Senior Software Engineer – NR-NTN Protocols (L1 & L2)

About the role

Skylo is seeking a Senior Software Engineer to join its Protocol Stack team in Espoo, Finland. You will design, implement, and optimise 5G New Radio Non‑Terrestrial Network (NR‑NTN) Layer 1 and Layer 2 protocol software for the company’s cloud‑native vRAN platform. The role collaborates closely with RF, systems and integration teams to bring satellite‑enabled connectivity to market at scale.

Key responsibilities

• Design, develop, and maintain C++ implementations of 5G NR‑NTN L1/L2 protocol stacks, including PHY adaptation, FAPI, MAC and DL/UL schedulers.
• Implement NTN‑specific L1 adaptations such as extended HARQ timers, timing‑advance pre‑compensation, link adaptation, and satellite Doppler compensation.
• Extend and optimise the MAC scheduler for NTN, handling HARQ retransmissions, coverage‑enhancement mode scheduling and constellation‑aware resource allocation.
• Design and implement the FAPI interface between MAC and PHY, managing P5/P7 messages, slot indications and timing/error events for NTN‑adapted slot structures.
• Develop DL/UL scheduler algorithms that address HARQ retransmission, coverage‑enhancement resources, constellation‑aware policies and QoS prioritisation under satellite link conditions.
• Collaborate with RF and baseband teams to validate L1/L2 protocol behaviour in laboratory and field NTN environments (LEO/GEO).

Required profile

• Senior‑level software engineer with strong C++ development experience.
• Proven experience with 5G NR protocol stacks and Layer 1/Layer 2 implementations.
• Knowledge of satellite communications and Non‑Terrestrial Network (NTN) concepts.
• Ability to work closely with cross‑functional RF, systems and integration teams.
• Willingness to work onsite three days per week in Espoo.

Required skills

• C++ programming
• 5G NR and NR‑NTN protocol knowledge
• PHY layer development
• MAC layer development
• FAPI interface implementation
• HARQ mechanisms
• Scheduler algorithm design
• Satellite communications (LEO/GEO) awareness