Spatially Adaptive TV Broadcast System: Hardware in the Loop Operational Analysis

When a digital TV system is operating far in excess of the operational threshold, there is no discernible advantage to either the user or broadcaster due to the hard failure characteristics of digital TV. In a digital network, this threshold can vary due to changes in the propagation medium and user receiving equipment, necessitating a transmit power margin sufficient to cover all propagation and equipment variations. Hence if the system could be adaptively tuned to operate at just above the threshold, then significant energy savings could be made. A spatially adaptive system was evaluated through hardware-in-the-loop analysis; here a channel emulator was used to physically model array gain and fading conditions, and feedback nodes were constructed allowing broadcast powers to be manipulated based on evaluating user feedback. The effects of such a system on the U.K. Digital terrestrial television (DTT) network were evaluated and the advantages highlighted potential power savings of up to 2.1 dB being obtainable. This equates to an electricity reduction of between 33 million and 58 million kWh per year, saving between £3.5 million and £6.1 million ($4.4 million and $7.6 million) and reducing carbon emissions by between 13.7 million and 24 million CO₂e. This paper thus illustrates the potential energy savings for a DTT network, using the U.K. as a worked example.