Graph based automatic centralized PCI assignment in LTE

Physical Cell Identity (PCI) is cell identifier on the physical layer which can be used to create synchronization signals. There is a mapping between synchronization signals and physical cell identity, and then User Equipment (UE) can search cells through this mapping. Traditionally, PCI was configured during network planning process. While with 3G Long Term Evolution (LTE) has been prevalent in the future network, auto configuration of radio parameters has become a necessity. This paper proposed an automatic centralized PCI assignment mechanism using OAM as central server to collect cell information of the network, and create an abstract graph using information given which reflects the relationship in real-world network. After that, an enhanced graph-coloring algorithm which can greatly reduce time complexity while keeping a high PCI utility ratio was provided to create a collision and confusion free PCI for the new cell.