The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform

Huiliang Shang - One of the best experts on this subject based on the ideXlab platform.

  • demonstration of 575 mb s downlink and 225 mb s uplink bi directional scm wdm visible light communication using rgb led and phosphor based led
    Optics Express, 2013
    Co-Authors: Yuanquan Wang, Yiguang Wang, Nan Chi, Jianjun Yu, Huiliang Shang
    Abstract:

    We propose and experimentally demonstrate a novel full-duplex bi-directional subcarrier multiplexing (SCM)-wavelength division multiplexing (WDM) visible light communication (VLC) system based on commercially available red-green-blue (RGB) light emitting diode (LED) and phosphor-based LED (P-LED) with 575-Mb/s downstream and 225-Mb/s upstream transmission, employing various modulation orders of quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM). For the downlink, red and green colors/wavelengths are assigned to carry useful information, while blue chip is just kept lighting to maintain the white color illumination, and for the uplink, the low-cost P-LED is implemented. In this demonstration, pre-equalization and post-equalization are also adopted to compensate the severe frequency response of LEDs. Using this scheme, 4-user downlink and 1-user uplink transmission can be achieved. Furthermore, it can support more users by adjusting the bandwidth of each sub-Channel. Bit error rates (BERs) of all links are below pre-forward-error-correction (pre-FEC) threshold of 3.8x 10−3 after 66-cm free-space delivery. The results show that this scheme has great potential in the practical VLC system.

  • demonstration of 575 mb s downlink and 225 mb s uplink bi directional scm wdm visible light communication using rgb led and phosphor based led
    Optics Express, 2013
    Co-Authors: Yuanquan Wang, Yiguang Wang, Nan Chi, Huiliang Shang
    Abstract:

    We propose and experimentally demonstrate a novel full-duplex bi-directional subcarrier multiplexing (SCM)-wavelength division multiplexing (WDM) visible light communication (VLC) system based on commercially available red-green-blue (RGB) light emitting diode (LED) and phosphor-based LED (P-LED) with 575-Mb/s downstream and 225-Mb/s upstream transmission, employing various modulation orders of quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM). For the downlink, red and green colors/wavelengths are assigned to carry useful information, while blue chip is just kept lighting to maintain the white color illumination, and for the uplink, the low-cost P-LED is implemented. In this demonstration, pre-equalization and post-equalization are also adopted to compensate the severe frequency response of LEDs. Using this scheme, 4-user downlink and 1-user uplink transmission can be achieved. Furthermore, it can support more users by adjusting the bandwidth of each sub-Channel. Bit error rates (BERs) of all links are below pre-forward-error-correction (pre-FEC) threshold of 3.8x 10−3 after 66-cm free-space delivery. The results show that this scheme has great potential in the practical VLC system.

Yuanquan Wang - One of the best experts on this subject based on the ideXlab platform.

  • demonstration of 575 mb s downlink and 225 mb s uplink bi directional scm wdm visible light communication using rgb led and phosphor based led
    Optics Express, 2013
    Co-Authors: Yuanquan Wang, Yiguang Wang, Nan Chi, Jianjun Yu, Huiliang Shang
    Abstract:

    We propose and experimentally demonstrate a novel full-duplex bi-directional subcarrier multiplexing (SCM)-wavelength division multiplexing (WDM) visible light communication (VLC) system based on commercially available red-green-blue (RGB) light emitting diode (LED) and phosphor-based LED (P-LED) with 575-Mb/s downstream and 225-Mb/s upstream transmission, employing various modulation orders of quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM). For the downlink, red and green colors/wavelengths are assigned to carry useful information, while blue chip is just kept lighting to maintain the white color illumination, and for the uplink, the low-cost P-LED is implemented. In this demonstration, pre-equalization and post-equalization are also adopted to compensate the severe frequency response of LEDs. Using this scheme, 4-user downlink and 1-user uplink transmission can be achieved. Furthermore, it can support more users by adjusting the bandwidth of each sub-Channel. Bit error rates (BERs) of all links are below pre-forward-error-correction (pre-FEC) threshold of 3.8x 10−3 after 66-cm free-space delivery. The results show that this scheme has great potential in the practical VLC system.

  • demonstration of 575 mb s downlink and 225 mb s uplink bi directional scm wdm visible light communication using rgb led and phosphor based led
    Optics Express, 2013
    Co-Authors: Yuanquan Wang, Yiguang Wang, Nan Chi, Huiliang Shang
    Abstract:

    We propose and experimentally demonstrate a novel full-duplex bi-directional subcarrier multiplexing (SCM)-wavelength division multiplexing (WDM) visible light communication (VLC) system based on commercially available red-green-blue (RGB) light emitting diode (LED) and phosphor-based LED (P-LED) with 575-Mb/s downstream and 225-Mb/s upstream transmission, employing various modulation orders of quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM). For the downlink, red and green colors/wavelengths are assigned to carry useful information, while blue chip is just kept lighting to maintain the white color illumination, and for the uplink, the low-cost P-LED is implemented. In this demonstration, pre-equalization and post-equalization are also adopted to compensate the severe frequency response of LEDs. Using this scheme, 4-user downlink and 1-user uplink transmission can be achieved. Furthermore, it can support more users by adjusting the bandwidth of each sub-Channel. Bit error rates (BERs) of all links are below pre-forward-error-correction (pre-FEC) threshold of 3.8x 10−3 after 66-cm free-space delivery. The results show that this scheme has great potential in the practical VLC system.

Alan C Bovik - One of the best experts on this subject based on the ideXlab platform.

  • a joint source Channel distortion model for jpeg compressed images
    IEEE Transactions on Image Processing, 2006
    Co-Authors: Muhammad Sabir, Hamid R Sheikh, Robert W Heath, Alan C Bovik
    Abstract:

    The need for efficient joint source-Channel coding (JSCC) is growing as new multimedia services are introduced in commercial wireless communication systems. An important component of practical JSCC schemes is a distortion model that can predict the quality of compressed digital multimedia such as images and videos. The usual approach in the JSCC literature for quantifying the distortion due to quantization and Channel errors is to estimate it for each image using the statistics of the image for a given signal-to-noise ratio (SNR). This is not an efficient approach in the design of real-time systems because of the computational complexity. A more useful and practical approach would be to design JSCC techniques that minimize average distortion for a large set of images based on some distortion model rather than carrying out per-image optimizations. However, models for estimating average distortion due to quantization and Channel Bit errors in a combined fashion for a large set of images are not available for practical image or video coding standards employing entropy coding and differential coding. This paper presents a statistical model for estimating the distortion introduced in progressive JPEG compressed images due to quantization and Channel Bit errors in a joint manner. Statistical modeling of important compression techniques such as Huffman coding, differential pulse-coding modulation, and run-length coding are included in the model. Examples show that the distortion in terms of peak signal-to-noise ratio (PSNR) can be predicted within a 2-dB maximum error over a variety of compression ratios and Bit-error rates. To illustrate the utility of the proposed model, we present an unequal power allocation scheme as a simple application of our model. Results show that it gives a PSNR gain of around 6.5 dB at low SNRs, as compared to equal power allocation.

  • a joint source Channel distortion model for jpeg compressed images
    International Conference on Image Processing, 2004
    Co-Authors: Muhammad Sabir, Hamid R Sheikh, Robert W Heath, Alan C Bovik
    Abstract:

    The need for efficient joint source-Channel coding is growing as new multimedia services are introduced in commercial wireless communication systems. An important component of practical joint source-Channel coding schemes is a distortion model to measure the quality of compressed digital multimedia such as images and videos. Unfortunately, models for estimating the distortion due to quantization and Channel Bit errors in a combined fashion do not appear to be available for practical image or video coding standards. This paper presents a statistical model for estimating the distortion introduced in progressive JPEG compressed images due to both quantization and Channel Bit errors. Important compression techniques such as Huffman coding, DPCM coding, and run-length coding are included in the model. Examples show that the distortion in terms of peak signal to noise ratio can be predicted within a 2 dB maximum error.

Nan Chi - One of the best experts on this subject based on the ideXlab platform.

  • demonstration of 575 mb s downlink and 225 mb s uplink bi directional scm wdm visible light communication using rgb led and phosphor based led
    Optics Express, 2013
    Co-Authors: Yuanquan Wang, Yiguang Wang, Nan Chi, Jianjun Yu, Huiliang Shang
    Abstract:

    We propose and experimentally demonstrate a novel full-duplex bi-directional subcarrier multiplexing (SCM)-wavelength division multiplexing (WDM) visible light communication (VLC) system based on commercially available red-green-blue (RGB) light emitting diode (LED) and phosphor-based LED (P-LED) with 575-Mb/s downstream and 225-Mb/s upstream transmission, employing various modulation orders of quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM). For the downlink, red and green colors/wavelengths are assigned to carry useful information, while blue chip is just kept lighting to maintain the white color illumination, and for the uplink, the low-cost P-LED is implemented. In this demonstration, pre-equalization and post-equalization are also adopted to compensate the severe frequency response of LEDs. Using this scheme, 4-user downlink and 1-user uplink transmission can be achieved. Furthermore, it can support more users by adjusting the bandwidth of each sub-Channel. Bit error rates (BERs) of all links are below pre-forward-error-correction (pre-FEC) threshold of 3.8x 10−3 after 66-cm free-space delivery. The results show that this scheme has great potential in the practical VLC system.

  • demonstration of 575 mb s downlink and 225 mb s uplink bi directional scm wdm visible light communication using rgb led and phosphor based led
    Optics Express, 2013
    Co-Authors: Yuanquan Wang, Yiguang Wang, Nan Chi, Huiliang Shang
    Abstract:

    We propose and experimentally demonstrate a novel full-duplex bi-directional subcarrier multiplexing (SCM)-wavelength division multiplexing (WDM) visible light communication (VLC) system based on commercially available red-green-blue (RGB) light emitting diode (LED) and phosphor-based LED (P-LED) with 575-Mb/s downstream and 225-Mb/s upstream transmission, employing various modulation orders of quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM). For the downlink, red and green colors/wavelengths are assigned to carry useful information, while blue chip is just kept lighting to maintain the white color illumination, and for the uplink, the low-cost P-LED is implemented. In this demonstration, pre-equalization and post-equalization are also adopted to compensate the severe frequency response of LEDs. Using this scheme, 4-user downlink and 1-user uplink transmission can be achieved. Furthermore, it can support more users by adjusting the bandwidth of each sub-Channel. Bit error rates (BERs) of all links are below pre-forward-error-correction (pre-FEC) threshold of 3.8x 10−3 after 66-cm free-space delivery. The results show that this scheme has great potential in the practical VLC system.

Yiguang Wang - One of the best experts on this subject based on the ideXlab platform.

  • demonstration of 575 mb s downlink and 225 mb s uplink bi directional scm wdm visible light communication using rgb led and phosphor based led
    Optics Express, 2013
    Co-Authors: Yuanquan Wang, Yiguang Wang, Nan Chi, Jianjun Yu, Huiliang Shang
    Abstract:

    We propose and experimentally demonstrate a novel full-duplex bi-directional subcarrier multiplexing (SCM)-wavelength division multiplexing (WDM) visible light communication (VLC) system based on commercially available red-green-blue (RGB) light emitting diode (LED) and phosphor-based LED (P-LED) with 575-Mb/s downstream and 225-Mb/s upstream transmission, employing various modulation orders of quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM). For the downlink, red and green colors/wavelengths are assigned to carry useful information, while blue chip is just kept lighting to maintain the white color illumination, and for the uplink, the low-cost P-LED is implemented. In this demonstration, pre-equalization and post-equalization are also adopted to compensate the severe frequency response of LEDs. Using this scheme, 4-user downlink and 1-user uplink transmission can be achieved. Furthermore, it can support more users by adjusting the bandwidth of each sub-Channel. Bit error rates (BERs) of all links are below pre-forward-error-correction (pre-FEC) threshold of 3.8x 10−3 after 66-cm free-space delivery. The results show that this scheme has great potential in the practical VLC system.

  • demonstration of 575 mb s downlink and 225 mb s uplink bi directional scm wdm visible light communication using rgb led and phosphor based led
    Optics Express, 2013
    Co-Authors: Yuanquan Wang, Yiguang Wang, Nan Chi, Huiliang Shang
    Abstract:

    We propose and experimentally demonstrate a novel full-duplex bi-directional subcarrier multiplexing (SCM)-wavelength division multiplexing (WDM) visible light communication (VLC) system based on commercially available red-green-blue (RGB) light emitting diode (LED) and phosphor-based LED (P-LED) with 575-Mb/s downstream and 225-Mb/s upstream transmission, employing various modulation orders of quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM). For the downlink, red and green colors/wavelengths are assigned to carry useful information, while blue chip is just kept lighting to maintain the white color illumination, and for the uplink, the low-cost P-LED is implemented. In this demonstration, pre-equalization and post-equalization are also adopted to compensate the severe frequency response of LEDs. Using this scheme, 4-user downlink and 1-user uplink transmission can be achieved. Furthermore, it can support more users by adjusting the bandwidth of each sub-Channel. Bit error rates (BERs) of all links are below pre-forward-error-correction (pre-FEC) threshold of 3.8x 10−3 after 66-cm free-space delivery. The results show that this scheme has great potential in the practical VLC system.