LEO Regenerative 5G RAN reference solution architecture being developed

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AccelerComm, the Layer 1 5G IP specialists, Radisys and TTP, an independent technology and product development company based in the UK, are jointly formulating a high-performance Regenerative 5G RAN reference solution and architecture based on 3GPP for deployment on low-earth orbit (LEO) satellites

The partnership will combine expertise and IP from these companies, together with additional technology from other partners, to propose a 5G regenerative gNodeB solution that is tailored to support high-performance 5G services in the challenging environment of a Non-Terrestrial Network (NTN). 

In a typical LEO deployment, a constellation of fast-moving satellites covers a wide geographical area using many beams per satellite to cover a multitude of subscribers. The 5G Regenerative NTN solution includes Option-2 split gNB with a distributed unit (DU) on the satellite payload with a ground-based centralised unit (CU) and 5GC.

The solution can handle unique regenerative NTN-specific requirements of extremely high mobility with frequency re-association between the DU, GW and CU serving a region and large-sized cells spanning multiple countries requiring country-specific CN routing. Moreover, any gNodeB platform for space applications will be highly constrained in size, weight, and power, and must be able to work in a hostile space environment. 

The joint LEO Regenerative reference solution will be designed to meet the growing demand for satellite-based eMBB (enhanced Mobile Broadband) and IoT (Internet of Things) services making it suitable for businesses and organisations that need to connect people and devices in remote locations, or for governments looking to provide internet access to all citizens.

The solution can support a large number of beams and high subscriber density and will be delivered on a space-hardened platform optimised for low power and size.  It includes a range of advanced developments in the areas of beam-to-cell mapping, beam forming, NTN beam management and well-defined interfaces to SATCOM infrastructure.

The O-RAN compliant gNodeB leverages Radisys’ split NTN-capable CU, DU software with AccelerComm’s LEOphy and RFDSP’s Low-Phy, a Layer 1 modem that delivers enhanced performance for low-earth orbit satellite communications combined with TTP’s DFE and Beam Scheduler.

Radisys’ CU/DU supports optimised mechanisms for handling signalling load due to high mobility, along with a power-optimised scalable software that manages the varying system requirements of beams and users.  LEOphy boasts the lowest error rates, with dedicated features to overcome the specific challenges of NTN channels, such as high path losses, differential delays, Doppler shift, long propagation delays, and rapid fluctuations in signal amplitude and phase caused by atmospheric effects. As a result, it ensures a high-reliability link without having to resort to lower coding rates and low-order modulation schemes, thereby maximising spectral efficiency. TTP’s DFE supports Crest Factor Reduction (CFR) to improve the efficiency of the RF power amplifier and its Beam Scheduler enables optimized beam hopping and switching functionality to maximize network capacity based on real-time traffic demands. 

The 5G Regenerative gNodeB is combined for an end-to-end NTN solution, with Radisys’ 5GC, available on Kubernetes container platform and small form-factor x86, ARM, and can handle both NR-NTN and IoT devices.

“Deploying 5G gNodeB on a LEO satellite payload, brings a unique set of challenges for satellites passing over at extremely high speeds, including large cell coverage optimisation, high doppler handling and users’ mobility,” said Munish Chhabra, SVP and General Manager, Software and Services at Radisys. “With onboard regenerative deployments, the complexities compound. Onboard power and resource constraints require low compute, storage footprint CU, DU software and performance-efficient beam hopping that goes beyond 3GPP specifications.”

“There has been an explosion in interest around combining satellite and traditional mobile communications systems,” said Rob Barnes, Chief Marketing Officer at AccelerComm. “However, for satellite 5G to be truly successful there are several performance and efficiency challenges which have to be overcome. Solving these requires building on the existing 3GPP technologies to create a tailored solution built to deal with the unique challenges of operating around a thousand kilometres from Earth at speeds of over 7km per second, all while dealing with power and resource constraints. We are delighted to be working with our partners Radisys, RFDSP and TTP to develop this high-performance solution which will open-up a whole new market for delivering 5G services from space.”