• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.9C
• /
• pp.1219-1226
• /
• 2004

The objective of this paper is to proposed a new Hybrid Interference Cancellation(HlC) receiver to cancel MAI in a multirate DS-CDMA system based on multiple processing gain(MPG). We propose a new improved HIC scheme that divides the active users with different data rates split into a number of groups for effectives cancellation Between each group, GW-PIC is performed to cancel other group signals and within them, SIC is carried out to remove multiple access interference in group. We analyze the performance of the proposed receiver in terms of the bit error rate(BER) and examine its performance. As a conclusion, computer simulations show that the proposed schemes outperforms adaptive multistage PIC and conventional SIC receiver over AWGN channel.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.12A
• /
• pp.1303-1310
• /
• 2007

In IEEE 802.11b wireless network, stations synchronize themselves to the beacons periodically sent by the access point (AP) when they are running in low power mode. Stations stay awake for enough time to receive beacon because it is delayed in AP if the wireless channel has been being used by other traffic at each scheduled instant. In this paper, we propose a method that measures the delay of received beacons and calculates wake-up interval of station to receive the next one. Beacon transmission delay at the AP is analyzed. The proposed method is simulated and its characteristics are described in the analysis. The result measured in terms of station's wake-up interval shows some enhancement in energy consumption.

• Journal of the Korea Society of Computer and Information
• /
• v.12 no.3
• /
• pp.277-285
• /
• 2007

This research proposes a personalized mobile web contents creation method that uses web news channel contents-based analysis. It promptly acquires data through the RSS and RSS-linked web pages which have been supplied by the existing web sites for a news search. And then It applies a personalization method using analysis in contents filtering and generation. The proposed method will make creating mobile web contents easier while lowering wireless contents production costs. Moreover, It can be improved a user satisfaction for contents filtering and access with using analysis that fits in with a matter of user's specific interest.

• ETRI Journal
• /
• v.33 no.3
• /
• pp.310-319
• /
• 2011

In this paper, a new soft-fusion approach for multiple-receiver wireless communication systems is proposed. In the proposed approach, each individual receiver provides the central receiver with a confidence level rather than a binary decision. The confidence levels associated with the local receiver are modeled by means of soft-membership functions. The proposed approach can be applied to wireless digital communication systems, such as amplitude shift keying, frequency shift keying, phase shift keying, multi-carrier code division multiple access, and multiple inputs multiple outputs sensor networks. The performance of the proposed approach is evaluated and compared to the performance of the optimal diversity, majority voting, optimal partial decision, and selection diversity in case of binary noncoherent frequency shift keying on a Rayleigh faded additive white Gaussian noise channel. It is shown that the proposed approach achieves considerable performance improvement over optimal partial decision, majority voting, and selection diversity. It is also shown that the proposed approach achieves a performance comparable to the optimal diversity scheme.

• Proceedings of the IEEK Conference
• /
• summer
• /
• pp.310-312
• /
• 2004

Binary Exponential Back-off (BEB) scheme is widely adopted in both wire and wireless networks for collision resolution. The BEB suffers from several performance drawbacks including long packet delay and low utilization since it doubles the back-off size after each collision. In addition, operation of the BEB algorithm may lead to the last-come-first-serve result among competing users and the BEB is further unstable for every arrival rate greater than 0 due to its random access property[1,2]. In this paper, we propose a deterministic back-off algorithm to reduce contention interval as much as possible for accessing the channel without collision in the back-off process. Simulation results show that our scheme offers a higher throughput as well as a lower packet transfer delay than the BEB by taking advantage of its lower collision ratio in saturation state.

• Journal of National Security and Military Science
• /
• s.3
• /
• pp.169-196
• /
• 2005

The point of Bush administraion’s foreign policy is to support the promotion and stability of Democracy in Iraq and counter terrorism and spread of WMD with his strong propulsive force caused by his reelection. In such an environment, there are his leadership, his team, himself, Kim Jung Il, and a new understanding of North Korea after September 11 as the effective factors of Bush administration’s policy toward Pyongyang. Bush administration’s foreign policy of North Korea also shows the process of North Korea’s nuclear weapon program and the future scenario of the Korean Peninsula with "the persistence of solving North Korea’s nuclear weapon program such as the method having done in Lybia", "the holding unconditional talks with Pyongyang, and "the continual concerns with human rights in North Korea." The purpose of Bush administration’s foreign policy of North Korea is to make North Korea do not support terrorism rather than remove the nuclear weapon in North Korea. The process of outlining South Korea’s policy toward North Korea must be considered for "national interest" with reasonable analyses not just hopes For this, South Korea must access systematically human rights of North Korea, prepare projects for a daring approach on North Korea, and strengthen South Korea’s defense ability toward North Korea with deep alliance with U.S and systematize the mutual understanding channel between U.S and South Korea. In conclusion, South Korea must try to get specific methods and practices about Bush administration’s foreign policy of North Korea with national wisdom

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.39 no.1
• /
• pp.42-48
• /
• 2002

In this paper, a decision method using multiple threshold values for PN code acquisition in Direct Sequence Code Division Multiple Access (DS-CDMA) systems is described. We apply this technique to the conventional double dwell serial search algorithm and analyze it in terms of mean code acquisition time. For the analysis, we present mathematical model of proposed algorithm and also perform the simulation under IMT-2000 channel models. Numerical results show that our proposed scheme outperforms the conventional one by 0.2 - 0.5 sec with respect to the mean code acquisition time because multiple threshold values mitigate the possible decline in search performance caused by the use of a single threshold.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.8 no.1
• /
• pp.61-72
• /
• 1997

The implementation of base station transceiver for Wideband CDMA(Code Division Multiple Access) PCS(Personal Communication Service) system using spread spectrum CDMA technology is presented in this paper. The receiver that requires wide dynamic range and high sensitivity and the transmitter that has good spurious emission supression were designed and implemented with 5 MHz RF channel bandwidth. This paper shows the some factors that should be considered and simulated using the RF simulation S/W with commercial and customized components. The implemented transceiver based on the simulation gave good results that satisfied the functional specifications of the transceiver.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.5 no.4
• /
• pp.18-29
• /
• 1994

In this paper, the performance of stepped serial search scheme and matched filter scheme for code acqusition in FH / CDMA are evaluated under land mobile radio communication channel environments. And delay lock loop scheme is used as code tracking system. As the results for code acquisition system, it is shown that the performance of stepped searial scheme is superior to matched filter scheme, because system complexity is reduced and system performance is improved by increasing the hopping frequency not to substitute for special hardware. Also, it is shown that its performance is improved under Rayleigh/ Rician fading environments. As the results for code tracking system, it is found that mean hold time is increased due to the increase of the number of lock state and hopping frequency, M.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.26 no.6
• /
• pp.1505-1511
• /
• 2016

Live streaming is a method to provide media service by sending recoded media to a user's video player. In order to provide video and audio contents in real-time for a large number of users simultaneously, live streaming compatible protocols such as RTMP (Real Time Messaging Protocol), HLS (Http Live Streaming), are required. In this paper, we analyzed vulnerability of paid live streaming services with the captured packets from the applications used by six major OTT (over-the-top) companies in Korea supporting live streaming services. We found that streaming channels were not encrypted and access control mechanisms were not properly used. Thus, guest users can freely use paid live streaming services.