With the development of 5G and Internet of Things technologies, the application process of smart transportation in smart cities continues to advance. Sensors are a key source of information for smart transportation, and their data commonly includes complicated traffic scene information. Urban traffic scheduling and efficiency can be significantly increased by deploying data from smart sensors to forecast traffic flows. Despite the fact that some related works have focused on the prediction task of traffic flows, they have not completely mined the traffic spatiotemporal information present in smart sensor data. We offer a novel graph spatio-temporal attention algorithm (GSAA) for traffic prediction in this paper. To completely exploit the geographical and temporal correlations among complicated roadways for traffic forecast, the algorithm combines a spatiotemporal attention mechanism with a graph neural network.To take full advantage of how much effect various hyperparameters provide, deep reinforcement learning is used to obtain the optimal hyperparameters while the predictive model is trained. Experimental results on real-world public datasets show that the algorithm proposed in this paper achieves performance improvements of about 5.47% and 13.10% over the MAE (mean absolute error) than the best baseline strategies for short-term and long-term traffic forecasting, respectively.

The tremendous potential of sensing and communication technologies has been explored and implemented for different remote event monitoring applications over the past two decades. However, the applicability of sensing and communication technologies is not necessarily limited to aboveground environments—it is also implementable and applicable for subterranean, underground scenarios. However, as opposed to air medium, underground communication medium is quite harsh due to the presence of heterogeneous underground materials along with underground aqueous components. In this article, we provide a technical overview of different underground wireless communication technologies, namely radio, acoustic, magnetic, and visible light, along with their potentials and challenges for several underground applications. We also lay out a detailed comparison among these technologies along with their pros and cons using detailed experimental results.

The popularity of concurrent transmissions (CT) has soared after recent studies have shown their feasibility on the four physical layers specified by BLE 5, hence providing an alternative to the use of IEEE 802.15.4 for the design of reliable and efficient low-power wireless protocols. However, to date, the extent to which physical layer properties affect the performance of CT has not yet been investigated in detail. This article fills this gap and provides an extensive study on the impact of the physical layer on CT-based solutions using IEEE 802.15.4 and BLE 5. We first highlight through simulation how the impact of errors induced by relative carrier frequency offsets on the performance of CT highly depends on the choice of the underlying physical layer. We then confirm these observations experimentally on real hardware and with varying environmental conditions through an analysis of the bit error distribution across received packets, unveiling possible techniques to effectively handle these errors. We further study the performance of CT-based data collection and dissemination protocols in the presence of RF interference on a large-scale testbed, deriving insights on how the employed physical layer affects their dependability.

With the easy access to mobile networks and the proliferation of video applications, video traffic is occupying a great portion of the network traffic, which poses a new challenge of how to alleviate the heavy backhaul traffic and ensure the high quality of experience for video services. As a promising solution towards addressing this challenge, video caching in edge networks has recently received significant attention, which mostly considers the video popularity and the user preference for the video. However, few studies consider the user behavior and the user preference for different parts of the video that indeed have an essential impact on caching efficiency. Hence, this article proposes a new caching and resource scheduling scheme for adaptive bitrate videos by incorporating these fine-grained factors. We first model the video service problem as a nonlinear integer programming problem, which can be divided into a cache placement problem and an online resource scheduling problem. Then, we design efficient algorithms based on several techniques, including greedy strategy, relaxation, and rounding, to solve the two problems. Extensive experimental results based on two real-world datasets show that the proposed solution achieves superior performance compared with several state-of-the-art caching approaches.

The agriculture is the backbone of economic system, and it plays an essential part in the survival of a nation’s prosperity. In addition to providing raw materials and food, it also offers numerous employment opportunities. Consequently, agriculture necessitates modern technology to increase productivity. In these circumstances, Wireless Sensor Networks (WSNs) are used to detect climatic parameters like light, humidity, carbon dioxide, acidity, soil moisture, and temperature in an agricultural field. However, the research that is being done at the moment is unable to circumvent the issue that safety and effectiveness cannot coexist. Several studies employ time-consuming cryptographic security structures, whereas the majority of lightweight systems are designed without reviewing certain security aspects like resistance to ephemeral secret leakage (ESL) attacks, perfect forward secrecy, and so on. According to our opinion, this issue may be overcome through the use of lightweight cryptographic primitives, paying particular attention to protocol weaknesses, and keeping in mind the ever-changing security needs of individuals. We present an extensive lightweight three-factor authentication protocol with diverse security criteria, along with the adaptive privacy preservation, that is suited for user-friendly situation in the WSN enviroment. This is accomplished by removing all extraneous cryptographic structures. It has been illustrated that proposed protocol is much better in terms of the privacy and security aspects via the usage of security aspects, proof of the real-or-random (ROR) model, protocols of internet security, and applications that are subjected to experimental validation utilizing automated validation. and comparison with other protocols’ security aspects. The performance analysis shows how superior our proposed protocol is to other competing protocols in terms of communication and computational overheads, with respective efficiencies of 53% and 39%. Moreover, using the ROR model reveals that this study has benefits in performance compared with other competing research.

With the increasing use of Internet-of-Things–enabled sensors, it is important to have effective methods to query the sensors. For example, in a dense network of battery-driven temperature sensors, it is often possible to query (sample) only a subset of the sensors at any given time, since the values of the non-sampled sensors can be estimated from the sampled values. If we can divide the set of sensors into disjoint so-calledrepresentative sampling subsets, in which each represents all the other sensors sufficiently well, then we can alternate between the sampling subsets and, thus, increase the battery life significantly of the sensor network. In this article, we formulate the problem of finding representative sampling subsets as a graph problem on a so-calledsensor graphwith the sensors as nodes. Our proposed solution,SubGraphSample, consists of two phases. In Phase-I, we create edges in thesimilarity graphbased on the similarities between the time-series of sensor values, analyzing six different techniques based on proven time-series similarity metrics. In Phase-II, we propose six different sampling techniques to find the maximum number ofrepresentative sampling subsets. Finally, we proposeAutoSubGraphSample, which auto-selects the best technique for Phase-I and Phase-II for a given dataset. Our extensive experimental evaluation shows thatAutoSubGraphSamplecan yield significant battery-life improvements within realistic error bounds.

Partitioning the Maximal Redundant Rigid Components (MRRC) and Maximal Global Rigid Components (MGRC) in generic 2D graphs are critical problem for network structure analysis, network localizability detection, and localization algorithm design. This article presents efficient algorithms to partition MRRCs and MGRCs and develops an open-sourced toolbox, GPART, for these algorithms to be conveniently used by the society. We firstly propose conditions and an efficient algorithm to merge the over-constrained regions to form the maximal redundant rigid components (MRRC). The detected MRRCs are proved to be maximal and all the MRRCs are guaranteed to be detected. The time to merge the over-constrained regions is linear to the number of nodes in the over-constrained components. To detect MGRCs, the critical problem is to decompose 3-connected components in each MRRC. We exploit SPQR-tree based method and design a local optimization algorithm, called MGRC_acce to prune the unnecessary decomposition operations so that the SPQR-tree functions can be called much less number of times. We prove the MGRCs can be detected inside MRRCs using at most O(mn ) time. Then a GPART toolbox is developed and extensively tested in graphs of different densities. We show the proposed MRRC and MGRC detection algorithms are valid and MGRC_acce greatly outperforms the direct SPQR-tree based decomposition algorithm. GPART is outsourced at https://github.com/inlab-group/gpart .

Wireless power transfer (e.g., based on RF or magnetic) enables convenient device charging, and triggers innovative applications that typically call for faster, smarter, economic, and even simultaneous adaptive charging for multiple smart devices. Designing such a wireless charging system meeting these multi-requirements faces critical challenges, mainly including the better understanding of real-time energy receivers’ status and the power-transferring channels, the limited capability and the smart coordination of the transmitters and receivers. In this work, we devise Camel , a context-aware MIMO MRC-WPT (magnetic resonant coupling based wireless power transfer) system, which enables adaptive charging of multiple devices simultaneously with a novel context sensing scheme. In Camel , we craft an innovative MIMO MRC-WPT channels’ state estimation and collision-aware parallel in-band communication among multiple transmitters and receivers. We design and implement the Camel prototype and conduct extensive experimental studies. The results validate our design and demonstrate that Camel can support simultaneous charging of as many as 10 devices, high-speed context sensing within 50 ms, and efficient parallel communication among transceivers within proximity of ∼0.5 m.

Due to their large bandwidth and impressive data speed, millimeter-wave (mmWave) radios are expected to play a key role in the 5G and beyond (e.g., 6G) communication networks. Yet, to release mmWave’s true power, the highly directional mmWave beams need to be aligned perfectly. Most existing beam alignment methods adopt an exhaustive or semi-exhaustive space scanning, which introduces up to seconds of delays. To eliminate the need for complex space scanning, this article presents an Ultra-wideband (UWB)-assisted mmWave communication framework, which leverages the co-located UWB antennas to estimate the best angles for mmWave beam alignment. One major challenge of applying this idea in the real world is the barrier of limited antenna numbers. Commercial-Off-The-Shelf (COTS) devices are usually equipped with only a small number of UWB antennas, which are not enough for the existing algorithms to provide an accurate angle estimation. To solve this challenge, we design a novel Multi-Frequency MUltiple SIgnal Classification (MF-MUSIC) algorithm, which extends the classic MUltiple SIgnal Classification (MUSIC) algorithm to the frequency domain and overcomes the antenna limitation barrier in the spatial domain. Extensive real-world experiments and numerical simulations illustrate the advantage of the proposed MF-MUSIC algorithm. MF-MUSIC uses only three antennas to achieve an accurate angle estimation, which is a mere 0.15° (or a relative difference of 3.6%) different from the state-of-the-art 16-antenna-based angle estimation method.

The ability to recognize and detect changes in human posture is important in a wide range of applications such as health care and human–computer interaction. Achieving this goal using loose-fit garments instrumented with sensors is particularly challenging, due to the complex interaction between garments and human body. Herein we present a method to detect and recognize human posture with casual loose-fitting smart garments integrated with highly sensitive, stretchable, optical transparent, and low-cost strain sensors. By attaching these sensors to an off-the-shelf casual jacket, we developed a smart loose-fitting sensing garment that enables posture recognition using a deep learning model, domain-adaptive Convolutional Neural Networks–Long Short-Term Memory (CNN-LSTM). This deep learning model overcame the noise and variation due to the complex interaction between loose-fitting garments and human body. Considering that users’ labeled data are usually not available in the training stage, an additional domain discriminator path on the conventional CNN-LSTM model has been introduced to further improve the adaptability. To evaluate the potential of this loose-fitting smart garment, three case studies were conducted under realistic conditions: recognitions of human activities, stationary postures with random hand movements and slouch. Our results demonstrate the potential of the proposed smart garment system for practical applications.