Investigations of single frequency networks for digital mobile radio systems based on COFDM

The application of COFDM (coded orthogonal frequency division multiplexing) transmission schemes allows the implementation of power and bandwidth efficient transmitter networks, the so-called single frequency networks. Dependent on the network configuration, the transmission quality can be improved by macro diversity gain, but contrary to that fact, self interference can lower system performance in several locations of the coverage area. The knowledge of these effects is important for network planning. New measurement techniques are required to investigate the properties of single frequency networks. In this contribution, a wideband channel sounder is described for measuring complex transfer functions of the radio channels within a single frequency network. The method is especially designed to distinguish between the signal components of the different transmitters. The complex superposition of the signals in a single frequency network is obtained additionally. The procedure was tested in several field trials. Some results of the evaluation of the measurements are given in the paper.