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Transmission of Multiple Signals through an Optical Fiber Using Wavefront Shaping
Published on: March 20, 2017
Channel coding for progressive images in a 2-D time-frequency OFDM block with channel estimation errors.
Laura Toni1, Yee Sin Chan, Pamela C Cosman
1TERA, Italian Institute of Technology (IIT), Genova, Italy. laura.toni@iit.it
Summary
This study enhances mobile wireless transmission reliability for progressive image bitstreams using combined time and frequency diversity techniques in OFDM networks. Results show significant improvements in image quality, with up to 9.4 dB PSNR gain in challenging channel conditions.
Area of Science:
- Wireless Communications
- Information Theory
- Digital Signal Processing
Background:
- Mobile wireless environments face challenges like fading channels, impacting multimedia transmission reliability.
- Diversity techniques (time and frequency) are crucial for robust communication, especially for progressive image bitstreams.
- Orthogonal Frequency Division Multiplexing (OFDM) networks offer a framework for implementing these diversity strategies.
Purpose of the Study:
- To investigate the simultaneous use of time and frequency diversity for transmitting progressive image bitstreams in OFDM networks.
- To analyze the effectiveness of channel coding, specifically Forward Error Correction (FEC) and erasure codes, in mitigating channel impairments.
- To evaluate the impact of various channel conditions, including fading, coherence bandwidth/time, and channel estimation errors, on image quality.
Main Methods:
- Utilized a 2-D time-frequency resource block in an OFDM network.
- Implemented symmetric n-channel FEC-based multiple descriptions with channel erasure codes in the frequency domain.
- Employed a concatenation of Rate-Compatible Punctured Convolutional (RCPC) codes and Cyclic Redundancy Check (CRC) codes in the time domain.
- Considered intercarrier interference and channel estimation errors in the system model.
Main Results:
- Demonstrated significant gains in image quality (measured by Peak Signal-to-Noise Ratio - PSNR) compared to systems without temporal coding.
- Quantified up to a 9.4 dB PSNR increase in a specific scenario with flat fading, low Doppler, and imperfect Channel State Information (CSI).
- Analyzed tradeoffs between frequency-domain erasure codes and time-domain convolutional codes under diverse physical environments.
Conclusions:
- The proposed 2-D time-frequency coding scheme effectively improves the transmission reliability of progressive image bitstreams in mobile wireless environments.
- Simultaneous application of time and frequency diversity, coupled with appropriate channel coding, offers substantial performance benefits.
- The study provides valuable insights into optimizing multimedia communication systems over fading channels.
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