Kapdong Kim

A Scalable Multicasting with Group Mobility Support in Mobile Ad Hoc Networks

In mobile ad hoc networks, an application scenario requires mostly collaborative mobility behavior. The key problem of those applications is scalability with regard to the number of multicast members as well as the number of the multicast group. To enhance scalability with group mobility, we have proposed a multicast protocol based on a new framework for hierarchical multicasting that is suitable for the group mobility model in MANET. The key design goal of this protocol is to solve the problem of reflecting the node`s mobility in the overlay multicast tree, the efficient data delivery within the sub-group with group mobility support, and the scalability problem for the large multicast group size. The results obtained through simulations show that our approach supports scalability and efficient data transmission utilizing the characteristic of group mobility.

QoS based routing for integrated multimedia services

This paper proposes two routing algorithms, bandwidth-delay-loss based routing (BDLR) algorithms, which support the selection of an efficient routing path by considering the characteristics and quality of service (QoS) requirements of integrated services over the integrated services packet network (ISPN), and also compares their performance with that of other related routing algorithms by the simulation with the various input combinations of real-time and non-real-time traffic over the ISPN. The simulation shows that the BDLR algorithms have great advantages in the transmission delay, in satisfying the QoS requirements, and in the adaptation to the traffic environment over the other routing algorithms proposed previously for the ISPN.

Dynamic Topology Control and Routing in Wireless Ad Hoc Networks

In this letter we consider topology control and routing problem in wireless networks where equipped with point-to-point wireless links such as directional antennas or free space optics. In point-to-point wireless networks, each node has a limited number of transceivers and hence can communicate with only a limited number of nodes within its transmission range. The selection of the limited number of neighbors is very critical for the network performance. In this letter, we propose a topology control algorithms which consider the topology control and routing of each demand is considered simultaneously. For this, we introduce the degree constraint shortest path problem for finding optimal (shortest) paths in wireless point-to-point networks. Also, we propose two topology control algorithms: minimum hop (MHA) and resource availability ratio (RAR) algorithm. The resource availability ratio algorithm considers not only the available link bandwidth but also the available interfaces between neighbors. By simulation experiments, we compare the performance of each algorithm.

EXT3NS: Multimedia File System Supporting Network/Storage Card

The EXT3NS is a file system based on a special HIW device, called NS card for multimedia data. In general, normal computer has high level of CPU utilization for networking operations with gigabit level and several copy operations. Therefore, we have developed the NS card to alleviate this overhead. EXT3NS provides the standard APIs to read and write files in storage unit of NS card. The performance measurements on our system show obvious performance improvements. Especially, the system shows much less servers CPU utilization and less fluctuation of client bitrate, hence more reliable streaming service is possible.

A Study on Logical Cooperative Entity-Based Multicast Architecture Supporting Heterogeneous Group Mobility in Mobile Ad Hoc Networks

In mobile ad hoc networks, an application scenario requires mostly group mobility behavior in the mix of group moving nodes and individually moving nodes. The nodes of those applications tend to belong to the movement group with similar movement behavior. Group mobility is one of the good methods to improve scalability, and reduces the protocol overhead. In this paper, we propose the multicast architecture which regards nodes that have equal group mobility in the heterogeneous group mobility network as the single entity with the multiple interfaces and composes multicast tree, The logical cooperative entity-based multicast architecture accommodates the scalability, the multicast tree simplification, and the protocol overhead reduction which arc obtained from the hierarchical multicast architecture, while it maintains the nat multicast architecture for the data transmission. It also prevents the concentration of the energy consumption dispersing data forwarding load into the several ingress/egress nodes. Results obtained through simulations show that logical cooperative entity based multicast protocol with multiple interfaces offers the protocol scalability and the efficient data transmission.

On Multiple Description Streaming with Cluster-based Server

The cluster system with shared-nothing storage cannot escape from the problem of skewed request toward specific contents. This paper, therefore, suggests streaming method using MDC (multiple description coding) instead of using single original content; this method is able to cope with skewed request in shared-nothing storage server as well as to continue to provide services in case of the system failure. Also, the system can support adaptive streaming service according to user player type, network status, the load of server, and client

A study on bandwidth guarantee method of subscriber based diffserv in access network

In this paper, we describe the structure of the access network and we propose bandwidth guarantee scheme for subscriber and service. The scheme uses two kinds of the classification table, which are called ”service classification table” and ”subscriber classification table.” Using the classification table, we can identify the flow of the subscriber and service. Also, we compute the number of hash table entry to minimize the loss ratio of flows using the M/G/k/k queueing model. Finally, we apply to deficit round robin (DRR) scheduling through virtual queueing per subscriber instead of aggregated class.