Enhancing Throughput in 5G-NTN through Early RLC Layer Retransmissions

Lower layer retransmission schemes in 5G Non-Terrestrial Networks (5G-NTN), in particular Hybrid Automatic Repeat Request (HARQ) from the Medium Access Control (MAC) layer, are severely hampered by the large Round Trip Times (RTTs) imposed by satellite components. In this demonstration, we show that enabling Radio Link Control (RLC) layer retransmissions can significantly increase throughput without additional processing complexity. Using the OpenAirInterface (OAI) 5G-NTN suite, we showcase the effectiveness of RLC Acknowledged Mode (AM) retransmissions in facilitating early recovery of lost packets and maintaining reasonable Quality of Service (QoS), even in the absence of HARQ feedback from the MAC layer.