Virtual extension of cell IDs in a femtocell environment

In this paper, we solve a cell identification problem in a femtocell environment. In the densely deployed area, the number of Physical Cell Identifiers (PCIs) for femtocells may not be sufficient. The scarcity of PCIs results in identification ambiguity due to duplicated PCIs in a certain area, which may result in handover failure. Using time synchronization between femtocells and macro cells, we propose a scheme to efficiently identify cells in a femtocell environment. Our scheme can increase the number of cell identifiers up to 1024 times using even coarse local time synchronization, without changing the existing physical layer specification. Since time synchronization occurs locally, we can apply the proposed scheme to asynchronous as well as synchronous wireless systems. We verify the proposed scheme via simulations.