Interference mitigation in a femtocell access point

A base station, for use in a cellular network, the base station having a first coverage area, and being located in a second coverage area associated with a second base station, and the base station being configured to:

• estimate a distribution of respective first path losses between the base station and points in the first coverage area;
• estimate a second path loss between the base station and a user equipment that is attached to the second base station by estimating a distribution of respective second path losses between the base station and one or more nearby user equipments that are attached to the second base station;
• and
• determine on the basis of said estimated first and second path losses whether the base station is causing interference with transmissions from the second base station by comparing a value of the first path loss corresponding to a first proportion of points in the first coverage area with a value of the second path loss corresponding to a second proportion of samples obtained from said nearby user equipments that are attached to the second base station.

A method of operating a base station in a cellular network, the base station having a first coverage area, and being located in a second coverage area associated with a second base station, the method comprising:

• estimating a distribution of respective first path losses between the base station and points in the first coverage area;
• estimating in the base station a second path loss between said base station and a user equipment that is attached to the second base station by:
• estimating the average transmit power of the user equipment that is attached to the second base station by estimating a third path loss between the user equipment that is attached to the second base station and said second base station, wherein the step of estimating the third path loss comprises:
• estimating a distribution of respective fourth path losses between the second base station and points in the first coverage area;
• and
• estimating the third path loss as equal to a determined value of the fourth path loss, wherein the determined value of the fourth path loss is exceeded by the fourth path loss that applies for a specified percentage of said points in the first coverage area;
• detecting in the base station signals transmitted by the user equipment that is attached to the second base station;
• and
• estimating the second path loss from a difference between the estimated average transmit power and the power of the detected signals transmitted by the user equipment that is attached to the second base station;
• and
• determining on the basis of said estimated first and second path losses whether the base station is causing interference with transmissions from the second base station.

A base station, for use in a cellular network, the base station having a first coverage area, and being located in a second coverage area associated with a second base station, and the base station being configured to:

• estimate a distribution of respective first path losses between the base station and points in the first coverage area;
• estimate a second path loss between the base station and a user equipment that is attached to the second base station by:
• estimating the average transmit power of the user equipment that is attached to the second base station by estimating a third path loss between the user equipment that is attached to the second base station and said second base station by:
• estimating a distribution of respective fourth path losses between the second base station and points in the first coverage area;
• and
• estimating the third path loss as equal to a determined value of the fourth path loss, wherein the determined value of the fourth path loss is exceeded by the fourth path loss that applies for a specified percentage of said points in the first coverage area;
• detecting in the base station signals transmitted by the user equipment that is attached to the second base station;
• and
• estimating the second path loss from a difference between the estimated average transmit power and the power of the detected signals transmitted by the user equipment that is attached to the second base station;
• and
• determine on the basis of said estimated first and second path losses whether the base station is causing interference with transmissions from the second base station.