Shared Software Radio Unit for NTN NB-IoT Systems: A scalability analysis of time-domain carrier combination at split 8
Author
Sørensen, Svend Luka Domancic
Term
4. semester
Education
Publication year
2026
Submitted on
2026-04-06
Pages
50
Abstract
Narrowband Internet of Things (NB‑IoT) has evolved from an LTE enhancement into a 5G‑integrated technology. This thesis studies a system that combines three established approaches: a functional split known as split 8 (a point in the radio processing chain in the time domain), a bent‑pipe non‑terrestrial network (NTN) deployment, and a shared Open RAN Radio Unit (O‑RU) serving multiple O‑RAN Distributed Units (O‑DUs). The proposed O‑RU shifts the frequency of and time‑domain combines NB‑IoT carriers from multiple O‑DUs into a single wideband feeder‑link signal at split 8. A user‑plane architecture for this shared O‑RU is designed, implemented as a software O‑RU, and evaluated on a testbed. Validation confirms that the composite wideband signal is formed correctly and that each carrier can be cleanly recovered. A performance study then measures the maximum number of carriers that can be served concurrently as the number of worker cores varies, for upsampling factors of 2 and 4. With upsampling factor 2, the system is spectrally limited to 14 carriers regardless of core count; with upsampling factor 4, it becomes computationally limited, supporting 10, 16, 21, 24, and 24 carriers with one through five worker cores, respectively.
Narrowband Internet of Things (NB‑IoT) er gået fra at være en LTE‑udvidelse til at være integreret i 5G. Denne afhandling undersøger et system, der kombinerer tre velkendte tilgange: et såkaldt split 8‑funktionssplit (et punkt i radiosignalbehandlingen i tidsdomænet), en bent‑pipe NTN‑udrulning (ikke‑terrestrisk netværk) og en delt Open RAN Radio Unit (O‑RU), der betjener flere O‑RAN Distributed Units (O‑DU’er). Den foreslåede O‑RU frekvensforskydder og kombinerer NB‑IoT‑bærere fra flere O‑DU’er til ét bredbånds feeder‑link‑signal i tidsdomænet ved split 8. En brugerplan‑arkitektur for denne delte O‑RU er designet, realiseret som en softwarebaseret O‑RU og evalueret i et testbed. Validering viser, at det sammensatte bredbåndssignal dannes korrekt, og at hver bærer kan genskabes rent. En efterfølgende ydelsestest måler, hvor mange bærere der kan serviceres samtidig som funktion af antallet af worker‑kerner, for opsamlingsfaktorer på 2 og 4. Ved opsamlingsfaktor 2 er systemet spektralt begrænset til 14 bærere uanset antal kerner, mens det ved opsamlingsfaktor 4 bliver beregningsmæssigt begrænset og understøtter 10, 16, 21, 24 og 24 bærere med henholdsvis én til fem worker‑kerner.
[This apstract has been rewritten with the help of AI based on the project's original abstract]