FREQUENCY PLANNING FOR A CELLULAR COMMUNICATION SYSTEM

1 . An apparatus for frequency planning for a cellular communication system, the apparatus comprising:

means for receiving measurement reports from a plurality of remote stations;

interference determining means for, for each of a plurality of cells, determining a neighbour cell interference relationship between at least a first neighbour cell and a second neighbour cell of the cell in response to measurement reports from remote stations served by the cell, the neighbour cell interference relationship being indicative of an interference from the first neighbour cell to the second neighbour cell; and

means for determining a frequency plan in response to the neighbour cell interference relationships.

2 . The apparatus of claim 1 wherein the interference determining means comprises means for determining the neighbour cell interference relationship for the first neighbour cell and the second neighbour cell in response to measurement reports received only from remote stations in an overlap region between the cell and the second cell.

3 . The apparatus of claim 2 wherein the interference determining means comprises means for determining that a measurement report is from a remote station in the overlap region if measurement data of the measurement report meets an overlap criterion.

4 . The apparatus of claim 3 wherein the overlap criterion comprises a requirement that a receive signal quality measure of a pilot signal from a base station serving the second cell exceeds a threshold.

5 . The apparatus of claim 4 wherein the threshold is dependent on a receive signal quality measure of a pilot signal from a base station serving the cell.

6 . The apparatus of claim 3 wherein the overlap criterion comprises a requirement that a receive signal quality measure of a pilot signal from a base station serving the second cell exceeds receive signal quality measures of pilot signals from base stations serving other neighbour cells of the cell.

7 . The apparatus of claim 2 wherein the interference determining means is arranged to scale the neighbour cell interference relationship for the first neighbour cell and the second neighbour cell in response to an amount of measurement reports received from the overlap region.

8 . The apparatus of claim 1 wherein the neighbour cell interference relationship for the first neighbour cell and the second neighbour cell is determined in response to a difference between a receive signal quality measure of a pilot signal from a base station serving the second cell and a receive signal quality measure of a pilot signal from a base station serving the first cell.

9 . The apparatus of claim 1 wherein the interference determining means is arranged to determine the neighbour cell interference relationship for the first neighbour cell and the second neighbour cell in response to a proportion of measurement reports that meet a criterion.

10 . The apparatus of claim 1 wherein the interference determining means is arranged to scale the neighbour cell interference relationship for the first neighbour cell and the second neighbour cell in response to an amount of handovers from the cell to the second cell.

11 . The apparatus of claim 1 further comprising:

matrix means for generating an interference matrix in response to the neighbour cell interference relationships, each matrix coefficient of the interference matrix reflecting an interference relationship between a cell pair associated with the matrix coefficient; and

wherein the frequency planning means is arranged to determine the frequency plan in response to the interference matrix.

12 . The apparatus of claim 11 wherein the matrix means is arranged to generate a matrix coefficient for a cell pair comprising cells not being neighbour cells of each other in response to neighbour cell interference relationships for the cell pair determined for a plurality of cells having both cells of the cell pair as neighbour cells.

13 . The apparatus of claim 11 wherein the matrix means is arranged to generate a matrix coefficient reflecting an interference relationship from the first cell to the second cell in response to neighbour cell interference relationships for the first and the second cell determined for plurality of cells from which remote stations may handover to the second cell.

14 . The apparatus of claim 11 wherein the matrix means is arranged to generate a matrix coefficient reflecting an interference relationship from the first cell to the second cell in response to a neighbour cell interference indication determined substantially as:

I

X

,

Y

=

∑

n



F



(

R



(

X

n

,

Y

n

)

)

wherein X represents the first cell, Y represents the second cell, R(X n ,Y n ) is the neighbour cell interference relationship for the first cell and the second cell determined for cell n, F is an arbitrary function and the summation n is over all cells having the first cell and the second cell as neighbour cells and from which a remote station can handover to the second cell.

15 . The apparatus of claim 1 wherein the cellular communication system is a Global System for Mobile communication, GSM.

16 . A method of frequency planning for a cellular communication system, the method comprising:

receiving measurement reports from a plurality of remote stations;

for each of a plurality of cells, determining a neighbour cell interference relationship between at least a first neighbour cell and a second neighbour cell of the cell in response to measurement reports from remote stations served by the cell, the neighbour cell interference relationship being indicative of an interference from the first neighbour cell to the second neighbour cell; and

determining a frequency plan in response to the neighbour cell interference relationships.