US 6,285,874 B1 · Cell identification based on distance

Abstract

The present invention relates generally to the problem of determining the identity of a cell for e.g. cell handoff or automatic frequency planning, and more particularly to the problem of determining the true identity of a cell when only the transmission frequency and a non-unique identity code is known. A candidate list is created for each cell. This candidate list is created based on a function of various elements e.g. distance, transmission power, cell type, and antenna placement. The cells are then ranked on the candidate list based on this function. When a particular frequency/code combination is detected, the candidate list is then consulted, and the highest ranking cell with the same frequency/code combination is chosen as being the signal source. In an alternative embodiment the neighbor cell list is used to create the candidate list. If there are no matches on this list for the detected frequency/code combination, then the neighbors of the cells on the candidate list are also added to the candidate list which is then checked for a match.

Claims32

Dependent claims

defining a virtual distance from said first cell to said second cell;
detecting, in said first cell, a non-unique identification transmitted from a cell other than said first cell;
checking said candidate list for said first cell for a matching, non-unique identification;
and
concluding that the cell identity on said candidate list, for which the non-unique identification matches the non-unique identification transmitted from said other cell, and for which said virtual distance is shortest, is the identity of the cell from which the signal was transmitted.

2 more elements

A method for determining the identity of a cell from which a signal is transmitted in a cellular mobile communications system having a plurality of cells, said cells having base stations for receiving and transmitting radio signals to and from at least one mobile station, said mobile station being situated in a first cell, said first cell having a neighbor cell list including a plurality of fields corresponding to neighbor cells of said first cell and fields for non-unique identification of a neighbor cells, said first cell also having a candidate list and a non-unique identification of said second cell, said method comprising the steps of:

a first step of detecting, in said first cell, a non-unique identification transmitted from a cell other than said first cell;
a second step of adding said plurality of fields for said cells in said neighbor cell list to said candidate list;
a third step of checking said candidtate list for a matching non-unique identification;
if there is no match then checking the neighbor cell lists for each cell on said candidate list and modifying said candidate list by repeating said second step and adding fields for each cell on each neighbor cell list for each cell on said candidate list and then repeating said third step and checking the modified candidate list for a matching non-unique identification.

1 more element

Dependencies are inferred from the claim text.

Cell identification based on distance

Life of this patent

Cell identification based on distance

Life of this patent

Abstract

Claims32