Young-Tae Han

Centralized Scheduling Mechanism for Enhanced End-to-End Delay and QoS Support in Integrated Architecture of EPON and WiMAX

The integration of Ethernet Passive Optical Network (EPON) with IEEE 802.16 (WiMAX) is regarded as a promising access solution in realizing fixed mobile convergence (FMC) networks. The complementary features of EPON and WiMAX can bring not only wide bandwidth and mobility to subscriber stations (SS) but also economic efficiency to network providers. For successful convergence of EPON and WiMAX, there are some technical issues to resolve bandwidth allocation and QoS support in the MAC layer. Specifically, the independent scheduling (IS) mechanism to transmit data between EPON and WiMAX can cause performance degradation. For realizing EPON and WiMAX integration, this paper investigates three possible integrated architecture: independent ONU-BS (IOB), combined ONU-BS (COB), and hybrid ONU-BS (HOB). The emphasis on this paper is how to reduce the End-to-End (ETE) delay between EPON and WiMAX. For doing this, we propose a centralized scheduling (CS) mechanism that shortens the packet delay and the time of transmitting data upon requesting bandwidth for the SS. Simulation results witness that the proposed CS mechanism improves ETE delay, throughput, and QoS support compared to the IS when the cycle time of EPON and the frame size of WiMAX are 1 ms and 5 to 10 ms, as well as 2 ms and 5 ms, respectively.

Energy-Aware Hybrid Data Aggregation Mechanism Considering the Energy Hole Problem in Asynchronous MAC-Based WSNs

The energy hole problem is caused by earlier turning off of sensor nodes nearer the sink due to more frequent data transmission, particularly in asynchronous MAC-based Wireless Sensor Networks (WSNs). To resolve this issue, this letter proposes an Energy-aware Hybrid Data Aggregation Mechanism (EHDAM) that is designed to adaptively control the number of data transmission with burst length based and time-out based transmissions. Especially, EHDAM adjusts the burst length threshold value in reciprocal proportion to the remaining energy state of the node so that reducing the number of data transmission; hence, EHDAM extends lifetimes of the nodes affected by the energy hole problem.

A novel server selection method to achieve delay-based fairness in the server palm

It is pivotal to achieve delay-based fairness when users access the same content, especially in real-time services, from content-replicated servers based upon the client-server communication model. To resolve this issue, this letter proposes a novel server selection method of providing users with delay-based fairness from all the corresponding servers by applying the delay-based dynamic deficit round robin (D3RR) scheme. The deficit counter of the D3RR is adjusted based upon round trip times (RTTs) of data traffic measured by passive-based probing which ensures low resource waste. Performance evaluation results highlight that the delay variance among all the corresponding servers can be maintained as low as possible and delay-based fairness is guaranteed without unnecessary waste of resources.

Distinctive Traffic Characteristics of Pure and Game P2P Applications

Many literatures related to game and Peer-to-Peer (P2P) applications are focused on the performance enhancement. Few years ago, game applications just use the client and server model. However, today many game applications use the P2P model. Thus, there are many similarities between P2P and game applications over the P2P model. Though, many network providers desire to know the distribution of applications on their networks. These similarities between game and P2P applications make hard to identify each other. Thus, we characterize the differences between game and P2P applications.

A Novel Bandwidth Estimation Model for e-Government Communication Network

To provide QoS, the bandwidth estimation technology is necessary. However, the existing bandwidth estimation only uses the peak rate; hence it leads to the waste of network resources. In this paper, we propose the suitable bandwidth estimation model (SBEM) for e-government communication network to assign the proper bandwidth. First, we analyze the real traffic and develop the traffic model. The traffic model is validated by the traced packets collected at NCIA center. Then we propose the suitable bandwidth estimation model and explain the procedure of the proposed model.

A New Attainable TCP Throughput Measurement Tool for Long Distance High Speed Networks

TCP has a long slow start duration and low utilization in that duration, especially in long distance high speed networks. In this letter, we propose a new attainable TCP throughput measurement tool to minimize the effect of a transient state by detecting TCP states and excluding the transient state. The evaluations are conducted on both the testbed and the Internet, and the results verify that the estimated throughput by the proposed method is closer to the actual bandwidth than that of Iperf, while maintaining the same measurement time in long distance high speed networks.

Traffic analysis of the live P2P personal broadcasting service in the campus network

Recently, the Peer-to-Peer (P2P) technology has been emerging as a promising technology for QoS issued services especially in delivering video contents (e.g., video on demand (VoD), live streaming services, etc). Although traffic of P2P streaming services has been much increased, little information on their traffic behaviors or workload is available on research community. In this paper, for the best of our knowledge, we first present traffic characteristics of one of popular live personal broadcasting services based upon P2P, namely Afreeca, in Korea, which supports various types of video qualities. Based upon the deep packet inspection and comprehensive analysis at packet and flow levels, we illustrate traffic characteristics in regard to streaming rates, distributions pertaining to packet sizes and inter-arrival times, session duration, and popularity of the broadcasting jockeys (BJs), etc with several numerical models exploiting goodness of fitting test.

Experimental evaluation of end-to-end available bandwidth measurement tools

Accurate bandwidth measurement is essential for network management, monitoring, and planning. Various active probing-based strategies and tools are have been developed for estimating available bandwidth. However, the test result of each tool could be different according to the strategies and tools even in the same network environment. The purpose of this paper is to give comprehensive information to users with interpretive comparison and performance test. The comparison and test with regard to measurement effciency, and traffc load of probing packets. including IGI/PTR, pathload, pathChirp, spruce, and Iperf, are performed in dynamic network environments.

Identification of P2P Traffic SET-based in Broadband Convergence Network

We propose a SET-based identification method of P2P traffic in BcN by considering the P2P network architecture and created number of SETs.

A new application identification method using the hybrid mapping for Broadband Convergence Network (BcN)

We identify applications using hybrid mapping with signature mapping and protocol mapping. Basically, mapping needs much time. Thus, we make a set and check the limited number of packets to reduce the mapping time.