Gautham Prasad
Non-terrestrial network (NTN) is an umbrella term that encompasses cellular communication networks served by base stations floating in air. Low orbit flying objects, such as drones and uncrewed aerial vehicles (UAV) to higher orbit satellites make up the majority of NTN enablers. NTN may also include flying end-users, for example, airplanes in an air-to-ground (ATG) network.
NTNs primarily target underserved and unserved areas. A vast portion of these areas are made up of Internet-of-Things (IoT) terminals. IoT NTNs comprise both wide-area IoT networks (WINs) and local-area IoT networks (LINs). The former provides global service continuity for telematic applications with IoT nodes placed or moving over a wide area and reporting sensing and other information to a central server. Some example industry verticals of telematics applications in WINs are [1]:
- Automotive: NTNs assist in delivering/gathering data to/from nodes over a wide area for high density platooning, traffic flow optimization, vehicle software updates, remote automotive diagnostics, user driving behavior tracking, safety status reporting, remote access functions, among others.
- Energy and smart grid: Critical surveillance of oil, power, and gas infrastructure (e.g., pipeline status) can be achieved with NTNs without the uncertainty of monitoring infrastructure being in out-of-coverage regions or out-of-coverage instances.
- Transportation: A central control of remote road alerts, digital signage, asset tracking, and fleet management can be achieved irrespective of the location of the vehicle or the controlled infrastructure due to the ubiquitous coverage of NTN.
- Agriculture: Livestock management and farming assistance can be improved using NTN by covering service areas that are typically underserved by conventional terrestrial cellular networks.
LINs typically comprise a group of sensors located in a confined area on board a moving platform (e.g., on board a vessel, truck, or train) [1]. A centralized entity may also be on board the platform. NTNs serve as a crucial connector to link the sensors and/or the centralized entity with a mobile core network regardless of the location/movement of the platform.
IoT-NTN is standardized by the 3rd generation partnership project (3GPP) by building on long-term evolution (LTE) standard that supported LTE-machine type communication (LTE-M) and narrowband IoT (NB-IoT). In its latest release (Rel. 17), 3GPP standardized the operation of IoT-NTN along the lines of its enhanced mobile broadband (eMBB) counterpart in new radio (NR) – NTN by focusing largely on timing enhancements, synchronization, and hybrid automatic repeat request (HARQ) enhancements. To assist with these, Rel. 17 assumes that an IoT user equipment (UE) is equipped with a global navigation satellite system (GNSS) module [2].
Owing to the prevalence of IoT devices served by NTNs, 3GPP has dedicated a majority of agenda items in the radio access network (RAN) working group – 1 to IoT NTN, focusing mainly on two topics: HARQ disabling to counter HARQ stalling, and reducing the reliance on GNSS [3]. The latter may be unique to IoT NTN, where overcoming the heavy reliance on GNSS could improve the battery life of IoT UEs and improve operations during long transmissions introduced due to multiple packet repetitions.
Ofinno continues to drive research in NTN to design cutting edge technologies to provide seamless global connectivity, not just between people but also among things. Ofinno, along with other founding and full members of the NextG Alliance, has also been spearheading the advancement of NTN in 6G cellular communications by tackling key issues faced in deploying network coverage to areas that are difficult or cost prohibitive to serve using terrestrial networks.
References
[1] 3GPP TR 38.811 V15.4.0, “Study on New Radio (NR) to support non-terrestrial networks,” Sep. 2020.
[2] 36.763, “Study on Narrow-Band Internet of Things (NB-IoT) / enhanced Machine Type Communication (eMTC) support for Non-Terrestrial Networks (NTN) (Release 17),” June, 2021.
[3] R1-2203217, “Draft Agenda”, 3GPP TSG RAN WG1 #109-e, e-Meeting, May 9th – 20th, 2022.
