• Proceedings of the IEEK Conference
• /
• 2008.06a
• /
• pp.427-428
• /
• 2008

본 논문에서는 IEEE 802.11 MAC Layer의 Reception, Transmission 검증을 위해 PLI (Programing Language Interface)를 이용한 방법을 제안한다. PLI를 이용한 검증은 시스템 Level의 검증으로써 설계단계에서 문제점을 확인하고 수정할 수 있다. 그러므로 불필요한 개발비의 낭비를 줄일 수 있고 개발 기간 단축의 효과를 거둘 수 있다. 검증을 위해 Mentor Graphics 사의 HDL (Hardware Description Language) 시뮬레이터인 Modelsim 6.1g Version을 사용하고 PLI를 이용하여 검증 환경을 구축한다.

• International Journal of Control, Automation, and Systems
• /
• v.6 no.1
• /
• pp.119-125
• /
• 2008

This paper examines the use of a wireless Fieldbus based on IEEE 802.15.4 MAC protocol. The superframe of IEEE 802.15.4 is applied to a transmission scheme of real-time mixed data. The transmission and bandwidth allocation scheme are proposed for real-time communication using a superframe. The proposed wireless Fieldbus protocol is able to transmit three types of data (periodic data, sporadic data, and non real-time messages), and guarantee realtime transmission simultaneously within a limited timeframe.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.48 no.4
• /
• pp.84-91
• /
• 2011

Recently, WBAN(Wireless Body Area Network) which has progressed standardization based on IEEE 802.15.6 standardization is a network for the purpose of the short-range wireless communications within around 3 meters from the inner or outer human body. Effective QoS control technique and data efficient management in limited bandwidth such as audio and video are important elements in terms of users and loads in short-range wireless networks. In this paper, for high-speed WBAN IEEE 802.15.6 standard, the dynamic allocation to give an efficient bandwidth management and weighted fair queueing algorithm have been proposed through the adjustment of the super-frame about limited data and Quality of Service (QoS) based on the queuing algorithm. Weighted Fair Queueing(WFQ) Algorithm represents the robust performance about elements to qualitative aspects as well as maintaining fairness and maximization of system performance. The performance results show that the dynamic allocation expanded transmission bandwidth five times and the weighted fair queueing increased maximum 24.3 % throughput and also resolved delay bound problem.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39B no.2
• /
• pp.95-101
• /
• 2014

Scalable video coding (SVC) encodes multimedia data into a base layer and enhancement layers to cope with variable network conditions in an adaptive manner. In SVC, enhancement layers can be decoded only when the base layer is successively received. However, existing works on SVC transmissions in IEEE 802.11 WLANs do not fully investigate this characteristic and thus their performance can be degraded. In this paper, we propose a SVC-aware retransmission (SAR) scheme in IEEE 802.11 WLANs. The SAR scheme applies different retransmission policies for base and enhancement layers by obtaining the optimal number of frames to be retransmitted. As a result, the SAR scheme can reduce unnecessary retransmissions and minimize the transmission latency. Simulation results demonstrate that the SAR scheme can reduce unnecessary data transmission by 12.6% and the transmission latency by 6.6~19.1% compared to conventional retransmission schemes.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.43 no.1 s.343
• /
• pp.49-56
• /
• 2006

This paper describes the design and the verification of IEEE 802.15.4 LR-WPAN 2.4GHz Physical layer for Ubiquitous Sensor Network(USN). We designed the Carrier Frequency Offset(CFO) compensation satisfied the frequency tolerance of IEEE 802.15.4 LR-WPAN and the adaptive matched filter that re-setting of the threshold for the symbol synchronization of the various USN environment. The multiplications is reduced 1/16 by this method each other at i, q phases and has 0.5dB performance improvement in detection probability. Proposed baseband system is designed with verilog HDL and implemented using FPGA prototype board.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.6A
• /
• pp.624-634
• /
• 2008

The mobile station which is about to do handover in IEEE 802.16e networks scans its neighboring base station channels to decide its next target base station. However, due to the lack of location information of its subscribers, the serving base station cannot provide any reliable candidate channel which is actually attachable by the scanning mobile stations, which makes the mobile station suffer from the long scanning time. Sometimes, long scanning time may cause the degradation of quality of service due to repeatable scan-duration or failure to start the handover procedure in time. To overcome these problems, in this paper, we propose a new protocol so called fast group scanning scheme, in which multiple mobile stations form a group to scan their neighboring base station channels simultaneously. Main contribution of this proposal is to find and decide a reliable target base station within a short scanning time. The fast group scanning scheme can be deployed to the cell network of the serving base station with a dynamic neighboring base station list management.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.6A
• /
• pp.537-543
• /
• 2007

In this paper, we propose a new stopping criterion for the turbo processing (Turbo-BLAST) of MIMO-OFDM system. To reduce the high computational complexity of turbo-BLAST, it is desirable to lessen the outer-loop iteration number. In a system such as IEEE 802.16e Mobile WiMax, no CRC bits are available except the last encoding packet of a transmitted burst, so early stopping criteria without the help of CRC bits are needed. The proposed criterion counts the sign differences between received parity bits and the re-encoded parity bits from received information bits. With the tail-biting code which is accepted for IEEE 802.16e, a method that the re-encoder operates at half complexity is also proposed. Computer simulations show that the proposed stopping criterion approaches the performance of GENIE aided criterion with less average number of iterations than the other early stopping criteria.

• Journal of Korea Multimedia Society
• /
• v.8 no.4
• /
• pp.509-515
• /
• 2005

This paper explores the throughput of DCF protocol with both the traffic intensity and MSDU size at the MAC layer in the 802.11a wireless LAN. By exploring the throughput of DCF protocol with the data rate of 6Mbps, 12 Mbps, 24 Mbps and 54 Mbps, we find the fact that the less the data rate be, the higher the throughput be. We also find, from the throughput calculation by means of traffic intensity and MSDU size, that the longer the MSDU size is, the higher the throughput is. We also found the traffic intensity that the throughput is at the maximum point with the fixed MSDU size.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.9A
• /
• pp.803-813
• /
• 2005

This paper explores the throughput performance of CSMA/CA-based DCF protocol over frequency-selective, slow Ricean fading channels with both the $E_{b}/N_{o}$ and BER at the MAC layer in the 802.1 la wireless LAN. By exploring the throughput of DCF protocol with the data rate of 6Mbps, 12 Mbps, 24 Mbps and 54 Mbps, we find the fact that the higher the $E_{b}/N_{o}$ be and the less the BER be, the higher the throughput be.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.26 no.6
• /
• pp.1561-1569
• /
• 2016

As the use of the sensor device increases in IoT environment, the need for device security is becoming more and more important When a sensor device is deployed in IEEE 802.15.4-based LoWPAN, it has to perform the join operation with PAN Coordinator and the binding operation with another device. In the join and binding process, authentication and key distribution of the device are performed using the pre-distributed network key or certificate. However, the network key used in the conventional method has problems that it's role is limited to the group authentication and individual identification is not applied in certificate issuing. In this paper, we propose a secure join and binding protocol in LoWPAN environment that solves the problems of pre-distributed network key.