Implementation of Wireless Backhaul and Inter-Tower Communications With MIMO in ATSC 3.0

Abstract

Wireless backhaul, i.e., in-band distribution links (IDL) and inter-tower communications networks (ITCN) were previously proposed as key enabling technologies for the next-generation digital broadcasting systems, e.g., the Advanced Television Systems Committee (ATSC) 3.0 system. Both ITCN/IDL can be operated in the spectrum-efficient in-band full-duplex (IBFD) mode and the same frequency band is shared between the broadcast service signal and the ITCN/IDL signals. It is desirable to integrate multi-input multi-output (MIMO) into ITCN/IDL transmission to increase the throughput and reduce the portion of spectrum occupation by ITCN/IDL. However, due to the backward compatibility constraint, conventional symmetrical MIMO techniques cannot be applied directly to the existing broadcast infrastructure without affecting legacy receivers. In this paper, the practical implementation of a non-symmetrical MIMO for ITCN/IDL while maintaining backward compatibility is considered. In addition to the existing broadcasting antenna, the non-symmetrical MIMO comprises an additional low-power RF feeder cable and one or more highly directional antennas to achieve low-cost MIMO implementation for high throughput data distribution and inter-tower communications. When the broadcast service signal and the MIMO signal are multiplexed in Time Division Multiplexing (TDM) format, the signal structure is ATSC 3.0 standard compliant. When the broadcast service signal and the MIMO signal are multiplexed in Layer Division Multiplexing (LDM) format, modification of the ATSC 3.0 standard, i.e., introducing a new pilot encoding scheme, is required. Moreover, MIMO self-interference cancellation (SIC) is investigated for IBFD operation.