In the realm of driving technologies, fully autonomous vehicles have not been widely adopted yet, making advanced driver assistance systems (ADAS) crucial for enhancing driving experiences. Among these, car-following behavior modeling plays a pivotal role, forming the foundation for systems that ensure safe and efficient vehicle interactions. However, current approaches often rely on fixed parameters, failing to capture the diverse social preferences and driving styles of individuals. To overcome these limitations, we propose the Editable Behavior Generation (EBG) model, a data-driven car-following model that allows for adjusting driving discourtesy levels. The framework integrates diverse courtesy calculation methods into long short-term memory (LSTM) and Transformer architectures, offering a comprehensive approach to capture nuanced driving dynamics. By integrating various discourtesy values during the training process, our model generates realistic agent trajectories with different levels of courtesy in car-following behavior. Experimental results on the naturalistic datasets showcase a reduction in Mean Squared Error (MSE) of spacing and MSE of speed compared to baselines, establishing style controllability. To the best of our knowledge, this work represents the first data-driven car-following model capable of dynamically adjusting discourtesy levels. Our model provides valuable insights for the development of ADAS that take into account drivers’ social preferences.

Traffic oscillations pose safety and efficiency challenges in mixed scenarios involving connected and automated vehicles (CAVs) and human-driven vehicles (HDVs). Existing control strategies fail to handle the unpredictability of HDV behaviors, resulting in disruptive "stop-and-go" traffic patterns. This study proposes a novel algorithm that uses Deep Reinforcement Learning (DRL) integrated into a distinctive "CAV-AHDV-CAV" structure for car-following events. The consecutive HDVs are treated as an aggregated unit called Aggregated HDVs (AHDVs) to eliminate stochasticity and leverage collective traffic features as inputs, addressing the driver heterogeneity issue. Our training and testing were conducted using a dataset of 9,200 car-following events extracted from the HighD dataset. In these events, the lead vehicle serves as our CAV in front, while the following vehicle represents the AHDV. We simulated our controlled vehicle to follow the AHDV, aiming to achieve the vehicle equilibrium state with respect to both the AHDV and the CAV in front. The results demonstrate a reduction in the impact of HDVs and an enhancement of equilibrium states compared to baseline models. Specifically, we achieved a speed mean square error (MSE) of 3.151 and spacing MSE values of 50.484 (with respect to the AHDV) and 47.855 (with respect to the CAV). These findings offer robust and adaptable control strategies for efficient and safe mixed traffic dominated by CAVs.

This study proposes to find the most appropriate transport modes with an awareness of user preferences (e.g., costs, times) and trip characteristics (e.g., purpose, distance). The work was based on real-life trips obtained from a map application. Several methods including gradient boosting tree, learning to rank, multinomial logit model, automated machine learning, random forest, and shallow neural network have been tried. For some methods, feature selection and over-sampling techniques were also tried. The results show that the best-performing method is a gradient-boosting tree model with the synthetic minority oversampling technique (SMOTE). Also, results of the multinomial logit model show that (1) an increase in travel cost would decrease the utility of all the transportation modes; (2) people are less sensitive to the travel distance for the metro mode or a multi-modal option that contains metro, i.e., compared to other modes, people would be more willing to tolerate long-distance metro trips. This indicates that metro lines might be a good candidate for large cities.

Sleep apnea is a serious sleep disorder where patients have multiple extended pauses in breath during sleep. Although some portable or contactless sleep apnea detection systems have been proposed, none of them can achieve fine-grained sleep apnea detection without strict requirements on the device or environmental settings. To address this problem, we present DeepApnea, a deep learning based sleep apnea detection system that leverages patients' wrist movement data collected by smartwatches to identify different types of sleep apnea events (i.e., central apneas, obstructive apneas, and hypopneas). Through a clinical study, we identify some special characteristics associated with different types of sleep apnea captured by smartwatch. However, there are many technical challenges such as how to extract informative apnea features from the noisy data and how to leverage features extracted from the multi-axis sensing data. To address these challenges, we first propose signal pre-processing methods to filter the raw accelerometer (ACC) data, smoothing away noise while preserving the respiratory signal and potential features for identifying sleep apnea. Then, we design a deep learning architecture to extract features from three ACC axes collaboratively, where self attention and cross-axis correlation techniques are leveraged to improve the classification accuracy. We have implemented DeepApnea on smartwatches and performed a clinical study. Evaluation results demonstrate that DeepApnea can significantly outperform existing work on identifying different types of sleep apnea.

Tile-based streaming techniques have been widely used to save bandwidth in$360^{\circ }$video streaming. However, it is a challenge to determine the right tile size which directly affects the bandwidth usage. Moreover, downloading and processing many small tiles consume a large amount of energy on mobile devices. To solve this problem, we propose to encode the video by taking into account the viewing popularity, where the popularly viewed areas are encoded as macrotiles. We propose techniques for identifying and building macrotiles, and adjusting their sizes to take into account practical issues such as head movement randomness. In some cases, the user's viewing area may not be covered by the constructed macrotiles, and then the conventional tiling scheme is used. To support macrotile based$360^{\circ }$video streaming, the client selects the right tiles (a macrotile or a set of conventional tiles) with the right quality level to maximize the QoE under bandwidth constraint. We formulate this problem as an optimization problem which is NP-hard, and then propose a heuristic algorithm to solve it. Through extensive evaluations based on real head movement traces, we demonstrate that the proposed algorithm can significantly improve QoE, save bandwidth usage, and reduce energy consumption.

Tile-based streaming has been widely used in 360° video streaming to adapt to varying network conditions. However, downloading and processing many small tiles consumes a large amount of energy on mobile devices. To address this issue, we propose techniques to encode video by considering the viewing popularity, where the tiles requested by users of similar interests are encoded as a large tile (called Ptile). When encoding Ptiles, we propose to further save energy by reducing the insignificant frames in each video segment, i.e., reducing the frame rate to save energy while satisfying some QoE constraint. Based on real video traces, we model the impact of video features (i.e., video bitrate, frame rate) and user behavior (i.e., view switching) on QoE, and model the impact of video features on power consumption. Based on the QoE model and the power model, we formulate the energy-efficient and QoE-aware 360° video streaming problem as an optimization problem, and propose a control theory based algorithm to solve it. Through extensive evaluations based on real traces, we demonstrate that the proposed algorithm can significantly reduce the energy consumption (49.7%) and improve the QoE (7.4%).

High quality video streaming for mobile devices implies high energy consumption due to the transmitted data and the variation of wireless signals. As an example, transmissions in mobile scenarios (e.g., inside a moving bus) consumes more energy for devices than when accessing from a static environment (e.g., at home). The QoE for the user does not substantially increase when watching high bitrate videos in a vibrating environment (i.e., a moving vehicle), as the context, in this case vehicle’s vibration, affects the perceived QoE. To address this problem, we propose to save energy by considering the context (environment) of video streaming. To model the impact of context, we exploit the embedded accelerometer in smartphones to record the vibration level during video streaming. Based on quality assessment experiments, we collect traces and model the impact of video bitrate and vibration level on QoE, and model the impact of video bitrate and signal strength on power consumption. Based on the QoE model and the power model, we formulate the context-aware and energy-aware video streaming problem as an optimization problem. We present an optimal algorithm which can maximize QoE and minimize energy. Since the optimal algorithm requires perfect knowledge of future tasks, we propose an online bitrate selection algorithm. To further improve the performance of the online algorithm, we propose a crowdsourcing based bitrate selection algorithm. Through real measurements and trace-driven simulations, we demonstrate that the proposed algorithms can significantly outperform existing approaches when considering both energy and QoE.

Tile-based streaming techniques have been widely used to save bandwidth in 360° video streaming. However, it is a challenge to determine the right tile size which directly affects the bandwidth usage. To address this problem, we propose to encode the video by considering the viewing popularity, where the popularly viewed areas are encoded as macrotiles to save bandwidth. We propose techniques to identify and build macrotiles, and adjust their sizes considering practical issues such as head movement randomness. In some cases, a user's viewing area may not be covered by the constructed macrotiles, and then the conventional tiling scheme is used. To support popularity-aware 360° video streaming, the client selects the right tiles (a macrotile or a set of conventional tiles) with the right quality level to maximize the QoE under bandwidth constraint. We formulate this problem as an optimization problem which is NP-hard, and then propose a heuristic algorithm to solve it. Through extensive evaluations based on real traces, we demonstrate that the proposed algorithm can significantly improve the QoE and save the bandwidth usage.

For conventional aerial manipulators, the robotic arm is rigidly attached to the quadrotor. Consequently, the maneuver of the quadrotor will affect the motion of the robotic arm when it is used for tasks such as inspection. In this paper, we propose a novel aerial manipulator with a self-locking gimbal system which can switch between motion coupled and decoupled mode. Furthermore, a dynamic gravity compensation mechanism is designed, where the location of the battery and the number of teeth are optimized to minimize the weight imbalance of the robotic arm during its motions. To the best of the authors’ knowledge, this is the first aerial manipulator with a motion-decoupled mechanism. Experimental results demonstrate that the proposed manipulator design can significantly improve the performance of the manipulator for general inspection tasks.

Although streaming video at a higher bitrate (resolution) can lead to better Quality of Experience (QoE), a larger amount of data will have to be downloaded and processed on smartphones and thus consuming more energy. On a moving bus where the wireless signal is weak, more energy will have to be spent on maintaining high bitrate video streaming than at a static environment such as at home or a cafe where the wireless signal is strong. On the other hand, the user perceived QoE does not increase too much by watching high bitrate videos in a vibrating environment (i.e., a moving vehicle), because the perception of video quality is affected by the environment such as the vibration or shaking on a moving bus. To address this problem, we propose to save energy by considering the context (environment) of video streaming. To model the impact of context, we exploit the embedded sensors (e.g., accelerometer) in smartphones to record the vibration level during video streaming. Based on quality assessment experiments, we collect traces and model the impacts of video bitrate and vibration level on QoE, and model the impacts of video bitrate and signal strength on power consumption. Based on the QoE model and the power model, we formulate the energy-aware and context-aware video streaming problem as an optimization problem. We present an optimal algorithm which can maximize QoE and minimize energy. Since the optimal algorithm requires perfect knowledge of future tasks, we further propose an online bitrate selection algorithm. Through real measurements and trace-driven simulations, we demonstrate that the proposed algorithm can significantly outperform existing approaches when considering both energy and QoE.

The energy consumed by video streaming includes the energy consumed for data transmission and CPU processing, which are both affected by the CPU frequency. High CPU frequency can reduce the data transmission time but it consumes more CPU energy. Low CPU frequency reduces the CPU energy but increases the data transmission time and then increases the energy consumption. In this paper, we aim to reduce the total energy of mobile video streaming by adaptively adjusting the CPU frequency. Based on real measurement results, we model the effects of CPU frequency on TCP throughput and system power. Based on these models, we propose an Energy-aware CPU Frequency Scaling (EFS) algorithm which selects the CPU frequency that can achieve a balance between saving the data transmission energy and CPU energy. Since the downloading schedule of existing video streaming apps is not optimized in terms of energy, we also propose a method to determine when and how much data to download. Through trace-driven simulations and real measurement, we demonstrate that the EFS algorithm can reduce 30 percent of energy for the Youtube app, and the combination of our download method and EFS algorithm can save 50 percent of energy than the default Youtube app.

Heterogeneous network (HetNet) deploying a number of small cells in a macro cell improves network capacity as well as data rate at hot spots and cell edges. The mobility management with HetNet is challenging due to its complexity. In this paper an efficient handover scheme is proposed considering the asymmetric characteristics of macro and pico cells in HetNet. The proposed scheme ranks the candidate cells for handover using a multi-criteria decision making (MCDM) algorithm and the information on the movement of user equipment (UE). When the received power is too low, if the UE can detect a suitable target eNB of good quality, handover is triggered promptly even before the time-to-trigger window expires to avoid radio link failure. Even though the received signal from the serving cell is high enough for communication, handover is also triggered for the UE when the downlink SINR is below a threshold. The performance of the proposed scheme is evaluated by computer simulation and compared with two well-known handover algorithms with respect to the number of handovers per second, goodput per UE, and packet loss rate. The simulation with LTE-Sim reveals that the proposed scheme significantly enhances the goodput while reducing packet loss and unnecessary handover.