Listen-While-Talking: Toward dApp-based Real-Time Spectrum Sharing in O-RAN
Rajeev Gangula, Andrea Lacava, Michele Polese, Salvatore D'Oro, Leonardo Bonati, Florian Kaltenberger, Pedram Johari, Tommaso Melodia
TL;DR
The paper addresses the challenge of realizing real-time spectrum sharing in CBRS without relying on centralized SAS coordination. It introduces a dApp-based extension to O-RAN that performs spectrum sensing on I/Q samples extracted through an E3 interface and feeds control actions to the gNB to adapt scheduling by barring PRBs when incumbents are detected. Key contributions include a complete OpenAirInterface-based demo, a programmable sensing slot approach, an E3-enabled data path, and a simple energy-threshold inference that closes the sensing-control loop in real time. The work demonstrates the viability of dApp-driven, user-plane spectrum awareness within disaggregated RANs, enabling dynamic, low-disruption spectrum access in next-generation networks.
Abstract
This demo paper presents a dApp-based real-time spectrum sharing scenario where a 5th generation (5G) base station implementing the NR stack adapts its transmission and reception strategies based on the incumbent priority users in the Citizen Broadband Radio Service (CBRS) band. The dApp is responsible for obtaining relevant measurements from the Next Generation Node Base (gNB), running the spectrum sensing inference, and configuring the gNB with a control action upon detecting the primary incumbent user transmissions. This approach is built on dApps, which extend the O-RAN framework to the real-time and user plane domains. Thus, it avoids the need of dedicated Spectrum Access Systems (SASs) in the CBRS band. The demonstration setup is based on the open-source 5G OpenAirInterface (OAI) framework, where we have implemented a dApp interfaced with a gNB and communicating with a Commercial Off-the-Shelf (COTS) User Equipment (UE) in an over-the-air wireless environment. When an incumbent user has active transmission, the dApp will detect and inform the primary user presence to the gNB. The dApps will also enforce a control policy that adapts the scheduling and transmission policy of the Radio Access Network (RAN). This demo provides valuable insights into the potential of using dApp-based spectrum sensing with O-RAN architecture in next generation cellular networks.