Goo Yeon Lee

Numerical analysis of optimum timer value for time-based location registration scheme

In this letter, we analyze a time-based update method in location management and calculate the optimal time-interval. We obtain the probability that a mobile terminal (MT) is j rings away from the center cell. And using these values, an exact analysis is made for the time-based location management cost. From the result, when the time-based method is applied to location update, we can get the optimal time-interval which minimizes the location management cost.

Hybrid Location-Update Scheme for Mobile Networks

In this paper, we propose a hybrid location-update scheme, which combines the time- and movement-based location-update approaches. In the proposed scheme, a mobile user updates its location after the following two events have occurred: First, the mobile crossed <i>n</i> cell boundaries, and then, a time interval <i>T</i> elapsed. We also examine the inverse scheme, where an update is performed after the <i>n</i> boundary crossings occur subsequent to the time interval <i>T</i> . We evaluate our scheme by applying it to various mobility models, such as <i>exponential</i> <i>cell-residence</i> <i>times</i> <i>with</i> <i>a</i> <i>constant</i> <i>mobility</i> <i>pattern</i>, <i>exponential</i> <i>cell-residence</i> <i>times</i> <i>with</i> <i>a</i> <i>gamma-distributed</i> <i>mobility</i> <i>pattern</i> , <i>hyperexponential</i> <i>cell-residence</i> <i>times</i>, and <i>cell-residence</i> <i>times</i> <i>with</i> <i>a</i> <i>small</i> <i>coefficient</i> <i>of</i> <i>variation</i>. From our numerical analysis and simulation results, we learn that the movement-based-only method (i.e., <i>T</i> = 0) performs well when the coefficient of variation of the cell-residence time is relatively small. However, when the coefficient of variation is large, the proposed hybrid scheme (i.e., T> 0,n > 0) outperforms each of the two approaches, namely, the time- and movement-based location-update schemes, when these schemes are individually applied.

Simple, Practical, and Effective Opportunistic Routing for Short-Haul Multi-Hop Wireless Networks

In this paper, we propose a simple and practical opportunistic routing algorithm, and we analyze its performance along a multi-hop wireless network path, while considering link-level interference among the network nodes. Through our analysis, we show that our algorithm results in significant improvement in throughput, especially for short-haul paths. The proposed algorithm can be easily integrated into most routing protocols with only minor modifications. Consequently, the algorithm provides a practical and effective approach for implementation of opportunistic routing in wireless networks.

Wireless Certificate Management Protocol Supporting Mobile Phones

PKI (Public Key Infrastructure) in wired internet is not suitable for the mobile phone because of the limitation of performance such as less memory and less powerful CPU. Therefore, we need to develop a wireless PKI that provides the similar security level as the wired PKI to support a mobile phone. Especially, certificate management is the start point of PKI. In this paper, we propose a lightweight and secure Wireless Certificate Management Protocol(CMP) that is executable to the mobile phone that has a constrained communication environment and limitation of performance, and show the implementation results of the scheme on the mobile phone. We minimize data sizes processed in mobile phone, and optimize protocols for the certificate management. This results in the reduced module sizes to be able to execute in mobile phone and shows as the same level as the wired CMP.

Efficient rekey interval for minimum cost on secure multicast system using group key

In this paper, we investigate a rekey mechanism for secure multicast group communications and relate the mechanism to the amount of disclosed information from group key exposure. We also combine cost for the disclosed information and cost for group key updates and analyze the optimum rekey interval. Using the results of the analysis in this paper, we can manage secure multicast groups efficiently with the minimal cost on the bases of number of group members, each members security level and withdrawal rates.

Mutual authentication protocols for the virtual home environment in 3G mobile network

In the virtual home environment (VHE), which was proposed to offer global roaming and personal service environment portability, users profiles and service logic are conveyed from home network to visited network to provide services at the visited network. Because users profiles and service logics may contain confidential information, some procedures for mutual authentication among entities for offering confidence are needed. For these issues, we propose and analyze two 3-party mutual authentication protocols adaptable to the VHE in 3G; the password based mutual authentication protocol and the mutual authentication protocol with trusted third party.

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.

Optimal time-interval for time-based location update in mobile communications

We analyze a time-based update method in location management and calculate the optimal time-interval. We obtain the probability that an NIT is j rings away from the center cell. And using these values, an exact analysis is made for the time-based location management cost. From the result, when the time-based method is applied to location update, we can get the optimal time-interval which minimizes the location management cost.

Efficient Location Management Scheme using MLR considering Local Usages

In this paper, we propose middle location register (MLR) which is located between VLR and Main. It distributes the location queries of calls beyond VLRs which would be heavy load to HLR, otherwise. We also analyze the overall cost of the MLR system. From the results of the analysis, we insist that MLR reduces the overall cost compared to the normal HLR system

Prevention of Black-Hole Attack using One-Way Hash Chain Scheme in Ad-Hoc Networks

In this paper, we consider the specific case of a black-hole attack in ad-hoc networks caused by an incorrect route reply from an intermediate node. As a solution to this problem, we propose a scheme based on a one-way hash chain mechanism and Further-Request/Further-Reply exchange. We prove the effectiveness of the scheme in terms of security and its efficiency in terms of network performance.