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We investigate new methods for reliable provisioning of dynamic content requests in optical metro networks. Our methods leverage content replication across multiple edge datacenters and multipath routing.

We propose a flow-based adaptive resource allocation in SDM-OPS networks. It attained 24.6% of packet loss probability and 13.8% of the proportion of Degraded Flows compared to baseline methods. Furthermore, its feasibility was verified via functional experiment using real testbed emulated as SDM environment.

We evaluate the requirements for future spatial-division multiplexing networks operating at throughput higher than 1 Pb/s and discuss possible solutions to support ultra-high capacity.

Safety is crucial for autonomous drones. This paper proposed a new application to realize a high-reliable drone under the edge computing environment. To realize safer drones, we focus on the unexpected and unsupposed situations in drone flight and aim to cope with the situations by calculating the countermeasures for various expected scenarios beforehand. Especially, this paper focused on local path planning, and parallelization of the local path planning is proposed to calculate the many paths to escape the expected obstacles in various scenarios. Experimental results show the effectiveness of the proposed method.

Novel open and disaggregated optical-networking technologies promise to enhance multi-vendor interoperability thanks to their open interfaces in both data-plane and control/management-plane (C/M-plane). From the viewpoint of disaster resilience in optical networks, such interoperability will significantly improve the flexibility in product selection with regard to replacing damaged subsystems with products of different vendors. In this paper, we discuss various approaches for rapid post-disaster recovery in optical networks (including legacy optical networks) employing disaggregated subsystems, namely, the emergency first-aid unit (FAU) with open application programming interfaces and protocols. We address the following problems (and introduce the solutions that we are currently investigating): (1) how to take advantage of the new disaggregated resources and surviving legacy optical resources to achieve early recovery, (2) how to achieve integrated control of FAUs and non-FAU legacy ROADMs, and (3) how to quickly recreate the lost optical performance monitoring (OPM) capability with FAUs and perform a robust telemetry under the restricted bandwidth in the degraded C/M-plane networks.

We propose a method to grasp packet congestion status in downstream of the transit route using Q learning, and to properly offload the packets in each node in optical packet switching networks.

We propose a lightpath provisioning method in coordination with content data placement / cache control in elastic optical networks for content delivery of big data network services and demonstrate 26% improvement of blocking probability.

End-to-end network slicing over a multi-layer transport network is demonstrated, showing that network automation in coordination with edge cloud enables 5G applications such as autonomous driving vehicle and automatic resource management for service function chaining.

We developed a high-speed optical power control system with an acoust-optics-tunable-filter and a multiple RF signal generator and demonstrated collective power equalization for 8-wavelength multiplexed optical signals with power difference less than 0.3 dB.

Multi-homed wireless video streaming systems concurrently send video frames of one video content from multiple wireless access networks. The coexistence of Long Term Evolution (LTE) and Wi-Fi systems is one of the typical multi-homed wireless environments. To utilize such multiple wireless access links for high-quality streaming, we need to overcome two issues: rate decrement in the LTE channel due to cellular congestion and channel quality fluctuation in Wi-Fi channels due to noise, interference, and channel fading. To this end, we propose a hybrid digital-analog video transmission scheme, which integrates digital video coding, near-analog modulation, and compressive sensing, considering Wi-Fi offloading. To avoid an effect of the cellular congestion, the proposed scheme offloads a part of digital-encoded video data, which are originally transmitted in the LTE channel, to available Wi-Fi channels if LTE's data rate becomes insufficient during the streaming session. In addition, the proposed scheme uses a combination of compressive sensing and near-analog modulation for video delivery in Wi-Fi channels to ensure the received video quality can be proportionally improved according to the instantaneous quality of the Wi-Fi channels. From evaluations, the proposed Wi-Fi offloading technique keeps better video quality even when the capacity of LTE channel becomes limited within a streaming session. In addition, it was found that the received video quality can be gracefully improved according to the number of receivable Wi-Fi access points and each Wi-Fi channel quality.

Recent progress of computer networks realizes advanced network services such as high-resolution video streaming and Internet of things (IoT) but it requires further huge amount of traffic. To expand transmission capacity, various studies develop time division multiplexing (TDM), wavelength division multiplexing (WDM), and spatial division multiplexing (SDM) technologies. Time-division packet spatial super-channel (pSSC) is expected as one of promising solutions to realize high throughput with low cost. We have developed a switching node system for the pSSC transmissions. The pSSC is suitable for large data transmission. On the other hand, overhead of pSSC is not negligible in the case of small size data transmissions. This paper proposes a fractional pSSC switching system design for both large and small data transmissions. We introduce the spatial super-channel slicing concept and ILP solution for effective data transmission having bimodal distribution of data size. Effect on slice spatial channel was validated through simulation where it is 50% better than no slicing system.

We propose traffic offloading method reducing loss rate for optical packet and circuit integrated network, which exploits intentionally life-sustained OCS paths after finishing communication for both OPS offloading and instant establishment of forthcoming OCS path request.

Crosstalk-aware algorithms need to check candidate optical paths to find final solutions and mitigate the influence of crosstalk. To address this issue while lower processing complexity, we propose a strict and less computationally method which decreases the influence of crosstalk.

We propose YANG models and the control-plane architecture for an optical packet and circuit integrated network. This enables operators to manipulate the OPS network topologies meeting different requirements. We demonstrate the dynamic control of the OPS topology manipulation.

This paper experimentally demonstrates a data center network based on multi-core fiber (MCF) and packet spatial super-channels (pSSCs) with 8 spatial channels, 64 wavelength channels and PDM-8PSK modulated payloads with a capacity of 83.33 Tb/s/port. The electro-absorption switching gate transparency is also demonstrated for PDM-QPSK and PDM-8PSK modulation formats.

Data center network (DCN) traffic is expected to grow at an overwhelming annual rate over the following years. In addition, DCN traffic is characterized by dense traffic matrices and bursty, time-variant hot-spots within the network. Current DCNs utilize electronical switches interconnected with high-capacity point-to-point optical links. Research suggests that this approach may not be able to meet the future scalability demands, resulting in a capacity bottleneck combined with an elephantine energy consumption. In this work, we introduce a time-division optical switching system for future DCNs that makes use of coherently-modulated packet spatial super-channels (pSSC) over multi-core fibers (MFCs), to be deployed as a converged inter-intra DCN in the top branches of the DCN topology. The fundamental subsystems of this converged network are the core-joint optical switches, able to simultaneously switch all the wavelength channels on all spatial channels of a MCF. The different types of core-joint optical switches are modulation format transparent and feature different parameters such as granularity and insertion loss (IL), enabling the use of each core-joint switch type for a specific function within the network, such as pSSC forwarding or MCF path protection. We develop three types of core-joint optical switches: 1) a ns-fast, high IL electro-absorption-based switch, 2) a $\mu \text{s}$ -fast, intermediate IL acousto-optic-based optical switch, and 3) a ms-fast, low IL mirror-based optical switch. In a network testbed consisting of pSSCs at 32 GBd with 64 wavelength channels, we experimentally demonstrate a switching capacity of 53.3 Tb/s using PDM-QPSK modulated payloads and 83.3 Tb/s using PDM-8PSK modulated payloads. We also demonstrate network restoration capabilities in less than 10 ms in the event of a MCF fiber cut.

With the development of communication services, backbone networks need to deal with various types of traffic by utilizing appropriate switching systems in a flexible manner. Optical packet and circuit integrated (OPCI) networks offer both optical packet-switching (OPS) and optical circuit-switching (OCS) and have been studied for this purpose. A space division multiplexing-based OPCI network provides significant communication capacity and shares spectrum resources for OPS and OCS traffic demands on the same physical infrastructure to efficiently accommodate future services. For appropriate resource utilization, the ratio of spectrum resources between OPS and OCS must be flexibly managed based on the dynamically changing traffic. One of important issues of OPCI networks is sharing spectrum resources under a dynamic traffic model. In this paper, we propose a dynamic spectrum-sharing method for both OPS and OCS data transmissions to enhance resource utilization. The spectrum-sharing method consists of dynamic resource boundary management and load-balancing by exploiting integer linear programming periodically in operation. We evaluate the proposed method with computer simulation and verify its effectiveness in terms of both OPS loss probability and OCS blocking probability.

We present elasticity and agility in softwarized optical network construction, service continuation, and service update. Programmability among multiple network protocols and multiple classes of transmission and processing speeds is a necessary solution for lower CAPEX and agile network setup. We present beyond 100 Gbps hardware-support programmability in optical edge. Existing services should be kept transient quality against sudden traffic changes and failures. We also show proper optical power management using burst-tolerable EDFAs in network protection for service continuation of in-service paths.

Wireless video delivery using multiple transmission paths has been studied in recent years to improve the received video quality. Hybrid WiFi-VLC is one of the promising multi- path techniques for indoor communications. Hybrid WiFi- VLC uses radio and visible light bands for transmissions. When a sender simply transmits videos over the hybrid path, the received video quality will be low due to two features of the visible light band. First one is the quality of visible light path will be significantly changed depending on the position and angle of devices, unlike the conventional radio communication. The second one is visible light path is typically one-way link. It means the conventional schemes have not been possible to provide video contents of adequate quality for each user. In order to address the above-mentioned issues, this paper proposes a video transmission scheme for hybrid WiFi-VLC environments. The proposed scheme integrates two-dimensional discrete wavelet transform (2D-DWT), digital video coding, and pseudo-analog modulation to provide baseline quality over radio paths and realize graceful quality enhancement according to the quality of visible light paths without the channel state information. Evaluations show that the proposed method improves PSNR performance by 11 dB compared to a simple method of dividing and transmitting video data over the radio and visible light paths across signal-to-noise ratios of 0 to 25 dB.

Real-time multi-view video streaming plays an important role in new interactive and augmented video applications such as telepresence, remote surgery, and entertainment. Multiview video streaming approaches exploit time and inter-camera domain correlations in video frames for compression, thereby obtaining two benefits: video traffic reduction and video quality maintenance. However, excessive video encoding requires long periods of time for encoding/decoding computation in real-time multi-view video streaming and this process is vulnerable to frame loss, both of which may induce stalling and skipping during video playback at the user node. To address these problems, we propose Adaptive Multi-view Video Streaming (AMVS) system for real-time streaming. AMVS employs a greedy algorithm to adaptively select a prediction structure with low encoding/decoding computation based on the available network bandwidth. AMVS encodes and transmits multi-view video by considering the similarity of the user's request and the efficiency of transmission. Evaluations using Joint Multiview Video Coding (JMVC) demonstrated that AMVS achieves low encoding/decoding computation and high video quality while satisfying bandwidth limitations.

We experimentally demonstrate a 7-core 2×2 switching node for time-division spatial superchannels with a record data-rate of 53 Tb/s on SDM networks, full packet-granularity by nanosecond-fast electro-absorption gate array switching and network protection capabilities with 7-core microsecond-fast acousto-optical modulator switches.

Progressive download for multi-view video delivery is one of promising techniques to provide immersive and interactive experiences to users. In conventional multi-view video systems, a user downloads videos of all viewpoints of one content to realize smooth view switching. However, it causes increase of video traffic, and thus low video quality within an available download rate. To download only a desired viewpoint is another approach for reduction on volume of video traffic. However, playback stalls occur after view switching. The stalls induce low user's satisfaction for applications. In this paper, we aim at two objectives: 1) to achieve reduction on video traffic and 2) to achieve reduction on the number of playback stalls. To this end, we propose a new multi-view video delivery scheme for progressive download. The main idea of the proposed scheme is that the user only downloads potential videos, which are potentially played back by the user, to realize both traffic reduction and smooth view switching. In addition, we propose two download scheduling algorithms to prevent playback stalls even in a low download rate. The first algorithm prevents stalls in frequent view switching cases while the other prevents stalls in gazing cases. Evaluations using Joint Multi-view Video Coding (JMVC) encoder and multi-view video sequences show that the proposed method reduces video traffic by 55.1% compared with a simulcast scheme. In addition, the proposed method decreases the number of playback stalls during video playback by 86.0% compared with a request and response scheme.

Optical circuit and packet integrated network is a promising network architecture that can deal with various sizes/types of data efficiently. In this integrated network, paths (routes) for circuit and packet switching are assumed to be calculated and selected independently. However, this approach is insufficient in terms of efficiency and rapidity of total path calculation. Calculating appropriate paths with shorter computation time is necessary. In this paper, we propose and evaluate a high-speed multipath computation method that quickly calculates end-to-end paths for optical circuit switching by making use of the calculation results of next hop information for packet switching.

The multi-view video streaming is one of promising technologies for emerging video services. For those applications of multi-view video streaming, video frames of all viewpoints, i.e., cameras, are needed to be transmitted to viewers because the demands of all the viewers' view-switching are unpredictable. However, existing transmission schemes are highly vulnerable to frame loss. Specifically, the frame loss in one viewpoint induces a collapse of decoding for other viewpoint videos. To improve loss-resilience, we propose a multi-path based multi-view video transmission. Our scheme encodes video frames into multiple descriptions that are mutually independent of each other, by using inter-view prediction. It then transmits each description using multiple transmission paths. Our scheme makes three contributions:1) it reduces video traffic even for a large number of cameras, 2) it prevents an increase in the number of undecoded video frames caused by one frame loss, and 3) it conceals frame loss by using the video frames in the other paths. Our scheme generalizes to an arbitrary number of transmission paths and discusses the detailed performance at the number of the paths of 2. Evaluations show that our proposed scheme improves video quality by 3 dB compared to existing transmission schemes in loss-prone environments.

Various video distribution services have emerged, such as Ultra High Definition (UHD) videos, 3D videos and multi-view videos. Despite the fact that the issue of video distribution in best-effort networks is addressed in vast amount of literatures, little work has been done so far to consider video distribution systems in bandwidth guaranteed networks. In this paper, we propose a P2P-based UHD multi-view video distribution system in order to realize high quality play-back and rapid view switch by distributing UHD multi-view video in best-effort and guaranteed networks cooperatively. Through computer simulations, we demonstrate that the proposed system is suitable for future UHD multi-view video distribution systems.

To deal with exponential traffic growth, Elastic Optical Networks (EONs) are necessary because they enable to provide large capacity transmissions. In EONs, multiple widths of spectra are assigned to optical paths. Therefore, fragmentation in frequency domain degrades network performance. We propose a spectrum allocation method to reduce blocking probability and node costs, especially in spatially and spectrally elastic all-optical networks. This paper demonstrates the connection alignment that classifies frequency slots into several prioritized areas.

We propose novel optical node architecture based on the Architecture on Demand concept with sophisticated spectrum and core allocation in Multi-Core Fiber Elastic Optical Networks. More than 85% of flexible spectrum selective switches can be reduced by replacing fixed-grid MUXs/DEMUXs.

Elastic Optical Network (EON) is expected as one of future networks in terms of spectrum flexibility. While Routing and Wavelength Assignment (RWA) problem is one of the key issues in traditional Wavelength Division Multiplexing (WDM) networks, Routing and Spectrum Assignment (RSA) problem has much impact on network performance in EONs. On the other hand, Data-Center (DC) traffic and/or mobile back-haul traffic keep on increasing. To deal with such forthcoming huge capacity of applications, Space Division Multiplexing (SDM) technologies, such as Multi-Core Fiber (MCF) and few-mode fiber, are intensively researched. From network perspective, this paper focuses on Routing, Spectrum and Core Assignment (RSCA) problem for future SDM-EON. Introducing multi-core fibers makes RSA problem more complex because fiber-core dimension is newly expanded. In addition, physical impairment caused by MCF must be taken into account. In this paper, first, the target RSCA problem is divided into the routing and SCA problems, and K-shortest path based pre-computation method is introduced as the routing solution. Next, according to whether MCF has inter-core crosstalk or not, we propose SCA methods with crosstalk awareness and with prioritized area concept, respectively. Finally, the paper evaluates the effectiveness of the proposed algorithms compared with representative ones.

In order to expand the transmission capacity of optical backbone networks, many innovative technologies such as Elastic Optical Network (EON) and Space Division Multiplexing (SDM) have intensively researched. These advanced network technologies require new optical node structures which can fully utilize the additional channels of the next-generation networks. Architecture on Demand (AoD) concept enables to construct flexible and scalable optical node structure by dynamically reconfiguring interconnections of building modules according to switching requests. Because resource allocation methods have impact on switching requests, the number and the types of building modules required for AoD nodes are dependent on not only traffic patterns but also spectrum allocations. In this paper, we propose spectrum and core allocation method based on spectrum region which is related with corresponding building modules of AoD nodes in Multi-Core Fiber Elastic Optical Networks (MCF-EONs). The proposed spectrum regions make two advantages. The one is reducing spectrum fragmentation which is an challenging issue in EONs. The other is replacing building modules of AoD nodes with simple and low-cost ones. Finally, we evaluate the proposed spectrum and core allocation method through computer simulations. The simulation results demonstrate that reducing spectrum fragmentation improves blocking probabilities and replacing building modules reduces modular costs of AoD nodes.

Video streaming using hierarchical cache servers is effective to provide high quality services to many users. However, less-accessed videos tend to be sparsely cached on cache servers far from users. Streaming qualities are degraded due to relatively high packet loss rate and long delay. In order to address the issues on heavy and bursty packet loss over such long distance transmission, we have focused on recovery characteristic of a multi-server Forward Error Correction (FEC) function named “Inter-Stream FEC.” In this paper, we propose a high quality streaming system exploiting hierarchical cache servers. The proposed system improves users' experience by adaptively applying Inter-Stream FEC. We also propose a parity data request method combines with parity server selection considering cache status of individual server and disjointness between paths. Simulation results show the proposed system can achieve higher restoration performance compared with a streaming system using traditional FEC, particularly when bursty loss occurs.

With improvement of network performance, content distribution services such as live streaming have been widely spread. For these services, it is effective to use a multicast distribution system. However, conventional multicast distribution systems are best-effort services using the Internet, which do not guarantee the Quality of Services (QoS). On the other hand, Software Defined Network (SDN) and In-network cache are attracted much attention as new frameworks which are different from the conventional network. In this paper, we propose a multicast distribution system with functions of placement and retransmission, exploiting In-network cache for QoS guarantee and time-shift viewing. We implement a prototype system using Open Flow, and evaluated the performance on the proposed system through computer emulations.

Live streaming distribution services have spread as one of the most popular services. The technique of creating contents has been developed, and users can use it easily. Accordingly, the number of contents rapidly increased. In the existing content distribution system, users must select an interesting content from a large amount of contents in the Internet. It takes long time to find out the most interesting content. Moreover, when they switch to other content, it takes long delay because they need a procedure of joining another distribution network anew. Thus, the system which helps users view satisfied contents and provides fast content switching service is needed. In this paper, we introduce a dedicated server to help users switch to another desired content. We also propose the system which recommends real-time contents on the basis of category information and provides fast content switching service by maintaining reserved peers in advance. Our simulation results show that the proposed system can provide satisfying contents to all users with short delay.

Recently, network services based on distributed components that provide services by using components running on remote nodes have attracted much attention. Advanced services can be provided at a lower cost by using existing components. We have previously proposed a method that ensures a stable QoS for each service by allocating components dynamically according to changes in access frequency. In that method, however, we considered only CPU resources rather than network resources. In this paper, we propose a method for providing bandwidth-guaranteed services stably by considering available wavelength resources in backend servers on a platform with a WDM optical network.

On real-time video streaming, the distribution with multi-tree Application Level Multicast (ALM) is effective in terms of delay and jitter. In constructing multi-tree networks, a joining node selects counterpart nodes based on their performance or bandwidth capacity and they are connected each other. However, tree-based ALM has the overhead of reconstructing the tree topology when any node leaves. Multi-tree ALM has the large overhead of reconstruction. In addition, ALM does not consider distance between nodes on IP networks. This causes increasing delay and wasting network resources. In this paper, for the purpose of churn resilience, reduction of traffic volume and short delay, we propose a construction method of overlapped cluster-trees considering inter-node distance for resilient live video streaming. The proposed construction method consists of two main functions; clustering neighbor nodes on IP network and adjusting the cluster size. The overlapped cluster-trees are resilient to churn. Clusters autonomously manage member nodes according to the cluster size. The performance of the proposed methods is evaluated through extensive computer simulation. The result shows that the proposed cluster-trees can decrease transmission delay and increase resilience to churn compared with conventional multi-tree ALM.

Optical WDM networks are expected for future multimedia services. The multimedia services require stable connections with various length of holding time. While some multimedia services use optical path connections in only minute, other multimedia services use them in several hours. As network perspective, the overhead of connection setup has much influence in the case of short-term connections. On the other hand, longterm connections occupy assigned network resources for long periods. Thus, it is important to assign the appropriate wavelength considering the holding time. Furthermore, the network traffic is large and rapidly changes in time. Therefore, the method that accurately estimates the state of the current traffic and predicts the state of future traffic becomes more important. In this paper, we propose a novel traffic prediction method that can deal with large changes in traffic in optical WDM networks. The proposed prediction method is classified into two categories; “short-term traffic state estimation” and “longterm traffic trend prediction”. Traffic is predicted by using these two methods cooperatively and complementarily. We also propose a wavelength assignment method exploiting this traffic prediction. The proposed wavelength assignment method sets optical paths considering the prediction information and the holding time of connections. Each connection with different holding time is allocated wavelength resources in the limited range based on the traffic prediction information dynamically. We evaluate the performance of the proposed method by computer simulations and confirm that the proposed method can achieve better performance than the traditional method does.

Recently, with the variety of contents in video streaming services, the demand for system assisting users' content selection is increasing. P2P live streaming distribution is one of the solutions to reduce load of distributors. In P2P live streaming, users select desired contents with the help of content catalog. Users join content network and then, play back some contents. In traditional streaming system, special servers need to collect information for content recommendation in order to assist interesting content selection from multiple contents. This method is unsuitable for P2P live streaming. This paper proposes new P2P live streaming system that can select and distribute recommended contents on time based on users' similarity derived by access log of contents in an autonomous and decentralized manner.

In this paper, we propose a data recovery method that exploits multiple video streams. The proposed method gives priority to each data of multiple streams in terms of recovery from packet losses, and it is designed for recovering important data with higher probability. The priority of each data is set based on both inherent importance within a stream and loss probabilities of multiple streams. Specifically, this method deals with the data of less received streams as the important data. Moreover, we focus on the creation method of redundant data to be transferred from extra server for multiple worse conditioned streams, which greatly affects the recovery capability, and propose the creation method which is less influenced from the network condition. Our simulation results show that the proposed method can recover more important data with higher probability. Furthermore, the proposed method can also achieve almost the same restoration ratio among streams of recovery targets which have different loss probabilities.

Network services based on distributed components, which provide advanced network services with lower cost by flexibly assigning and reusing useful components running on remote servers, are attracting increasing attention. In this study, we propose a new platform which provides sustainable QoS and faster service time by allocating components dynamically with fault-tolerance. Specifically, we assume that many kinds of components are running on component servers and each component has its own Service Level Agreement (SLA). The proposed platform achieves to make a load-balancing system to meet SLA for service time. Moreover, the platform can provide faster service time to allocate components dynamically considering inter-component communication delay. Finally, to show the performance of our platform, we perform simulation experiments and prototyping.

In this paper, we propose a video data recovery method that exploits multiple streams. The proposed method gives priority to each data of multiple streams in terms of recovery from packet loss, and it is designed for recovering important data with higher probability. The priority of each data is calculated based on both inherent importance in one stream and loss probabilities of multiple streams. Specifically, this method deals with the data of less received streams as the important data. Moreover, the proposed method decides appropriate number of parity packets. This is because the transmission of too many parity packets might affect the other traffic, while that of too few packets might recover insufficient amount of data. The proposed method can improve video quality of total multiple streams. Our simulation results show that the proposed method can recover more important data with higher probability. Furthermore, the proposed method can also achieve almost the same restoration ratio among streams of recovery targets.

Application level multicast with multiple distribution trees is effective for real-time streaming in terms of low delay and jitter. However, failure of upstream nodes drastically influences on the performance of many downstream nodes in multiple tree-based multicast. This degradation of video data continues until reconstruction of distribution trees finishes. Therefore, it is important to recover from the isolation as fast as possible. In this paper, we propose proactive and reactive approaches in order to resolve this problem. The proactive approach realizes fast recovery from isolation and efficient randomized forwarding by distribution trees cooperation. Each node forwards received data to its child nodes not only in the tree but also in other trees according to a pre-determined probability. In contrast, in the reactive approach, an isolated node requests forwarding from other nodes after detecting the parent node's trouble. This approach achieves quick response by requesting to near nodes. Moreover, we propose the hybrid method combining these two approaches. This hybrid method has advantages of both the proactive and reactive approaches. Finally, we evaluate the performances of the proposed methods through computer simulations, and confirm the effectiveness of the proposed methods.

With the appearance of various live-streaming distribution services, the demand for private distribution service is increasing. The content in this service is provided by an individual user, and therefore the distributor’s bandwidth is narrow compared to that of traditional streaming service. One of effective ways for reducing transmission load of distributor is to adopt P2P technology. The P2P live-streaming distribution services actually become popular. We have proposed P2P live streaming system which performs high performance in private distribution. However, the system has not been well considered about the performance degradation when nodes leave. This paper presents and evaluates churn resilience of P2P live-streaming system suitable for private distribution. In this paper, we focus on the maintenance of important nodes which affects the performance of distribution critically. Specifically, when important nodes leave from the system, we promote a high performance node to a new important node. When a higher-performance node newly joins into the system, the important node with lowest performance is replaced with that node. Simulation results show that the resilience for churn provided by our system is comparable to previous systems based on Cool streaming.

In this paper, we propose a new service platform which provides stable QoS by allocating components dynamically with considering fault-tolerance. We assume that many kinds of components are running on component servers and each component has its own SLA. The proposed platform achieves to make a load-balancing system to meet SLA of these components SLA and considering the number of replications necessary to offer a continuous service in case of failure. Finally, by implementation of its prototyping system, we confirm that the proposed platform is effective and feasible to provide the network services based on distributed components.

P2P live streaming distribution services which can reduce load of distributor becomes commonly. The contents of these services are provided by not only corporations but also individuals. In existing systems for business services, however, transmission load of distributor still remains in high level to keep quality of service higher. Thus, it is difficult for private content distributors to provide for their own streaming contents. This paper presents and evaluates P2P live streaming system suitable for private distribution. This system constructs network considering transmission bandwidth of each node. In particular, a certain number of broadband nodes are carefully selected and set at the point nearby the distributor's node in P2P network. A set of the selected broadband nodes plays a role of a virtual distributor with large amount of transmission bandwidth and provides contents to peers instead of Origin. The original contribution of our proposal includes double mesh P2P network structure for scalable and efficient private live streaming services, and its detailed design description. In this method, network bandwidth is used effectively. As a result, it is expected to achieve the private distribution with higher scalability. With simulation experiments, we confirmed that the proposed system presents about half load of distributor compared with the existing system.