• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.14 no.8
• /
• pp.3201-3223
• /
• 2020

Wireless communication has become the promising technology in the recent times because of its applications in Internet of Things( IoT) devices. The IEEE 802.15.4e has become the key technology for IoT devices which utilizes the Time-Slotted Channel Hopping (TSCH) networks for the communication between the devices. In this paper, we develop a Two Level Scheduling Algorithm (TLSA) for scheduling multiple packets with different arrival rate at the source nodes in a TSCH networks based on the link activated by a centralized scheduler. TLSA is developed by considering three types of links in a network such as link i with packets arrival type 1, link j with packets arrival type 2, link k with packets arrival type 3. For the data packets arrival, two stages in a network is considered.At the first stage, the packets are considered to be of higher priority.At the second stage, the packets are considered to be of lower priority.We introduce level 1 schedule for the packets at stage 1 and level 2 schedule for the packets at stage 2 respectively. Finally, the TLSA is validated with the two different energy functions i.e., y = e^ax - 1 and y = 0.5x² using MATLAB 2017a software for the computation of average and worst ratios of the two levels.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.2 no.1
• /
• pp.37-49
• /
• 2008

At the present time the task of designing a highly integrated ZigBee radio frequency (RF) receiver with an excellent coexistence performance is still very demanding and challenging. This paper presents a number of system issues and design considerations for a ZigBee RF receiver, namely IEEE 802.15.4, for coexistence with wireless devices in the 2.4-GHz ISM-band. With regard to IEEE 802.15.4, the paper analyzes receiver performance requirements for; system noise figure (NF), system third-order intercept point (system-IIP3), local oscillator phase noise and selectivity. Based on some assumptions, the paper illustrates the relationship between minimum detectable signal (MDS) and various situations that involve the effects of electromagnetic interference generated by other wireless devices. We infer the necessity of much more stringent specification requirements than the published standard for various wireless communication field environments

• ETRI Journal
• /
• v.38 no.6
• /
• pp.1074-1084
• /
• 2016

This paper presents a transmission method for improving human body communications in terms of spectral efficiency, and the performances of bit-error-rate (BER) and frame synchronization, with a highly simplified structure. Compared to the conventional frequency selective digital transmission supporting IEEE standard 802.15.6 for wireless body area networks, the proposed scheme improves the spectral efficiency from 0.25 bps/Hz to 1 bps/Hz based on the 3-dB bandwidth of the transmit spectral mask, and the signal-to-noise-ratio (SNR) by 0.51 dB at a BER of $10^{-6}$ with an 87.5% reduction in the detection complexity of the length of the Hamming distance computation. The proposed preamble structure using its customized detection algorithm achieves perfect frame synchronization at the SNR of a BER of $10^{-6}$ by applying the proposed pre-processing to compensate for the distortions on the preamble signals due to the band-limit effects by transmit and receive filters.

• TTA Journal
• /
• s.110
• /
• pp.61-68
• /
• 2007

UWB는 2002년부터 FCC에서 상용을 허용한 이후 IEEE802.15.3a에서 DS-CDMA 방식과 MB-OFDM 방식을 논의해 왔으나 표준안 도출에 실패한 후 지금은 WiMedia Alliance와 UWB Forum에서 각기 표준화 진행중이다. Intel, Microsoft, HP 등이 주축인 WiMdeia Alliance는‘PAN 환경에서 장치간의 무선 멀티미디어 연결과 상호운용성’을 위하여 구성되었으며, 2003년 MBOA와 합병하여 MBOA 기술을 기반으로 하는 물리계층 및 MAC 계층 기능 규격을 ECMA 등에 표준으로 등록하였고, 그 외 표준화 단체에 표준안 채택을 위한 노력을 계속하고 있다. 또한 USB Forum, Bluetooth, IEEE1394 등에 MBOA 기반 응용이 사용될 수 있도록 노력하고 있으며, 2005년 MBOA 기반의 Certified Wireless USB 규격으로 UWB 시장을 선점하기 시작하였으며, Bluetooth 및 IEEE1394에서도 MBOA 기반 표준이 진행되고 있다. 본 고는 WiMedia Alliance의 최근 표준 활동과 WiMedia 규격을 활용한 국내.외 기술동향에 대하여 살펴보고자 한다.

• Information and Communications Magazine
• /
• v.24 no.9
• /
• pp.104-110
• /
• 2007

UWB는 2002년부터 FCC에서 상용을 허용한 이후 IEEE802.15.3a에서 DS-CDMA 방식과 MB-OFDM 방식을 논의해 왔으나 표준안 도출에 실패한 후 지금은 WiMedia Alliance와 UWB Forum에서 각기 표준화 진행중이다. Intel, Microsoft, HP 등이 주축인 WiMdeia Alliance는 "PAN 환경에서 장치간의 무선 멀티미디어 연결과 상호 운용성"을 위하여 구성되었으며, 2003년 MBOA와 합병하여 MBOA 기술을 기반으로 하는 물리계층 및 MAC 계층 기능 규격을 ECMA 등에 표준으로 등록하였고, 그 외 표준화 단체에 표준안 채택을 위한 노력을 계속하고 있다. 또한 USB Forum, Bluetooth, IEEE1394 등에 MBOA 기반 응용이 사용될 수 있도록 노력하고 있으며, 2005년 MBOA 기반의 Certified Wireless USB 규격으로 UWB 시장을 선점하기 시작하였으며, Bluetooth 및 IEEE1394에서도 MBOA 기반 표준이 진행되고 있다. 본 고는 WiMedia Alliance의 최근 표준 활동과 WiMedia 규격을 활용한 국내 외 기술동향에 대하여 살펴보고자 한다.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.7
• /
• pp.292-299
• /
• 2013

In this paper, we developed a data transmission system over coaxial cable based on the IEEE 802.15.3 MAC and Ultra-Wideband(UWB) Physical Layer. This system is capable of operation in both wireless and wired medias. When operating on coax cable it is capable of Gigabit bi-directional data rate operation on in-home coax wiring and over Hybrid-Fiber-Coax(HFC) cable infrastructure. The developed system transceives command, control and data over a 75 ohm coax system in a home or office. This system operates at a center frequency of 4GHz with a total occupied bandwidth of 1.33Ghz centered on 4GHz. The system uses BPSK modulation and sends symbols at a maximum power level of +15dBm. It has been tested and works through up to three CATV RF splitters in a home environment.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.16 no.11 s.102
• /
• pp.1075-1085
• /
• 2005

The purpose of this paper is to design the architecture for synchronization of MB-OFDM UWB system that is being processed the standardization for Alt-PHY of WPAN(Wireless Personal Area Network) at IEEE802.15.3a and to analyze the implementation loss due to 4 parallel synchronization architecture for design or link margin. First an overview of the MB-OFDM UWB system based on IEEE802.15.3a Alt-PHY standard is described. The effects of non-ideal transmission conditions of the MB-OFDM UWB system including carrier frequency offset and sampling clock offset are analyzed to design a full digital architecture for synchronization. The synchronization architecture using 4-parallel structure is then proposed to consider the VLSI implementation including algorithms for carrier frequency offset and sampling clock offset to minimize the effects of synchronization errors. The overall performance degradation due to the proposed synchronization architecture is simulated to be with maximum 3.08 dB of the ideal receiver in maximum carrier frequency offset and sampling clock offset tolerance fir MB-OFDM UWB system.

• 한국IT서비스학회:학술대회논문집
• /
• 2006.05a
• /
• pp.181-185
• /
• 2006

최근 차량에 설치된 단말기를 통해 길안내 서비스, 교통정보 서비스 등 다양한 정보를 제공하는 텔레매틱스 서비스가 활발하게 연구되고 있다. 하지만 현재 대다수의 텔레매틱스 서비스는 최대 15m 의 공간오차를 가진 GPS 기술을 이용하기 때문에 차량의 정확한 위치정보를 파악하기는 힘들다. 따라서 본 논문에서는 무선 센서노드를 이용해 GPS 보다 정확한 차량의 위치정보와 속도를 감지하고 노드 간 통신 프로토콜로서 Telematics Scheduling Protocol(TSP)[1]을 사용하여 교차로 중앙에 위치한 베이스 스테이션으로 전송하여 교차로에서 발생할 수 있는 차량 충돌을 예측하며 충돌 위험 정보를 교차로에 근접한 자동차에게 알려주는 텔레매틱스 교통안전시스템[1]을 소개한다. 또한 교통안전시스템으로서의 신뢰성과 실시간성을 비교평가하기 위하여 TSP 프로토콜, IEEE 802.11[2]과 802.15.4[3]를 대상으로 네트워크 시뮬레이터 ns-2[4]를 이용하여 시뮬레이션한다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.3
• /
• pp.327-332
• /
• 2017

As Internet of Things (IoT) technology advances, there is a growing demand for location-based services (LBSs) to identify users' mobility and identity. The initial LBS system was mainly used to measure position information by measuring the phase of a signal transmitted from a global positioning system (GPS) satellite or by measuring distance to a satellite by tracking the code of a carrier signal. However, the use of GPS satellites is ineffective, because it is difficult to receive satellite signals indoors. Therefore, research on wireless communications systems like ultra-wide band (UWB), radio frequency identification (RFID), and ZigBee are being actively pursued for location recognition technology that can be utilized in an indoor environment. In this paper, we propose an LBS system that includes the 2.45GHz band for chirp spread spectrum (CSS), and the 3.1-10.6GHz band and the 250-750MHz bands for UWB using the IEEE 802.15.4a standard for low power-based location recognition. As a result, we confirmed that the 2.45GHz Industrial, Scientific and Medical (ISM) band RF transceiver and the ranging function can be realized in the hardware and has 0dBm output power.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.7 no.5
• /
• pp.106-121
• /
• 2008

In this paper, we proposed and designed the protocol for energy efficiency and the center of data aiming at the design of a Multi Location Awareness System that recognizes a shadow site in parking and tunnel, which stands on the basis of CSS(Chirp Spread Spectrum) method using ISM Band of IEEE 802.15.4a that aware close location with wireless RF only. As a result of the protocol measurement, it displays the observation errors of less than 15cm, the data error rate of less than 5%, and can implement the Multi Location Awareness System with maximum length of life for 13.5 days using battery of 3V(1500 mAh).