• Journal of Internet Computing and Services
• /
• 제7권1호
• /
• pp.173-178
• /
• 2006

In this paper, a channel estimation based on the time-domain windowing and its imperfectness in OFDM-based multiple-antenna transmission systems are analyzed with an emphasis on a preamble design for multi-channel separation, From the computer simulation results, the OFDM-CDMA system applying a space-time-frequency diversity with a full-rate full diversity code can give the diversity of D = 4 and D = 8 for both multi-user cases of maximum user and half user capacities, respectively

• Proceedings of the IEEK Conference
• /
• 대한전자공학회 2004년도 ICEIC The International Conference on Electronics Informations and Communications
• /
• pp.176-180
• /
• 2004

In this paper we introduce a bandwidth allocation algorithm and admission control policy for IEEE 802.16 broadband wireless access standard. The proposed mechanism is practical and compatible to the IEEE 802.16. Our scheme provides QoS support to high priority traffic and high throughput in low priority traffic. The simulation show that the proposed scheme includes QoS support for real-time traffic and we presented that BS determine a efficient contention mini-slot size. We have shown the relationship between traffic size and its QoS requirements and the network performance.

• Electronics and Telecommunications Trends
• /
• 제35권5호
• /
• pp.83-91
• /
• 2020

In this paper, the contemporary deployment of broadband and Internet-of-Things (IoT) services based on the Low Earth Orbit (LEO) satellite communication network is presented. First, the global service and key technologies of small and nanosatellites are briefly addressed, and then, the progress of relevant standard technologies is explained. Finally, the overall potential for the future development of the LEO satellite communication network is highlighted.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• 제12권10호
• /
• pp.1801-1807
• /
• 2008

A home network is a collection and connection of many electronic and electrical devices in home in order to make daily life comfortable, entertaining and safe. The convergence of Ethernet and wireless technology to a single shared broadband connection in residential gateway is the key feature of the home network. This kind of heterogeneous network has realized the need to implement different QoS mechanisms. Basically, in this paper we propose to integrate IP QoS and Wireless QoS mechanisms for QoS assurance in home network. This paper compares the combination of PCF with two queuing algorithms Low Latency Queuing (LLQ) and Custom Queuing (CQ) and concludes that the combination of CQ and PCF performs best for home network.

• Proceedings of the KIEE Conference
• /
• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
• /
• pp.397-399
• /
• 2005

Handover is one of the most important factors that may degrade the performance of TCP connections and real-time applications in wireless data networks. We proposed a seamless handover with Motion Prediction in IEEE 802.16e-based broadband wireless access networks. By intergrating MAC and network layer handovers efficiently, this scheme minimizes the handover delay and eliminates packet losses during handover Simulations show that this scheme achieves loss-free packet delivery without packet duplication and increases TCP throughput significantly.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 한국해양정보통신학회 2008년도 춘계종합학술대회 A
• /
• pp.233-236
• /
• 2008

Wire wireless integrated service of BcN(Broadband convergence Network) is expanding. Information Security issue is highlighted for opposing attack of getting information illegally on wire wireless network. The user of PKI(Public Key Infrastructure) cipher system among Information security technology receives various security services about authentication, confidentiality, integrity, non-repudiation and access control etc. A mobile client and server are loaded certificate and wireless internet cryptography module for trusted data send receive. And data sends receives to each other after certification process through validity check of certificate. Certificate and data security system is researched through PKI on wireless network environment and data security system in this paper.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• 제12권9호
• /
• pp.1638-1645
• /
• 2008

WiBro(Wireless Broadband Internet) is the standard of high-speed portable internet based on OFDMA/TDD techniques, and the subset of consolidated version of IEEE802.16e Wireless MAN standard. In this paper, we propose the design method of WiBro system using the SOFM Blind Equalization. Proposed design method used SOFM neural network blind equalization with Bussgang algorithms in the Broadband 16 QAM WiBro system receiver. To verificate the proposed design method usability, the MSE and the BER are simulated. The simulation results shown that is improved the equalization performances of the proposed WiBro system using the SOFM Blind equalization than the existing WiBro system.

• The KIPS Transactions:PartA
• /
• 제11A권3호
• /
• pp.109-114
• /
• 2004

Increasing popularity of WLAN and advancement of WPAN allow user to connect to the Internet easily today. The increasing of number of networking mobile device such as laptop and PDA requires computing devices to share high speed Internet line or work on networks in most cases. This has stimulated the demand of access point that supports multiple network interfaces. This paper describes the process of design, implementation and test of the wired/wireless integrated access point that supports multiple network interfaces such as wired LAN, wireless LAN, Bluetooth, and Broadband network. We designed and developed the hardware system and protocol software to integrate heterogeneous network. The system has shown compatibility with standard specification and good performance through testing with various network devices.

• Journal of Communications and Networks
• /
• 제2권1호
• /
• pp.35-45
• /
• 2000

this paper presents the concept of "mobile ATM', a proposal for third-generation (3G) mobile communication network infrastructure capable of supporting flexible evolution of radio technologies from today's cellular and data services towards future wireless multimedia services. Mobile ATM provides generic mobility management and QoS-based transport capabilities suitable for integration of multiple radio access technologies including cellular voice. wireless data, and future broadband wireless services. The architecture of a mobile ATM network is outlined in terms of the newly-defined "W-UNI" interface at the radio link and "M-UNI"and "M-UNI" interface which supports unified access for WATM and non-ATM mobile terminals through corresponding interworking functions (IWF) is explained. leading to an understanding of how different radio access technologies are supported by the same ATM-based core network infrastructure. Generic mechanisms for handoff and location management within the core mobile network are discussed. and related protocol extensions over the "W-UNI" and "M-UNI/NNI"interfaces are proposed. the issue of "crossover switch (COS)" selection in mobile ATM is considered, and a unified handoff signaling syntax which supports flexibility in COS selection is described. Typical signaling sequences for call connection and handoff using the proposed protocols are outlined. Experimental results form a proof-of-concept mobile ATM network prototype are presented in conclusion.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제10권5호
• /
• pp.2394-2406
• /
• 2016

ABE has become an effective tool for data protection in cloud computing. However, since users possessing the same attributes share the same private keys, there exist some malicious users exposing their private keys deliberately for illegal data sharing without being detected, which will threaten the security of the cloud system. Such issues remain in many current ABE schemes since the private keys are rarely associated with any user specific identifiers. In order to achieve user accountability as well as provide key exposure protection, in this paper, we propose a key-insulated ciphertext policy attribute based encryption with key exposure accountability (KI-CPABE-KEA). In our scheme, data receiver can decrypt the ciphertext if the attributes he owns match with the self-centric policy which is set by the data owner. Besides, a unique identifier is embedded into each user's private key. If a malicious user exposes his private key for illegal data sharing, his identity can be exactly pinpointed by system manager. The key-insulation mechanism guarantees forward and backward security when key exposure happens as well as provides efficient key updating for users in the cloud system. The higher efficiency with proved security make our KI-CPABE-KEA more appropriate for secure data sharing in cloud computing.