A soft decision 16-QAM demodulation algorithm for multipath affected DVB-T systems

In 1998, the United Kingdom started the world´s first commercial digital terrestrial television service. The system used was the European digital video broadcast-terrestrial (DVB-T) but due to technological constraints at the time, the system chosen was the 2K system - a system that uses 1705 carriers to convey the digital television services through a hostile terrestrial environment. Today, these constraints are no longer applicable but in order to maintain backwards compatibility to the older set top boxes, the 2K system is still used. The 2K system has the disadvantage of excluding the possibility of employing a single frequency network (SFN) - something that can help minimize the required bandwidth for television services. This paper demonstrates an observed phenomenon that explains why DVB-T fails to meet the required BER criteria and also shows how this phenomenon can be used in a computationally inexpensive technique for estimating the relative path attenuation of a multipath signal and how it can be used to estimate the parameters required for a soft decision QAM demapper.