ARA is an at-scale Platform for Advanced Wireless Research (PAWR), specifically tailored to the unique community, application, and economic context of rural regions. It features the first-of-its-kind real-world implementation of long-distance, high-capacity wireless backhaul and access systems spanning over 30 km in diameter. Leveraging both software-defined radios and programmable Commercial Off-The-Shelf (COTS) systems, ARA orchestrates the wireless resources alongside the networking and compute resources for enabling end-to-end experiments involving user equipment, base stations, edge computing, and cloud infrastructure. Such an integration facilitates the coevolution of rural-focused wireless innovation and applications, while helping to advance the frontiers of advanced Next-G wireless systems such as Open RAN. As of summer 2024, ARA is publicly accessible with 7 base stations (BSes) and over 30 user equipment (UEs). In this demo, we share advanced wireless research experiments enabled by ARA, involving MU-MIMO in TV White Space (TVWS) bands, long-range mmWave and microwave backhaul communications, and open-source 5G NR protocol stacks such as srsRAN and OpenAirInterface (OAI).

5G-and-beyond cellular networks are set to enable ultra-reliable, low-latency communications (URLLC), catering to a wide range of applications such as real-time control and extended reality (XR). For these URLLC applications, it is crucial to ensure per-packet communication reliability and high throughput. To this end, we propose a novel joint scheduling and power control approach, denoted by PktR, that ensures application-specific per-packet communication reliability as well as high channel spatial reuse and high network throughput. PktR is designed as a close-loop system, incorporating Gain-Ratio-K (GRK) interference modeling, optimization, and transmit power control mechanisms. PktR ensures predictable interference control for receivers and fine-tunes transmit power at transmitters in a highly agile manner. Our measurement studies demonstrate for the first time the feasibility of ensuring per-packet communication reliability in live cellular systems, by showing that PktR ensures high per-packet communication SINR (e.g., 20dB) and high success probability (e.g., 0.9) across diverse network and environmental settings. Through local, distributed coordination, PktR also outperforms state-of-the-art solutions significantly. For instance, besides ensuring predictable guarantee of required per-packet communication reliability in scenarios where existing solutions are unable to provide such guarantees for up to 31.01 % of the network links, PktR improves the network throughput by a factor up to 1.596.

Time synchronization is a critical component in network operation and management, and it is also required by Ultra-Reliable, Low-Latency Communications (URLLC) in next-generation wireless systems such as those of 5G, 6G, and Open RAN. In this context, we design and implement AraSync as an end-to-end time synchronization system in the ARA wireless living lab to enable advanced wireless experiments and applications involving stringent time constraints. We make use of Precision Time Protocol (PTP) at different levels to achieve synchronization accuracy in the order of nanoseconds. Along with fiber networks, AraSync enables time synchronization across the AraHaul wireless x-haul network consisting of long-range, high-capacity mmWave and microwave links. In this paper, we present the detailed design and implementation of AraSync, including its hardware and software components and the PTP network topology. Further, we experimentally characterize the performance of AraSync from spatial and temporal dimensions. Our measurement and analysis of the clock offset and mean path delay show the impact of the wireless channel and weather conditions on the PTP synchronization accuracy.

Thanks to the availability of large bandwidth and high-gain directional antennas at the millimeter-wave (mmWave) bands, mmWave communications have been considered as one of the primary solutions to meet the high data rates needs in vehicular networks. Unicast in mmWave vehicle-to-vehicle (V2V) communications has been well-studied, but much less attention has been paid to V2V broadcast which is required by many V2V applications such as active safety. To fill the gap, this paper systematically investigates mmWave V2V broadcast by considering the unique properties of mmWave signal propagation in V2V environments as well as the impacts of directional antennas and interference, aiming to provide unique insight into mmWave V2V broadcast and to shed light on designing effective V2V broadcast protocols. Based on widely-accepted, high-fidelity system models, we mathematically analyze the receiver-side signal-to-interference-plus-noise-ratio (SINR) and broadcast coverage, and we study the impacts of blockage, inter-vehicle distance, vehicle density and beam pattern. Through comprehensive numerical analysis, we find out that, instead of a single unique optimal beamwidth, there exists an optimal range of beamwidth, in which the beamwidths have similar performance and can maximize the coverage. We also find out that the selection of carrier sensing range plays an important role as it highly influences the performance of the whole vehicular networks.