Concurrent transmissions (CTX) are a state-of-the-art technique for low-power wireless networking, enabling performance unmatched by conventional routing-based approaches. However, their use is notoriously complex, as it hinges on many low-level system aspects distracting developers from the protocol logic. This is exacerbated in ultra-wideband (UWB) radios, recently shown to enable higher CTX performance than IEEE 802.15.4 and BLE, but significantly more energy-hungry, posing new problems to developers. A case in point is the deep sleep mode in popular UWB radios: it yields negligible consumption (50 nA) in periods of inactivity—crucial in real-world deployments—during which, however, clock drifts may disrupt the tight time synchronization required by CTX. Existing systems avoid the complexity of reconciling these conflicting needs via solutions with significantly higher consumption, hampering real-world applicability. We address these challenges with SAMU, a novel framework allowing developers to fully exploit the advantages of CTX over UWB via simple, expressive, and flexible abstractions removing the underlying complexity, embodied in an optimized and efficient runtime support. A distinctive trait of SAMU is the fine-grained control it provides over individual CTX, unlocking design opportunities unavailable in existing frameworks offering only high-level building blocks (e.g., CTX-based floods). We illustrate the power of SAMU by showing how existing CTX protocols can be easily built atop it, and evaluate the resulting performance in a large-scale testbed. Our results confirm that SAMU successfully combines high-level programming with a low-latency, energy-efficient, and reliable runtime support, providing a foundation for the protocol design and real-world deployment of CTX-based systems.

Wireless networked control systems (WNCS) are at the forefront of academic and industrial efforts, due to the high deployment flexibility and low cost offered by their untethered multihop operation. However, they pose the unavoidable challenge of matching the reliability and latency of wired systems, exacerbated by energy efficiency constraints. Mainstream solutions, in industry and academia alike, largely rely on the routing-based protocol stacks for IEEE 802.15.4 narrowband radios. We identify an alternative to the status quo in the unexplored synergy between concurrent transmissions (CTX) and ultra-wideband (UWB) radios. Low-power wireless stacks based on CTX are known to offer order-of-magnitude improvements w.r.t. mainstream ones in reliability, latency, and energy-efficiency—i.e., the key WNCS requirements above. UWB is very popular in localization applications but rarely considered in multihop networking despite its high data rate and resilience to interference, yielding a beneficial impact on the requirements above. We elicit the potential of this synergy via a novel UWB stack based on a state-of-the-art CTX design. We quantitatively demonstrate its effectiveness in supporting different closed-loop control strategies in a realistic scenario via experiments in a 36-node, 6-hop cyber-physical testbed enabling direct comparison between the original narrowband system and our UWB one. Results show that the UWB stack achieves$10\times $higher reliability and$3\times $lower latency with half the energy consumption, pushing the envelope of low-power networking support for wireless control.

In many low-power wireless systems, a condition occurring at some nodes (e.g., an anomalous sensor sample, an aperiodic packet to transmit, a new joining node) determines whether the entire network should be awake (e.g., to react to the anomaly, deliver the packet, update the node group) or enter sleep. State-of-the-art protocols exploit periodic network-wide floods based on concurrent transmissions (e.g., via Glossy) to establish the global decision quickly, reliably, and efficiently. Still, time is of the essence: the faster the network agrees, the faster it either reacts or enters sleep.

Applications of ultra-wideband (UWB) for distance estimation (ranging) and localization often involve users wearing tags. Unfortunately, the human body causes significant signal attenuation, reducing ranging accuracy. This specific case of non-line-of-sight (NLOS) condition has received little attention in the literature. Further, state-of-the-art techniques tackling generic NLOS are often based on machine learning, limiting their exploitation on embedded devices. We pursue an alternative approach and show that the features offered by the UWB transceiver, largely neglected by the literature, can be directly exploited to reliably detect human occlusions and optimize ranging accordingly. We base our findings on an extensive exper-imental campaign exploring many radio, system, and deployment dimensions in two environments, resulting in practical guidelines immediately available to the designers of UWB-based systems.

Research advances in low-power wireless systems have greatly benefited from the availability of public testbeds. However, none is currently available for the increasingly popular ultra-wideband (UWB) radios enabling communication and localization. We present Cloves, the first public large-scale testbed supporting UWB.

Event-triggered control (ETC) holds the potential to significantly improve the efficiency of wireless networked control systems. Unfortunately, its real-world impact has hitherto been hampered by the lack of a network stack able to transfer its benefits from theory to practice specifically by supporting the latency and reliability requirements of the aperiodic communication ETC induces. This is precisely the contribution of this paper. Our Wireless Control Bus (WCB) exploits carefully orchestrated network-wide floods of concurrent transmissions to minimize overhead during quiescent, steady-state periods, and ensures timely and reliable collection of sensor readings and dissemination of actuation commands when an ETC triggering condition is violated. Using a cyber-physical testbed emulating a water distribution system controlled over a real-world multi-hop wireless network, we show that ETC over WCB achieves the same quality of periodic control at a fraction of the energy costs, therefore unleashing and concretely demonstrating its full potential for the first time.

Concurrent transmissions (CTX) enable low latency, high reliability, and energy efficiency. Nevertheless, existing protocols typically exploit CTX via the Glossy system, whose fixed-length network-wide floods are entirely dedicated to disseminating a single packet.

Aperiodic data collection received little attention in wireless sensor networks, compared to its periodic counterpart. The recent Crystal system uses synchronous transmissions to support aperiodic traffic with near-perfect reliability, low latency, and ultra-low power consumption. However, its performance is known under mild interference-a concern, as Crystal relies heavily on the (noise-sensitive) capture effect and targets aperiodic traffic where "every packet counts". We exploit a 49-node indoor testbed where, in contrast to existing evaluations using only naturally present interference to evaluate synchronous systems, we rely on JamLab to generate noise patterns that are not only more disruptive and extensive, but also reproducible. We show that a properly configured, unmodified Crystal yields perfect reliability (unlike Glossy) in several noise scenarios, but cannot sustain extreme ones (e.g., an emulated microwave oven near the sink) that instead are handled by routing-based approaches. We extend Crystal with techniques known to mitigate interference-channel hopping and noise detection-and demonstrate that these allow Crystal to achieve performance akin to the original even under multiple sources of strong interference.