• Title/Summary/Keyword: Radio frequency interference

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Interference Issuses of Radio Frequency Identification Devices in Magnetic Resonance Imaging Systems and Computed Tomography Scan

  • Periyasamy, M.;Dhanasekaran, R.
    • Journal of Magnetics
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    • v.20 no.3
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    • pp.295-301
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    • 2015
  • We evaluated certain issues related to magnetic resonance imaging (MRI) coupled with the use of active 2.5 GHz radio frequency identification (RFID) tags for patient identification using low field (0.3 T) MRI and computed tomography (CT) scans. We also investigated the performance of the RFID reader located outside the MRI room by considering several factors. A total of ten active RFID tags were exposed to several MRI sequences and X-rays of CT scan. We found that only card type active RFID tags are suitable for patient identification purpose in MRI environment and both wristbands as well as card tags were suitable for the same in CT environment. Severe artifacts were found in the captured MRI and CT images when the area of the imaging was in proximity to the tags. No external factors affected the performance of active RFID reader stationed outside the MRI scan room.

A Study on the Measurement and Analysis of Radio Interferences from China (중국으로부터의 전파간섭 측정 및 분석에 관한 연구)

  • 강영흥;백정기;이성수;이형수
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.12 no.5
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    • pp.740-746
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    • 2001
  • Radio interferences have been a frequent problem on the TRS service, which has been in operation in the southern coastal area of Korea since 1994. By Korea-Japan joint analysis, the main reasons of the radio interferences are due to the radio ducting signal from the seaside of Japan. As the mobile services become spreading in China as well as Japan, interference problems between Korea and China will occur more frequently in various frequency bands. Therefore, in this paper we propose a method for measurement and analysis of the radio interference signal, and summarize the measurement results of interference from China, which was performed to solve the interference problem between Korea and China.

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Performance Evaluation of Time Hopping Binary PPM Impulse Radio System according to Interference Environment (간섭 환경에 따른 TH Binary PPM IR 시스템의 성능 평가)

  • Lee, Yang-Sun;Kang, Heau-Jo
    • Journal of Advanced Navigation Technology
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    • v.6 no.4
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    • pp.318-325
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    • 2002
  • In this paper, the effects of the interference environments on the performance of the time hopping(TH) binary PPM impulse radio(IR) system are presented. Based on the monocycle pulse available within the frequency of 3.1~10.6 GHz permitted for application by FCC, a PPM-modulated TH IR system simulator was designed and followed by the analysis of the monocycle pulse characteristics as well as the system performance. Particularly for the evaluation of the system performance, the multiple access interference and the narrowband system interference signals were considered as the interference signals. Since the narrowband system interference signal has very narrow bandwidth and very large amplitude compared with those of IR system, the analysis of the IR system performance was implemented by considering the interference power and band fraction ratio of the narrowband interference signal.

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A Multi-Dimensional Radio Resource Scheduling Scheme for MIMO-OFDM Wireless Systems

  • Li, Lei;Niu, Zhisheng
    • Journal of Communications and Networks
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    • v.8 no.4
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    • pp.401-409
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    • 2006
  • Orthogonal frequency division multiplexing (OFDM) and multiple input multiple output (MIMO) technologies provide additional dimensions of freedom with spectral and spatial resources for radio resource management. Multi-dimensional radio resource management has recently been identified to exploit the full dimensions of freedom for more flexible and efficient utilization of scarce radio spectrum while provide diverse quality of service (QoS) guarantees. In this work, a multi-dimensional radio resource scheduling scheme is proposed to achieve above goals in hybrid orthogonal frequency division multiple access (OFDMA) and space division multiple access (SDMA) systems. Cochannel interference (CCI) introduced by frequency reuse under SDMA is eliminated by frequency division and time division between highly interfered users. This scheme maximizes system throughput subjected to the minimum data rate guarantee. for heterogeneous users and transmit power constraint. By numerical examples, system throughput and fairness superiority of the our scheduling scheme are verified.

Performance Analysis on the Narrowband Interference Rejection of Impulse Radio System in Frequency Coexistence Environment (주파수 공존 환경에서 Impulse Radio 시스템의 협대역 간섭 제거 성능 분석)

  • Jang, Se-In;Lee, Yang-Sun;Kim, Si-Gwan
    • Journal of Advanced Navigation Technology
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    • v.14 no.5
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    • pp.745-751
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    • 2010
  • In this paper, the proposed a narrowband interference cancellation techniques for the frequence sharing of Ultra wideband Impulse Radio communication system and narrowband communication system. In this system, the narrowband communication signals can cause intolerant interferences to Impulse Radio signals. In this paper, Ultra wideband Impulse Radio system have been analyzed in AWGN, MAI and NI(Narrowband Interference) environment. Also, performance improvement has been obtained by adopting an adaptive notch filtering scheme using Complex Filter Bank and CCI canceller. The results show that there is a substantial enhancement in performance by employing the adaptive notch filtering and/or CCI canceller.

A study on Conditions of Frequency Coordination for High Speed Radio Access Network in domestic 5㎓ Band (국내 5㎓ 대역 초고속 무선 접속망의 공유조건 연구)

  • 박진아;박승근;박덕규;오용선
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2000.10a
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    • pp.247-252
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    • 2000
  • In this paper, we discuss frequency allocation and sharing for high speed radio access network in domestic 5㎓ the band. In order to evaluate the possibility of frequency sharing between meterological radar and high speed radio access network we analyses radio interference of meterological radar by means of minimum coupling loss method and Monte Carlo simulation And simulations show that it is necessary to use DFS(Dynamic Frequency Selection) scheme for frequency sharing between meterological radar and high speed radio access network.

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A study on Conditions of Frequency Coordination for High Speed Radio Access Network in domestic 5GHz Band (국내 5GHz대역 초고속 무선 접속망의 공유조건 연구)

  • 박진아;박승근;박덕규;오용선
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.4 no.4
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    • pp.751-758
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    • 2000
  • In this paper, we discuss frequency allocation and sharing for high speed radio access network in domestic 5GHz the band. In order to evaluate the possibility of frequency sharing between meteorological radar and high speed radio access network, we analyses radio interference of meteorological radar by means of minimum coupling loss method and Monte Carlo simulation. And simulations show that it is necessary to use DFS(Dynamic Frequency Selection) scheme for frequency sharing between meteorological radar and high speed radio access network.

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Analysis of interference on Digital Radio Receiver (디지털 라디오 수신기에 마치는 전파 간섭 분석)

  • Hong, Moo-Hyun;Kim, Ju-Seok;Lee, Yong-Tae;Baek, Myung-Sun;Kim, Kyung-Seok
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.11A
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    • pp.1059-1065
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    • 2010
  • Recently, analog broadcasting are being converted into digital radio broadcasts, Among the various ways that HD Radio is a candidate for the U.S. approach, Digital Radio will transmit a digital signal to existing analog FM/AM. It provides clear sound quality, traffic information, weather information and various value-added services. In addition, the converted digital radio will be able to meet demand to growing demand for analog FM. In this paper, Digital FM Radio system in the same frequency band using electric field strength of the received digital radio broadcasting interference effects were analyzed. And Digital FM Radio Receiver interference effects were analyzed by interference signal power and signal power. Results were confirmed by applying equation at minimum field strength and SNR.

Minimum BER Power Allocation for OFDM-based Cognitive Radio Networks

  • Xu, Ding;Li, Qun
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.9 no.7
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    • pp.2338-2353
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    • 2015
  • In this paper, the optimal power allocation algorithm that minimizes the aggregate bit error rate (BER) of the secondary user (SU) in a downlink orthogonal frequency division multiplexing (OFDM) based cognitive radio (CR) system, while subjecting to the interference power constraint and the transmit power constraint, is investigated under the assumption that the instantaneous channel state information (CSI) of the interference links between the secondary transmitter and the primary receiver, and between the primary transmitter and the secondary receiver is perfectly known. Besides, a suboptimal algorithm with less complexity is also proposed. In order to deal with more practical situations, we further assume that only the channel distribution information (CDI) of the interference links is available and propose heuristic power allocation algorithms based on bisection search method to minimize the aggregate BER under the interference outage constraint and the transmit power constraint. Simulation results are presented to verify the effectiveness of the proposed algorithms.

Channel Allocation Scheme considering Inter-Link Interference for Cognitive Radio Networks (인지무선통신에서 링크 간 간섭을 고려한 채널할당기법)

  • Kwon, Young-Min;Park, Hyung-Kun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.6
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    • pp.1080-1082
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    • 2016
  • In a multi-hop CR (Cognitive Radio) network, each node find a path to destination node through several links. If links have the same frequency channel, there can be a serious interference among the links and it can reduce the network capacity. In multi-channel CR networks, each channel has different capacity according to the inter-link interference, and each channel has different traffic properties of primary users. In this paper, we propose channel scheduling scheme to minimize channel interferences and collision with primary users. Simulation results show the improvement of channel capacity and collision rate with primary users.