In digital video transmission, latency is caused not only by network delays but also by overhead in various devices. This study proposes the design of a low-latency IP video transmission (less than 40 ms) that can augment human vision via IP networks. In addition, we also provide a remote control experience to demonstrate that low-latency visual transmission facilitates remote collaboration between humans and robots. In a demo with the low-latency system, users will be able to experience remote control operations like never before, gaining a sense of agency that goes beyond a mere remote experience.

Internet-native audio-visual services are witnessing rapid development. Among these services, object-based audiovisual services are gaining importance. In 2014, we established the Software Defined Media (sDM) consortium to target new research areas and markets involving object-based digital media and Internet-by-design audio-visual environments. In this paper, we introduce the SDM architecture that virtualizes networked audio-visual services along with the development of smart buildings and smart cities using Internet of Things (IoT) devices and smart building facilities. Moreover, we design the SDM architecture as a layered architecture to promote the development of innovative applications on the basis of rapid advancements in software-defined networking (SDN). Then, we implement a prototype system based on the architecture, present the system at an exhibition, and provide it as an SDM API to application developers at hackathons. Various types of applications are developed using the API at these events. An evaluation of SDM API access shows that the prototype SDM platform effectively provides 3D audio reproducibility and interactiveness for SDM applications.

This paper proposes a direction for a White Space management scheme to enhance spectrum efficiency by considering unoccupied channel conditions according to the density of DTV transmitters and relays. Unoccupied channels are predicted to foresee White Space within three pilot areas, Uljin, Gangjin and Danyang, in Korea. We considered two DTV service coverage criteria based on two kinds of minimum field strength at Pt. 73 of 47 CFR which is determined according to the date of the TV license acquisition. No-talk regions depending on the DTV coverage criteria were derived by calculating the DTV propagation distances through empirical path loss models such as ITU-R P.1546. With these results, we derived the secondary service operation margins and calculated the enhanced spectrum efficiencies according to the distance and carrier frequency of terrestrial trunked radio (TETRA) - trunked mode operation (TMO) service as secondary users.

Distributed hash table (DHT) is a specialized distributed system that aims to lookup hashed identifiers efficiently in order to route messages to and from the corresponding nodes and objects. However DHTs are mechanisms sensitive to churn (the continuous and interleaved process of arrival / departure of nodes). As a result, they often cause loss of stored objects and failures in the lookup, a serious issue for all overlay networks. In this paper, we propose a dynamic replica location method using the session log in DHT. Our method can determine dynamically the effective number of replicas on session running periods among anticipate nodes. We also implemented a prototype based on an existing DHT routing algorithm, and we evaluated the performance of the prototype. Our proposed method was shown to reduce data loss and the cost for locating replication.

Recently, Technology of sensor networks develops rapidly. In addition, people have started utilizing many kinds of sensors. Sensors independently collect environmental information all over the world. Unfortunately those sensed data are not shared and open to the public. Therefore, we have constructed super-large-scale sensor network system to share sensed data collected from sensors all over the world. We call such a project Live E!. In a part of Live E!, To sense a public area in whole, we assume public objects(mailbox, bus stop, dumpster) uniformly allocate in a district evenly is equipped with a sensor and a wireless device. The public objects often dose not have connectivity to a network. Those are Isolated Wireless Sensor Nodes (ISNs). .. Then, we need to consider the way of collecting from the ISNs. Accordingly, we utilize a Patrol Node (PN) that moves around ISNs, and collects sensed data from ISNs. The ISN stores the sensed data until the time PN comes back. However, because the communication time to the PN depends on the speed of the PN, ISNs can not necessarily transmit all the maintained sensed data to the PN. Therefore, we suggest that the ISN should send adaptive data according to the speed of PN. We propose a technique for transmitting adaptive data depending on the movement of the PN. In addition, we have implemented a prototype of our proposal and verified the effectiveness of our proposed system. Finally, we show that our system improves the performance of the sensor network.

It is vital to achieve a disaster recovery system that allows a backup site to take over a primary site's IT services while the primary site is down. We propose a flexible replication mechanism based on service requirements such as system performance, recovery time objective (RTO), and recovery point objective (RPO). For high flexibility, the mechanism controls the replication schedule by monitoring the application's database accesses in the database connection library and matching the accesses with previously registered access patterns. In our experiments, we confirmed that the proposed mechanism outperforms other existing mechanisms, especially in situations with network delays and packet losses

We examine the delay performance of packets from constant-bit-rate (CBR) traffic whose delay is affected by non-real-time traffic. The delay performance is analyzed by solving the nD/D/1 queue with vacations. We obtain an exact and closed form solution, hence obviating the need of any approximations or numerical Laplace inversions. We then provide various numerical results for low-bit-rate transmission links, in which packets can experience large delay. From our quantitative evaluation, we conclude that there exists an optimum packet size for a given delay bound. In extremely slow links, such as modem links, transmission control protocol (TCP) packets should be segmented to reduce the CBR delay. We therefore investigate the delay impact of TCP packet sizes as well.

In long haul networks, delay in congestion notification can cause an extended period of congestion which may in turn result in cell loss, and poor utilization of the network. In this regard we investigate various congestion notification strategies and show our results in this paper. Moreover, we identify deficiencies and problems associated with the enhanced proportional rate control algorithm (EPRCA) which is one of the explicit rate control algorithms recommended by the ATM Forum. These deficiencies cause unfairness in bandwidth utilization among contending sources. We suggest modifications in EPRCA and call it the modified enhanced proportional rate control algorithm (EPRCAM). We argue that EPRCAM will lead to better link utilization and fair bandwidth allocation between sources. In our simulation model, EPRCAM results in as high as a 97.5% link utilization without cell loss.

This paper presents a new architecture of optical cross-connect (OXC) system to integrate various kinds of transmission systems like wavelength division multiplex (WDM) transmission systems, ultra short pulse transmission systems etc. This architecture also has the following advantages described in a lot of previous studies: providing a large number of lightwave paths with a small number of required wavelength converters; network failure restoration with desirable features (compactness, small power consumption, and bit rate independency); service integration. In this paper, we evaluate impact of our architecture, especially with regard to the number of required components like wavelength converters (WCNVs) and wavelength multiplexers/de-multiplexers (WMuxs/WDMuxs) to allocate lightwave paths.

This paper discusses the concept of the working set for data-flow machines in order to establish one of the criteria for the realization of cost effective data-flow machines. The characteristics of program execution in conventional machines and data-flow machines are compared. Then, a definition of the working set for data-flow machines is proposed, based on the simultaneity of execution and the principle of locality. Several segmentation, fetch, and removal policies are described. Evaluation is made in terms of feasibility, efficiency, and performance, through computer simulations.