Method and system for radio frequency measurement and automatic frequency planning in a cellular radio system

• US 5,966,657 A
• Filed: 07/24/1997
• Issued: 10/12/1999
• Est. Priority Date: 07/24/1997
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Sporre, Matts
• Primary Examiner(s): LOOMIS, PAUL A
• Application Number:
  US08/900,206
• Time in Patent Office: 810 Days
• Field of Search: 455/437, 455/446, 455/447, 455/450, 455/452, 455/455, 455/423, 455/424, 455/425
• US Class Current: 455/425
• CPC Class Codes: H04W 72/21 in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/541 using the level of interference

Abstract

A mobile station operating in a digital cellular system such as GSM is ordered to perform signal strength measurements on non-BCCH carrier frequencies by including an identification of those frequencies twice in the bit map comprising the BA-list. The mobile station formats a measurement report containing signal strength measurements of both BCCH and non-BCCH carrier frequencies and send it to the network which uses the data for automatic frequency allocation within the network.

Claims

1. A method for obtaining information on non-BCCH carrier frequency channels within a particular cell of a cellular radio telecommunications network operating in accordance with an air interface standard which includes a broadcast control channel (BCCH) carrying control messages from a base station to mobiles stations operating with the cell which said base station is serving and a slow associated control channel (SACCH) carrying messages in both directions between each of said mobile stations and said base station while said mobile station is in active mode within said cell, said method comprising:

sending within a SACCH message from the base station serving said particular cell to said mobile station operating in active mode within that cell, a list of the non-BCCH carrier frequency channels upon which measurements are to be performed by the mobile station;

measuring at the mobile station the signal strength of each of the non-BCCH carrier frequencies specified in the SACCH message; and

formatting a measurement report containing an identification of the particular non-BCCH carrier frequency channels measured by the mobile station along with the measurement results and sending said measurement report to the base station serving that cell within a SACCH message.

2. A method for obtaining information on non-BCCH carrier frequency channels within a particular cell of a cellular radio telecommunications network as set forth in claim 1 wherein:

said particular non-BCCH carrier frequencies on which signal strength measurements are to be made are identified to the mobile station by being included twice in said list of carrier frequency channels sent on the SACCH to be measured by the mobile station.

3. A method for obtaining information on non-BCCH carrier frequency channels within a particular cell of a cellular radio telecommunications network as set forth in claim 1 wherein:

said measurement report sent by the mobile station to the base station is of a standard length containing a fixed number of octets of data and includes a first data field containing indicia which indicate the number of BCCH-carriers on which measurement reports are included and thereby indicate that the remaining octets of that report contain the channel designations and signal strength measurements of the non-BCCH carriers measured by the mobile station.

4. A method for obtaining information on non-BCCH carrier frequency channels within a particular cell of a cellular radio telecommunications network as set forth in claim 1 wherein:

said measurement report sent by the mobile station to the base station is of a standard length containing a fixed number of octets of data and includes a second data field containing indicia which indicates that because the measurements ordered to be made and reported based upon the list sent from the base station to the mobile station are sufficient in number that they cannot all be contained in this measurement report, there is another measurement report to follow containing additional information from this cycle of measurement by the mobile station.

5. A method for obtaining information on non-BCCH carrier frequency channels within a particular cell of a cellular radio telecommunications network as set forth in claim 1 wherein the information sent from the base station to the mobile station includes a list of both BCCH-carrier frequency channels and non-BCCH carrier frequency channels upon which measurements are to be made by the mobile station and wherein said list is sent on the SACCH in the form of system 5, system 5_bis and 5_ter message blocks.

6. A method for obtaining information on non-BCCH carrier frequency channels within a particular cell of a cellular radio telecommunications network as set forth in claim 1 wherein the list sent to the mobile station by the base station on the SACCH indicates that no BCCH-carriers are to be included in the measurement report to be sent by the mobile station.

7. A data format for a frequency channel measurement report to be sent from a mobile station operating within a cell of a cellular system to a base station currently serving that mobile station within that cell wherein the body of said measurement report includes a fixed number of octets of data and may contain measurement reports on one or more broadcast control channel (BCCH) frequencies of other cells which are neighbors to said cell and wherein said data format of said measurement report comprises:

an overhead section within which information related to the mobile station sending the report and the cell within which it is operating is included;

a first identification section containing a multi-bit code which identifies the number of BCCH frequency channels upon which measurements are being reported in said report;

a BCCH-channel measurement section containing the measurement reports on said identified number of BCCH frequency channels along with their associated channel designations;

a second identification section containing an indication that additional information is to follow in the remaining octets of said report;

a non-BCCH channel measurement section containing additional information to be sent from the mobile station to the base station which fills substantially all of the remaining octets in said report.

8. A data format for a frequency channel measurement report to be sent from a mobile station operating within a cell of a cellular system to the base station currently serving that mobile station within that cell as set forth in claim 7 wherein:

said non-BCCH channel measurement section contains measurement reports on traffic channels (TCH) measured within said cell by said mobile station along with their associated channel designations.

9. A data format for a frequency channel measurement report to be sent from a mobile station operating within a cell of a cellular system to the base station currently serving that mobile station within that cell as set forth in claim 7 wherein:

said first identification section contains the multi-bit code which indicates that no BCCH frequency channel measurements are being reported in said report; and

said BCCH-channel measurement section is substantially filled with TCH frequency channel measurements along with their associated channel designations.

10. A data format for a frequency channel measurement report to be sent from a mobile station operating within a cell of a cellular system to the base station currently serving that mobile station within that cell as set forth in claim 7 wherein said measurement report also contains a field indicating that the report is part of a sequence of reports in a single cycle of measurements.

11. A method for obtaining information on radio frequency channels within a particular cell of a cellular radio telecommunications network operating in accordance with an air interface standard which includes a broadcast control channel (BCCH) carrying control messages from a base station to mobiles stations operating with the cell which said base station is serving and a slow associated control channel (SACCH) carrying messages in both directions between each of said mobile stations and said base station while said mobile station is in active mode within said cell, said air interface standard providing for periodic measurement of the signal strength of the BCCH-carriers of the neighboring cells of said particular cell for purposes of possible handoff of said mobile station to a neighboring cell by sending a list of said neighboring BCCH-carriers to each mobile station in said particular cell within a message sent on the SACCH, said method comprising:

sending within said SACCH message containing said list of neighboring BCCH-carriers from the base station serving said particular cell to said mobile station operating in active mode within that cell, a list of non-BCCH carrier frequency channels upon which measurements are to be performed by the mobile station;

measuring at the mobile station the signal strength of each of the BCCH-carrier and non-BCCH carrier frequencies specified in the SACCH message; and

formatting a measurement report containing an identification of both the BCCH-carriers and the non-BCCH carrier frequency channels measured by the mobile station along with the measurement results; and

sending said measurement report from the mobile station to the base station serving that cell within a SACCH message.

12. A method for obtaining information on radio frequency channels within a particular cell of a cellular radio telecommunications network as set forth in claim 11 wherein:

said particular non-BCCH carrier frequencies on which signal strength measurements are to be made are identified to the mobile station by being included twice in said list of carrier frequency channels sent on the SACCH to be measured by the mobile station.

13. A method for obtaining information on radio carrier frequency channels within a particular cell of a cellular radio telecommunications network as set forth in claim 11 wherein:

said measurement report sent by the mobile station to the base station is of a standard length containing a fixed number of octets of data and includes a first identification data field containing indicia which indicate the number of BCCH-carriers on which measurement reports are included and thereby indicates that the remaining octets of that report contain the channel designations and signal strength measurements of the non-BCCH carriers measured by the mobile station.

14. A method for obtaining information radio frequency channels within a particular cell of a cellular radio telecommunications network as set forth in claim 11 wherein:

said measurement report sent by the mobile station to the base station is of a standard length containing a fixed number of octets of data and includes a second identification data field containing indicia which indicates that because the measurements ordered to be made and reported based upon the list sent from the base station to the mobile station are sufficient in number that they cannot all be contained in this measurement report, that there is another measurement report to follow containing additional information from this cycle of measurement by the mobile station.

15. A method for obtaining information on radio frequency channels within a particular cell of a cellular radio telecommunications network as set forth in claim 11 wherein said air interface standard provides for system 5 information to be sent within SACCH messages from said serving base station to mobile stations within said particular cell and wherein said list of frequency channels on which information is to be measured is sent in the form of system 5, system 5_bis and system 5_ter message blocks.

16. A method for obtaining information on radio frequency channels within a particular cell of a cellular radio telecommunications network as set forth in claim 11 wherein the list sent to the mobile station by the base station on the SACCH indicates that no BCCH-carriers are to be included in the measurement report to be sent by the mobile station.

17. A method of performing automatic frequency allocation within a cellular radio telecommunications system operated in accordance with an air interface standard which includes a broadcast control channel (BCCH) carrying control messages from a base station to mobile stations operating with the cell which said base station is serving and a slow associated control channel (SACCH) carrying messages in both directions between each of said mobile stations and said base station while said mobile station is in active mode within said cell, said method comprising the steps of:

measuring on the uplink at the base station the signal strength on a plurality of carrier frequencies within a plurality of the cells of said system;

measuring on the downlink at at least one mobile station within each of said plurality of cells the signal strength on a plurality of carrier frequencies, said step of measuring on the downlink further including the steps of;

sending within a SACCH message from the base station serving each of said cells to a mobile station operating in active mode within that cell, a list of the non-BCCH carrier frequency channels upon which measurements are to be performed by the mobile station;

measuring at the mobile station the signal strength of each of the non-BCCH carrier frequencies specified in the SACCH message; and

formatting a measurement report containing an identification of the particular non-BCCH carrier frequency channels measured by the mobile station along with the measurement results;

sending the measured signal strengths of the carrier frequencies measured at each mobile station to their respective serving base stations in the form of the measurement report using a SACCH message;

assembling within the system a composite signal strength value for each of the carriers which is currently allocated within a selected one of said plurality of cells by the system frequency plan and a composite signal strength value for each of the carriers which is not allocated within said same selected one of said plurality of cells by the system frequency plan;

determining whether any non-allocated frequencies within said cell are less interfered with than any allocated frequencies in said cell;

modifying said system frequency plan by replacing a more interfered with frequency in said cell with a less interfered with frequency to improve the quality of service within said cell.

18. A method of performing automatic frequency allocation within a cellular radio telecommunications system as set forth in claim 17 wherein said step of modifying said system frequency plan by replacing a more interfered with frequency in said cell with a less interfered with frequency to improve the quality of service within said cell includes iteratively replacing the most interfered with frequency in said with the least interfered with frequency until no further improvement in quality of service can be obtained within each cell.

19. A method of performing automatic frequency allocation within a cellular radio telecommunications system as set forth in claim 17 wherein within said step of measuring on the downlink at at least one mobile station within each of said plurality of cells the signal strength on a plurality of carrier frequencies, and wherein:

said particular non-BCCH carrier frequencies on which signal strength measurements are to be made are identified to each mobile station by being included twice in said list of carrier frequency channels sent on the SACCH to be measured by each mobile.

20. A system for obtaining information on non-BCCH carrier frequency channels within a particular cell of a cellular radio telecommunications network operating in accordance with an air interface standard which includes a broadcast control channel (BCCH) carrying control messages from a base station to mobiles stations operating with the cell which said base station is serving and a slow associated control channel (SACCH) carrying messages in both directions between each of said mobile stations and said base station while said mobile station is in active mode within said cell, said system comprising:

means for sending within a SACCH message from the base station serving said particular cell to said mobile station operating in active mode within that cell, a list of the non-BCCH carrier frequency channels upon which measurements are to be performed by the mobile station;

means for measuring at the mobile station the signal strength of each of the non-BCCH carrier frequencies specified in the SACCH message; and

means for formatting a measurement report containing an identification of the particular non-BCCH carrier frequency channels measured by the mobile station along with the measurement results; and

means for sending said report to the serving base station of that cell within a SACCH message.

21. A system for obtaining information on non-BCCH carrier frequency channels within a particular cell of a cellular radio telecommunications network as set forth in claim 20 wherein:

said particular non-BCCH carrier frequencies on which signal strength measurements are to be made are identified to the mobile station by being included twice in said list of carrier frequency channels sent on the SACCH to be measured by the mobile station.

22. A system for obtaining information on non-BCCH carrier frequency channels within a particular cell of a cellular radio telecommunications network as set forth in claim 20 wherein:

said measurement report sent by the mobile station to the base station is of a standard length containing a fixed number of octets of data and includes a first identification data field containing indicia which indicate the number of BCCH-carriers on which measurement reports are included and thereby indicate that the remaining octets of that report contain the channel designations and signal strength measurements of the non-BCCH carriers measured by the mobile station.

23. A system for obtaining information on non-BCCH carrier frequency channels within a particular cell of a cellular radio telecommunications network as set forth in claim 20 wherein:

said measurement report sent by the mobile station to the base station is of a standard length containing a fixed number of octets of data and includes a second identification data field containing indicia which indicates that because the measurements ordered to be made and reported in based upon the list sent from the base station to the mobile station are sufficient number that they cannot all be contained in this measurement report, that there is another measurement report to follow containing additional information from this cycle of measurement by the mobile station.

24. A system for obtaining information on non-BCCH carrier frequency channels within a particular cell of a cellular radio telecommunications network as set forth in claim 20 wherein the information sent from the base station to the mobile station includes a list of both BCCH-carrier frequency channels and non-BCCH carrier frequency channels upon which measurements are to be made by the mobile station and wherein said list is sent on the SACCH in the form of system 5, system 5_bis and system 5_ter message blocks.

25. A system for obtaining information on non-BCCH carrier frequency channels within a particular cell of a cellular radio telecommunications network as set forth in claim 20 wherein the list sent to the mobile station by the base station on the SACCH indicates that no BCCH-carriers are to be included in the measurement report to be sent by the mobile station.

26. A system for obtaining information on radio frequency channels within a particular cell of a cellular radio telecommunications network operating in accordance with an air interface standard which includes a broadcast control channel (BCCH) carrying control messages from a base station to mobiles stations operating with the cell which said base station is serving and a slow associated control channel (SCCH) carrying messages in both directions between each of said mobile stations and said base station while said mobile station is in active mode within said cell, said air interface standard providing for periodic measurement of the signal strength of the BCCH-carriers of the neighboring cells of said particular cell for purposes of possible handoff of said mobile station to a neighboring cell by sending a list of said neighboring BCCH-carriers to each mobile station in said particular cell within a message sent on the SACCH, said system comprising:

means for sending within said SACCH message containing said list of neighboring BCCH-carriers from the base station serving said particular cell to said mobile station operating in active mode within that cell, a list of non-BCCH carrier frequency channels upon which measurements are to be performed by the mobile station;

means for measuring at the mobile station the signal strength of each of the BCCH-carriers and non-BCCH carrier frequencies specified in the SACCH message; and

means for formatting a measurement report containing an identification of both the BCCH-carriers and the non-BCCH carrier frequency channels measured by the mobile station along with the measurement results; and

means for sending said measurement report to the base station serving that cell within a SACCH message.

27. A system for obtaining information on radio frequency channels within a particular cell of a cellular radio telecommunications network as set forth in claim 26 wherein:

said particular non-BCCH carrier frequencies on which signal strength measurements are to be made are identified to the mobile station by being included twice in said list of carrier frequency channels sent on the SACCH to be measured by the mobile station.

28. A system for obtaining information on radio carrier frequency channels within a particular cell of a cellular radio telecommunications network as set forth in claim 26 wherein:

said measurement report sent by the mobile station to the base station is of a standard length containing a fixed number of octets of data and includes a first information data field containing indicia which indicate the number of BCCH-carriers on which measurement reports are included and thereby indicates that the remaining octets of that report contain the channel designations and signal strength measurements of the non-BCCH carriers measured by the mobile station.

29. A system for obtaining information radio frequency channels within a particular cell of a cellular radio telecommunications network as set forth in claim 26 wherein:

said measurement report sent by the mobile station to the base station is of a standard length containing a fixed number of octets of data and includes a second information data field containing indicia which indicates that because the measurements ordered to be made and reported in based upon the list sent from the base station to the mobile station are sufficient in number that they cannot all be contained in this measurement report, that there is another measurement report to follow containing additional information from this cycle of measurement by the mobile station.

30. A system for obtaining information on radio frequency channels within a particular cell of a cellular radio telecommunications network as set forth in claim 26 wherein said air interface standard provides for system 5 information to be sent within SACCH messages from said serving base station to mobile stations within said particular cell and wherein said list of frequency channels on which information is to be measured is sent in the form of system 5, system 5_bis and system 5_ter message blocks.

31. A system for obtaining information on radio frequency channels within a particular cell of a cellular radio telecommunications network as set forth in claim 26 wherein the list sent to the mobile station by the base station on the SACCH indicates that no BCCH-carriers are to be included in the measurement report to be sent by the mobile station.

32. A system for performing automatic frequency allocation within a cellular radio telecommunications system operated in accordance with an air interface standard which includes a broadcast control channel (BCCH) carrying control messages from a base station to mobile stations operating with the cell which said base station is serving and a slow associated control channel (SACCH) carrying messages in both directions between each of said mobile stations and said base station while said mobile station is in active mode within said cell, said system comprising:

means for measuring on the uplink at the base station the signal strength on a plurality of carrier frequencies within a plurality of the cells of said system;

means for measuring on the downlink at at least one mobile station within each of said plurality of cells the signal strength on a plurality of carrier frequencies, said means for measuring on the downlink further including;

means for sending within a SACCH message from the base station serving each of said cells to a mobile station operating in active mode within that cell, a list of the non-BCCH carrier frequency channels upon which measurements are to be performed by the mobile station;

means for measuring at the mobile station the signal strength of each of the non-BCCH carrier frequencies specified in the SACCH message; and

means for formatting a measurement report containing an identification of the particular non-BCCH carrier frequency channels measured by the mobile station along with the measurement results;

means for sending the measured signal strengths of the carrier frequencies measured at the mobile stations to each of their respective serving base stations in the form of the measurement report;

means for assembling within the network a composite signal strength value for each of the carriers which is currently allocated within a selected one of said plurality of cells by the system frequency plan and a composite signal strength value for each of the carriers which is not allocated within said same selected one of said plurality of cells by the system frequency plan;

means for determining whether any non-allocated frequencies within said cell are less interfered with any allocated frequencies in said cell;

means for modifying said system frequency plan by replacing a more interfered with frequency in said cell with a less interfered with frequency to improve the quality of service within said cell.

33. A system for performing automatic frequency allocation within a cellular radio telecommunications system as set forth in claim 32 wherein said step of modifying said system frequency plan by replacing the most interfered with frequency in said cell with a less interfered with frequency to improve the quality of service within said cell includes iteratively replacing the most interfered with frequency with the least interfered with frequency repeated until no further improvement in quality of service can be obtained within each cell.

34. A system for performing automatic frequency allocation within a cellular radio telecommunications system as set forth in claim 32 wherein within said step of measuring on the downlink at at least one mobile station within each of said plurality of cells the signal strength on a plurality of carrier frequencies,

said particular non-BCCH carrier frequencies on which signal strength measurements are to be made are identified to each mobile station by being included twice in said list of carrier frequency channels sent on the SACCH to be measured by each mobile.