Method for uplink spectrum monitoring for sparse overlay TDMA systems

• US 6,792,268 B1
• Filed: 09/07/2001
• Issued: 09/14/2004
• Est. Priority Date: 09/07/2001
• Status: Expired due to Fees

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Prabhu, Sushil Kumar, Benveniste, Mathilde
• Primary Examiner(s): BARNIE, REXFORD N
• Application Number:
  US09/947,367
• Time in Patent Office: 1,103 Days
• Field of Search: 455/450, 455/452, 455/447, 455/423, 455/446, 455/454, 455/455, 455/63, 455/444, 455/449, 455/464, 455/426, 455/513, 455/67.1, 455/67.2, 455/448, 455/62
• US Class Current: 455/423
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements

Abstract

Spectrum monitoring measurements are made by microcell base stations in a layered cellular network, while not serving calls or engaged in processing calls. The microcell base station transmits a first control message from to a microcell mobile station, to increase the duration for the mobile station to reside in the camping state on a control channel of the microcell base station. The microcell base station transmits a second control message from the microcell base station to the microcell mobile station, to increase the duration for the mobile station to reside in a call origination state while attempting to access a control channel of the microcell base station. Then, to perform the spectrum monitoring measurement, the base station'"'"'s transmitter is turned off, the receiver is retuned to the frequency to be monitored, a signal strength measurement taken on that frequency, the receiver is retuned back to its assigned frequency, and the transmitter is turned back on, all in a short time interval. Because the measurement time is so short, it is possible to take spectrum-monitoring measurements without causing inactive mobiles registered on the measuring base station to reselect control channel. Mobiles initiating a call during a spectrum monitoring measurement by its base station are also delayed in their control channel reselection.

Claims

1. A method for performing spectrum monitoring measurements by a microcell base station in a layered cellular network that includes macrocell and microcell wireless systems which are layered in a common geographic area and which share the same the same RF spectrum, wherein the microcell system includes microcell base stations defining respective microcell wireless cells and serving microcell mobile stations located within the respective microcell cell and the macrocell system includes macrocell base stations defining respective macrocell wireless cells and serving macrocell mobile stations located within the macrocell wireless cell, comprising:

transmitting a control message from the microcell base station to the microcell mobile station, to delay reselecting another control channel;

turning off the microcell base station'"'"'s transmitter while not serving calls or engaged in processing calls of mobile stations;

comprising;

retuning the microcell base station'"'"'s receiver to a frequency to be monitored;

measuring a signal strength on that frequency;

retuning the receiver back to its assigned frequency, and turning on the transmitter;

whereby spectrum-monitoring measurements are made without impacting the service provided by the microcell system.

2. A method for performing spectrum monitoring measurements by a microcell base station in a layered cellular network that includes macrocell and microcell wireless systems which are layered in a common geographic area and which share the same the same RF spectrum, wherein the microcell system includes microcell base stations defining respective microcell wireless cells and serving microcell mobile stations located within the respective microcell cell and the macrocell system includes macrocell base stations defining respective macrocell wireless cells and serving macrocell mobile stations located within the macrocell wireless cell, comprising:

transmitting a control message from the microcell base station to a microcell mobile station, to increase a duration for the mobile station to reside in a camping state on a control channel of the microcell base station;

turning off the microcell base station'"'"'s transmitter while not serving calls or engaged in processing calls of mobile stations;

retuning the microcell base station'"'"'s receiver to a frequency to be monitored;

measuring a signal strength on that frequency;

retuning the receiver back to its assigned frequency, and

turning on the transmitter;

whereby spectrum-monitoring measurements are made without causing inactive mobiles registered on the microcell base station to reselect another control channel.

3. The method for performing spectrum-monitoring measurements of claim 2, which further comprises:

setting with said control message, a camping state delay timer to have a delay duration not less than an estimated measurement duration.

4. The method for performing spectrum-monitoring measurements of claim 3, which further comprises:

transmitting a second control message from the microcell base station to the microcell mobile station, to reset said camping state delay timer, to begin said delay duration before reselecting another control channel;

said delay duration causing periodic scanning of another control channel to be suspended for at least the desired measurement duration by forcing the mobile station temporarily out of the Camping state.

5. The method for performing spectrum-monitoring measurements of claim 4, which further comprises:

said second control message being a page notification to the mobile station, without follow up,

said page notification forcing the mobile out of the Camping state temporarily.

6. The method for performing spectrum-monitoring measurements of claim 4, which further comprises:

said second control message being an SSD update notification to the mobile,

said SSD update notification forcing the mobile out of the Camping state temporarily.

7. The method for performing spectrum-monitoring measurements of claim 4, which further comprises:

said second control message being a forced re-registration request to the mobile;

said forced re-registration request forcing the mobile out of the Camping state temporarily.

8. The method for performing spectrum-monitoring measurements of claim 3, which further comprises:

updating said estimated measurement duration;

transmitting a subsequent control message, to set the delay duration for the mobile station to reside in the camping state to be not less than said updated estimated measurement duration; and

performing a subsequent spectrum monitoring measurement.

9. The method for performing spectrum-monitoring measurements of claim 2, which further comprises:

setting with said control message, a camping state scan timer to have a scan period duration SCANINTERVAL not less than an estimated measurement duration.

10. The method for performing spectrum-monitoring measurements of claim 9, which further comprises:

setting the value of SCANINTERVAL to a maximum value in order to minimize a probability that a new call by the mobile station will be set up on a cell in the macrocell system following reselection of another control channel.

11. The method for performing spectrum-monitoring measurements of claim 10, which further comprises:

transmitting a second control message from the microcell base station to the microcell mobile station, to reset said camping state scan timer to begin said scan period before reselecting another control channel;

said beginning said scan period causing periodic scanning of another control channel to be suspended for at least the value of SCANINTERVAL by forcing the mobile station temporarily out of the Camping state.

12. The method for performing spectrum-monitoring measurements of claim 11, which further comprises:

said second control message being a page notification to the mobile station, without follow up,

said page notification forcing the mobile out of the Camping state temporarily.

13. The method for performing spectrum-monitoring measurements of claim 11, which further comprises:

said second control message being an SSD update notification to the mobile,

said SSD update notification forcing the mobile out of the Camping state temporarily.

14. The method for performing spectrum-monitoring measurements of claim 11, which further comprises:

said second control message being a forced re-registration request to the mobile;

said forced re-registration request forcing the mobile out of the Camping state temporarily.

15. A method for performing spectrum monitoring measurements by a microcell base station in a layered cellular network that includes macrocell and microcell wireless systems which are layered in a common geographic area and which share the same the same RF spectrum, wherein the microcell system includes microcell base stations defining respective microcell wireless cells and serving microcell mobile stations located within the respective microcell cell and the macrocell system includes macrocell base stations defining respective macrocell wireless cells and serving macrocell mobile stations located within the macrocell wireless cell, comprising:

transmitting a control message from the microcell base station to a microcell mobile station, to increase a duration for the mobile station to reside in a call origination state while attempting to access a control channel of the microcell base station;

turning off the microcell base station'"'"'s transmitter while not serving calls or engaged in processing calls of mobile stations;

retuning the microcell base station'"'"'s receiver to a frequency to be monitored;

measuring a signal strength on that frequency;

retuning the receiver back to its assigned frequency, and

turning on the transmitter;

whereby spectrum-monitoring measurements are made without causing inactive mobiles registered on the microcell base station to reselect another control channel.

16. The method for performing spectrum monitoring measurements of claim 15, which further comprises:

setting with said control message, a Max Retries maximum number of attempts to access a control channel to be a maximum value in order to minimize a probability that a new call by the mobile station will be set up on a cell in the macrocell system following reselection of another control channel.

17. A method for performing spectrum monitoring measurements by a microcell base station in a layered cellular network that includes macrocell and microcell wireless systems which are layered in a common geographic area and which share the same the same RF spectrum, wherein the microcell system includes microcell base stations defining respective microcell wireless cells and serving microcell mobile stations located within the respective microcell cell and the macrocell system includes macrocell base stations defining respective macrocell wireless cells and serving macrocell mobile stations located within the macrocell wireless cell, comprising:

transmitting a first control message from the microcell base station to a microcell mobile station, to increase a duration for the mobile station to reside in a camping state on a control channel of the microcell base station;

transmitting a second control message from the microcell base station to a microcell mobile station, to increase a duration for the mobile station to reside in a call origination state while attempting to access a control channel of the microcell base station;

turning off the microcell base station'"'"'s transmitter while not serving calls or engaged in processing calls of mobile stations;

retuning the microcell base station'"'"'s receiver to a frequency to be monitored;

measuring a signal strength on that frequency;

retuning the receiver back to its assigned frequency, and

turning on the transmitter;

whereby spectrum-monitoring measurements are made without causing inactive mobiles registered on the microcell base station to reselect another control channel.

18. The method for performing spectrum-monitoring measurements of claim 17, which further comprises:

setting with said first control message, a camping state delay timer to have a delay duration not less than an estimated measurement duration.

19. The method for performing spectrum monitoring measurements of claim 18, which further comprises:

setting with said second control message, a Max Retries maximum number of attempts to access a control channel to be a maximum value in order to minimize a probability that a new call by the mobile station will be set up on a cell in the macrocell system following reselection of another control channel.

20. The method for performing spectrum-monitoring measurements of claim 19, which further comprises:

transmitting a third control message from the microcell base station to the microcell mobile station, to reset said camping state delay timer, to begin said delay duration before reselecting another control channel;

said delay duration causing periodic scanning of another control channel to be suspended for at least the desired measurement duration by forcing the mobile station temporarily out of the Camping state.

21. The method for performing spectrum-monitoring measurements of claim 20, which further comprises:

said third control message being a page notification to the mobile station, without follow up,

said page notification forcing the mobile out of the Camping state temporarily.

22. The method for performing spectrum-monitoring measurements of claim 20, which further comprises:

said third control message being an SSD update notification to the mobile,

said SSD update notification forcing the mobile out of the Camping state temporarily.

23. The method for performing spectrum-monitoring measurements of claim 20, which further comprises:

said third control message being a forced re-registration request to the mobile;

said forced re-registration request forcing the mobile out of the Camping state temporarily.

24. The method for performing spectrum-monitoring measurements of claim 19, which further comprises:

updating said estimated measurement duration;

transmitting a subsequent control message, to set the delay duration for the mobile station to reside in the camping state to be not less than said updated estimated measurement duration; and

performing a subsequent spectrum monitoring measurement.