3GPP Release 17 supports Non-Terrestrial connectivity using, for example, satellites in transparent mode. While connected in transparent mode, both service and feeder link must be active simultaneously to obtain service. Signals are mirrored by the satellite between user terminal and ground station. In the case of LEO satellites, connectivity to a ground station must be established before service can be provided to user terminals. Hence, connectivity is provided while the satellite is visible.
Compared to the transparent mode (Rel-17), the regenerative mode will include enhancements and optimizations for NGSO satellite systems, considering the moving of the non-Geostationary satellites, enabling efficient blind search of user devices, etc. The regenerative will enable UEs to communicate with the NodeB even when a feeder link is not active, and makes communication everywhere on the globe possible. In the regenerative mode, the NodeB will be located on the satellites themselves.
Being able to support 5G NB-IoT services with a GEO system depends on various factors, all going back to your system infrastructure and set-up (e.g what bands you are operating on, what capacity you have, what user devices, which antennas are required, etc.). We can help you in generating a neutral, third party answer to this, with our 3GPP and NTN expertise we apply when developing the software for those systems. More specifically, we can help you in answering this question, by designing an individual pre-assessment or feasibility study based on your individual needs and system set-up. The goal is to verify the viability of supporting 5G NB-IoT, and to calculate the system capacity and business case, for example.
For this, we bring in our expertise for simulations of the link budget, and the assessment of the system capabilities. Pilot projects (lab tests, proof of concepts, and in orbit demonstrations) are also on our agenda, with the goal to pave your way to a commercial 5G NB-IoT NTN system.
With 3GPP Release 17 standards for development of user terminals are available. Several enterprises in user terminal supply chain like GateHouse SatCom have been active in the standardization work and are quite advanced in their product offerings. However, the exact timing will be balanced with demand and priorities. And of course the availability of satellite networks supporting the release 17 Non-terrestrial services. GateHouse SatCom is not aware of any chipsets currently supporting 3GPP Release 17 NTN services.
With Rel-17´s protocol coding freeze in June this year, we recommend looking into 5G as soon as possible. Based on this timeline, software protocols for the UE and the satellite side will be available for first lab tests and proof of concepts shortly thereafter, until they are expected to be commercially available in Mid 23. We recommend using the time until then, to understand your system set-up and requirements, and the time for testing and proofing the concept within your infrastructure, so that you are ready when Rel-17 can be implemented into commercial systems.
The 3GPP standards specify multimode user terminals that are capable of obtaining service without modifications on both terrestrial and non-terrestrial networks. Tests have been conducted with hardware conforming to earlier releases where only software was modified to obtain service. Hence, power consumption is expected to be equal to previous releases for user terminals working in hybrid mode. To close the link budget user terminals are expected to have line of sight visibility to satellites when used on satellite based networks.
With help of the NPSS, NSSS and NRS, a signal can be detected, and during the decoding of it, the frequency offset can be determined. That this frequency offset can be very high, and becomes lower the closer the satellite comes to the UE can be calculated and resolved by the processing algorithm.
It is expected that standard, off-the-shelf chipsets will be used, alongside with standard NB-IoT supporting devices which we know from terrestrial networks today. The 5G NB-IoT for space needs to be able to run on them, which will be enabled by supporting chipsets. As we are not a chipset company, we cannot say anything in regards to the costs. But similar costs to TN supporting chipsets are expected.
With Rel-17 being frozen this June, UE software will be commercially available shortly thereafter. Then it depends on chipset companies to have chipsets supporting non-terrestrial networks. Adaptations are not expected to be major, but they need to be done. And the question is when chipset companies see a market in the 5G NB-IoT NTN technology. We expect that it is only a matter of time, as companies are publishing trials as we speak.
There are no changes to the protocol or services available under 3GPP release 17 for non-terrestrial networks. A PDP Context can be established and maintained for data transmission as for terrestrial networks. Hence it is not needed to apply the random access procedure as long as the connection is not broken. For NGSO communication, the transmission will be likely a few minutes, and for GEO transmission the context can be kept longer active.
GateHouse SatCom has no insight into future evolutions of 5G. Changes and additions to the standards are agreed upon between contributing participants. In some backhauling solutions DVB-S is used over the satellite link to connect remote NodeB to the Core Network.
GateHouse SatCom is building NodeB to be integrated in Satellite networks in three different scenarios:
1) on the ground supporting transparent mode,
2) in the satellite supporting in-orbit processing and regenerative mode, and
3) at the remote side supporting backhauling of 5G services establishing a remote cell.
We are working with suppliers of LTE and 5G Core Network, but unfortunately we have no insight into the complexity of integrating a Cellular Core into a Satellite Core.
There are already existing satellite core networks build on 3G and 4G cell core networks offering mobile data services.
Question 1: We see two issues with the use of transparent mode in NGSO systems. 1) As the satellites are only visible from both ground station and user terminals in a relatively short time period it is only possible to obtain service in smaller time intervals. 2) Since ground stations must be located in the same satellite footprint as the user terminals there will be large parts of the earth surface like the oceans where is not possible to obtain services.
Question 2: Handover of traffic connections resulting from moving NGSO satellites is not supported in release 17 and in transparent mode there is no on-board processing. The procedure and algorithms for handover currently implemented in standard compliant user terminals will not be able to support setting up a 2nd link for handover of the traffic. We expect this to come as part of one of the following releases.