Patent ID: 8626213

Claim:
A method in a communication network node for detecting a collision between physical cell identities in a communication network system, the communication network system comprising radio base stations, each radio base station configured to serve at least one cell and send a reference signal to user equipments in that at least one cell over a radio interface, the reference signal comprising reference symbols corresponding to a physical cell identity of said at least one cell, the method comprising: performing, by the communication network node, a physical cell identity collision test by fractionally distributing reference symbol transmission gaps in the time and frequency domains within a given frame of a reference signal to be sent in a cell by a radio base station; wherein during reference symbol transmission gaps some reference symbols are not sent, to enable user equipments in that cell to detect if another radio base station is sending reference symbols corresponding to the same physical cell identity, while other reference symbols remain unaffected by said reference symbol transmission gaps.