Iksoo Kim

A Seamless Multimedia Service in Wireless Network

This paper presents a seamless multimedia service in WLAN. In this paper, the environment of WLAN for seamless video service consists of a switching agent (SA), some access points (AP) and mobile nodes (MNs). The SA supports handover mechanism for MNs when they move one AP to another, and retransmits video streams from video server to the requesting AP. The proposed handover mechanism needs additional 2-byte as IP header which is used for an identification number (ID#) of AP that the MNs are joined. The SA changes the path of successive video streams using the ID# generated when the MN moves to a specific AP. The proposed system can support seamless video service without cutoff and reconnection to video server according to the handover.

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.

Overlay multicast routing architecture in mobile wireless network

In this paper we propose overlay multicast (Mcast) routing architecture that uses basic trees and their neighboring mobile nodes (NMN) in mobile wireless network. The basic trees are generated according to hop-counts from mobile nodes (MN) toward base node. NMNs are 1-hop away from a MN and exist in other basic trees. NMNs identify only whether they have Mcast group MNs in mapping table, and never broadcast MNs’ Mcast request. But MNs on an identical basic tree must broadcast Mcast request to parent or child MNs when they don’t have Mcast group in mapping table. MNs don’t have Mcast routing table but have only mapping table to convert logical address into physical IP address. The proposed Mcast routing architecture has effectiveness to solve shortcomings in mobile wireless network and sensor networks since it can decrease effectively flooding traffic restricted to MNs on a basic tree.

Web-Cached Multicast 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. Each video stream is divided into blocks which are the same size of multicast grouping interval I m . Blocks then are evenly distributed into different HENs according to their popularity and the order of requests. Only when the playback time exceeds the amount of cached video data, server generates new multicast channel. Since the interval of multicast can be dynamically expanded according to the popularity of videos, it can be reduced the servers workload and the network bandwidth. We adopt the cache replacement strategy as LFU (Least-Frequently-Used) for popular videos, LRU (Least-Recently-Used) for unpopular videos, and the method for replacing the first block of video last to reduce end-to-end latency. 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.

A Seamless Multimedia Service Technique for Mobile Digital Library

This paper deals with a technique to support seamless multimedia service in mobile digital library. Multimedia services in mobile digital library are to be cutoff frequently while mobile node(MN) moves among access points(AP). The MN in order to get continuous service has to acquire a new IP address and reconnect whenever it accesses to a new AP. In this case, it cannot avoid cutoff service and reconnect to the multimedia server on digital library. To provide seamless multimedia service on digital library in WLAN, this paper adopts smooth handover mechanism using AP numbers as IP header that is composed of only 10-bits and technique that IP address acquired from AP accessed for the first time when MN enter the WLAN does not change. This proposed mechanism can provide a seamless service without cutoff and reconnect in mobile digital library.

Path-Connectivity for Mobile Digital Library Service in Hybrid Ad-Hoc Network

This paper deals with path-connectivity for digital library system in ad-hoc network. One of the critical problems for service in (hybrid) ad-hoc network is service shutting down frequently due to multi-hop connectivity drawback according to mobile node(MN)s’ movement. To solve this problem we adopt a technique that a few MNs having 1-less hop manage a number of MNs having 1-more hop, and access points that has cache to reduce delay in hybrid ad-hoc network. Therefore this proposed technique has a robustness for connection break up because it has multiple paths to infra-network(AP).

Video Service Algorithm Using Web-Cached Technique in WLAN

This paper presents the strategy for video service using caching technique in WLAN. The environment of WLAN includes mobile nodes(MN) and an access point(AP) that have memory for store video clips transmitted from AP and video server, respectively. The operation for the proposed system has two modes, the 1 st mode is AP mode that all MNs are serviced through AP, and the 2 nd mode is an ad-hoc mode that is serviced only through other MNs without AP connecting. The operation of ad-hoc mode is that the requesting MN is serviced directly from the video clip cached on other MN without the connection to AP or multimedia server(MS). Otherwise the proposed system uses AP mode that requesting MN is serviced under the control of AP, thus MN connects to AP’s cache or MS.

Content delivery with spatial caching scheme in mobile wireless networks

Future wireless/mobile system will be served streaming service to support various applications. In this environment, users can access all the required information whenever and wherever they may be. In this paper, we proposed a new scheme that minimizes the network bandwidth consumption and the service blocking rate in mobile network. Our proposed scheme consists of location estimation and caching strategy. To estimate nodes current location, we use hexagonal cellular based plane and cascading dynamic address scheme which make mobile equipments, mobile router (MR) and mobile node (MN), calculate the distance from sender and estimate the existence possibility of the alternative route toward sender. The service blocking can be minimized by using caching strategy. In evaluation, we examined our proposed scheme in the view of the total network bandwidth consumption and the connecting probability as well as the impact of each cache capacity. From simulation results, we confirm that the proposed scheme offers substantially better performance.

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.