Time and frequency distribution over packet switched networks

Moving from time division multiplexing (TDM)-based to packet-based network, frequency distribution has become a significant issue for network operators in view of strong requirements necessary for applications such as the backhauling of different wireless technologies. In this context the International Telecommunication Union, Telecommunication Standardization Sector (ITU-T), Internet Engineering Task Force (IETF) and Institute of Electrical and Electronics Engineers (IEEE) have competing standards to identify the right answer in terms of migration and achievable performance. This competition promotes segmentation of the network synchronization architecture, since the synchronization technologies are evolving separately at the expense of the benefits of interworking, potentially leading to future interoperability issues. Following a brief description of the aforementioned synchronization technologies focusing on their relative strengths and weaknesses, potential interworking schemes will be discussed. Both accurate frequency and time distribution will be considered. Time distribution, in particular, appears to be a key issue for emerging wireless network technologies, such as Worldwide Interoperability for Microwave Access (WiMAX) and Long Term Evolution (LTE). Finally, we will propose a new vision of a unified synchronization management approach in order to simplify the deployment of adapted synchronization technologies in various environments.