Method for interference mitigation for femtocell base stations of a WiMAX network

1. Method for interference mitigation for femtocell base stations of a Worldwide Interoperability for Microwave Access (WiMAX) network, wherein said femtocell base station is located within the transmission range of at least one macrocell base station and/or at least one other femtocell base station, characterized in that said femtocell base station performs downlink measurements to detect neighboring macrocell and/or femtocell base stations and reports results of said downlink measurements to at least one higher layer network controller, wherein said network controller allocates transmission parameters to said WiMAX femtocell base stations on the basis of at least said reported measurement results and the current resource occupation in said network.

2. Method according to claim 1 , wherein said downlink measurement and said reporting of measurement results is performed by said femtocell base station upon entering said network.

3. Method according to claim 2 , wherein said downlink measurement and said reporting of measurement results is performed each time said femtocell base station receives a request for a data connection from a mobile station.

4. Method according to claim 1 , wherein said downlink measurement and said reporting of measurement results is performed each time said femtocell base station receives a request for a data connection from a mobile station.

5. Method according to claim 1 , wherein said downlink measurement and said reporting of measurement results is performed periodically during existing data connections.

6. Method according to claim 1 , wherein said downlink measurements include the scanning of received downlink preamble sequences.

7. Method according to claim 1 , wherein the transmission parameters allocated by said network controller to said femtocell base station include the transmission power, the preamble sequence, and/or the set of subchannels.

8. Method according to claim 1 , wherein said network controller checks whether Fractional Frequency Re-Use (FFR) and/or frequency segmentation is applied in macrocell base stations co-located to said femtocell base station.

9. Method according to claim 1 , wherein said network controller checks whether there are any carrier frequencies and/or subchannels that are not used neither by macrocell base stations co-located to said femtocell base station nor by neighboring femtocell base stations.

10. Method according to claim 1 , wherein said femtocell base station is configured to send dedicated transmission power testing preambles.

11. Method according to claim 10 , wherein macrocell and/or femtocell base stations co-located to said femtocell base station, upon identifying said dedicated transmission power testing preambles, report their related measurements to said network controller.

12. Method according to claim 11 , wherein said network controller adjusts said femtocell base station's transmission parameters, in particular its transmission power, based on the received measurement reports.

13. Method according to claim 1 , wherein femtocell base stations of said network are grouped according to predefined criteria, in particular their geographic location, and wherein all femtocell base stations of a specific group are allocated the same transmission parameters.

14. Method according to claim 1 , wherein said femtocell base station, before increasing its transmission power, increases its transmission power on the preamble only and waits for the response of other macrocell and/or femtocell base stations.

15. Method according to claim 14 , wherein mobile stations that receive said femtocell base station's increased transmission power preamble perform measurements on said preamble and report the measurement results to their own base stations.

16. Method according to claim 15 , wherein macrocell and/or femtocell base stations are configured to vote on said femtocell base station's transmission power according to the measurement reports received from their connected mobile stations.

17. Method according to claim 1 , wherein said femtocell base station is configured to inform said network controller of the termination of data connections with mobile stations.