Sharing and Compatibility Studies for IMT and DTTB Systems in the Sub-700 MHz UHF Band

In this paper, we present a simulation-based study for the coexistence of an International Mobile Telecommunication (IMT) system with a Digital Terrestrial Television Broadcasting (DTTB) system. The study considers the coexistence of the two systems in the sub-700 MHz band and presents interference analysis results for locations in the Kingdom of Saudi Arabia (KSA). The study includes different terrains in which each of the two systems is deployed, e.g., mountains, sea, desert, etc. Using an advanced terrain-aware simulation software (HTZ from Advanced Topographic and Digital Imaging (ATDI), the coexistence problem is studied in these cases which represent some of the most common types of terrains. The goal is to quantify the level of interference in each of the case studies and compare it with the protection ratio in terms of either the carrier-to-interference-plus noise
$C/(I+N)$
or interference-to-noise
$(I/N)$
ratios, depending on the simulation parameters and following the standard approach used in such studies. These two measures help in providing the proper recommendations on the coexistence of the IMT and DTTB systems. This study is structured into two main parts. The first part focuses on studying the interference induced by IMT base station (BS) and IMT user equipment (UE) on the DTTB receiver in the sub−700 MHz band (from 614 to 694 MHz) which corresponds to the 5G N71 band, whereas the second part considers the interference induced by DTTB system on IMT BS and IMT UE. The investigation has revealed that in most of those situations, separation distances (exclusion zones) are found to be relatively within a reasonable range from the border compared with the size of the whole network. This indicates that IMT network could be deployed in many locations close to the DTTB network with tolerable effect. The most challenging case is the effect of DTTB system on the up-link (UL) of IMT network, which necessitates the use of additional mitigation techniques to reduce the interference.