Application Specific Message Research Articles

ViSig

Visual body signals are designated body poses that deliver an application-specific message. Such signals are widely used for fast message communication in sports (signaling by umpires and referees), transportation (naval officers and aircraft marshallers), and construction (signaling by riggers and crane operators), to list a few examples. Automatic interpretation of such signals can help maintaining safer operations in these industries, help in record-keeping for auditing or accident investigation purposes, and function as a score-keeper in sports. When automation of these signals is desired, it is traditionally performed from a viewer's perspective by running computer vision algorithms on camera feeds. However, computer vision based approaches suffer from performance deterioration in scenarios such as lighting variations, occlusions, etc., might face resolution limitations, and can be challenging to install. Our work, ViSig, breaks with tradition by instead deploying on-body sensors for signal interpretation. Our key innovation is the fusion of ultra-wideband (UWB) sensors for capturing on-body distance measurements, inertial sensors (IMU) for capturing orientation of a few body segments, and photodiodes for finger signal recognition, enabling a robust interpretation of signals. By deploying only a small number of sensors, we show that body signals can be interpreted unambiguously in many different settings, including in games of Cricket, Baseball, and Football, and in operational safety use-cases such as crane operations and flag semaphores for maritime navigation, with > 90% accuracy. Overall, we have seen substantial promise in this approach and expect a large body of future follow-on work to start using UWB and IMU fused modalities for the more general human pose estimation problems.

Modeling and analysis of traffic warning message dissemination system in VANETs

As the preferred underpinning technology of intelligent transportation systems (ITS), vehicular ad hoc networks (VANETs) have been widely used to cope with various traffic problems. However, implementing application-specific message dissemination in VANETs with fewer message dissemination is a challenge since, in fact, it is not meaningful for some vehicles to get such a message for the application requirements for alleviating traffic congestion. Thus, this paper proposes a traffic warning message dissemination system (TWMDS) framework together with a protocol for traffic warning messages (TWMs) dissemination called the reverse routing protocol (RRP). With TWMDS, when an abnormal traffic event (ATE) occurs, the vehicle causing this event generates a standardized TWM. This message is then forwarded only to the vehicles that may enter the potential congestion area (PCA) via vehicle-to-vehicle and vehicle-to-intersection interactions. In addition, three colored petri net models are developed to model and analyze the interaction behavior of TWMDS. In this way, we show the correctness and reliability of RRP and provide a feasibility measure for the subsequent development and implementation of TWMDS. Finally, we use Veins framework integrating OMNeT++ and SUMO to simulate the TWMDS functional modules, which further validates that RRP has a higher application value compared with three other routing protocols in TWMDS. With TWMDS, drivers can re-route their traveling paths as soon as possible to alleviate traffic congestion.

Improved ASM-TER Training Sequence Detection and Fine Doppler Frequency Estimation Methods from a Satellite

To detect terrestrial application-specific messages (ASM-TER) signals from a satellite, a novel detection method based on the fast computation of the cross ambiguity function is proposed in this paper. The classic cross ambiguity function’s computational burden is heavy, and we transform the classic cross ambiguity function to a frequency domain version to reduce the computational complexity according to Parseval’s theorem. The computationally efficient sliding discrete Fourier transform (SDFT) is utilized to calculate the frequency spectrum of the windowed received signal, from which the Doppler frequency could be estimated coarsely. Those subbands around the Doppler frequency are selected to calculate the ambiguity function for reducing the computational complexity. Furthermore, two local sequences with half length of the training sequence are utilized to acquire a better Doppler frequency tolerance; thus, the frequency search step is increased and the computational complexity could be further reduced. Once an ASM-TER signal is detected by the proposed algorithm, a fine Doppler frequency estimation could be obtained easily from the correlation peaks of the two local sequences. Simulation results show that the proposed algorithm shares almost the same performance with the classic cross ambiguity function-based method, and the computational complexity is greatly reduced. Simulation results also show that the proposed algorithm is more resistant to cochannel interference (CCI) than the differential correlation (DC) algorithm, and the performance of fine Doppler frequency estimation is close to that of the Cramér–Rao lower bound (CRLB).

A Novel Random Access Algorithm for Very High Frequency Data Exchange (VDE)

VHF Data Exchange System (VDES) is considered as an important component of the future maritime communication system by the International Maritime Organization (IMO). On the basis of the existing Automatic Identification System (AIS), VDES adds the other two higher capacity subsystems: Application Specific Message (ASM) and VHF Data Exchange (VDE). The Random Access Channel (RACH) of VDE was first introduced in the International Telecommunication Union (ITU) Recommendation M.2092-0. As the slot planning principle of RACH in VDE is by interval, which is significantly different from the continuous slot map for access algorithms in AIS, the existing slot access algorithms cannot meet the requirements of VDE. The simulation results show that the VDE slot map can reduce the normalized throughput of the existing algorithm by 39%. A novel random access algorithm called Adaptive Traffic Load Contention Resolution Diversity Slotted ALOHA (ATL-CRDSA) is proposed in this paper. The algorithm combines the load control strategy and contention resolution scheme to overcome the challenges of the new RACH of VDE. Simulation results show that ATL-CRDSA has remarkable improvement on RACH, making it very efficient and providing low latency of the packets. The insights gained from this study may be of assistance to the Media Access Control (MAC) layer design for upcoming versions of VDES standard.

Measurement Framework for Assessing Reliable Real-Time Capabilities of Wireless Networks

Network latency and reliability are becoming critical performance indicators for future mission critical services based on wireless connectivity. In this article we present a portable and low-cost measurement framework for quantifying the endto- end (E2E) latency and reliability of communication systems based on single or multiple links. The proposed framework is tailored for characterization of access diversity mechanisms, for example, multi-connectivity or hybrid access methods, which are expected to be essential for ultra-reliable wireless communications in 4G and 5G networks. An active-probe measurement approach is adopted, consisting of a client that transmits timestamped packets to a server, and vice versa, via one or multiple communication links under test. The setup allows us to measure the one-way latency performance in uplink and downlink separately, and allows fully synchronized measurements of multiple links in parallel to understand the benefits of multi-connectivity mechanisms. Traffic generation is flexible in terms of packet size, transport protocol (TCP or UDP), and inter-arrival time interval of the generated packets, hence being a powerful tool for benchmarking the performance for different application-specific message flows. Special emphasis is put on the tail of the latency distribution, that is, the latency that can be achieved with a certain probability constraint, for example, 99.9 percent or beyond. Given the challenge of measuring such rare events, we measure and validate the stability of the measurement equipment to ensure that the observed performance is not compromised by undesired behavior or malfunction of the equipment. The system has a measurement error below 400 μs with 99.9 percent confidence and below 3.1 ms with 99.999 percent confidence. The capability and applicability of the measurement framework is illustrated by a measurement test of two simultaneous LTE connections that provide robust communications to an aerial drone.

NorSat-2: Enabling advanced maritime communication with VDES

Satellite AIS is well recognized as a system for vessel traffic monitoring and maritime safety. The growing demand for maritime data services has led to the development of a new VHF Data Exchange System (VDES), which will provide two-way communication at higher data rates than possible with current AIS systems. Within the VHF maritime frequency band (156.025–162.025 MHz), VDES integrates AIS with channels for Application Specific Messages (ASM) to support the distribution of maritime data, including meteorological data and traffic information. Expanding VDES to a satellite platform will facilitate a global data exchange between ships and shore via satellite. NorSat-2 is the first satellite to incorporate a VDES payload, in addition to an advanced AIS receiver, both of which are in-orbit reconfigurable software-defined radios developed by Kongsberg Seatex.NorSat-2 was developed and built by the Space Flight Laboratory (SFL) under contract to the Norwegian Space Centre, with contribution from Space Norway for accommodation of the VDES payload. With a mass of 16 kg, the satellite design is based on SFL's Next-generation Earth Monitoring and Observation (NEMO) bus, which has proven flight heritage to be a robust and reliable microsatellite platform. To enable directional communication over VHF for the VDES payload, SFL has developed a three-element deployable Yagi-Uda antenna. The antenna is stowed during launch and deployed on-orbit upon command receipt. In addition to NorSat-2's S-band telemetry and command system, the satellite also has an enhanced S-band feeder uplink which is capable of achieving data rates of up to 1 Mbps.NorSat-2 launched onboard a Soyuz on July 14, 2017 into a 600 km polar sun synchronous orbit. It is the fourth Norwegian satellite on-orbit and is one of the first satellites to supply VDES services, in addition to complementing Norway's existing satellite AIS network.This paper describes the NorSat-2 mission, with an emphasis on the unique and innovative aspects that are the VDES payload, deployable Yagi antenna, and enhanced S-band uplink.

VHF Data Exchange System (VDES): an enabling technology for maritime communications

This work presents an overview of the radio interface of VHF Data Exchange System (VDES), which is currently on its way to become an ITU standard supported by International Association of Marine Aids to Navigation and Lighthouse Authorities. VDES includes the already existing collision avoidance tracking system Automatic Identification System and the messaging system Application Specific Messages. Additionally, a new third component for digital maritime communications of any kind, named VHF Data Exchange is included. On the one hand, there is a traditional terrestrial component, on the other hand, a satellite communication link is also envisioned partly by the same spectrum usage. In this article, focus is given towards the technical design aspects and challenges of this hybrid communications transmission scheme.

AIS RF Monitoring Service Using Application Specific Message

The AIS is an automatic tracking system used on ships and by vessel traffic services for identifying and locating vessels through electronically exchanging data with other nearby ships and VTS stations. Defining new application specific message has augmented the functionalities and informational content of AIS. This paper proposes RF monitoring service using AIS application specific message. The vessel, which has an AIS RF monitoring device, measures and monitors the sensitivity of the AIS signal transmitted from other nearby ships, AtoN devices and base stations. It can facilitate maintenance of the AIS devices and can also determine the AIS signal strength.

Integrating ROS and MATLAB [ROS Topics

The Robot Operating System (ROS) has gained wide currency for the creation of working robotic systems, initially in the laboratory but now also in industry. Despite ongoing evolution, the fundamental principles of publishing and subscribing on topics, application-specific messages, invoking services, and sharing parameters have remained constant.The primary programming environment for those working with ROS is C++ and Python, though using Java is also possible.

AISバイナリメッセージを用いた見張り情報の共有

As an application of the ASM (Application Specific Message) of AIS (Automatic Identification System), which is so called “binary message”, The author developed a system which shares information of the targets tracked by ARPA(Automatic Rader Plotting Aid) with other ships and boats equipped with AIS receivers. The system transmits two types of position data; one is absolute positions and the other is relative positions to the tracker. In 2013, for both data types, the accuracy of the tracked positions was evaluated at Tateyama comparing with the GPS data of a boat under tracking, and this paper reports the result.

AIS-ASM 기반 신규 서비스 도입을 위한 선행 연구

AIS는 해양안전 분야의 핵심서비스이다. 그 중 바이너리 메시지를 전달하는 6번 메시지와 8번 메시지를 활용한 다양한 서비스들이 등장하고 있으며, 이에 MSC는 2010년 AIS-ASM 사용에 대한 권고를 발표한 바 있다. AIS-ASM을 통한 해양안전정보 제공은 해양사고 예방이나 안전 제고 등에 기여할 수 있지만, 새로운 서비스가 VDL에 추가 부하를 가져올 수 있으므로 서비스 도입 절차가 반드시 필요하다. 본 논문에서는 AIS-ASM 서비스 분석을 통해 각 서비스를 도입하기 위해 확장되어야 하는 기능 또는 체계들을 정리하고, 지속적으로 수집한 AIS 정보 분석을 통해 현행 AIS 운용 환경을 관찰한 결과를 소개한다. 또한 이를 바탕으로 신규 AIS-ASM 서비스 도입을 위해 수행하여야 하는 선결 연구주제들을 정리한다. VDL 활용 감시시스템, 비정상 AIS 기기 감지 및 제거, 해양안전서비스 가치분석 등이 요구된다. AIS is a core service in the maritime safety domain. AIS Message type #6 and #8(for binary date) can be used for carrying any kind of MSI(Maritime Safety Information). The MSC(Maritime Safety Committee) approved SN/Circ. 289 on Guidance on the use of AIS Application-Specific Messages in 2010. The MSI that carried by AIS-ASM can support to reduce the maritime accidents. Since a new AIS-ASM service places an additional load on the VDL(VHF Data Link), there should be a deployment process for new AIS-ASM services. In this paper we analyze the AIS-ASM services and survey the extended functions and systems for each AIS-ASM service. We also present the survey of the statistical analysis of local AIS messages. and suggest preliminary research topics for the deployment of new AIS-ASM services. VDL monitoring system, system for detection and removal of malfunctioning AIS equipments, and value analysis process of the MSI services are required.

국내 해상교통관제센터의 요구사항 분석을 통한 차세대 VTS의 항행지원 서비스 시나리오

최근 해상안전을 위한 국제적 기술 개발 및 표준화가 활발하게 진행되고 있다. 특히 e-Navigation을 지향한 기술들이 개발되고 있으며 국내에서도 차세대 해상교통관제기술개발의 필요성이 제기되고 있다. 그리고 현재 국내 환경에 맞는 차세대 VTS (Vessel Traffic Service)를 진행하기 위해서는 국내 VTS 센터의 관제사로부터 요구사항을 수렴하여 이를 시스템 개발에 적용할 필요성이 요구되어 왔다. 따라서 본 논문은 차세대 VTS의 요구사항을 정의하기 위해 15개 국내 해상교통 관제센터로부터 요구 사항을 수렴하고 항행지원 위주의 결과를 분석하여 그 결과를 제시하고자 한다. 그리고 항행지원 요구 사항 분석을 통해 새로운 항행지원 서비스로서 기존 VTS 시스템에서 지원하지 않았던 차세대 VTS용 ASM(Application Specific Messages) 서비스를 제안하고 이를 구현하여 AIS 실제 장비와 연동 및 시뮬레이션 단말시험을 통해 그 가능성과 효과를 검증하고자 한다. Recently, researches of technology and standardization for maritime safety are proceeding internationally. In particular, some technologies and strategies for e-Navigation have been developed and the necessity of development of next generation VTS (Vessel Traffic Service) has been raised in Korea. In order to construct user oriented VTS system for domestic environment, VTS operators are asked for their requirements related to developing VTS and the opinions should be reflected in the VTS. So in this paper, we collect the requirements from fifteen VTS centers in the country and we also analyze them. Furthermore, we propose an ASM (Application Specific Messages) service, which was not supported by current VTS, and we verify the proposed ASM through AIS (Automatic Identification System) system and simulation terminal for maritime safety.

A user test of Automatic Navigational Intention Exchange Support System using an intelligent ship-handling simulator

Authors evaluated the feasibility of the “Automatic Navigational Intention Exchange Support System using AIS (ANIESS)”, which we have developed since 2007. ANIESS is a communication system to exchange navigational intensions (e.g. Port to Port passing) between encountered ships by using short-range communication means such as application specific message of automatic identification system (AIS). A series of simulator experiments for evaluation of the ANIESS were carried out participating five active seamen. The scenarios are composed of basic encounter situations. Each subject experienced the collision avoidance manoeuvre using the ANIESS and the automatic collision avoidance system (ACAS), which is installed to a simulator. Then, they assessed the collision avoidance manoeuvre using ANIESS subjectively regarding the way and the suitable time for the support of the ANIESS, comparing to their own usual operations. As the result, we found the appropriate way and time for the support. We also got some suggestions on the way and the time for starting collision avoidance manoeuvre to improve the ACAS. Finally, we confirmed the effectiveness in basic encounter condition from the subjective evaluation and also found some issues to improve the ANISS and ACAS.

Associative routing for wireless sensor networks

Traditionally routing in computer networks has focused on finding paths along which data packets could be delivered to pre-identified destination nodes. Most existing routing protocols rely on the use of network addresses as unique node or group identifiers that are usually numeric and independent of any application semantics. The semantically-oblivious identification has forced network designers to incorporate resource/service discovery techniques at higher layers of the network stack, resulting in unnecessary overhead. While such overhead can be tolerated in high-speed wired networks, it significantly limits performance and network lifetime in wireless infrastructure-less networks with battery-powered resource-constrained devices like sensor networks. Moreover, sensor nodes are more naturally anonymous and therefore assigning unique identifiers to individual node limits network scalability and imposes significant overhead on resource management. In this paper, we propose associative routing as a class of routing protocols that enables dynamic semantically-rich descriptive identification of network resources and services. As such, associative routing presents a clear departure from most current network addressing schemes, eliminating the need for a separate phase of resource/service discovery. We hypothesize that since, in essence, resource discovery operates similarly to path discovery then both can be performed in a single phase, leading to significant reduction in traffic load and communication latency without any loss of generality. We also propose a framework for associative routing and present adaptive multi-criteria routing (AMCR) protocol as a realization of associative routing for sensor networks. AMCR exploits application-specific message semantics, represented as generic criteria, and adapts its operation according to observed traffic patterns. Analytical results demonstrate the effectiveness, efficiency, and scalability of AMCR.

Error detection and diagnosis for fault tolerance in distributed systems

The early error detection and the understanding of the nature and conditions of an error occurrence can be useful to make an effective and efficient recovery in distributed systems. Various distributed system extensions were introduced for the implementation of fault tolerance in distributed software systems. These extensions rely mainly on the exchange of contextual information appended to every transmitted application specific message. Ideally, this information should be used for checkpointing, error detection, diagnosis and recovery should a transient failure occur later during the distributed program execution. In this paper, we present a generalized extension suitable for fault-tolerant distributed systems such as communication software systems and its detection capabilities are shown. Our extension is based on the execution of message validity test prior to the transmission of messages and the piggybacking of contextual information to facilitate the detection and diagnosis of transient faults in the distributed system.