Hwa Jong Kim

Performance analysis of authentication and key distribution scheme for mobile multi-hop relay in IEEE 802.16j

Mobile multi-hop relay (MMR) network is known to be easy to install and convenient to manage because of its self-organizing and self-healing characteristics. However, MMR is vulnerable to security problems because of the same reason. In this paper, we propose a new hybrid authentication and key distribution algorithm for IEEE 802.16j MMR service. The proposed scheme uses centralized authentication when a mobile station or a relay station initially joins the MMR network and uses distributed authentication for hop-by-hop authentication between mobile nodes. We examine the procedure of the proposed scheme and its usefulness when applied to MMR networks. We also analyze the performance of the hybrid scheme. The proposed scheme can be used in any mobile multi-hop network as well as IEEE 802.16j MMR network.

A Contents Service Profit Model Based on the Quality of Experience and User Group Characteristics

Generally, it is known that only quality-assuring services can provide a reasonable profit model. However until now a practical profit model considering the service cost and quality simultaneously has not been introduced yet. Recently, the Quality of Experience (QoE) was suggested to measure user’s real satisfaction level. The QoE is expected to be used for efficient service provisioning and criteria for accurate satisfaction measuring. This paper introduces a profit model for the contents providers considering the costs for quality services and the QoE together. Especially, we assume that the QoE with user’s feedback can be interpreted as the intention to pay for the services. We take into account that QoE is dependent on service area, demographic information and user group characteristics. The proposed profit model can be used for contents providers to find an optimum investment which maximizes the profit.

A Scalable and Practical Authentication Protocol in Mobile IP

Due to the proliferation of mobile devices connected to the Internet, implementing a secure and practical Mobile IP has become an important goal. A mobile IP can not work properly without authentication between the mobile node (MN), the home agent (HA) and the foreign agent (FA). In this paper, we propose a practical Mobile IP authentication protocol that uses public key cryptography only during the initial authentication. The proposed scheme is compatible with the conventional Mobile IP protocol and provides scalability against the number of MNs. We also show that the proposed protocol offers secure operation.

Design and Performance Evaluation of a Scalable Authentication Protocol in Mobile IP

Recently, along with the proliferatin of mobile devices connected through Internet, a secure and practical mobile IP implementation became an important issue. A mobile IP can not work properly without authentication between the mobile node (MN), the home agent (HA) and the foreign agent (FA). In this paper, we propose a practical mobile IP authentication protocol with public key cryptography only during the initial authentication. The proposed scheme is compatible with the conventional mobile IP protocol and provides scalability for the number of MNs. We also showed the secure operation of the proposed protocol and performance evaluation of the proposed protocol was made.

Signal Interference of Ubiquitous Wireless Networks on Data Throughput

Ubiquitous wireless networks consist of many wireless access points and devices, which share and contend for wireless medium. Generally, wireless devices are trying to generate high throughput and have longer signal coverage which also bring unnecessary signal interference to neighboring wireless networks, and result in decreased network throughput. Signal interference is an inevitable problem because of the broadcast nature of wireless transmission. However it could be minimized by reducing signal coverage of wireless devices. On the other hand, small signal coverage means low transmission power and low data throughput. In the paper, we analyze the relationship among signal strength, coverage, interference and network throughput in ubiquitous wireless networks by simulation on various network topologies.

Packet diversity in wireless uplink channels

A packet diversity scheme is introduced to increase uplink channel efficiency in a wireless network where forward error correction is used. The packet diversity allows neighbor base stations to receive uplink packets from a mobile terminal in order to increase the efficiency of the uplink channel. By allowing multiple base stations to receive the same packets, we can improve the error correction capability in an uplink channel. By incorporating the packet diversity we can reduce the parity overhead of each packet for a given tolerable loss probability, which improves the link efficiency.