Byungsik Yoon

Seamless Lawful Interception Handover for 3G IP Multimedia Subsystem (IMS)

After the 9.11 terror attack, lawful Interception (LI) has emerged as an important tool for anti-terrorist activity. Law enforcement agents and administrative government bodies effectively monitor suspicious target users of permanent IP-based network devices by LI in Packet Data Networks (PDNs). However, it is difficult to perform LI in monitoring migrating users from a location to another, who change their IPs due to the proliferation of portable Internet devices enabling 3G IP Multimedia Subsystems (IMS). The existing, manual handover technique in 3G IMS makes it even more difficult to continue the LI activities due to time-lag reissuance of LI authority warrants when the target users move to a new LI jurisdiction via a roaming service. Our proposed model is a seamless LI handover mechanism in 3G IMS to support mobility detection of the target users. The LI warrants are transferred to the new LI agent automatically with the target users when they move to a new LI jurisdiction. Thus, time-lag human intervention of reissuance of the LI warrants is removed and enables the LI authorities to continue monitoring. In the simulation of our proposed mechanism, the quality of lawful interception achieves a mean score of over 97.5% out of the possible 100% maximum score, whereas the quality of the existing mechanism has a mean score of 22.725%.

A seamless lawful interception architecture for mobile users in IEEE 802.16e networks

Lawful interception (LI) involves legally accessing private communication such as telephone calls or email messages. Numerous countries have been drafting and enacting laws concerning the LI procedures. With the proliferation of portable Internet services such as the IEEE 802.16e wireless mobile networks, surveillance over illegal users is an emerging technical issue in LI. The ever-migrating users and their changing IPs make it harder to provide support for seamless LI procedures on 802.16e networks. Few studies, however, on seamless LI support have been conducted on the 802.16e mobile networks environments. Proposed in this paper are a seamless LI architecture and algorithms for the 802.16e networks. The simulation results demonstrate that the proposed architecture improves recall rates in intercepting mobile user, when compared to the existing LI architectures.

The real-time implementation of 3D sound system using DSP

This paper describes a real-time 3D sound system implemented with the use of an embedded DSP. We develop a new headphone-based 3D sound algorithm by applying a source localization method using the head-related transfer function (HRTF). Localizing 5.1-channel data to the appropriate location using our algorithm generates the virtual 3D sound. The real-time implementation is achieved using a TMS320C6713 DSP chip. We describe the hardware design. As a result of a DSP implementation and a subjective listening test, this 3D sound system can be applied to mobile applications.

IP Traceback Methodology Using Markov Chain and Bloom Filter in 802.16e

Recently, network resource is extremely vulnerable to DDoS attacks which has become a pressing problem due to scarce an efficient method to locate the real attacker. Especially, the more network topology advanced and complex such as 802.16e (WiBro), IP traceback is difficult. According to, in this paper, the IP Traceback methodology using Markov chain based on XOR operation is proposed in 802.16e. Also the paper provides a traceback method including: receiving data including access control router information according to a path of an attacker; filtering the data to hash the data, and storing the resultant hashed information; determining whether the data is normally received on the basis of the hashed information; and predicting a path loss on the basis of the determination result. Therefore, it is possible to perform an accurate IP traceback using a probabilistic packing marking method and a hash-based traceback method.

The real-time implementations of AMR codec for IMT-2000 system

We present the software and hardware implementations of AMR codec for IMT-2000 system. The real-time implementations of AMR codec algorithm are achieved using TMS320C62xx DSP chip and Teak-Lite DSP core. We describe respectively efficient software schemes for coding AMR codec algorithm and hardware designs. The AMR codec is evaluated and confirmed in 3GPP test sequences, stand-alone test system and ETRI IMT-2000 prototype system

3G IP Multimedia Subsystem based framework for lawful interception

Issues related to lawful interception, such as invasion of privacy and efficient investigation, are presently at the forefront of social consciousness. Interception technology has to consistently evolve in order to keep pace with new and varied network structures. Thus, standard lawful interception documents that are appropriate for the existing PSTN, 2G and 3G, and packet-based communication are being proposed. In particular, newly arising services based on IP Multimedia Subsystems (IMSs) that support multimedia streaming, data transmission, and voice over IP, make lawful interception even more imperative. In this paper, we propose an architecture for IMS/Session Initiation Protocol based Lawful Interception (LI) in wireless 3G networks. We also propose LI techniques that are differentiated according to the IMS characteristics where content service providers are separated from network providers. Using the standards of dynamic triggering technologies for commissioning the authority to intercept among multiple network providers as a basis, we analyze IMS architecture and service operation methods. We then propose an LI architecture that is appropriate for IMS services. In addition, we present the results of a quality of service performance analysis conducted on our proposed interception architecture for various numbers of IMS users.