Yongsuk Park

A Survey of Security Threats on 4G Networks

Many communication societies such as ITU and IEEE are working on 4th generation (4G) communication. This paper provides an overview of standardization activities focusing on the network security architectures and a survey of security threats on 4G networks. Our survey shows that a number of new security threats to cause unexpected service interruption and disclosure of information will be possible in 4G due mainly to the fact that 4G is an IP-based, heterogeneous network. We also found there still remain several open issues although many are working on fixing and/or designing new security architectures for 4G.

Computation-and-storage-efficient key tree management protocol for secure multicast communications

In secure multicast communication, group key management plays an essential role for the guarantee of data confidentiality and integrity. Because communication bandwidth is a limited resource, most group key management schemes for scalable secure multicast communications have focused on reducing the number of update messages, i.e., communication cost. To alleviate the scalability problem, a key tree structure was proposed and many group key management schemes have since adopted this approach. Though a key tree structure reduces communication cost, it often requires, as a tradeoff, a more powerful computing capability for executing several cryptography algorithms and having enough storage for various kinds of keys, i.e., computation cost and storage cost, respectively. However, in mobile devices with limited computation power and storage space, it is crucial to minimize simultaneously the overheads of computation and storage as well as that of communication. In this paper, we propose a computation-and-storage-efficient key tree structure, and a key tree management protocol for secure multicast communication. By considering the resource information of each group members device, the proposed protocol manages the key tree structure to maximize the efficiency of the computation and storage costs, and to minimize the increment of the communication cost. Through analysis and simulations using three kinds of cost metrics, it demonstrated that the proposed protocol saves computation and storage costs at the expense of a very small increase in communication cost as a tradeoff when the number of total members and the ratio of members leaving in a batch update interval are moderately large.

An energy-efficient transmission strategy for wireless sensor networks

In this work we propose an energy-efficient transmission strategy for wireless sensor networks that operate in a strict energy-constrained environment. Our transmission algorithm consists of two components: a binary-decision based transmission and a channel-aware backoff adjustment. In the binary-decision based transmission, decision on whether to transmit or not is absolutely dependent on the current channel conditions. Specifically, transmission is initiated only when the channel quality exceeds a specified threshold, so that unsuccessful transmissions causing a waste of energy are avoided whenever possible. Using the Markov decision process (MDP) formulation we obtain the optimum threshold for successful transmission. A channel-aware backoff adjustment, the second component of our proposal, is introduced to favor nodes with better channel conditions. By intelligently combining these two ingredients our transmission algorithm attempts to maximize energy efficiency. Extensive simulations are performed to verify the performance of our proposal over fading wireless channels. Numerical results show that our transmission algorithm outperforms the existing approaches in terms of energy efficiency, thereby further prolonging the network lifetime.

A Hybrid Adaptive Security Framework for IEEE 802.15.4-based Wireless Sensor Networks

With the advent of ubiquitous computing society, many advanced technologies have enabled wireless sensor networks which consist of small sensor nodes. However, the sensor nodes have limited computing resources such as small size memory, low battery life, short transmission range, and low computational capabilities. Thus, decreasing energy consumption is one of the most significant issues in wireless sensor networks. In addition, numerous applications for wireless sensor networks are recently spreading to various fields (health-care, surveillance, location tracking, unmanned monitoring, nuclear reactor control, crop harvesting control, u-city, building automation etc.). For many of them, supporting security functionalities is an indispensable feature. Especially in case wireless sensor networks should provide a sufficient variety of security functions, sensor nodes are required to have more powerful performance and more energy demanding features. In other words, simultaneously providing security features and saving energy faces a trade-off problem. This paper presents a novel energy-efficient security architecture in an IEEE 802.15.4-based wireless sensor network called the Hybrid Adaptive Security (HAS) framework in order to resolve the trade off issue between security and energy. Moreover, we present a performance analysis based on the experimental results and a real implementation model in order to verify the proposed approach.

Security Architecture for IEEE 802.15.4-based Wireless Sensor Network

A wireless sensor network consists of low power devices which have limited computing resources. Thus, energy consumption is one of the most significant issues in wireless sensor network environment. For various sensor network applications, security features are also to be a rising big issue more and more. If wireless sensor network supports a variety of security functions, more powerful devices and more energy are required. On the other hand, providing security feature and energy consumption together face a trade-off. Therefore, in this paper we propose a novel efficient security architecture in IEEE 802.15.4-based wireless sensor network called Hybrid Adaptive Security Framework. The goal of the proposed security framework is to provide hybrid adaptive security suites to each packet according to various WSN considerations.

Development of Portable T-DMB Receiver for Data Services

In December 2005, Korea launched terrestrial DMB (T-DMB) services for the first time in the world, making multimedia broadcasting services available in the mobile environment. In addition to high-quality digital radio (audio) and television (video), diverse data services, such as traffic and travel information, BIFS, and visual radio, are currently being serviced. At the moment, there are no mobile/portable T-DMB terminals in the market that can support all the data services available. In this paper, we present a low-power portable T-DMB receiver, which can decode not only T-DMB video services but also various data services. In particular, it can simultaneously decode DMB video and data services within the same ensemble.

Maximizing responsiveness of touch sensing via charge multiplexing in touchscreen devices

This paper presents a novel touch sensing scheme for capacitive touchscreen devices that is capable of maximizing the responsiveness of touch sensing, thereby enabling the realization of high-speed/resolution touchscreens. The heart of our proposed scheme is to measure various combinations of channels of the touchscreen in a way to preserve orthogonality among channels, and to detect the presence of touch by decomposing the measurements into orthogonal components. After designing the measurement and detection algorithms in detail, we demonstrate via simulation that our proposed scheme indeed works.

Plus-tree: a routing protocol for wireless sensor networks

We study tree-based routing protocols for wireless sensor networks. The existing tree-based algorithm has a few shortcomings; (1) it may take a long path since sensor node must transmit packets via either its parent or its children nodes and (2) it is vulnerable to a link failure since the tree has to be reconstructed in case of a single link failure. We propose Plus-Tree, a routing protocol, which overcomes the shortcomings and improves the performance of the existing protocol. A node in Plus-Tree may have neighbor links other than tree links that can be used for alternative path. Simulation results show that Plus-Tree performs better than the existing tree-based protocol with respect to hop counts.

Implementation of RF4CE-Based Wireless Auto Configuration Architecture for Ubiquitous Smart Home

This paper is to present a new novel architecture to provide smart and easy control and sharing between various CE and IT devices. The proposed architecture is based on RF4CE which has a reliable standard enhances the IEEE 802.15.4 standard by providing a simple networking layer and standard application profiles that can be used to create a multi-vendor interoperable solution for use within the home. We develop H/W prototype and demonstrate verification scenarios using RF4CE-based Wireless Auto Configuration (REWACON) architecture.

Resource-Aware Routing Algorithms for Multi-hop Cellular Networks

The cellular network systems are expected to evolve into Multi-hop Cellular Network (MCN). While a mobile terminal and the base station have a direct connection in a conventional cellular network, in MCN a mobile terminal may reach the base station via relays by using multi-hopping. The relay can be either mobile terminal referred to client relay or dedicated relay referred to infra relay that has capabilities like those of the base station. In this paper, we focus on routing mechanism in multi-hop cellular networks. In particular, we study routing performance metrics for multi-hop cellular networks which consider energy efficiency and the relay capabilities.