Analog Cancellation in ATSC 3.0 for Enabling Inter-Tower Communications Network

Inter-Tower Communications Network (ITCN) is a use case of considerable relevance within ATSC. In ITCN, each of the transmitting centers is connected to each other, forming a mesh network. However, this situation makes the towers transmitters and receivers simultaneously, which generates a self-interference (SI) signal in the receiving antenna. Digital cancellation techniques can reduce the impact of the SI signal considerably. In contrast, digital cancellation devices have a limited dynamic range and cannot guarantee the necessary cancellation. For this reason, analog cancellation has two advantages: SI reduction and no influence on the dynamic range. This paper proposes to use analog cancellation techniques within a fully compliant ATSC 3.0 transceiver chain. The work provides an analog cancellation technique review and an architectural design of the ATSC block diagram. Moreover, the evaluation process assumes different loopback signal amplitudes and tests the performance of the proposed analog cancellation technique. Results indicate that the loopback channel estimation and the loopback signal regeneration are the parameters that limit the efficiency of the analog cancellation module. Finally, the relevance of the loopback signal delay has been identified as critical, and a solution is proposed.