Synchronisation in WCDMA mobile networks

Abstract

This article resumes technical specifications delt with in ITU-T and 3GPP reviewing required synchronization in WCDMA type of mobile communications’ radiobases (NodeB) for the proper behavior of the main functionalities. Though the specifications define two types of WCDMA, FDD and TDD, networks nowadays are deploying the first one, by separating uplink from downlink in different frecuency bands. In addition, technical evolution allowed for NodeB traffic to be transported over IP/Ethernet networks. Specifications differentiate frecuency synchronization, phase synchronization and time synchronization. Transmission of traffic over IP/Ethernet uncover new problems synchronization-wise which previous TDM technologies did not suffer. A field study on a FDD WCDMA network analyzing synchronism and its effects on traffic shows
the results of deploying different synchronization mechanisms between nodes in a mobile telephony network. The importance of synchronized state required by the nodes is confirmed, as are the problems when a critical traffic prioritization mechanism is not implemented in a packet
transport network.