Access point power control

1. A method of controlling a basestation in a cellular wireless communications network, the method comprising:

determining whether or not a carrier that has been selected for communicating with UEs is unused by neighbouring macrolaver basestations or other basestations;

wherein a carrier is unused if there are no detected macrolayer basestation or other basestation CPICH signals and the received signal strength indicator (RSSI) on the carrier is below a minimum interference threshold;

if the carrier is not unused by neighbouring macrolayer basestations or other basestations, determining whether an interference caused by neighbouring macrolayer basestations is greater than or less than an interference caused by neighbouring other basestations;

if said carrier is unused by neighbouring macrolayer basestations or other basestations, setting the total transmit power of the basestation at a first power level;

if said carrier is not unused by neighbouring macrolayer basestations or other basestations, and the interference caused by neighbouring macrolayer basestations is greater than the interference caused by neighbouring other basestations, setting the total transmit power of the basestation at a second power level; and

if said carrier is not unused by neighbouring macrolayer basestations or other basestations, and the interference caused by neighbouring macrolayer basestations is less than the interference caused by neighbouring other basestations, setting the total transmit power of the basestation at a third power level.

2. A method as claimed in claim 1 , further comprising:

within the basestation, autonomously and dynamically adapting a maximum value for a total transmit power of one or more mobile devices having wireless connections to the basestation.

3. A method as claimed in claim 1 or 2 , comprising adapting said maximum value for the total transmit power based on:

rules applied by a central management system to minimise interference impacts at a macrolayer of said network and with nearby basestations.

4. A method as claimed in claim 1 or 2 , comprising adapting said maximum value for the total transmit power based on:

measurements of the received signal strength and signal quality of surrounding macrolayer basestations and other basestations.

5. A method as claimed in claim 1 or 2 , comprising adapting said maximum value for the total transmit power based on:

knowledge of the transmit power of, and path loss to, surrounding macrolayer basestations and other basestations, said knowledge being derived from information decoded from broadcast channel transmissions thereof and measured received signal strengths.

6. A method as claimed in claim 1 or 2 , comprising adapting said maximum value for the total transmit power based on:

knowledge of historical statistics for the path loss between said basestation and permitted UEs in call therewith said basestation, and based on a predetermined maximum permitted path loss figure.

7. A method as claimed in claim 1 or 2 , comprising adapting said maximum value for the total transmit power based on:

knowledge of round trip delays for a communications path between said basestation and a user terminal within a target coverage area, and based on a predetermined maximum permitted round-trip delay.

8. A method as claimed in claim 1 or 2 , comprising adapting said maximum value for the total transmit power based on:

knowledge of access attempts by non-permitted users.

9. A method as claimed in claim 1 , comprising adapting said maximum value for the total transmit power based on:

knowledge of whether a measured dominant interferer is a macrolayer basestation or a nearby access point.

10. A method as claimed in claim 9 , wherein said knowledge of whether a measured dominant interferer is a macrolayer basestation or a nearby access point is based on identity information conveyed in the received broadcast channel of said interferer and RF signal measurements therefrom.

11. A method as claimed in claim 1 , comprising adapting said maximum value for the total transmit power based on:

knowledge of historical statistics for a received signal/interference ratio as measured at UEs in call with the basestation, and based on a predetermined minimum signal/interference ratio.

12. A method as claimed in claim 11 , wherein measurements of said received signal/interference ratio are specifically requested by the basestation.

13. A method as claimed in claim 1 , comprising adapting said maximum value for the total transmit power based on:

knowledge of historical statistics for a path loss between UEs in call with the basestation and nearby nodeBs.

14. A method as claimed in claim 13 , wherein measurements of said path loss are specifically requested by the basestation.

15. A method as claimed in claim 1 , further comprising:

within the basestation, autonomously and dynamically selecting a carrier for communicating with UEs.

16. A method as claimed in claim 15 , comprising adapting the carrier based on:

measurements of the received signal strength and signal quality of surrounding macro layer basestations and other basestations.

17. A method as claimed in claim 15 or 16 , comprising adapting the carrier based on:

a comparison of the detected interference on the carrier with an interference threshold.

18. A method as claimed in claim 1 , further comprising:

within the basestation, autonomously and dynamically adapting a scrambling code used to code communications sent from the basestation.

19. A method as claimed in claim 18 , comprising adapting the scrambling code based on:

measurements of the received signal strength and signal quality of surrounding basestations.

20. A method as claimed in claim 18 or 19 , comprising adapting the scrambling code based on:

a comparison of the detected interference on the carrier, when using the scrambling code, with an interference threshold.

21. A method as claimed in claim 1 , further comprising:

determining whether said first, second or third power levels are greater than a maximum permitted power threshold; and

if said first, second or third power levels are greater than a maximum permitted power threshold, resetting the total transmit power of the basestation to said maximum permitted power threshold; and

if said first, second or third power levels are not greater than a maximum permitted power threshold, maintaining the total transmit power of the basestation at its set level.

22. A method as claimed in claim 1 , comprising setting the first power level as a function of an average minimum signal power required by a user equipment to support a particular service, and a minimum indoor path loss.

23. A method as claimed in claim 1 , comprising setting the second power level as a function of the interference caused by a neighbouring macrolayer basestation, and a minimum indoor path loss.

24. A method as claimed in claim 1 , comprising setting the third power level to be equal to the downlink transmit power of a neighbouring other basestation.

25. A method of controlling a basestation in a cellular wireless communications network, the method comprising:

determining whether or not a carrier that has been selected for communicating with UEs is unused by neighbouring macrolaver basestations or other basestations;

wherein a carrier is unused if there are no detected macrolayer basestation or other basestation CPICH signals and the received signal strength indicator (RSSI) on the carrier is below a minimum interference threshold;

if the carrier is not unused by neighbouring macrolayer basestations or other basestations, determining whether the interference caused by neighbouring macrolayer basestations is greater than or less than the interference caused by neighbouring other basestations;

if said carrier is unused by neighbouring macrolayer basestations or other basestations, setting the total transmit power of said one or more mobile devices at a first power level;

if said carrier is not unused by neighbouring macrolayer basestations or other basestations, and the interference caused by neighbouring macrolayer basestations is greater than the interference caused by neighbouring other basestations, setting the total transmit power of said one or more mobile devices at a second power level;

if said carrier is not unused by neighbouring macrolayer basestations or other basestations, the and the interference caused by neighbouring macrolayer basestations is less than the interference caused by neighbouring other basestations, setting the total transmit power of said one or more mobile devices at a third power level.

26. A method as claimed in claim 25 , further comprising:

determining whether said first, second or third power levels are greater than a maximum permitted power threshold; and

if said first, second or third power levels are greater than a maximum permitted power threshold, resetting the total transmit power of the basestation to said maximum permitted power threshold; and

if said first, second or third power levels are not greater than a maximum permitted power threshold, maintaining the total transmit power of the basestation at its set level.

27. A method as claimed in claim 25 , comprising setting the first power level as a function of an average minimum signal power required by a user equipment to support a particular service, and a minimum indoor path loss.

28. A method as claimed in claim 25 , comprising:

if it is determined that the interference caused by neighbouring macrolayer basestations is greater than the interference caused by neighbouring other basestations, calculating the basestation to neighbouring macrolayer basestation path losses; and

setting the second power level as a function of an average minimum signal power required by a user equipment to support a particular service, and a smallest path loss between the basestation and a neighbouring macrolayer basestation.

29. A method as claimed in claim 25 , comprising setting the third power level to be equal to the downlink transmit power of a neighbouring other basestation.

30. A basestation, for use in a mobile communications network, the basestation comprising:

an interface, for transmitting and receiving signals;

wherein the basestation is configured to

determine whether or not a carrier that has been selected for communicating with UEs is unused by neighbouring macrolayer basestations or other basestations;

wherein a carrier is unused if there are no detected macrolayer basestation or other basestation CPICH signals and the received signal strength indicator (RSSI) on the carrier is below a minimum interference threshold;

if the carrier is not unused by neighbouring macrolayer basestations or other basestations, determine whether the interference caused by neighbouring macrolayer basestations is greater than or less than the interference caused by neighbouring other basestations;

if said carrier is unused by neighbouring macrolayer basestations or other basestations, set the total transmit power of said one or more mobile devices at a first power level;

if said carrier is not unused by neighbouring macrolayer basestations or other basestations, and the interference caused by neighbouring macrolayer basestations is greater than the interference caused by neighbouring other basestations, set the total transmit power of said one or more mobile devices at a second power level;

if said carrier is not unused by neighbouring macrolayer basestations or other basestations, and the interference caused by neighbouring macrolayer basestations is less than the interference caused by neighbouring other basestations, set the total transmit power of said one or more mobile devices at a third power level.

31. A basestation, for use in a mobile communications network, the basestation comprising:

an interface, for transmitting and receiving signals;

wherein the basestation is configured to

determine whether or not a carrier that has been selected for communicating with UEs is unused by neighbouring macrolayer basestations or other basestations;

wherein a carrier is unused if there are no detected macrolayer basestation or other basestation CPICH signals and the received signal strength indicator (RSSI) on the carrier is below a minimum interference threshold;

if the carrier is not unused by neighbouring macrolayer basestations or other basestations, determine whether an interference caused by neighbouring macrolayer basestations is greater than or less than an interference caused by neighbouring other basestations;

if said carrier is unused by neighbouring macrolayer basestations or other basestations, set the total transmit power of the basestation at a first power level;

if said carrier is not unused by neighbouring macrolayer basestations or other basestations, and the interference caused by neighbouring macrolayer basestations is greater than the interference caused by neighbouring other basestations, set the total transmit power of the basestation at a second power level; and

if said carrier is not unused by neighbouring macrolayer basestations or other basestations, and the interference caused by neighbouring macrolayer basestations is less than the interference caused by neighbouring other basestations, set the total transmit power of the basestation at a third power level.