• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.6
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• pp.719-726
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• 2014

This paper addresses quality of experience(QoE) and how to measure and evaluate QoE including its subjective aspects. Adopting the real measurements on the field, a various quality metric have been measured for VoIP(voice over IP) service provided through a wireless interface of WiBro(Wireless Broadband). By analyzing the measured values and correlation between the metrics, we attempt to find a method to evaluate QoE of the VoIP service in a objective way. As a result, it has been shown that QoE of the VoIP service through WiBro network has close relation to the packet-level end-to-end delay, and the delay has close relation to received signal strength indicator(RSSI).

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.5 s.347
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• pp.104-112
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• 2006

In this thesis, we analyze performance related to reduction scheme of intercell interference causing serious problems in wiBro system. Frequency reusing factor(FUF) is 1 in WiBro system, and it means that a adjacent cell uses same frequency band. This channel environment raises intercell interference problem, which provokes serious problems related to system performance and channel capacity. Consequently, it affects deterioration in system performance as a whole. We analyze intercell interference when appling a various schemes such as (DCA)Dynamic Channel Allocation, CS(Channel Segregation), IMUFR(Interference Mitigation Using Frequency Reuse), IDMA(Interleave Division Multiple Access), IDMA(Interleave Division Multiple Access), FH-OFDM, CRSA(Conceptual Random Subcarrier Allocation), and HDD

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.10
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• pp.7-12
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• 2011

The effect of frequency interference situation between WiBro and WLAN in TV White Space band was taken into account in this paper. We assumed the using frequency in each system is applied in co-channel. When it comes to co-channel interference case, the minimum distance between WiBro ME and WLAN UE should be at least 210m if the maximum transmitter power of WiBro UE of 25dBm is limited. Analysis results of this paper can provide efficient reference and guideline to make spectrum plan for deploying WiBro and WLAN in TVWS.

• The KIPS Transactions:PartD
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• v.15D no.2
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• pp.257-262
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• 2008

This paper describes the implementations of the application service based on embedded Linux; Personal Audio Recorder (PAR) which uses WiBro network for data communications and CDMA network for voice communications. At PAR, when PAR client starts voice recording on a dual-mode terminal, the CDMA voice data of caller and callee is transmitted to storage server located in the Internet through WiBro network. Then, PAR server stores voice data on storage server according to the call number and call time. In case of shortage of storage space on terminal, PAR makes user to store voice data. And, PAR can search a catalog of stored data on server and play the specific content.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.2
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• pp.23-32
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• 2010

WiBro(Wireless Broadband), the service based on IEEE 802.16e(mobile WiMAX) standard, is a wireless broadband Internet technology being developed by the domestic telecommunication industry. In this paper, we analyze security vulnerabilities of WiBro focusing on initial authentication phase and propose a specification-based intrusion detection system that can detect those vulnerabilities. We first derive a specification from the normally operational process of the initial authentication based on PKMv2 EAP-AKA and formalize the derived specification as a state transition diagram. Proposed system executes the intrusion detection based on those specification and state transition diagram. In this paper, to verify the detection capability of proposed system, we construct a test bed network and execute scenario-based test.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.10
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• pp.17-26
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• 2010

This is concerned with the technology to monitor the vehicle operation, failure and disorder by using WiBro portable device. More precisely, the technology makes it possible that the information collection device is connected to both ECU(Electronic Control Unit) which is the device for controlling engine, transmission, brake, air-bag, etc that are connected to in-vehicle network and OBD-II connector that is for data collection from various sensors. In addition, with a WiBro portable device (cell phone, PDA, PMP, UMPC, etc). equipped with a vehicle diagnostic programs, information for operation, failure and malfunction can be obtained and analyzed in real-time, and alarm is alerted when the vehicle is in abnormal status, which makes the early reactions to the status. Furthermore, the collected data can be sent through WiBro network to the server managed by the company specialized in managing the vehicles, thus the technology could help the drivers who have less knowledge about their auto-vehicles have safe and economic driving. There is always a possibility of malfunction due to various types of noise that are caused by wring-harness when the device is wired-connected. In this research, in order to overcome this problem, we propose a system configuration that can do monitoring and diagnosis with a device for collecting data from vehicle and a personal WiBro device. Also, we performed research on data acquisition and interlock for the system defined by the definition for information and data sharing platform.

• Information and Communications Magazine
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• v.23 no.4
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• pp.81-88
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• 2006

• Information and Communications Magazine
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• v.23 no.4
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• pp.47-59
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• 2006

• TTA Journal
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• s.126
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• pp.89-94
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• 2009

• Information and Communications Magazine
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• v.22 no.9
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• pp.128-137
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• 2005