correlating the reporting list and the planned neighbour list with respect to the control channels; and

analysing the correlated lists to determine whether any of the control channels is affected by bad frequency planning.

2. A method as claimed in claim 1, wherein the analysing step includes the steps of:

determining whether, for any of the control channels, there is more than one base station identifier in the planned neighbour list; and

if so, classifying that control channel in a first class.

3. A method as claimed in claim 1, wherein the analysing step includes the steps of:

determining whether, for any of the control channels, there is only one base station identifier in the reporting list which does not correspond to the base station identifier in the planned neighbour list; and

if so, classifying that control channel in a second class.

4. A method as claimed in claim 1, wherein the analysing step includes the steps of:

determining whether, for any of the control channels, there is more one base station identifier in the reporting list;

if so, determining whether that one of the base station identifiers in the reporting list having the larger/largest number of reports does not correspond to the base station identifier in the planned neighbour list; and

if so, classifying that control channel in a third class.

5. A method as claimed in claim 1, wherein the analysing step includes the steps of:

determining whether, for any of the control channels, there is more than one base station identifier in the reporting list;

if so, determining whether that one of the base station identifiers in the reporting list having the larger/largest number of reports corresponds to the base station identifier in the planned neighbour list but is not predominant in terms of the number of reports in term of number of respects; and

if so, classifing that control channel in a fourth class.

6. A method as claimed in claim 1, wherein the analysing step includes the steps of:

determining whether, for any of the control channels, there is at least one base station identifier in the reporting list but not in the planned neighbour list; and

if so, classifying that control channel in a fifth class.

7. A method as claimed in claim 1, further comprising the steps of:

determining whether, for any of the control channels, the base station identifier in the planned neighbour list cannot be unambiguously correlated with the, or one of the, base station identifiers in the reporting list; and

if so, classifying that control channel in a sixth class.

8. A method as claimed in claim 1, wherein the step of obtaining the planned neighbour list comprises obtaining data therefor from the operator of the system.

9. A method as claimed in claim 1, for use with a system in which the static network generates handover messages instructing mobile stations in the first cell to switch to different cells, each handover message including the control channel and base station identifier of said different cell, wherein the step of obtaining the planned neighbour list comprises the step of extracting from the static network such handover messages for handovers from said first cell, and producing the planned neighbour list from the control channels and corresponding base station identifiers in the extracted handover messages.

10. A method as claimed in claim 1, for use with a system in which the control channels are ordered in the control channel list in accordance with frequency (or channel number), and wherein the correlating step includes the step of primarily attempting to match the base station identifiers in the planned neighbour list, ordered according to control channel frequency (or channel number), with the base station identifiers in the reporting list, ordered according to position in the control channel list.

11. A method as claimed in claim 10, wherein the correlation step involves the steps of progressing through the planned neighbour list in order of control channel frequency (or channel number) and progressing through the reporting list in order of position in the control channel list.

12. A method as claimed in claim 11, wherein the correlating step includes, in each step of the progression:

determining whether the base station identifier for the current position in the planned neighbour list is related to any base station identifier, for the current position in the reporting list but not to any base station identifier, for the next position in the reporting list; and

if so, determining that that base station identifier in that current position in the planned neighbour list is associated with that base station identifier in that current position in the reporting list.

13. A method as claimed in claim 11, wherein the correlating step includes, in each step of the progression:

determining whether the base station identifier for the current position in the planned neighbour list is related to any base station identifier, for the current position in the reporting list and to any base station identifier, for the next position in the reporting list; and

if so;

determining whether the base station identifier for the next position in the planned neighbour list is related to any base station identifier, for the next position in the reporting list but not to any base station identifier, for the position after the next position in the reporting list, and, if so, determining that that base station identifier in that current position in the planned neighbour list is associated with that base station identifier in that current position in the reporting list; and

/or

determining whether the base station identifier for the next position in the planned neighbour list is not related to any base station identifier, for the next position in the reporting list, and, if so determining that that base station identifier in that current position in the planned neighbour list cannot be unambiguously associated with a base station identifier in the reporting list; and

/or

determining whether the base station identifier for the next position in the planned neighbour list is related to any base station identifier, for the next position in the reporting list and to any base station identifier, for the position after the next position in the reporting list, and, if so, recursively repeating the determining steps in respect of at least the subsequent positions in the planned neighbour list and the reporting list.

14. A method as claimed in claim 1, for use with a system in which the control channel list with which each mobile station is provided can change upon the mobile station changing from an idle mode to an active mode, the method further including the steps of:

detecting when one of the mobile stations changes from its idle mode to its active mode; and

in response to such a detection, temporarily discarding such reporting messages extracted from the static network and relating to that mobile station.

15. A method as claimed in claim 1, for use with a system in which the control channel list with which each mobile station is provided can change upon the mobile station being handed over from one cell to another, the method further including the steps of:

detecting when one of the mobile stations is handed over from one cell to another; and

in response to such a detection, temporarily discarding such reporting messages extracted from the static network and relating to that mobile station.

16. A method as claimed in claim 14, wherein the detection and discarding steps are controlled by a respective finite state machine for each mobile station which is in its active mode.

17. A method as claimed in claim 1 for use with such a system which is a GSM system, wherein:

the static network is a GSM Public Land Mobile Network (“

PLMN”

);

the control channels are GSM Broadcast Control Channels (“

BCCH”

s);

the base station identifiers are GSM Base Station Identity Codes (“

BSIC”

s);

the control channel list is a GSM BCCH Allocation (“

BA”

) list provided on a GSM Slow Association Control Channel (“

SACCH”

); and

the reporting messages are GSM Measurement Result (“

MEAS RES”

) messages.

18. An apparatus for analysing lists of neighbouring cells in a cellular telecommunications system comprising a plurality of active mobile stations and a static network, the static network having a first cell and a Plurality of cells neighbouring the first cell, some of the neighbouring cells being determined by an operator of the system as planned neighbouring cells, each of the cells having a base station, wherein:

each base station transmits, on a control channel, a signal including a base station identifier of that base station;

each mobile station in the first cell is provided with an ordered control channel list of control channel frequencies to be detected by that mobile station; and

each mobile station in said first cell reports messages to the static network indicating the base station identifiers of control channels detected by that mobile station and the position in the control channel list of the respective control channel, the apparatus comprising;

means for extracting from the static network such reporting messages for said first cell and producing a reporting list including, for each position in the control channel list, the number of times that any of the base station identifiers has been reported for that position;

means for receiving or generating a planned neighbour list of the control channels and respective base station identifiers of the planned neighbouring cells;

means for correlating the reporting list and the planned neighbour list with respect to the control channels; and

means for analysing the correlated lists to determine whether any of the control channels is affected by bad frequency planning.