Taejune Hwang

VOD service using web-caching technique on the head-end- network

To provide fluent on-demand services on Internet, the VOD servers have to possess a powerful processing ability and the network needs a vast bandwidth. The more clients request service, the more these resources are required. This paper presents a web-caching technique for providing fluent VOD services on Internet. This technique adopts some caches in the Head-End-Network that consists of a Switching-Agent (SA), some Head-End-Nodes and many clients. This technique distributively stores video streams in the order of request on some HENs which request an identical video item. Thus, storing streams on each HEN are different. When the client requests service for cached video items, connecting HEN receives streams from HENs which stored them and transmits them to client. These procedures are performed under the control of SA. Therefore this technique distributes the load of HENs, leads to equiloaded HEN and protects data duplication among HENs.

Multicast for multimedia delivery in wireless network

In this paper we propose a novel technique for multimedia service using multicast delivery in wireless network. It supports seamless multimedia service that uses basic tree and their neighboring mobile nodes (NMNs) in wireless network. The basic trees are generated based on hop-counts from each mobile node (MN) toward base node (BN). Each MN has some NMNs (1-hop away) which are composing the upper, lower or peer MNs within its transmission range and are located at different basic trees. MN joins to a specific multicast (Mcast) group through its basic tree. For protecting seamless service according to mobility of MNs that have already joined Mcast group, those MNs send periodically Mcast join message to their NMNs when they move to the other basic trees, and registers to those basic trees. In this case NMNs that received Mcast join message send it to their upper MN over the same basic tree when they don’t join Mcast group just like wired Mcast. But the MNs on the new basic tree do not send Mcast streams until the moved MN registers to a new basic tree for reducing the amount of traffic.

Multimedia Data Transmission Using Multicast Delivery in Digital Library

This paper presents the method for multimedia data transmission using multicast delivery in digital library. It is not conventional server-based multicast delivery but client-based on-demand one. The Multicast-Agent Scheduler for providing on-demand multimedia service using multicast in digital library generates immediately a multicast group address and port number when clients request an identical multimedia data, then it sends them to media server and clients. And then media server transmits requested multimedia streams to multicast group and the clients join the group automatically. This technique reduces media server load in digital library and maximizes the efficiency of network resources. And this paper implements multimedia transmission system in digital library with WMS (Window Media Services) and its API.

Web-Cached Multicast Technique for on-Demand Video Distribution

In this paper, we propose multicast technique in order to reduce the required network bandwidth by n times, by merging the adjacent multicasts depending on the number of HENs (Head-End-Nodes) n that request the same video. Allowing new clients to immediately join an existing multicast through patching improves the efficiency of the multicast and offers services without any initial latency. A client might have to download data through two channels simultaneously, one for multicast and the other for patching. The more the frequency of requesting the video is, the higher the probability of caching it among HENs increases. Therefore, the requests for the cached video data can be served by HENs. Multicast from server is generated when the playback time exceeds the amount of cached video data. Since the interval of multicast can be dynamically expanded according to the popularity of videos, it can be reduced the server`s workload and the network bandwidth. We perform simulations to compare its performance with that of conventional multicast. From simulation results, we confirm that the Proposed multicast technique offers substantially better performance.

Multicast VOD System for Interactive Services in the Head-End-Network

This paper proposes an interactive VOD system to serve truly interactive VCR services using multicast delivery, client buffer and web-caching technique which implements the distributed proxy in Head-End- Network(HNET). This technique adopts some caches in the HNET that consists of a Switching Agent(SA), some Head-End-Nodes(HEN) and many clients. In this model, HENs distributively store the requested video under the control of SA. Also, client buffer dynamically expands to support various VCR playback rate. Thus, interactive services are offered with transmitting video streams from network, HENs and stored streams on buffer. Therefore this technique makes the load of network occur In the limited area, minimizes the additional channel allocation from server and restricts the transmission of duplicated video contents

Implementation of New MOD System Using On-demand Multicasting Technique

This paper implements MOD system using multicast delivery. Conventional system provide server-based system in multicast delivery but implemented system provides on-demand client-based multicast system. The scheduler aggregates clients` request and it generate multcast group addresses and port numbers according to requested video items and service request time. Then it transmits immediately multicast address to MOD server and client who request service. And then MOD server transmits requested streams with a multicast group address and the client joins the group automatically. The scheduler assigns the same multicast group address when other clients request an identical video within the same scheduling duration. The system can reduce load of server and support many clients at the same time.

New distributive web-caching technique for VOD services

At present, one of the most popular services through internet is on-demand services including VOD, EOD and NOD. But the main problems for on-demand service are excessive load of server and insufficiency of network resources. Therefore the service providers require a powerful expensive server and clients are faced with long end-to-end delay and network congestion problem. This paper presents a new distributive web-caching technique for fluent VOD services using distributed proxies in Head-end-Network (HNET). The HNET consists of a Switching-Agent (SA) as a control node, some Head-end Nodes (HEN) as proxies and clients connected to HEN. And each HEN is composing a LAN. Clients request VOD services to server through a HEN and SA. The SA operates the heart of HNET, all the operations using proposed distributive caching technique perform under the control of SA. This technique stores some parts of a requested video on the corresponding HENs when clients connected to each HEN request an identical video. Thus, clients access those HENs (proxies) alternatively for acquiring video streams. Eventually, this fact leads to equi-loaded proxy (HEN). We adopt the cache replacement strategy using the combination of LRU, LFU, remove streams from other HEN prior to server streams and the method of replacing the first block of video last to reduce end-to end delay.