Occupancy sensing is essential for vehicle safety and security applications such as seat belt reminders, airbag deployment, intrusion detection, and child-left-behind alerts. This paper presents UMusic, a novel in-car occupancy sensing system that reuses the ultra-wideband (UWB) devices already installed for access control in modern vehicles. However, due to the compact size and metal structure, the in-car environment is full of reflected propagation paths, which cannot be precisely resolved even with UWB's wide-bandwidth feature. To overcome this challenge, UMusic introduces a reflected-path decomposition technique to extract a high-resolution power delay profile (PDP) from the channel impulse response (CIR) provided by commodity UWB devices, enabling precise environmental perception. By comparing PDPs in empty and occupied conditions, UMusic is able to detect the occupancy status in both a sedan and an SUV with multiple passengers across various scenarios. Our results show that UMusic achieves a 90.2% detection rate using a single CIR measurement collected within 50 ms, outperforming the state-of-the-art by 15.7%. When aggregating six consecutive CIR measurements, UMusic reaches 99.4% accuracy, demonstrating its effectiveness for real-world deployment.

Automobile manufacturers are building cars with passive keyless entry support – the ability for users to unlock and start their cars while having the car keys "in their pockets". In this regard, car manufacturers are currently installing Ultra-Wideband (UWB) radios in cars owing to their robustness to relay attacks and their precise ranging estimates. In this paper, we explore the possibility of using these UWB radios (that exist for keyless entry) as an orthogonal sensing modality. To test this hypothesis, we build CaraoKey, the first system that exploits the UWB keyless infrastructure as a "sensor". More specifically, CaraoKey leverages the UWB radios to infer the state of a car (empty, door, window or trunk open, person inside the car, etc.). It does so by building a multipath profile based on the Channel Impulse Response (CIR) that is computed by each UWB node. We design and implement a 14-node system (a superset of all possible node locations) and evaluate it at 7 different indoor and outdoor locations while capturing a wide range of factors such as cars, people, walls on the sides, etc. Our results indicate that CaraoKey can distinguish 8 different car states with 98% accuracy using 8 nodes, and nearly 94% accuracy using just 4 nodes.

Industrial communication systems increasingly deploy wireless technologies. In order to benefit from flexibility and cost saving potentials, wireless systems have to cope with the requirements of industrial applications, in particular timing constraints. Due to their hard and isochronous real-time characteristics, control applications on the field level of factory automation have not been considered for wireless communication, yet. This paper addresses the use of wireless Point-to-Point communication in conjunction with Industrial Ethernet protocols on field level by means of a modular gateway architecture. The main contributions of this work include: wireless Industrial Ethernet gateway design, its implementation on Sercos III and Wi-Fi based demonstrator platform and its evaluation by means of empirical measurements showing the applicability of the proposed approach.

The paper presents a detailed discussion of various issues involved in designing a medium access control (MAC) protocol for multihop wireless networks with nodes employing multiple beam smart antennas. Multiple beam smart antennas can form several beams simultaneously and can initiate concurrent transmissions or receptions .in them, thereby increasing the throughput of the bottleneck nodes. Traditional on-demand MAC protocols for omnidirectional and single beam directional antennas based on the IEEE 802.11 distributed coordination function (DCF) mechanism cannot take advantage of this unique capability of multiple beam antennas as they do not facilitate concurrent transmissions or receptions by a node. This paper introduces a novel protocol, hybrid MAC (HMAC), which enables concurrent packet reception (CPR) and concurrent packet transmission (CPT) at a node equipped with multiple beam antennas and is backward compatible with IEEE 802.11 DCF. Simulation results show the superior performance of HMAC in most ad hoc scenarios. Moreover, in some sample topologies, the throughput of HMAC is close to the theoretical maximum. The paper also presents a wireless mesh network architecture with heterogeneous antenna technologies and illustrates the advantages of employing multiple beam smart antennas and HMAC in such networks.

Abstract — We present two on-demand MAC protocols to provide differentiated service classes over multiple beam antennas. We use embedded feedback from neighboring nodes to synchronize data communication at multiple beams. The protocols use multilevel queues to organize data, and employ a quality of service (QoS) aware packet scheduler to facilitate disparate traffic flows. We further present a novel paradigm in wireless channel access – receiver initiated choice of sender (RICS). RICS organizes the senders into multilevel queues providing an elegant method to bias the probability of channel award to these nodes. Simulation results demonstrate successful provision for multiple service classes. Keywords- Differentiated service classes, multiple beam antennas, medium access control, Quality of Service, wireless ad hoc networks. I.

Energy efficiency and reliable data delivery are the two most important parameters for designing wireless sensor network protocols. Wireless communication is inherently unpredictable and error-prone. Hence, reliability is required to ensure that a packet reaches its desired destination; otherwise the energy expended in forwarding the packet is wasted On the other hand, energy-saving mechanisms are required for battery-constrained sensor networks. In this paper, we have designed an on-demand energy-efficient and reliable medium access control (E2RM: AC) protocol that enables reliable data delivery and energy conservation without affecting packet latency. We have demonstrated the superior performance of E2RMAC over existing energy-efficient and reliability-enforcing approaches in terms of reliability, latency, scalability and energy-efficiency.

Multiple beam antennas can initiate several data communications concurrently by forming spatially separable beams. However, their concurrent packet reception (CPR) capability is largely governed by the underlying medium access control (MAC) protocol. In this paper, we present an analytical framework to calculate CPR upper bounds of multiple beam antennas using on-demand MAC protocols. The model can be used for adaptively changing transmission probability of the nodes so as to achieve optimal performance. We consider both transmitter-initiated and receiver initiated medium access protocols with uniform and random distribution of nodes. Using the developed model, we compute CPR capability of IEEE 802.11 DCF and ESIF based mechanisms for multiple beam antennas. We verify our model using simulations

A wireless sensor network typically consists of a dense deployment of sensor nodes to achieve higher resolution and better network coverage. Having a dense network increases the fault-tolerance and robustness of the system. However, if not properly handled, it can lead to more collisions during transmission and also network congestion. Furthermore, wireless communication is inherently unpredictable and error-prone. Hence, it is imperative to design an efficient medium access control (MAC) protocol that facilitates guaranteed delivery of data over unreliable wireless links. In this paper, we have designed an on-demand reliable MAC (RMAC) protocol that enables timely delivery of data. We have demonstrated its superior performance over existing reliability-enforcing approaches in terms of reliability, latency, scalability and energy-efficiency

This paper introduces a novel cross layer medium access control protocol for multiple beam antennas to fully utilize their multiple-beam-forming capability. Our protocol, explicit synchronization via intelligent feedback (ESIF), uses feedback from neighboring nodes to synchronize data communication at multiple beams. ESIF exploits routing information to guarantee long-term fairness and minimize the energy and latency overheads. Unlike previous works on directional antennas that discuss range extension, we focus on optimal spatial reuse. Simulation results demonstrate that ESIF outperforms other on-demand access schemes based on IEEE 802.11 DCF for multiple beam antennas

Multiple beam antennas can receive (or transmit) data on multiple beams simultaneously. The aim of this paper is to show the limitations of using IEEE 802.11 distributed coordination function (DCF) based schemes for medium access control (MAC) in such antennas. We provide four different variants of IEEE 802.11 DCF based on-demand protocols to study this phenomenon. Our simulation results and analyses emphasize the need to develop a novel MAC protocol to fully exploit the capabilities of multiple beam antennas. We further provide some embryonic guidelines for the development of such a protocol

We consider the medium access control (MAC) protocol design for nodes in a wireless LAN that use a wide-azimuth switched beam smart antenna system comprised of a multiple beam antenna array. The one-hop performance of carrier sense multiple access (CSMA) as well as slotted aloha for such a system is presented analytically and through simulation. The problem of synchronization of multiple beams in CSMA is investigated in our analysis. Our results show that, under heavy offered load conditions, CSMA is a good choice with nodes that have multiple-beam smart antennas, despite the performance loss due to the beam synchronization, providing a stable throughput that approaches unity and is invariant to fluctuations in the offered load. Slotted Aloha, on the other hand, is capable of higher peak throughput in a narrow range of offered loads as more switched beams are employed, but performance drastically reduces beyond optimum offered loads. We also introduce a method, expanded receive rule (ERR), whereby the tight synchronization among different beams of a receiver node in CSMA is relaxed, which is observed to provide better throughput. Finally, we also present performance results for a 4-way-handshake-type carrier sense mechanism using multiple beam antennas.