Signal Isolation Characterization of ITCN In-Band Full-Duplex Communications

Future digital terrestrial television (DTT) systems are introducing revolutionary changes to their architectures and operation modes. One of the best examples is ATSC 3.0, which is pushing to incorporate the Internet Protocol (IP) into the protocol stack. This way, implementing new applications (e.g., target advertisement, connected cars, 4k/8k video content) is closer than ever. Indeed, recent works have suggested designing and implementing an Inter-Tower Communications Network (ITCN) and wireless In-band Distribution Link (IDL) inside the ATSC 3.0 forums. ITCN will interconnect all broadcast towers to form a communication network for control, monitoring, data communication, and localized datacast and broadcast services. Nevertheless, this application has a significant challenge: the self-interference (SI) or loopback signal that is generated and added to the received signal. To reduce the impact of the SI, the transmission centers combine different signal isolation and cancellation techniques. This paper focuses on characterizing the signal power isolation between the transmitted and the received signals under different conditions. In particular, this paper shows the signal isolation values measured during various field trials in real broadcast transmission centers. The results show that the total signal isolation varies depending on the transmission/reception configuration between 70-90 dB. Moreover, due to the measurements, we have demonstrated that the antenna distance is a more relevant parameter for signal isolation than the center frequency. Finally, the possible antenna pattern discrimination has been calculated and discussed.