SFN gain estimations based on frequency response

DVB-H (Digital Video Broadcasting, Handheld) is based on the terrestrial version of DVB, i.e. DVB-T, and it has been designed especially for the moving environment. The performance of the system takes into account the variations of the power levels and bursty interferences of the radio path. DVBH is adequate especially for the small handsets as the typical terminal screen size requires only a fraction of the bit stream capacity compared to DVB-T which is meant for the fixed reception with the antennas located in rooftop. DVB-H uses OFDM and is typically operated in a Single Frequency Network (SFN) mode. One of the important aspects of the use of a single frequency is that the transmitters are aligned via e.g. satellite systems synchronization signal. This means that all transmitters in the network are transmitting at the same time and a gain can occur in the areas where more than one signal are arriving at the same point in time, within the time width of the guard interval, and space (multipath fading). This gain can be described as a combined sine wave consisting of multipath radio waves arriving in at a point in time and space with a different phase. This phase difference is caused by the time delay which the mobile device is receiving the multipath components. This time delay can be can be visualized via the frequency response. This paper presents field test methodology for the in-depth performance analysis for the estimate of the SFN gain from drive test results. By applying the presented methodology, the estimation of the SFN gain can be taken into account in the DVBH radio link budget in realistic way.