Real-time Communication Services Research Articles

Development of Traffic Scheduling Based on TSN in Smart Substation Devices

Smart substations are an important trend in substation construction. With increasing data traffic, it is difficult for the traditional Ethernet network to meet the real-time requirements of control information in smart substations. Hence, in this paper, a deterministic network architecture for substations based on time-sensitive networks (TSN) has been developed in order to realize the domain-wide time synchronization and efficient real-time communication of the “three-layer and two-network” model in smart substations. Furthermore, a design scheme for substation automation equipment based on TSN is proposed. The proposed device realizes the timely transmission of real-time control information packets by utilizing the Earliest TxTime First (ETF) Qdisc technology of Linux and the timing sending capability of Intel 210 NIC. Furthermore, it collaborates with the time-aware shaper (TAS) traffic scheduling mechanism of TSN switches to ensure the end-to-end deterministic delay of time-sensitive traffic. As a result, it provides efficient real-time communication services with low latency and jitter for smart substation automation systems.

Cloud-Based Remote Real-Time Monitoring and Control System for Spring Fatigue Testing Machine

In recent years, the utilization of cloud technology has witnessed a surge, particularly in the domains of industrial automation and intelligent scenarios. However, the prevailing spring fatigue testing machine is still in the traditional single-machine working mode. In this mode, there are many problems such as low automation of testing equipment, poor experimental site environment, and the need for experimenters to be on duty for a long time. In order to solve the above problems, this paper builds a cloud-based remote monitoring and control system based on the high-temperature constant-force spring fatigue testing machine. The system is based on Browser/Server architecture, and clients can access it anytime and anywhere using a browser in a public network environment. The server is hosted on a public cloud platform and includes website service, data storage service, WebSocket real-time communication service, and remote video monitoring service. Clients can remotely monitor and control the testing machine in real time through the cloud. After experimental verification, the real-time monitoring and control messages delay is 11 ms, and the video monitoring delay is 291 ms, which can meet the actual needs of remote spring fatigue testing. This remote monitoring and control system improves the automation of the spring fatigue testing machine and improves the working environment of the experimenters. In addition, it can be applied to other reliability testing machines in the laboratory, and can further help build a workshop-level remote monitoring and control platform.

Virtual power plant for monitoring of distributed energy resources using extensible messaging and presence protocol

In order to solve the problems of interconnection and communication security of monitoring system the distributed energy resources (DER) with different ownership, the virtual power plant (VPP) can be effectively employed. This paper proposes the information model of DER monitoring terminal based on the IEC 61850–7–420, and studies the extensible message and presence protocol (XMPP) mapping to realize the real-time data communication service. The built-in security mechanisms TLS (Transport Layer Security) and SASL (simple authentication and security layer) of XMPP can ensure the security of information transmission. This paper also presents a platform to test the transmission performance of XMPP mapping, and the results show that XMPP properly meets the security communication requirements of DER monitoring system.

ABRF: Adaptive BitRate-FEC Joint Control for Real-Time Video Streaming

Adaptive Forward Error Correction (AFEC) algorithms are proposed to achieve efficient Forward Error Correction (FEC) in Real-Time Communication (RTC). However, current AFEC approaches suffer two key limitations. (1) They do not consider the squeezing effect of redundancy on source bitrate while the squeezing usually happens in real RTC applications with limited bandwidth. (2) They estimate the future packet loss simply, ignoring some critical features of packet loss like randomness and multi-pattern. These drawbacks stop them from providing better Quality of Experience (QoE) in RTC services. We propose ABRF, a general QoE-oriented Adaptive BitRate-FEC joint control algorithm. ABRF makes predictions on the network loss pattern in the coming time and jointly calculates the optimal bitrate-FEC decision based on a QoE model for real-time video streaming. Moreover, ABRF is equipped with a fast adaptation method which helps it generalize across diverse network environments. In terms of Video Multi-method Assessment Fusion (VMAF), experimental results tell that ABRF decreases VMAF degradation caused by packet loss by 68%-95% compared with other AFEC algorithms in real-time video streaming in real-world Internet.

Traversal Using Relays Around Nat by Coturn for Webrtc Systems

Real-time communication between people in the form of audio, images, video, and data is now a necessity. Web Real-Time Communication Technology, WebRTC, is implemented as an open web standard and is available to build such communication. WebRTC requires a server that functions as both signaling and media servers. Signaling server for establishing communication channels, exchanging information, and synchronizing changes. Media servers exchange media, codecs, bandwidth, and rate control. Different Real-time Protocol (RTP) topologies have different requirements on servers, including those caused by the NAT configuration used. This research focuses on the role of the TURN server using CoTurn to create web-based real-time communication services. How is the quality of WebRTC service when CoTurn is a TURN server to pass signaling and media. The method used is divided into three stages, namely: (1) installation and configuration, (2) building WebRTC, and (3) testing. This study shows that real-time communication in the form of audio and video can be carried out even through a symmetrical NAT configuration. It is just that with more than five users in the WebRTC system, communication is slowing down. The proposed further research is developing and engineering the RTP topology to increase the number of users. The CoTurn application can be installed on a Virtual Private Server (VPS) and configured as a TURN Server as a media server service in the WebRTC system.

BoB: Bandwidth Prediction for Real-Time Communications Using Heuristic and Reinforcement Learning

Bandwidth prediction is critical in any Real-time Communication (RTC) service or application. This component decides how much media data can be sent in real time. Subsequently, the video and audio encoder dynamically adapts the bitrate to achieve the best quality without congesting the network and causing packets to be lost or delayed. To date, several RTC services have deployed the heuristic-based Google Congestion Control (GCC), which performs well under certain circumstances and falls short in some others. In this paper, we leverage the advancements in reinforcement learning and propose BoB (Bang-on-Bandwidth) — a hybrid bandwidth predictor for RTC. At the beginning of the RTC session, BoB uses a heuristic-based approach. It then switches to a learning-based approach. BoB predicts the available bandwidth accurately and improves bandwidth utilization under diverse network conditions compared to the two winning solutions of the ACM MMSys'21 grand challenge on bandwidth estimation in RTC. An open-source implementation of BoB is publicly available for further testing and research.

Deployment of UAV-mounted Access Points for VoWiFi Service with guaranteed QoS

Unmanned Aerial Vehicle (UAV) networks have emerged as a promising means to provide wireless coverage in open geographical areas. Nevertheless, in wireless networks such as WiFi, signal coverage alone is insufficient to guarantee that network performance meets the quality of service (QoS) requirements of real-time communication services, as it also depends on the traffic load produced by ground users sharing the medium access.We formulate a new problem for UAVs optimal deployment in which the QoS level is guaranteed for real-time voice over WiFi (VoWiFi) communications. More specifically, our goal is to dispatch the minimum number of UAVs possible to provide VoWiFi service to a set of ground users subject to coverage, call-blocking probability, and QoS constraints. Optimal solutions are found using well-known heuristics that include K-means clusterization and genetic algorithms. Via numerical results, we show that the WiFi standard revision (e.g. IEEE802.11a/b/g/n/ac) in use plays an important role in both coverage and QoS performance and hence, in the number of UAVs required to provide the service.

Extending MQTT with Real-Time Communication Services Based on SDN.

MQTT is one of the most popular application-layer protocols used in the scope of the Internet-of-Things (IoT) and Industrial-Internet-of-Things (IIoT), given its suitability for resource-constrained embedded systems. However, MQTT Quality-of-Service policies do not support timeliness requirements, which is common in IIoT. The literature reports several research works that address this limitation, but they are limited in scope (e.g., improvements in the broker’s internal operation, control of the publisher’s data rate, and path optimizations). Conversely, this paper presents a comprehensive architectural approach, proposing a set of extensions to the MQTT protocol that allow applications to explicitly specify real-time requirements and instantiate corresponding network reservations to enforce the desired temporal behavior. Such reservations are enforced via Software Defined Networking, specifically the OpenFlow protocol, but other protocols that allow bandwidth reservations, e.g., TSN, can also be used. This paper presents the proposed system architecture together with extensive emulation and implementation results that validate the feasibility of the approach, showing that time-sensitive MQTT traffic can be effectively segregated and prioritized to meet application-defined real-time requirements. Using several combinations of network topologies and load levels and comparing to the absence of the proposed real-time mechanisms, both average and worst-case latencies of the time-sensitive traffic decreased to approximately half, while for the normal traffic, they increased by approximately 10%.

An Efficient Certificate-Based Aggregate Signature Scheme for Internet of Drones

Internet of drones (IoD) is a network of small drones that leverages IoT infrastructure to deliver real-time data communication services to users. On the one hand, IoD is an excellent choice for a number of military and civilian applications owing to key characteristics like agility, low cost, and ease of deployment; on the other hand, small drones are rarely designed with security and privacy concerns in mind. Intruders can exploit this vulnerability to compromise the security and privacy of IoD networks and harm the information exchange operation. An aggregate signature scheme is the best solution for resolving security and privacy concerns since multiple drones are connected in IoD networks to gather data from a certain zone. However, most aggregate signature schemes proposed in the past for this purpose are either identity-based or relied on certificateless cryptographic methods. Using these methods, a central authority known as a trusted authority (TA) is responsible for generating and distributing secret keys of every user. However, the key escrow problem is formulated as knowing the secret key generated by the TA. These methods are hampered by key distribution issues, which restrict their applicability in a variety of situations. To address these concerns, this paper presents a certificate-based aggregate signature (CBS-AS) scheme based on hyperelliptic curve cryptography (HECC). The proposed scheme has been shown to be both efficient in terms of computation cost and unforgeable while testing its toughness through formal security analysis.

Fully Distributed Packet Scheduling Framework for Handling Disturbances in Lossy Real-Time Wireless Networks

Along with the rapid growth of Industrial Internet-of-Things (IIoT) applications and their penetration into many industry sectors, real-time wireless networks (RTWNs) have been playing a more critical role in providing real-time, reliable, and secure communication services for such applications. A key challenge in RTWN management is how to ensure real-time Quality of Services (QoS) especially in the presence of unexpected disturbances and lossy wireless links. Most prior work takes centralized approaches for handling disturbances, which are slow and subject to single-point failure, and do not scale. To overcome these drawbacks, this article presents a fully distributed packet scheduling framework called FD-PaS . FD-PaS aims to provide guaranteed fast response to unexpected disturbances while achieving minimum performance degradation for meeting the timing and reliability requirements of all critical tasks. To combat the scalability challenge, FD-PaS incorporates several key advances in both algorithm design and data link layer protocol design to enable individual nodes to make on-line decisions locally without any centralized control. Our extensive simulation and testbed results have validated the correctness of the FD-PaS design and demonstrated its effectiveness in providing fast response for handling disturbances while ensuring the designated QoS requirements.

New patterns for geography field practice education based on location services

Abstract. Geography field practice plays an important role in the training of professionals for geographical science. Many universities in China even entire world with geography-related majors have planned it into the teaching program as a core of practical course. However, in the aspect of teaching pattern, it is still based on the traditional indoctrination teaching method, which is mainly taught by teachers and accepted by students. There are some problems in this teaching pattern, such as the poor practice quality due to the serious imbalance between teachers and students. It is urgent to adopt more powerful information technology to improve the traditional teaching pattern by starting from the practice process.At present, there are few studies both on geography field practice patterns and its informatization. The informative teaching pattern for geography field practice has not been proposed yet. The field practice teaching activities are closely related to the spatial location, so the rapid development of geographic information technology with LBS as the core brings an opportunity to solve the problems existing in the traditional pattern. Therefore, this study makes full use of the support advantages of location service to the geography field practice process, builds geography field practice patterns based on LBS, and promotes the new patterns into practical application by designing the Lushan geography field practice system. Based on the above ideas, this paper has mainly completed the following aspects:First, new patterns for geography field practice based on LBS are proposed. Based on the analysis of the traditional geography field practice process and related supporting technologies, the "dominant-subject" teaching theory is used as the theoretical basis for the pattern construction. In order to the transforming of the subject in geography field practice from teachers to students, GIS and LBS technologies are used to support it. Three geography field practice patterns, teacher-dominated, cooperated and student-dominated patterns, are proposed, and for each pattern, a typical spatial scenario is given. New patterns can reflect the characteristics of online-offline collaboration, teacher-student collaboration, and process-result collaboration.Second, implementation methods for above three patterns are designed. Lushan, China is selected as a typical research area for the application of geography field practice patterns. The application requirements of interns, tasks and processes for geographic information and location services are analyzed. The mechanism and implementation of LBS for three patterns are discussed. In the teacher-dominated pattern, the real-time position of teachers and students can be used to know the practicing status of students and provide support for the rational control of field practice progress. In the cooperated pattern, geography field practice can be effectively carried out by location-based explanation services, geographic information inquiry and real-time communication services between teachers and students. In the student-dominated pattern, points and routes inquiries with location-based and spatial analysis , as well as records of practicing trajectories and process, are important aids for students to carry out independent inquiry and for teachers to evaluate students’ practice results. In addition, this thesis designs the functional framework of the LuShan Geographic Field Practice Platform, and it is a solid foundation to apply new patterns in real scenes.Third, the application effects of the new practice patterns in Lushan geography field practice are analyzed. Based on the application of the Lushan geography field practice platform, online Q&A, practice points works and practice trajectory data during the practice process are analyzed. It can find the areas where problems are concentrated in, and it also can assess the completion of the practice task. Finally, the reasonable evaluation of the geography field practice effects for each pattern is given, and the improvement suggestions for the person control, task arrangement and schedule management of the follow-up field practice are also provided.

Teknologi Bluetooth dengan Mekanisme Multihop

Bluetooth is a wireless communication technology that is used to exchange information, at a lower cost, use low power, the ability to work or interact between applications through approved protocols is very good, and easy operation. The Bluetooth operating range works on the 2.4 GHz unlicensed ISM (Industrial, Scientific and Medical) frequency band using a frequency hopping tranceiver that is able to provide real-time data and voice communication services between Bluetooth hosts. When Bluetooth devices communicate with each other, they will form a dynamic network called piconet, a network consisting of master and slave, in one piconet of no more than 7 slaves. Bluetooth also supports connections between piconets called scattemets. The mechanism for connecting between one piconet and another is called a hop mechanism.

NFV-Based Architecture for the Interworking Between WebRTC and IMS

The emerging paradigm of network function virtualization (NFV) technology promises an efficient solution for optimized service deployment in the cloud computing environment thanks to its ability to dynamically add or remove virtual resources when there is a change in workload. Nevertheless, telecom providers are still facing a challenging issue in efficiently adopting NFV to deploy Web real-time communication (WebRTC) service on top of IP multimedia subsystem (IMS). Providing WebRTC service increases the inherent complexity of the IMS system in terms of the number of service nodes as virtual network functions (VNFs) and the way they interact, both of which play significant roles in the problem of optimally allocating resources. This paper proposes a virtualized interworking system between IMS and WebRTC called NFV-based interworking architecture, and describes the mechanism for VNFs to exchange messages with each other. We present an analytic system model considering the constraints of resources, quality of service (QoS), and service costs. A real-time Markov approximation-based resource allocation algorithm (RIDRA) is then designed allowing a provisioned resource at service nodes to be reconfigured in time to meet performance requirements. The proposed solution is evaluated on the large scale by simulation and on the small scale by our developed testbed. Experimental results reveal that our algorithm effectively responds to fluctuating service demands with a service cost reduced by 19% via efficiently allocating virtual resources while maintaining QoS requirement.

Edge Computing Gateway of the Industrial Internet of Things Using Multiple Collaborative Microcontrollers

An Internet of Things gateway serves as a key intermediary between numerous smart things and their corresponding cloud networking servers. A typical conventional gateway system uses a high-level embedded microcontroller (MCU) as its core; that MCU performs low-level perception-layer device network management, upper-level cloud server functions, and remote mobile computation services. However, in edge computing, many factors need to be considered when designing an IoT gateway, such as minimizing the response time, the power consumption, and the bandwidth cost. Regarding system scalability, computational efficiency, and communication efficiency, solutions that use a single MCU cannot deliver IoT functionality such as big data collection, management, real-time communication, expandable peripherals, and various other services. Therefore, this article proposes an innovative multi-MCU system framework combining a field-programmable- gate-array-based hardware bridge and multiple scalable MCUs to realize an edge gateway of a smart sensor fieldbus network. Through distributed and collaborative computing, the multi-MCU edge gateway can efficiently perform fieldbus network management, embedded data collection, and networking communication, thereby considerably reducing the real-time power consumption and improving scalability compared to the existing industrial IoT solutions.

Using Twitter for foresight: An opportunity?

Twitter is a popular micro-blogging service and platform for public real-time communication. Concerning foresight, the value of Twitter has not been discussed or examined yet. Here this article concentrates on and considers different applications to examine how to use Twitter in foresight exercises. First, Twitter is discussed as a data source for retrieving input to roadmapping or scenarios. Therefore, an analysis framework is introduced and illustrated for the case of #quantifiedself. Second, options are outlined how to interact with a global network of people using Twitter as communication platform, e.g., for being used during foresight workshops or receiving input for scenario development. As the results show, both, the monitoring of topics and technologies, but also the active user engagement, are supported. In summary, Twitter is an opportunity to extend the considered data sources and to increase the number of involved stakeholder views. While the reliability of Twitter data still requires critical reflection, this article implies many new research opportunities.

Performance improvement of offline phase for indoor positioning systems using Asus Xtion and smartphone sensors

Providing a customer with tailored location-based services (LBSs) is a fundamental problem. For location-estimation techniques with radio-based measurements, LBS applications are widely available for mobile devices (MDs), such as smartphones, enabling users to run multi-task applications. LBS information not only enables obtaining the current location of an MD but also pro- vides real-time push-pull communication service. For indoor environments, localization technologies based on radio frequency (RF) pattern-matching approaches are accurate and commonly used. However, to survey radio information for pattern-matching approaches, a considerable amount of time and work is spent in indoor environments. Consequently, in order to reduce the system-deployment cost and computing complexity, this article proposes an indoor positioning approach, which involves using Asus Xtion to facilitate capturing RF signals during an offline site survey. The depth information obtained using Asus Xtion is utilized to estimate the locations and predict the received signal strength (RF information) at uncertain locations. The proposed approach effectively reduces not only the time and work costs but also the computing complexity involved in determining the orientation and RF during the online positioning phase by estimating the user�s location by using a smartphone. The experimental results demonstrated that more than 78% of time was saved, and the number of samples acquired using the proposed method during the offline phase was twice as much as that acquired using the conventional method. For the on- line phase, the location estimates have error distances of less than 2.67 m. Therefore, the proposed approach is beneficial for use in various LBS applications.

Design, Implementation and Evaluation of Unified Communications on-premises and over the Cloud

Unified Communication (UC) is the integration of two or more real time communication systems into one platform. Integrating core communication systems into one overall enterprise level system delivers more than just cost saving. These real-time interactive communication services and applications over Internet Protocol (IP) have become critical in boosting employee accessibility and efficiency, improving customer support and fostering business agility. However, some small and medium-sized businesses (SMBs) are far from implementing this solution due to the high cost of initial deployment and ongoing support. Cloud based UC solution, UC as a Service (UCaaS), is now itself a maturing technology in the marketplace and it has revolutionized the IT industry, being the powerful platform that many businesses are choosing to migrate their on-premises UC solution onto. UCaaS solution has the potential to reduce the capital and operational expenses associated with deploying UC on their own. In this paper, we will discuss and demonstrate an open source on-premises UC solution, viz. “Asterisk” for use by businesses, and report on some performance tests using SIPp. This paper also discusses and demonstrates an open source UCaaS solution. The contribution from this research is the provision of technical advice to businesses in deploying UC and UCaaS, which is manageable in terms of cost, ease of deployment and support.

User Identity for WebRTC Services: A Matter of Trust

Secured interpersonal communications should come with asserted user identities and trust between the involved parties. No single trust model exists in Web Real-Time Communications services, so neither is there a single identity architecture. The authors discuss different models for provisioning user identity and their impact on user privacy.

깊이정보를 이용한 HEVC의 인코더 고속화 방법

최근 영상시스템 환경은 2D 비디오카메라에 깊이 카메라가 부착되어 2D 및 3D 어플리케이션을 지원하는 형태로 보편화 되고 있다. 이러한 3차원 멀티미디어 시스템 환경으로의 변화는 비디오 시스템에서 깊이정보 획득을 용이하게 만들었다. 깊이정보는 객체 구분, 배경영역 인지 등에 이용할 수 있는데, 2D 부호화에 이를 이용한다면 높은 부호화 효율을 얻을 수 있다. 따라서, 본 논문에서는 차세대 2D 비디오 코덱인 HEVC 인코더에 반영한 깊이정보 이용 비디오 부호화 방법을 제안한다. 제안방법으로, 현재 부호화하려는 CU가 배경영역에 위치할 경우 1) 주변블록의 SKIP 모드를 참조하여 결정하는 CU 분할 조기 결정, 2) 시간적 위치의 CU 정보를 이용하여 수행하는 CU 분할 구조 제한, 3) 배경영역에 따른 움직임 예측 탐색 범위 제한이 있다. 실험은 HEVC 참조 소프트웨어인 HM 12.0에 적용하였고, 실험결과 40% 이상의 부호화 복잡도가 감소했으며, BD-Bitrate는 0.5% 손실되었다. 특히, 마이크로소프트사에서 개발한 키넥트를 통해 획득한 영상을 이용한 실험 결과에서는 영상 품질의 큰 열화 없이 기존대비 최대 53%의 부호화 복잡도가 감소하는 결과를 나타내어, 향후 실시간 화상통신, 모바일 또는 핸드헬드 환경에서의 비디오 서비스 등에서 광범위하게 적용할 수 있을 것으로 기대된다. Many of today's video systems have additional depth camera to provide extra features such as 3D support. Thanks to these changes made in multimedia system, it is now much easier to obtain depth information of the video. Depth information can be used in various areas such as object classification, background area recognition, and so on. With depth information, we can achieve even higher coding efficiency compared to only using conventional method. Thus, in this paper, we propose the 2D video coding algorithm which uses depth information on top of the next generation 2D video codec HEVC. Background area can be recognized with depth information and by performing HEVC with it, coding complexity can be reduced. If current CU is background area, we propose the following three methods, 1) Earlier stop split structure of CU with PU SKIP mode, 2) Limiting split structure of CU with CU information in temporal position, 3) Limiting the range of motion searching. We implement our proposal using HEVC HM 12.0 reference software. With these methods results shows that encoding complexity is reduced more than 40% with only 0.5% BD-Bitrate loss. Especially, in case of video acquired through the Kinect developed by Microsoft Corp., encoding complexity is reduced by max 53% without a loss of quality. So, it is expected that these techniques can apply real-time online communication, mobile or handheld video service and so on.

A Transparent Communication System in Distributed Systems

This paper proposes a communication system in order to facilitate the development of communication for distributed systems based on TCP/IP network. The system provides real-time communication service based on UDP, subnetting network, broadcast and multi-NIC(Network Interface Card) configuration in the same host. It also provides reliable communication service based on TCP. These services are some application programming interfaces (APIs) that can be called in client applications with IHBs (Information Harbors) to identify the communication end-points. An IHB is a name defined in a network configuration file (NCF) to make network transparent so that all network concepts are invisible to the users. The NCF is the same for all client applications to guarantee the communication end-points identical. The system is general that can be applied in any network without any source codes needing to be modified and the use is very easy. To apply it to a new network, all of the work is to provide a NCF. The uses in many flight simulators show that the system is more efficient to implement communications.