A novel radio-map establishment based on fuzzy clustering for hybrid K-Nearest Neighbor (KNN) and Artifi cial Neural Network (ANN) position algorithm in WLAN indoor environment is proposed. First of all, the Principal...A novel radio-map establishment based on fuzzy clustering for hybrid K-Nearest Neighbor (KNN) and Artifi cial Neural Network (ANN) position algorithm in WLAN indoor environment is proposed. First of all, the Principal Component Analysis (PCA) is utilized for the purpose of simplifying input dimensions of position estimation algorithm and saving storage cost for the establishment of radio-map. Then, reference points (RPs) calibrated in the off-line phase are divided into separate clusters by Fuzzy C-means clustering (FCM), and membership degrees (MDs) for different clusters are also allocated to each RPs. However, the singular RPs cased by the multi-path effect signifi cantly decreases the clustering performance. Therefore, a novel radio-map establishment method is presented based on the modifi cation of signal samples recorded at singular RPs by surface fitting. In the on-line phase, the region which the mobile terminal (MT) belongs to is estimated according to the MDs firstly. Then, in estimated small dimensional regions, MT's coordinates are calculated byKNN positioning method for efficiency purpose. However, for the regions including singular RPs, ANN method is utilized because ofits great pattern matching ability. Furthermore, compared with other typical indoor positioning methods, feasibility and effectiveness of this hybrid KNN/ANN method are also verified by the experimental results in static and tracking situations.展开更多
PCM/PPK telemetry system is a multi-nary pulse modulation system.It is commonly used to transmit high-accuracy time information and some express signals.To the issue of security that telemetry data is transmitted in t...PCM/PPK telemetry system is a multi-nary pulse modulation system.It is commonly used to transmit high-accuracy time information and some express signals.To the issue of security that telemetry data is transmitted in the open space,a data encryption scheme in the PCM/PPK telemetry system is proposed.In this scheme,the PCM data of signal source are encrypted by stream cipher in which key streams are generated with clock control LSFR.The scheme can save system resource in the dual-modulation compound telemetry system.A backward key synchronization scheme is also proposed,which has the property of strong real-time and easy to implement.A simplified simulation model of PCM/PPK remote system is established based on the actual framework of telemetry system,and the model is simple and easy to simulate.The error performance of the system is analyzed in theory and tested by computer simulation.Also the security of the system is analyzed.The simulation and analysis results show that the encryption scheme can ensure the security of the telemetry data and does not cause error-diffusion.展开更多
In this paper, we propose and experimentally demonstrate a bi-directional indoor communication system based on visible light RGB-LED. Spectrally efficient modulation formats （QAM-OFDM）, advanced digital signal proce...In this paper, we propose and experimentally demonstrate a bi-directional indoor communication system based on visible light RGB-LED. Spectrally efficient modulation formats （QAM-OFDM）, advanced digital signal processing, pre- and post- equalization are adopted to compensate the severe frequency response of indoor channel. In this system, we utilize red-green-blue Light emitting diodes （LEDs）, of which each color can be used to carry different signals. For downlink, the low frequencies of each color are used while for uplink, the high frequencies are used. The overall data rate of downlink and uplink are 1.15-Gb/s and 300-Mb/s. The bit error ratios （BERs） for all channels after 0.7 m indoor delivery are below pre-forward- error-correction （pre-FEC） threshold of 3.8×10-3. To the best of our knowledge, this is the highest data rate in bi-directional visible light communication system.展开更多
This paper introduces a new-developed mine fire-resistant optical fiber cable (OFC)KL5004,its structural characteristics, main feature, the theory about fire resistance and its application in high output and efficienc...This paper introduces a new-developed mine fire-resistant optical fiber cable (OFC)KL5004,its structural characteristics, main feature, the theory about fire resistance and its application in high output and efficiency mine.展开更多
基金supported by National High-Tech Research & Development Program of China (Grant No. 2008AA12Z305)
文摘A novel radio-map establishment based on fuzzy clustering for hybrid K-Nearest Neighbor (KNN) and Artifi cial Neural Network (ANN) position algorithm in WLAN indoor environment is proposed. First of all, the Principal Component Analysis (PCA) is utilized for the purpose of simplifying input dimensions of position estimation algorithm and saving storage cost for the establishment of radio-map. Then, reference points (RPs) calibrated in the off-line phase are divided into separate clusters by Fuzzy C-means clustering (FCM), and membership degrees (MDs) for different clusters are also allocated to each RPs. However, the singular RPs cased by the multi-path effect signifi cantly decreases the clustering performance. Therefore, a novel radio-map establishment method is presented based on the modifi cation of signal samples recorded at singular RPs by surface fitting. In the on-line phase, the region which the mobile terminal (MT) belongs to is estimated according to the MDs firstly. Then, in estimated small dimensional regions, MT's coordinates are calculated byKNN positioning method for efficiency purpose. However, for the regions including singular RPs, ANN method is utilized because ofits great pattern matching ability. Furthermore, compared with other typical indoor positioning methods, feasibility and effectiveness of this hybrid KNN/ANN method are also verified by the experimental results in static and tracking situations.
文摘PCM/PPK telemetry system is a multi-nary pulse modulation system.It is commonly used to transmit high-accuracy time information and some express signals.To the issue of security that telemetry data is transmitted in the open space,a data encryption scheme in the PCM/PPK telemetry system is proposed.In this scheme,the PCM data of signal source are encrypted by stream cipher in which key streams are generated with clock control LSFR.The scheme can save system resource in the dual-modulation compound telemetry system.A backward key synchronization scheme is also proposed,which has the property of strong real-time and easy to implement.A simplified simulation model of PCM/PPK remote system is established based on the actual framework of telemetry system,and the model is simple and easy to simulate.The error performance of the system is analyzed in theory and tested by computer simulation.Also the security of the system is analyzed.The simulation and analysis results show that the encryption scheme can ensure the security of the telemetry data and does not cause error-diffusion.
基金supported by the NNSF of China(No.61177071, No.61250018)the Key Program of Shanghai Science and Technology Association (12dz1143000)
文摘In this paper, we propose and experimentally demonstrate a bi-directional indoor communication system based on visible light RGB-LED. Spectrally efficient modulation formats （QAM-OFDM）, advanced digital signal processing, pre- and post- equalization are adopted to compensate the severe frequency response of indoor channel. In this system, we utilize red-green-blue Light emitting diodes （LEDs）, of which each color can be used to carry different signals. For downlink, the low frequencies of each color are used while for uplink, the high frequencies are used. The overall data rate of downlink and uplink are 1.15-Gb/s and 300-Mb/s. The bit error ratios （BERs） for all channels after 0.7 m indoor delivery are below pre-forward- error-correction （pre-FEC） threshold of 3.8×10-3. To the best of our knowledge, this is the highest data rate in bi-directional visible light communication system.
文摘This paper introduces a new-developed mine fire-resistant optical fiber cable (OFC)KL5004,its structural characteristics, main feature, the theory about fire resistance and its application in high output and efficiency mine.
