Nowadays the Learning Management System (LMS) platforms provide limited bidirectional, interactive mechanisms that they are competent to handle personal or small-scale distance learning systems. These mechanisms are designed for one to many online tutorials, and the technology utilizes single-input by single-output video stream technology, the video and audio data need to be coupled with one or many Multipoint Control Units (MCU) to mix or convert them into a single output media stream. In this platform MCU is critical to LMS, however, such system is expensive, lack of capacity and difficult to be massively deployed.
Access-Grid (AG), an Open Source program, offers users capability to watch online multimedia audio-video contents from all the interconnected nodes of LMS through Multicast protocol, and supports groups-to-group high quality interactive distance learning. It requires all the networks to support the Multicast protocol. The MBONE (Multicast Backbone) can be used to connect different Multicast groups via Unicast communication. However, if the number of groups involving in the distance learning are large, the host computers or routers of the network will be heavily loaded because they need to handle the delivering of the media packets.
To use a QuickBridge for aggregating and delivering packages is an alternative of LMS and requires (N-1) *N *BW bandwidth . For example, if there is a 15 nodes online conference and each node uses 800kbps data rate to transmit audio-video contents, then the demanded bandwidth of the aggregation is 168 Mbps. The way of dispersing and controlling the data flow becomes important factors and will greatly affect the quality of the AG online conference.
This thesis modifies the procedure of AG and QuickBridge, and allows all the AG Clients to be able to transmit Unicast and Multicast packets in the online conference. It offers a Meeting Management Server to dynamically adjust topology and hub points, and achieves better elasticity to the system.
By modifying VIC and RAT procedure, the system controls the outbound audio-video data flow from each nodes of online conference, and reduces the demand of bandwidth. The system can directly provide end-to-end conferencing, using Unicast communication to connect the nodes in different Multicast groups, or using the Multicast on the backbone and then using unicast communication to the local nodes. The functionality of the LMS can be improved and capable of supporting multi-windows to multi-user interactive online conference for the users. The results of this thesis can be applied upon real-time interactive distance learning, online video conferencing and interactive online TV. It also helps to lower the cost of the system and reduce the requirement of network bandwidth.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0209107-002112 |
| Date | 09 February 2007 |
| Creators | Chen, Shun-Keng |
| Contributors | Chu-Sing Yang, none, none, none |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0209107-002112 |
| Rights | not_available, Copyright information available at source archive |
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