Call-detection algorithm for mitigating interference by low-cost internet-base-station (LCIB) pilot beacons with macro-network communications

• US 7,903,599 B1
• Filed: 09/12/2007
• Issued: 03/08/2011
• Est. Priority Date: 09/12/2007
• Status: Active Grant

• Current Assignee: Sprint Spectrum LLC (Deutsche Telekom AG)
• Original Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Inventors: Barbee, Bryan T., Sill, Timothy W., Talley, Ryan S., Prock, John W.
• Primary Examiner(s): Moe; Aung S
• Assistant Examiner(s): Haile; Feben
• Application Number:
  US11/854,511
• Time in Patent Office: 1,273 Days
• Field of Search: 370/310, 370/311, 370/317, 370/318, 370/328, 370/329, 370/330, 370/331, 370/332, 370/333, 370/334, 370/335, 370/336, 370/337, 370/338, 455/403, 455/21, 455/500, 455/501, 455/522, 455/63.1, 455/67.11, 455/67.13, 455/114.24, 709/223, 709/224, 375/224, 375/227, 375/295, 375/296, 375/297
• US Class Current: 370/318
• CPC Class Codes: H04W 52/16 Deriving transmission power values from another channel
• CPC Class Codes: H04W 52/244 Interferences in heterogeneous networks, e.g. among macro and femto or pico cells or other sector / system interference [OSI]
• CPC Class Codes: H04W 52/246 where the output power of a terminal is based on a path parameter calculated in said terminal
• CPC Class Codes: H04W 52/346 distributing total power among users or channels
• CPC Class Codes: H04W 52/36 with a discrete range or set of values, e.g. step size, ramping or offsets

Abstract

Methods and systems are provided for mitigating interference by low-cost Internet-base-station (LCIB) pilot beacons with macro-network communications. In an embodiment, an LCIB transmits a pilot beacon having a power level that is adjustable on a per-carrier basis. The LCIB determines that it does not have any registered mobile stations, and responsively turns the power level down or off while monitoring reverse-noise rise (RNR) on one or more carriers. The LCIB then detects a threshold RNR on a carrier, and responsively carries out a sub-process a first number of times on the carrier. The sub-process comprises (a) gradually increasing the power level while continuing to monitor RNR, (b) detecting a sudden RNR decrease, and responsively turning the power level down or off while continuing to monitor RNR, and then (c) detecting an RNR increase. The LCIB waits for the RNR to return to normal before increasing the power.

Claims

1. A method for a low-cost Internet base station (LCIB) to reduce interference with communications between mobile stations and macro-network base stations, each macro-network base station providing service on at least one carrier, the method comprising:

providing an LCIB that transmits a pilot beacon on each carrier in a set of one or more carriers, the pilot beacon having a power level that is adjustable on a per-carrier basis;

the LCIB determining that it does not have any mobile stations registered thereon, and responsively (a) setting the power level to a first low-power setting on each carrier in the set and (b) monitoring a reverse-noise rise (RNR) on each carrier in the set;

while monitoring the RNR on a first carrier in the set, the LCIB detecting that the RNR on the first carrier exceeds a first RNR threshold, and responsively carrying out a sub-process a first number of times on the first carrier, the sub-process comprising;

(a) gradually increasing the power level while continuing to monitor the RNR,

(b) while gradually increasing the power level, detecting a decrease in the RNR that exceeds an RNR-decrease threshold, and responsively setting the power level to a second low-power setting while continuing to monitor the RNR, and

(c) after setting the power level to the second low-power setting, detecting an increase in the RNR that exceeds an RNR-increase threshold; and

after carrying out the sub-process the first number of times on the first carrier, the LCIB waiting for the RNR on the first carrier to fall below a second RNR threshold before increasing the power level on the first carrier above the second low-power setting.

2. The method of claim 1, wherein the pilot beacon comprises a pilot channel, a paging channel, and a sync channel.

3. The method of claim 1, wherein the set comprises multiple carriers, and wherein the pilot beacon is a frequency-hopping pilot beacon that repeatedly cycles through each carrier in the set.

4. The method of claim 3, further comprising:

while monitoring the RNR on a second carrier in the set, the LCIB detecting that the RNR on the second carrier exceeds the first RNR threshold, and responsively carrying out the sub-process the first number of times on the second carrier; and

after carrying out the sub-process the first number of times on the second carrier, the LCIB waiting for the RNR on the second carrier to fall below the second RNR threshold before increasing the power level on the second carrier above the second low-power setting.

5. The method of claim 1, further comprising:

the LCIB performing a ranging process on each carrier in the set, the ranging process comprising a first phase and a second phase, the first phase comprising increasing the power level from a minimum value to a maximum value, the second phase comprising setting the power level to an operating value on each carrier in the set based on whether any mobile stations register with the LCIB during the first phase.

6. The method of claim 5, wherein the maximum value is selected from the group consisting of (a) a power level at which at least one unauthorized mobile station is first detected during the ranging process and (b) a stored upper bound for the ranging process.

7. The method of claim 5, wherein the LCIB determining that it does not have any mobile stations registered thereon comprises the LCIB determining that no mobile stations registered with the LCIB during the first phase, and wherein responsively setting the power level to the first low-power setting on each carrier in the set comprises setting the operating value to the first low-power setting.

8. The method of claim 5, wherein increasing the power level on the first carrier above the second low-power setting comprises performing the ranging process.

9. The method of claim 1, wherein the first low-power setting is equal to the second low-power setting.

10. The method of claim 1, wherein the first low-power setting is not equal to the second low-power setting.

11. The method of claim 1, wherein at least one of the first low-power setting and the second low-power setting corresponds to a zero-power setting.

12. The method of claim 1, further comprising the LCIB storing a baseline level of reverse-link noise, wherein monitoring the RNR on a given carrier comprises:

measuring a current level of reverse-link noise on the given carrier; and

calculating the RNR on the given carrier as the difference between the current level of reverse-link noise on the given carrier and the baseline level of reverse-link noise.

13. The method of claim 12, wherein storing the baseline level of reverse-link noise comprises:

periodically taking noise-level measurements on the reverse link of at least one carrier in the set; and

periodically calculating the baseline level as the average of the lowest X % of the noise-level measurements taken in the previous Y hours.

14. The method of claim 13, wherein X equals 10, and wherein Y equals 24.

15. The method of claim 1, wherein the first RNR threshold is equal to the second RNR threshold.

16. The method of claim 1, wherein the first number is 1 or 2.

17. The method of claim 1, further comprising:

determining that a first macro-network communication session caused the RNR on the first carrier to exceed the first RNR threshold,

wherein detecting the decrease in the RNR that exceeds the RNR-decrease threshold comprises confirming that the first macro-network communication session has not been handed off to the LCIB.

18. The method of claim 1, further comprising:

the LCIB periodically requesting re-registration from each of a set of one or more mobile stations, wherein the LCIB determining that it does not have any mobile stations registered thereon comprises the LCIB determining that no re-registrations have been received in a threshold amount of time.

19. A low-cost Internet base station (LCIB) for reducing interference with communications between mobile stations and macro-network base stations, each macro-network base station providing service on at least one carrier, the LCIB comprising:

a communication interface;

a processor; and

data storage comprising instructions executable by the processor to;

transmit a pilot beacon on each carrier in a set of one or more carriers, the pilot beacon having a power level that is adjustable on a per-carrier basis;

determine that the LCIB does not have any mobile stations registered thereon, and responsively (a) set the power level to a first low-power setting on each carrier in the set and (b) monitor a reverse-noise rise (RNR) on each carrier in the set;

while monitoring the RNR on a first carrier in the set, detect that the RNR on the first carrier exceeds a first RNR threshold, and responsively carry out a sub-process a first number of times on the first carrier, the sub-process comprising;

(a) gradually increasing the power level while continuing to monitor the RNR,

(b) while gradually increasing the power level, detect a decrease in the RNR that exceeds an RNR-decrease threshold, and responsively set the power level to a second low-power setting while continuing to monitor the RNR, and

(c) after setting the power level to the second low-power setting, detect an increase in the RNR that exceeds an RNR-increase threshold; and

after carrying out the sub-process the first number of times on the first carrier, wait for the RNR on the first carrier to fall below a second RNR threshold before increasing the power level on the first carrier above the second low-power setting.

20. A method carried out by a low-cost Internet base station (LCIB) having a pilot beacon that the LCIB transmits on each carrier in a set of one or more carriers, the pilot beacon having a power level that is adjustable on a per-carrier basis, the method comprising the LCIB:

carrying out a non-interference process in response to at least one of the following triggers;

(1) periodically requesting re-registration from each of a set of one or more mobile stations, and determining that no re-registrations have been received in a threshold amount of time, (2) being powered on, and (3) receiving a restart command, the non-interference process comprising;

(a) setting the power level to a first low-power setting on each carrier in the set;

(b) monitoring a reverse-noise rise (RNR) on each carrier in the set;

(c) while monitoring the RNR on a first carrier in the set, detecting that the RNR on the first carrier exceeds a first RNR threshold, and responsively carrying out a sub-process a first number of times on the first carrier, the sub-process comprising;

(i) gradually increasing the power level while continuing to monitor the RNR,

(ii) while gradually increasing the power level, detecting a decrease in the RNR that exceeds an RNR-decrease threshold, and responsively setting the power level to a second low-power setting while continuing to monitor the RNR, and

(iii) after setting the power level to the second low-power setting, detecting an increase in the RNR that exceeds an RNR-increase threshold; and

(d) after carrying out the sub-process the first number of times on the first carrier, waiting for the RNR on the first carrier to fall below a second RNR threshold before increasing the power level on the first carrier above the second low-power setting.