Bringing Collaborative Positioning to Native 5G Systems for Enhanced 2D & 3D Location Services

5G's large bandwidths and ubiquity make it a promising candidate for catalyzing future mobile services (emergency, V2X, XR, etc.) that benefit from accurate positioning over a wide area. However, we demonstrate that its heavy reliance on infrastructure base stations significantly limits its positioning ability in urban environments, where multi-story buildings and urban canyons are the norm, resulting in only a small fraction of devices being positioned, often only in 2D. To this end, we propose CAMP, a novel, collaboration-augmented paradigm for 2D and 3D positioning with cellular networks, where UEs leverage 5G NR's peer-peer Sidelink protocol to directly enable positioning measurements between each other in a scalable manner. Leveraging better connectivity (higher degree and SNR) between devices, CAMP overcomes the challenges inherent to infrastructure approaches. It brings algorithmic innovations in distributed, stochastic access and dynamic resource scheduling in a 5G-compliant manner to Sidelink measurements that are otherwise not scalable in conventional gNB-driven Sidelink operation. CAMP is implemented as a near real-time xApp service in the Open-RAN framework. Evaluations in a small cell 5G test-bed and a large-scale RAN on Colosseum, highlight its ability to position over 80% (72%) UEs with under 3m accuracy in 2D (3D) in real-world urban scenarios (compared to 30% with infrastructure approaches) and with 7-25x less overhead compared to baseline collaborative schemes.