Tower overlay over LTE-Advanced+ (TOoL+) — Field trial results

The term "Tower Overlay over LTE-Advanced+ (TOoL+)" describes the transmission of an extension of LTE-Advanced (LTE-A) offering broadcast services, especially live video, from a traditional High Tower High Power (HTHP) broadcast infrastructure, rather than in a cellular LTE-A network. Since LTE-A is optimized for the Low Tower Low Power (LTLP) environment of cellular networks, the use of a HTHP environment requires some modifications of the LTE-A standard, e.g. the definition of a dedicated broadcast carrier and of additional OFDM parameters with longer cyclic prefixes. These modifications are represented by the term LTE-A+. TOoL+ further supports a cooperative spectrum use by DVB-T2 (or ATSC 3.0 in the future) and LTE-A+. To evaluate the proposed modifications and the cooperative spectrum use in a real environment, two field trials in Paris, France, and the Aosta Valley, Italy, have been implemented for a first measurement campaign focusing on coverage verification and mobile reception performance. A Software Defined Radio (SDR) based TOoL+ receiver was developed to analyze the measured data and to enable the comparison of different decoding strategies, e.g. channel estimation algorithms. First analyses show that LTE-A+ is a suitable technology for HTHP broadcast to mobile devices as its coverage area is similar to that of DVB-T2.