Non-Terrestrial Network

The LTE modem supports 3GPP Internet of Things Non-Terrestrial Network (IoT NTN) based on Cat-NB1/NB2. This feature is available after installing firmware that implements the modified Cat-NB1/NB2 physical layer (PHY) and layer 2 and 3 level operation of the NTN radio protocol stack according to 3GPP specifications.

The IoT NTN radio layer extends cellular radio capabilities. The following are key features of IoT NTN:

• Supports major global Mobile Satellite Service (MSS) bands, including B249 in TDD mode
• Built-in coexistence of terrestrial networks in the same location
• Full integration into 3GPP network architectures and ecosystem
• Cat-NB1 and Cat-NB2 support
• Single-tone and multi-tone transmission
• UE location from an external GNSS source
• Support for different satellite deployment models, with simultaneous UE support
• UE ability to pre-compensate its Timing Advance and the frequency Doppler shift relative to the satellite position and satellite velocity through the network provided satellite ephemeris and a valid UE GNSS position
• Skylo proprietary optimisations

See 3GPP TS 36.300 and 3GPP TS 36.306 for more information.

IoT NTN operates on the global MSS bands, which are distinct from terrestrial bands. A satellite cell may cover a large geographical area up to hundreds of kilometres in diameter. The large earth fixed cells, and specifically moving cells, can cross country borders or cover areas with no territorial claims. Therefore, regulatory aspects also need to be carefully considered (see 3GPP TR 22.926).

IoT NTN is based on Cat-NB1/NB2 cellular radio standard that is included as part of the 3GPP R17 and later, with a priority on non-terrestrial (satellite) access. The standard covers both the transparent payload (non-regenerative) and the non-transparent (regenerative) payload deployment cases.

Depending on the satellite system and the constellation that is used, the following three types of service links between the UE and the satellite are supported:

• Earth fixed – provisioned by beam(s) continuously covering the same geographical areas all the time (for example, GSO satellites)
• Quasi Earth fixed – provisioned by beam(s) covering one geographic area for a limited period and a different geographic area during another period (for example, NGSO satellites generating steerable beams)
• Earth moving – provisioned by beam(s) whose coverage area slides over the Earth's surface (for example, NGSO satellites generating fixed or non-steerable beams)