Method and system for autonomously allocating frequencies to a radio system sharing frequencies with an overlapping macro radio system

• US 6,405,048 B1
• Filed: 02/05/1998
• Issued: 06/11/2002
• Est. Priority Date: 08/28/1996
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Haartsen, Jacobus C.
• Primary Examiner(s): Chang, Vivian
• Assistant Examiner(s): APPIAH, CHARLES NANA
• Application Number:
  US09/019,254
• Time in Patent Office: 1,587 Days
• Field of Search: 375/132, 375/133, 375/134, 375/137, 455/450, 455/451, 455/452, 455/454, 455/462, 455/465, 455/447, 455/448, 455/449, 455/464, 455/444, 370/332
• US Class Current: 455/464
• CPC Class Codes: H04W 16/12 Fixed resource partitioning
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 16/32 Hierarchical cell structures
• CPC Class Codes: H04W 48/10 using broadcasted information

Abstract

A system and a method to automatically select a frequency set in a low-tier radio communication system, sharing frequencies with an overlapping high-tier cellular radio system, that minimally interferes with the high-tier system employing frequency hopping is described. The present invention makes use of the broadcast information that is transmitted by the high-tier radio base stations on their broadcast control channels (BCCH), which contains not only the BCCH carrier frequencies of surrounding cells, but also information regarding the frequencies applied in the considered cell for frequency hopping traffic channels. With this broadcast information, the low-tier system can derive the frequency planning of the high-tier system, and can then derive a frequency set for low-tier usage that minimally interferes with the overlapping high-tier system. The advantage with this technique is that only measurements on BCCH carriers have to be performed, which are non-hopping, have a constant transmit power, and have a continuous (non-bursty) signal.

Claims

1. A method for determining a least-interfered radio communications link for a private radio system within a serving cell of an overlaying cellular system, the private radio system and the overlaying cellular system sharing a plurality of frequencies within said serving cell, said overlaying cellular system employing frequency hopping, the method comprising the steps of:

transmitting broadcast information on broadcast control channels (BCCHs);

determining, using the broadcast information, a set of frequency hopping channels being used within a plurality of cells surrounding said serving cell of said overlaying cellular system;

performing periodic received signal strength indicator (RSSI) measurements on BCCH carrier frequencies of a plurality of cells surrounding said serving cell, each said frequency hopping channel having at least one of said RSSI measurements associated therewith;

dividing said set of frequency hopping channels into a plurality of frequency hopping lists, each said frequency hopping channel corresponding to a respective one of said frequency hopping lists, wherein each frequency hopping list has associated therewith the RSSI measurements that are associated with the corresponding frequency hopping channels of said frequency hopping lists;

selecting a given one of said frequency hopping lists having the lowest maximum associated RSSI measurement value; and

adaptively selecting a given frequency hopping channel from said given one of said frequency hopping lists as the least-interfered radio communications link for said private radio system.

2. The method according to claim 1, wherein, prior to said step of determining, said method further comprises the steps of:

receiving, within said private radio system, downlink information from a given cell of said cellular system.

3. The method according to claim 2, wherein said given cell is the serving cell.

4. The method according to claim 2, wherein said given cell is one of said surrounding cells.

5. The method according to claim 2, wherein, in said step of determining, said determination excludes frequency hopping channels for said serving cell.

6. The method according to claim 1, wherein, prior to said step of determining, said method further comprises the steps of:

receiving, within said private radio system, downlink information from a broadcast control channel of said serving cell;

extracting from said downlink information a plurality of other broadcast control channels for a corresponding plurality of said surrounding cells;

receiving, within said private radio system, a plurality of surrounding cell downlink information from said plurality of other broadcast control channels;

measuring respective RSSI measurements associated with each of said other broadcast control channels; and

extracting, from the respective surrounding cell downlink information from said other broadcast control channels, respective frequency hopping channels associated with each said other broadcast control channel, said extracted frequency hopping channels forming said frequency hopping channel set.

7. The method according to claim 1, wherein, after said step of determining, said method further comprises the step of:

ordering said frequency hopping channels within said frequency hopping channel set pursuant to the respective RSSI measurements associated with said frequency hopping channels.

8. The method according to claim 1, wherein said determination of said set of frequency hopping channels is made within a private radio base station of said private radio system.

9. The method according to claim 1, wherein, after said step of determining, said set of frequency hopping channels are forwarded to said private radio system by a remote device, said determination of said set of frequency hopping channels being made within said remote device.

10. The method according to claim 9, wherein said remote device forwards said set of frequency hopping channels to said private radio system via a wireless communication.

11. The method according to claim 9, wherein said remote device is a mobile terminal in communication with said private radio system.

12. The method according to claim 9, wherein said set of frequency hopping channels is downloaded into said remote device via cellular Short Message Service.

13. The method according to claim 1, wherein said set of frequency hopping channels is downloaded into the private radio system via a wireline connection.

14. The method according to claim 1, wherein in said step of determining, the interference measurement associated with each said frequency hopping channel in said set includes a signal strength value of the respective surrounding cell control channel associated therewith.

15. The method according to claim 1, wherein said method further comprises the steps of:

generating a first list of BCCH carrier frequency RSSI measurements;

ordering said first list based on the periodic RSSI measurements performed on said BCCH carrier frequencies;

collecting respective associated Cell Allocation (CA) lists corresponding to said measured BCCH carrier frequencies; and

ordering each said frequency hopping channel in each of said frequency hopping lists pursuant to the respective associated RSSI measurement, the respective BCCH carrier frequency having the maximum RSSI measurement value in each ordered frequency hopping list being at one end of each said ordered frequency hopping list.

16. The method according to claim 1, wherein said cellular system employs both frequency hopping and non-frequency hopping communications.

17. The method according to claim 1, wherein said given frequency hopping channel comprises a multiplicity of frequencies over which said private radio system may frequency hop within said serving cell of said overlaying cellular system.

18. The system according to claim 1, wherein said BCCH carrier frequencies are non-hopping, have a constant transmit power, and have a continuous (non-bursty) signal.

19. The method according to claim 1, wherein the periodic RSSI measurements need only be performed on said BCCH carrier frequencies.

20. The method according to claim 1, wherein the periodic RSSI measurements performed on each said BCCH carrier frequency further indicates a signal strength of said respective associated frequency hopping channels corresponding to said respective one of said frequency hopping lists without explicitly measuring RSSI on said set of frequency hopping channels.

21. The method according to claim 1, wherein the set of frequency hopping channels is determined by utilizing at least one of the following:

BCCH Allocation (BA) lists and Cell Allocation (CA) lists, the BA and CA lists, when combined, determines which BCCH carrier frequencies are used in the plurality of cells surrounding said serving cell and which carrier frequencies are used for traffic channels (TCH) in said plurality of surrounding cells;

RSSI measurements periodically performed on said BCCH carrier frequencies; and

Base Station Identity Codes (BSICs).

22. In a communication system having a private radio system within a serving cell of an overlaying cellular system, the private radio system and the overlaying cellular system sharing a plurality of frequencies within said serving cell, said overlaying cellular system employing frequency hopping, circuitry within said private radio system for allocating a least-interfered radio communications link, said circuitry comprising:

transmission means for transmitting broadcast information on broadcast control channels (BCCHs);

determining means for determining, using the broadcast information, a set of frequency hopping channels for use by said private radio system within said serving cell;

means for performing periodic received signal strength indicator (RSSI) measurements on BCCH carrier frequencies of a plurality of cells surrounding said serving cell, each said frequency hopping channel having at least one of said RSSI measurements associated therewith;

dividing means for dividing said set of frequency hopping channels into a plurality of frequency hopping lists, each said frequency hopping channel corresponding to a respective one of said frequency hopping lists, wherein each frequency hopping list has associated therewith the RSSI measurements that are associated with the corresponding frequency hopping channels of said frequency hopping lists;

selection means for selecting a given one of said frequency hopping lists having the lowest maximum associated RSSI measurement value; and

selection means for adaptively selecting a given frequency hopping channel from said given one of said frequency hopping lists as the least-interfered radio communications link for said private radio system.

23. The system according to claim 22, wherein said communication system employs both frequency hopping and non-frequency hopping communications, the non-frequency hopping communications including BCCH carrier frequencies of serving and surrounding cells of said overlaying cellular system, and the frequency hopping communications including radio frequencies used for traffic channels (TCHs) in said serving and surrounding cells of said overlaying cellular system.

24. A method for determining a least-interfered radio communications link for a private radio system within a serving cell of an overlaying cellular system, the private radio system and the cellular system sharing a plurality of frequencies within the serving cell, the overlaying cellular system employing frequency hopping, the method comprising the steps of:

transmitting broadcast information on broadcast control channels (BCCHs);

determining, using the broadcast information, a set of frequency hopping channels being used within a plurality of cells surrounding the serving cell of the overlaying cellular system;

performing periodic received signal strength indicator (RSSI) measurements on BCCH carrier frequencies of a plurality of cells surrounding the serving cell, each said frequency hopping channel having at least one of the RSSI measurements associated therewith, the periodic RSSI measurements being performed on each BCCH carrier frequency without explicitly measuring RSSI on the set of frequency hopping channels;

dividing the set of frequency hopping channels into a plurality of frequency hopping lists, each said frequency hopping channel corresponding to a respective one of the frequency hopping lists, wherein each frequency hopping list has associated therewith the RSSI measurements that are associated with the corresponding frequency hopping channels of the frequency hopping lists;

selecting a given one of the frequency hopping lists having the lowest maximum associated RSSI measurement value; and

adaptively selecting a given frequency hopping channel from the given one of the frequency hopping lists as the least-interfered radio communications link for the private radio system.

25. The method according to claim 24, wherein the method further comprises the steps of:

combining the RSSI measurements, BCCH Allocation (BA) lists and Cell Allocation (CA) lists;

determining, using the combination, which BCCH carrier frequencies are suited for reuse in the serving cell;

generating a first list of BCCH carrier frequency RSSI measurements;

ordering the first list based on the periodic RSSI measurements performed on the BCCH carrier frequencies;

collecting respective associated Cell Allocation (CA) lists corresponding to the measured BCCH carrier frequencies; and

ordering each said frequency hopping channel in each of the frequency hopping lists pursuant to the respective associated RSSI measurement, the respective BCCH carrier frequency having the maximum RSSI measurement value in each ordered frequency hopping list being at one end of each said ordered frequency hopping list.

26. A communication system comprising:

an overlaying cellular system, the overlaying cellular system employing frequency hopping; and

a private radio system within a serving cell of the overlaying cellular system, the private radio system using both non-frequency hopping and frequency hopping communications wherein the non-frequency hopping communications including BCCH carrier frequencies of serving and surrounding cells of the overlaying cellular system and the frequency hopping communications including radio frequencies used for traffic channels (TCHs) in the serving and surrounding cells of the overlaying cellular system, the private radio system having circuitry for allocating a least-interfered radio communications link, the circuitry being further adapted for;

transmitting broadcast information on broadcast control channels (BCCHS);

determining, using the broadcast information, a set of frequency hopping channels for use by the private radio system within the serving cell;

performing periodic received signal strength indicator (RSSI) measurements on BCCH carrier frequencies of a plurality of cells surrounding the serving cell, each said frequency hopping channel having at least one of the RSSI measurements associated therewith;

dividing the set of frequency hopping channels into a plurality of frequency hopping lists, each said frequency hopping channel corresponding to a respective one of the frequency hopping lists, wherein each frequency hopping list has associated therewith the RSSI measurements that are associated with the corresponding frequency hopping channels of the frequency hopping lists;

selecting a given one of the frequency hopping lists having the lowest maximum associated RSSI measurement value; and

selecting a given frequency hopping channel from the given one of the frequency hopping lists as the least-interfered radio communications link for the private radio system.