The wide area network transports the station data transparently to the central systems. The control information is sent via this network as well.
The station fields are distributed over a region of roughly hundred kilometres in diameter andfor the international stations up to thousands of kilometres. For coherent data processing such as calculation of the correlation function and tied array beamforming, it is necessary to combine signals from all stations, which is performed at the central processing site. The wide area network transports the output data streams from the stations to the central processing site.
The main part of the LOFAR data that is transported throughout the network is observation data, in addition, a small part of the LOFAR data stream concerns monitoring and control data transport. The Wide Area Network consists of dark fiber and active communication equipment. Among these are network switches, optical multiplexers and media converters. The WAN will be implemented using 10 Gigabit Ethernet (10 GbE) technology. This is the obvious choice for distances up to ~40 km with a single transmitter/receiver pair, but will also be used for longer distances unless cheap and reliable alternatives are available (e.g. by reuse of existing infrastructure).
Data rates in the network vary from 2 to 20 gigabit per second, dependent on antenna location. The network will also be used for the transportation of data of the sensors of the LOFAR partners. The data from these sensors is routed also over the LOFAR network. This is done in a way that other running experiments are not influenced.