Hsin-Mu Tsai

National Taiwan University | NTU · Department of Computer Science and Information Engineering

Aim: The mobile network quality in ambulances can be variable and limited. This pilot study aimed to identify a suitable network setting for recognizing agonal respiration under limited network conditions. Methods: We recruited five emergency medical technicians, and each participant viewed 30 real-life videos with different resolutions, frame r...

Visible light communication (VLC) is seen as an interesting technology to complement the IEEE 802.11p-based systems commonly used for vehicle-to-vehicle (V2V) communication. However, the reliability of such a V2V-VLC link in real-world driving scenario had not been demonstrated up to very recently. The results obtained, at that time with orthogonal...

Recent research has shown that both radio and visible light waves can be used to enable communications in highly dynamic vehicular environments. However, the roles of these two technologies and how they interact with each other in future vehicular communication systems remain unclear. Understanding the propagation characteristics is an essential st...

Inertial measurement unit (IMU) has long suffered from the problem of integration drift, where sensor noises accumulate quickly and cause fast-growing tracking errors. Existing methods for calibrating IMU tracking either require human in the loop, or need energy-consuming cameras, or suffer from coarse tracking granularity. We propose to augment in...

Visible light communication (VLC) has gained great attention from both the industry and the academia as it can potentially provide a solution to alleviate the congestion in the wireless spectrum, offloading the ever-increasing data traffic to the untamed optical spectrum while taking advantage of the pervasive lighting infrastructure. On the other...

Recent studies have demonstrated the potential of light-to-camera communications for realizing applications such as localization, augmented reality and vehicle-to-vehicle communications. However, the fundamental requirement of visible light communications, flicker-free illumination, becomes a key limitation hindering existing technologies from serv...

Indoor positioning enables location-based services for a wide range of commercial applications [4]. Existing visible light positioning (VLP) systems [5, 7] leverage the high image resolution of a receiving camera to support high positioning accuracy. However, power-hungry cameras are not desirable in many scenarios, e.g., smart factories, where sma...

Existing visible light positioning (VLP) systems leverage the high image resolution of a receiving camera to support high positioning accuracy. However, power-hungry cameras might not always be applicable for many scenarios, such as smart factories, in which small objects require to be accurately localized and tracked. In this paper, we introduce C...

While both radio and visible light waves can serve as the transmission medium, the propagation channel plays a key role in the highly dynamic vehicular communication environment. We discuss salient properties of radio and visible light channels, including radiation pattern and path loss modeling. By comparing their similarities and highlighting the...

Traffic shockwave is one of the major causes for low road capacity and traffic jams. This paper seeks to answer an important question in the development of a traffic shockwave mitigation system: is it feasible to have human-driven vehicles as part of the system? To answer the question, we developed a real-time speed advisory system, utilizing vehic...

In this paper, we present a scooter collision avoidance system that can identify red-light runners (RLRs) at intersections. When the RLR behavior is detected, the system would advise the RLR to slow down immediately and warn nearby vehicles on the intersecting road in real time. In particular, we do not consider infrastructure-based solutions such...

This paper proposes LightBib, a novel marathoner recognition system utilizing visible light communications (VLC). In our system, each runner wears a pair of light strips which transmits the runner's ID with VLC, while cameras set along the running route can be used to decode the runner's ID from the pixels in the captured images. Our transmitter ut...

In countries such as Taiwan, with a high percentage of scooters, scooter-related accidents are responsible for most injuries and deaths of all traffic accidents. One viable approach to reduce the number of accidents is to utilize short-range wireless communications between the scooter and other vehicles. This would help neighboring vehicles to dete...

In countries such as Taiwan, with a high percentage of scooters, scooter-related accidents are responsible for most injuries and deaths of all traffic accidents. One viable approach to reduce the number of accidents is to utilize short-range wireless communications between the scooter and other vehicles. This would help neighboring vehicles to dete...

This paper proposes LiBeamScanner, an indoor positioning system that utilizes only a single custom light bulb and a light sensor to achieve extremely high positioning accuracy. Single light bulb means that a dense deployment of illuminaries is unnecessary, and the use of a light sensor, instead of a camera, implies that even systems with strict ene...

Automatically recognizing rear light signals of front vehicles can significantly improve driving safety by automatic alarm and taking actions proactively to prevent rear-end collisions and accidents. Much previous research only focuses on detecting brake signals at night. In this paper, we present the design and implementation of a robust hierarchi...

In this paper, a novel undersampled pulse amplitude modulation with subcarrier modulation (UPAMSM) is proposed to supporting high efficiency non-flickering visible light camera communication (CamCom). A post-compensation technique is employed to reduce nonlinear effects caused by camera gamma correction. In order to eliminate phase uncertainty betw...

Vehicular communication is characterized by a dynamic environment, high mobility, and comparatively low antenna heights on the communicating entities (vehicles and roadside units). These characteristics make vehicular propagation and channel modeling particularly challenging. In this article, we classify and describe the most relevant vehicular pro...

Recent literatures have demonstrated the feasibility and applicability of light-to-camera communications. They either use this new technology to realize specific applications, e.g., localization, by sending repetitive signal patterns, or consider non-line-of-sight scenarios. We however notice that line-of-sight light-to-camera communications has a...

Recently autonomously driven vehicle technologies become the potential researches in order to increase road safety, driving comfort, fuel efficiency and so on. This study focuses on the fuel-saving issue in automatic vehicle within the scope of the decision maker layer. An intelligent economic assistance strategy (EAS) is explained and aims to redu...

In this paper, an optical camera communication system utilizing the under-sampled phase shift ON-OFF keying modulation is proposed to support non-flickering visible light communication. This system sends three types of light symbols through light emitting diode (LED) lamps, which are recorded by a camera. By employing a dual LED lamp with a designa...

Automatically recognizing rear light signals of front vehicles can significantly improve driving safety by automatic alarm and taking actions proactively to prevent collisions and accidents. Much previous research only focuses on the detection of brake signals at night. In this paper, we propose a novel and robust framework to detect rear lights of...

Camera communication (CamCom) is a form of visible light communication (VLC) that makes use of a camera as the receiver. One very important advantage of CamCom is that the acquired images during the receiving process provide a means to visually associate the physical object with the transmitted information, since the receiver has the knowledge of w...

In this paper, we propose a framework to develop an M2M-based (machine-to-machine) proactive driver assistance system. Unlike traditional approaches, we take the benefits of M2M in intelligent transportation system (ITS): 1) expansion of sensor coverage, 2) increase of time allowed to react, and 3) mediation of bidding for right of way, to help dri...

It is believed that vehicle-to-vehicle (V2V) communications and accurate positioning with sub-meter error could bring vehicle safety to a different level. However, to this date it is still unclear whether the envisioned V2V standard, dedicated short-range communications, can become available in commercially available vehicle products, while widely...

Visible Light Communication (VLC) is a fast-growing technology that provides free-space wireless communications using LEDs and photodiodes. As LED becomes common in automotive lighting, Vehicular VLC (V2LC) becomes a new and low-cost solution to implement vehicle-to-vehicle (V2V) communications, in order to support many new safety and infotainment...

Traffic congestion in urban areas is a severe problem in many cities around the world. Conventional infrastructure-based solutions to detect traffic congestion, such as surveillance cameras and road surface inductive loops, have the limitations of high deployment costs and limited coverage. In recent years, due to the popularity of mobile devices,...

Over the past few years, Light Emitting Diode (LED) has become very common in automotive lighting due to its long service life, high resistance to vibration, and better safety performance due to its short rise time. A number of existing works use LEDs that already exist in vehicles, such as brake lights, turn signals, and headlamps, to carry out ve...

Understanding the status of the traffic signal at an intersection is crucial to many vehicle applications. For example, the information can be utilized to estimate the optimal speed for passing the intersection to increase the fuel efficiency, or to provide additional context information for predicting whether a vehicle would run the red light. In...

Scooters are commonly used in many countries due to their low sale price, better fuel economy, and the ability to easily navigate through heavy traffic congestions. Today in Taiwan, approximately 70% of the registered vehicles are scooters. However, due to the low cost nature of the scooters, many safety technologies developed for cars cannot be ad...

In Taiwan, accidents involving scooters have contributed to more than 70% of the total number of injuries and fatalities in traffic accidents and the numbers have been increasing for the past 8 years; it is therefore crucial to derive cost-effective safety solutions which can be used in scooters. To this end, we propose a cost-effective collision a...

In this paper, we evaluate the end-to-end throughput of CDMA-based Wireless Sensor Networks (WSN) with long-thin topologies using theoretical models. In order to minimize the multiple access interference (MAI) and improve the throughput, a power allocation scheme is required. Instead of using sophisticated power allocation algorithms, which require...

To evaluate the feasibility of vehicular ad-hoc network (VANET) applications, it is crucial to have an accurate estimation for the quality of the vehicle-to-vehicle (V2V) radio links and recently it has been shown that the link quality is highly dependent on the location and the velocity of the transmitting vehicle, the receiving vehicle, and their...

Intra-car wireless sensor networks

This paper describes the methodology and results of a series of experiments performed to characterize intra-car wireless channels . Specifically, the experiments target parameters such as the coherence time, statistics of channel loss, and fade statistics. Based on previous experiments, flat fading is assumed; the methodology is developed, and the...

Due to the increasing oil prices, reducing the weight of future cars will be important. One way to do this is by replacing wired sensors and their cables with wireless sensors. This could reduce the weight of cars, thus improving fuel efficiency. The replacement is anticipated to reduce the weight of an average passenger vehicle by up to 50 kg. How...

There is a growing interest in eliminating the wires connecting sensors to the microprocessors in cars due to an increasing number of sensors deployed in modern cars. One option for implementing an intra-car wireless sensor network is the use of ZigBee technology. In this article we report the results of a ZigBee-based case study conducted in a veh...

Due to an increasing number of sensors deployed in cars, recently there is a growing interest in implementing a wireless sensor network within a car. In this paper, we report the results of packet transmission experiments using ZigBee sensor nodes within a car under various scenarios. The results of the experiments suggest that both Received Signal...

Statistical characterization of in-car wireless communication channels has recently gained significance, mainly due to the possibility of deploying a wireless sensor network in the vehicle. In this paper, we report different aspects of a statistical analysis of four representative in- car wireless channels based on the received power data collected...

Building a wireless sensor network in a car has important benefits in terms of cost reduction, having an open architecture, and fuel efficiency. One option for implementing such an intra-car wireless network is to use RFID technology. In this paper, we report the results of extensive experiments carried out at Carnegie Mellon University in collabor...

In this paper we investigate the potential application of RFID technology in future cars as a cheaper, more reliable, and secure wireless alternative to the current wired operation in the engine compartment and other parts of a car where several sensors are connected to adapters which, in turn, are connected to a serial data bus for carrying the me...

Current ad hoc wireless routing protocols typically select the route with the shortest-path or minimum hop count to the destination. However, routes chosen according to such criteria tend to include longer hop-length links with possibly bad signal quality. It is expected that the routing protocol can be improved by eliminating the usage of routes w...