I build, deploy and validate end-to-end mobile networks from open-source and multi-vendor components: RAN, core, O-RAN, and Non-Terrestrial Networks. Most engineers work in one of those layers. The hard part, and the expensive part, is making them work together.
I'm also a Doctoral Researcher at the University of Oulu, Finland, working on AI-enabled waveform design and optimisation for 6G. Previously at the 5G Test Network (5GTN) Oulu and the 6G Flagship, where I led Horizon Europe 6G-XR deliverable D1.1 and Task T2.3 (AI-based slicing models), contributed to 5G!Drones D3.3, and worked on 5G/B5G testbed deployment with open-source and commercial RAN for UAV and XR use cases.
I care about doing the hard, honest engineering, down to the timing of a single random-access preamble.
I take on selected engagements in 5G/LTE/NTN and open-source RAN and core:
| Testbed deployment & validation | End-to-end 4G/5G networks built and verified in your environment, documented and handed over. |
| NTN scenario engineering | GEO and LEO satellite scenarios, orbital and timing configuration, protocol validation. |
| Protocol debugging | RAN and core failures at the protocol level: random access, RRC, NAS, session establishment, NTN timing. |
| Training & workshops | Hands-on sessions for engineering teams and research groups. |
Remote by default. Fixed-scope projects, day-rate engineering, or ongoing support retainers.
📩 sabbiraw.ahmed@gmail.com · LinkedIn
Open-Source 5G NR NTN Testbed A fully open-source testbed completing an end-to-end GEO satellite attach (sync, SIB19, 4-step RACH, RRC, NAS registration, PDU session) on OpenAirInterface and Open5GS. Includes a protocol-level fix making the gNB random-access response window NTN-aware, without which random access cannot complete at GEO round-trip delays. Published with a reference architecture document and a citable DOI.
LEO extension The same stack across a full low-earth-orbit satellite pass, with propagation delay and Doppler shift tracked live: delay 18.8 to 4.2 to 8.1 ms, Doppler crossing from +57.3 kHz through zero to -51.9 kHz as the satellite passes overhead.
- 📡 Open RAN & Core: OpenAirInterface (OAI), srsRAN (O-CU/O-DU), Open5GS, free5GC, Magma Core, UERANSIM
- 🎛️ O-RAN: O-RAN SC, FlexRIC, near-RT/non-RT RIC, xApps/rApps
- 🛰️ Non-Terrestrial Networks: 5G NR NTN, GEO/LEO, direct-to-device (D2D), 3GPP Release 17/18/19
- 🤖 AI/ML for networks: AI-enabled waveform design, network slicing models, RAN optimisation
- 🧪 Testbed engineering: end-to-end 5G SA deployment, RF simulation, protocol validation
- ☁️ Adjacent: Docker/Kubernetes for CNFs, network automation, B5G/6G research
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