Kazuyuki Tasaka

A media synchronization method for real-time group communication in a multiple device environment

This paper proposes a media synchronization method for real-time group communication within a multiple device environment. The method controls the output time of each media unit received at multiple devices and synchronizes them, even if the arrival time of the media unit temporarily fluctuates. This fluctuation is caused by variation in bandwidth and the network delay between different access networks. This paper also evaluates the system performance, in terms of aspects such as the average time of difference between the output and input times of each media unit, in order to confirm the effectiveness of the proposal.

A Web Synchronization Method for Browser-Based Communications

In this paper, we propose a web synchronization method (WSM) to share operation data on a browser and synchronize output time of data among browsers in browser-based communications such as video conferencing and remote control services. WSM continually provides users with an environment for smooth browser-based communications even if users are in a heterogeneous environment where network delay and rendering time among browsers fluctuate. This fluctuation causes the difference of output time among browsers and a lack of synchronization (out-ofsynchronization). This is perceived as being somewhat strange, or even annoying. Several methods have been studied to prevent out-of-synchronization for streaming content such as video and voice data. WSM synchronizes the output time of streaming content and/or non-streaming content after sharing browser operations (e.g., page movement) among conversational partners. WSM also maintains synchronization of the output time even if a device is connected to different access networks during a conversation. Synchronized output is realized by controlling the time to notify each browser of browser operations, and by controlling the time to send and output web content according to the network delay and rendering performance. For considering feasibility, WSM works on a web browser and does not need additional software. We implemented a prototype system and measured the difference in the output time among browsers. The results show that WSM achieves web synchronization within 300 ms while the target time was 320 ms.

A Novel Web Synchronization Method for Supporting Smooth Web Communication

Users employ various communication services such as browser-based remote assistance to support voice communication in a call center. However, there is an issue with web services regarding smooth communication due to out-of-synchronization of output time on browsers in an environment where network delay and rendering time fluctuates among devices. This status is perceived as being somewhat strange, or even irritating. Several methods have been studied to prevent out-of-synchronization for real-time services such as voice and video. We also target synchronization of browser operations (e.g. page movement) for web services. We propose a novel web synchronization method (WSM). WSM continues to synchronize the output time of web content among browsers. Synchronized output is realized by controlling the time to notify each browser of browser operations, and by controlling the time to send web content according to network delay and rendering performance. For usability, WSM is unnecessary for installing new software on a browser. We implemented a prototype system and measured the difference in the output time among browsers. The results show that WSM achieves web synchronization within about 300 ms (target time: 400 ms).

Implementation and evaluation of a collaborative content play method in a home network

Digital network appliances supporting DLNA (Digital Living Network Alliance) have been gaining wide acceptance in home networks (HNWs). To enhance the entertainment experiment in the HNW, we propose a collaborative content play method that automatically plays the user-selected content (e.g. music, photo) as main-content and other kinds of content to suit the mood of the main-content as sub-content in the same timing. Moreover, we show the performance evaluation of the proposed method in experimental test bed using multiple digital network appliances supporting DLNA.

A web synchronization method for supporting real and non-real-time web communication

We propose a web synchronization method that shares the same webpage and operations (e.g. button click) by browsers among users in not only real-time but also non-real-time to remotely support operations in various scenes. This method also synchronizes the output time of a scene in streaming content (e.g. voice and video) and the output time of other content (non-streaming content including the output result of operations at the scene). Conventional methods achieve a web synchronization to supplement voice/video communication with the support of operations in real-time for services such as call centers and e-learning. An operator can remotely operate a users browser instead of users. However, users cannot receive the services when support by an operator is unavailable. Therefore, we propose a novel method for enabling non-real-time web communication. The proposed method achieves web synchronization by automatically adding synchronization information to web content that specifies the time at when an operation is executed. The timing for synchronization is calculated according to the output time of streaming content and communication environments (network delay and rendering performance). We implemented a prototype system and measured the difference in the output time between browsers. The experimental results show that the proposed method achieves synchronization within 300-400ms (target time is 400ms).

An Account Provision and Management Architecture for Messaging Services in Emergencies

In this paper, we propose an account provision and management (APAM) architecture for messaging services such as web mail in an emergency such as a massive earthquake. The APAM architecture stably and continually provides people (users) who hope to confirm each other’s safety in a stricken area with message services, even if mobile phone lines and fixed lines are unavailable. This is realized by automatically establishing an emergent line such as a satellite line and stably providing the services from a server (emergent server) in the evacuation area. The emergent server provides all users with an emergent account and authenticates the account in the evacuation area so as to avoid traffic congestion in the emergent line (low-bandwidth line). If some users already have their own account, the emergent server and the server on the Internet binds the emergent account with their account for receiving message data from their relatives as usual. Moreover, even if users move to other evacuation areas to seek their relatives, this APAM architecture allows users to continually use the services by updating the binding information of the account. We deployed a prototype system and conducted experiments to evaluate the APAM architecture. The experimental results show that the APAM architecture can stably and continually provide 1,000 users (typical capacity of the area) with an emergent account and messaging services simultaneously.

An Account Provision and Management Architecture for Messaging Services in Emergency

In this paper, we propose a novel architecture for account provision and management in an emergency such as a massive earthquake. This architecture stably and constantly provides messaging services such as web mail to people (users) who want to confirm each others safety in a stricken area. Even if the mobile phone line and fixed line are unavailable in an emergency, the proposed architecture allows users to stably use the services using their device such as a smartphone as usual by providing an emergency account from the server in the evacuation area to all users and binding the emergency account with their own account. Moreover, even if users move to other evacuation areas for seeking their relatives who have become separated from them, this architecture allows users to constantly use services by updating the binding information of the account. We deployed a prototype system based on this architecture to show its effectiveness. Experimental results using this prototype system show that the proposed architecture can provide an emergency account and services to 1,000 users (capacity of the area) simultaneously.

A dynamic session switching method between digital network appliances

This paper presents a novel method, which dynamically switches sessions established by Universal Plug and Play (UPnP) and Session Initiation Protocol (SIP) to maintain the content delivery between digital network appliances when a user moves to/from home. UPnP is used when both appliances are in the home and SIP is used when at least one of them is outside. The proposed method targets session switching at a rate fast enough to ensure users may not be aware of it. This paper shows the performance of a prototype system based on the proposed method and its effectiveness.