• Title, Summary, Keyword: interference

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A GNSS Interference Detection Method Based on Multiple Ground Stations

  • Kim, Sun Young;Kang, Chang Ho;Yang, Jeong Hwan;Park, Chan Gook;Joo, Jung Min;Heo, Moon Beom
    • Journal of Positioning, Navigation, and Timing
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    • v.1 no.1
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    • pp.15-21
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    • 2012
  • For a GNSS receiver's robustness against RFI and the high accuracy of navigation solution in GNSS, interference source detection and mitigation are needed. In this paper, an adaptive lattice IIR notch filter is employed to track single-tone continuous wave and swept continuous wave interference signals, and an interference detection method is proposed. Furthermore, this paper presents interference source characterization algorithm using multiple ground stations' interference detection results. The measurement of the signal powers from each ground station is used to build weighting factors to estimate the type of the interference. The performance of interference detection algorithm is simulated for scenarios of GPS signal in the presence of single-tone continuous wave interference and swept continuous wave interference.

Analysis on Co-channel Interference of Human Body Communication Supporting IEEE 802.15.6 BAN Standard

  • Hwang, Jung-Hwan;Kang, Tae-Wook;Kim, Youn-Tae;Park, Seong-Ook
    • ETRI Journal
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    • v.37 no.3
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    • pp.439-449
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    • 2015
  • Human body communication (HBC) is being recognized as a new communication technology for mobile and wearable devices in a body area network (BAN). This paper presents co-channel interference experienced by HBC supporting the physical layer in the IEEE 802.15.6 BAN standard. To analyze the co-channel interference, a co-channel interference model is introduced, and space-domain and time-domain parameters representing an interference environment are generated using the co-channel interference model. A new signal-to-interference ratio (SIR) parameter depending on the peak amplitudes of the data signals causing co-channel interference is defined; co-channel interference can be easily analyzed and modelled using the newly defined SIR. The BER degradation model derived using the co-channel interference model and SIR in this paper can be effectively used to estimate the performance.

Interference Localization for Cellular OFDMA Systems (셀룰러 OFDMA 시스템을 위한 간섭의 집중화)

  • Rim, Min-Joong
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.44 no.3
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    • pp.51-60
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    • 2007
  • Cellular OFDMA systems may suffer from various amounts of inter-cell interferences according to subcarriers. If it is possible to estimate the interference level of each subcarrier, the performance can be improved by adjusting the magnitude of channel decoder input signals inversely proportional to the interference amounts. While conventional cellular systems prefer to use interference averaging techniques for mitigating inter-cell interferences, this paper shows that localizing inter-cell interferences to the reduced number of subcarriers can significantly improve the system performance assuming thatinterference estimation can be employed. If interference estimation is not used, it is more favorable to use interference averaging techniques to avoid excessive interference levels to certain subcarriers. On the other hand, if interference estimation can be employed, interference localization is more beneficial than interference averaging.

Radial Contact Force Measurement of Lip Seals with a Split Shaft Device (스플릿트샤프트 장치를 이용한 립실의 접촉력측정)

  • Kim, Wan-Doo
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • pp.158-162
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    • 1996
  • A split shaft device is commonly used to measure the radial force of lip seals. The radial force measured with this device includes some inevitable error. This error is caused by the fact that the split shafts cannot maintain a perfect circle when the interference becomes larger or smaller than some initial interference. In this study, a theoretical model for the calculation of the radial contact force has been carried out, and an explicit equation for the measurement error as a function of the initial interference and the interference to be measured has been obtained. The error when the interference is small is not dependent upon the material properties and the shape of the lip seal, but rather upon the amplitude of the initial interference and the interference to be measured. When the interference is larger or smaller than the initial interference, the measured contact force is always underestimated or overestimated.

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A Signal Subspace Interference Alignment Scheme with Sum Rate Maximization and Altruistic-Egoistic Bayesian Gaming

  • Peng, Shixin;Liu, Yingzhuang;Chen, Hua;Kong, Zhengmin
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.8 no.6
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    • pp.1926-1945
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    • 2014
  • In this paper, we propose a distributed signal subspace interference alignment algorithm for single beam K-user ($3K{\geq}$) MIMO interference channel based on sum rate maximization and game theory. A framework of game theory is provided to study relationship between interference signal subspace and altruistic-egoistic bayesian game cost function. We demonstrate that the asymptotic interference alignment under proposed scheme can be realized through a numerical algorithm using local channel state information at transmitters and receivers. Simulation results show that the proposed scheme can achieve the total degrees of freedom that is equivalent to the Cadambe-Jafar interference alignment algorithms with perfect channel state information. Furthermore, proposed scheme can effectively minimize leakage interference in desired signal subspace at each receiver and obtain a moderate average sum rate performance compared with several existing interference alignment schemes.

Multi user interference cancellation in satellite to ground uplink system Based on improved WPIC algorithm

  • Qingyang, Guan
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.10 no.11
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    • pp.5497-5512
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    • 2016
  • An improved optimal weights based on parallel interference cancellation algorithm has been proposed to cancel for interference induced by multi-user access satellite to ground uplink system. Due to differences in elevation relative motion between the user and the satellite, as well as access between users, resulting in multi-user access interference (Multi-user Access Interference, MUI), which significantly degrade system performance when multi-user access. By steepest gradient method, it obtained based on the MMSE criterion, parallel interference cancellation adjust optimal weights to obtain the maximum SINR. Compared to traditional parallel interference cancellation (Parallel Interference Cancellation, PIC) algorithm or serial interference cancellation ( Successive interference Cancellation, SIC), the accuracy of which is not high and too many complex iterations, we establish the multi-user access to the satellite to ground up link system to demonstrate that the improved WPIC algorithm could be provided with high accuracy and relatively low number of iterations.

Multi-Mode Precoding Scheme Based on Interference Channel in MIMO-Based Cognitive Radio Networks

  • Jung, Minchae;Hwang, Kyuho;Choi, Sooyong
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • pp.137-140
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    • 2011
  • A precoding strategy is one of the representative interference management techniques in cognitive radio (CR) network which is a typical interference-limited environment. The interference minimization approach to precoding is an appropriate scheme to mitigate the interference efficiently while it may cause the capacity loss of the desired channel. The precoding scheme for the maximal capacity of the desired channel improves the capacity of the desired channel while it increases the interference power and finally causes the capacity loss of the interfered users. Therefore, we propose a precoding scheme which satisfies these two conflicting goals and manages the interference signal in such an interference-limited environment. The proposed scheme consists of two steps. First, the precoder nulls out the largest singular value of the interference channel to mitigate the dominant interference signal based on the interference minimization approach. Second, the transmitter calculates the sum capacities per mode and selects a mode to maximize the sum capacity. In the second step, each mode consists of the right singular vectors corresponding to the singular values except the largest singular value eliminated in the first step. Simulation results show that the proposed precoding scheme not only efficiently mitigate the interference signal, but also has the best performance in terms of the sum capacity in a MIMO-based CR network.

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An Adaptive Narrowband Interference Excision Filter with Low Signal Loss for GPS Receivers

  • Shin, Mi-Young;Park, Chan-Sik;Lee, Ho-Keun;Lee, Dae-Yearl;Lee, Sang-Jeong
    • 제어로봇시스템학회:학술대회논문집
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    • pp.1234-1238
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    • 2005
  • As the low power GPS signal is susceptible to interference, interference can seriously degrade the performance of GPS receiver. This paper designs a ANIEF(Adaptive Narrowband Interference Excision in Frequency domain) filter that removes narrow band interferences with low signal loss. This filter uses the pre-correlation technique and attempts to filter out the interference in the frequency domain. The interference excision performance of the designed filter is evaluated for various interferences using the ANIEF filter inserted GPS software receiver and the interference generator. Interferences considered in this paper are single-tone CWI(Continuous Wave Interference), multi-tones CWI, pulsed CWI, and swept CWI. The narrowband interference excision filter in frequency domain is very effective against various interferences and the strong interference with a simple structure. However, the signal power loss is unavoidable while transforming. In this paper, the hamming window and overlap technique are adopted to reduce the signal power loss. Finally, the interference excision performance and the reduced signal power loss of the ANIEF filter are shown.

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Intentional GNSS Interference Detection and Characterization Algorithm Using AGC and Adaptive IIR Notch Filter

  • Yang, Jeong Hwan;Kang, Chang Ho;Kim, Sun Young;Park, Chan Gook
    • International Journal of Aeronautical and Space Sciences
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    • v.13 no.4
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    • pp.491-498
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    • 2012
  • A Ground Based Augmentation System (GBAS) is an enabling technology for an aircraft's precision approach based on a Global Navigation Satellite System (GNSS). However, GBAS is vulnerable to interference, so effective GNSS interference detection and mitigation methods need to be employed. In this paper, an intentional GNSS interference detection and characterization algorithm is proposed. The algorithm uses Automatic Gain Control (AGC) gain and adaptive notch filter parameters to classify types of incoming interference and to characterize them. The AGC gain and adaptive lattice IIR notch filter parameter values in GNSS receivers are examined according to interference types and power levels. Based on those data, the interference detection and characterization algorithm is developed and Monte Carlo simulations are carried out for performance analysis of the proposed method. Here, the proposed algorithm is used to detect and characterize single-tone continuous wave interference, swept continuous wave interference, and band-limited white Gaussian noise. The algorithm can be used for GNSS interference monitoring in an excessive Radio Frequency Interference environment which causes loss of receiver tracking. This interference detection and characterization algorithm will be used to enhance the interference mitigation algorithm.

A STUDY ON THE CHANCE OF MANDIBULAR MOVEMENT AND MASTICATORY MUSCLE ACTIVITY REFLECTED BY BALANCING-SIDE OCCLUSAL INTERFERENCE (균형측 교합장애로 인한 하악운동 및 저작근 활성도의 변화에 관한 연구)

  • Lee, Yun-Jeong;Park, Nam-Soo;Choi, Boo-Byung
    • The Journal of Korean Academy of Prosthodontics
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    • v.36 no.4
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    • pp.533-548
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    • 1998
  • The purpose of this study was to investigate the influence of balancing interference on the mandibular movement and masticatory muscle activity. 5 subjects(male. average age of 24.3) without dysfuction in masticatory system were selected. The balancing interference was provided by construction of cast metal crown and onlay on the upper and lower first molars. Clinical examination, changes displacement and velocity, and muscle activity were recorded and analyzed by means of BioPak system(Bioresearch Inc., Milwaukee Wisconsin. USA). The results were as follows ; 1. In clinical examination, various symptoms were reported by all subjects after application of interference. Almost symptoms were subsided after elimination of interference. 2. In the border movements in frontal plane, lateral border movement toward non-interference side was changed according to the interference after application of interference. Immediately after removal of interference, border movements' pattern was recovered as same as before experiment. 3. During gum chewing on the non-interference side, horizontal movement was decreased immediately after application of interference(p<0.05). 1 week after application of interference, horizontal movement was more decreased in 3 subjects and showed a chopping type masticatory stroke. But in 2subjects, horizontal movement was increased to avoid interference. 4. In EMG of the mandibular rest position, no significant changes were showed in the experiment period(p>0.05). 5. During gum chewing on the interference side, the activity of opposite temporal muscle was increased immediately after application of interference(p<0.05). 1 week after application of interference. The activity of ipsilateral temporal muscle and left and right masseter muscles was increased (p<0.05). 1 week after elimination of interference, increased muscle activity was recovered about the same level as before experiment. 6. During gum chewing on the non-interference side, 1 week after application of interference, the activity of ipsilateral temporal muscle was increased (p<0.05). 1 week after elimination of interference. increased muscle activity was returned about the same level as before experiment.

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