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Voice Quality Evaluation for Wireless Transmission with ROHC

Voice Quality Evaluation for Wireless Transmission with ROHC. S. Rein and F.H.P. Fitzek and M. Reisslein

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Voice Quality Evaluation for Wireless Transmission with ROHC

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  1. Voice Quality Evaluation for Wireless Transmission with ROHC S. Rein and F.H.P. Fitzek and M. Reisslein Voice Quality Evaluation for Wireless Transmission with ROHC. 2003. in International Conference on Internet and Multimedia Systems and Applications (IMSA 2003), pages 461-466. Honolulu, USA.

  2. Protocol suite with ROHC Original voice Transmitted voice GSM Encoder GSM Decoder RTP RTP UDP UDP IP IP Communication System IP UDP RTP GSM ROHC ROHC ROHC GSM link UMTS link error simulation link

  3. Methodology for ROHC evaluation Calculate gain for ROHC Predict ROHC speech quality Predict speech quality Distorted speech Original speech Distorted speech Communication System with ROHC Communication System without ROHC

  4. Voice quality evaluation framework • Usually expensive software required (state of the art PESQ software available for 10.000 U.S.$) • Alternative methodology: used a set of elementary objective metrics to predict the subjective voice quality • Metrics represent sensible engineering trade off to networking studies • Performance of the metrics is usually verified by a correlation analysis

  5. Voice quality metrics: Correlations to subjective quality

  6. Combined Metric • Every metric covers different distortion types • Coding and noise distortions in the time and frequency domain • Good reliability by including metrics verified by different authors

  7. Segmental Cross Correlation • Varying delay with IP packet voice • Reference and transmitted voice file have to be synchronized • Developed segmental cross correlation (SCC) algorithm in the time domain • SCC makes elementary metrics usable for modern communication systems

  8. Segmental Synchronization Segmental Synchronization missing samples wrongly inserted

  9. Results: Delay jitter measurements

  10. Results: SNR measurements

  11. Results: voice quality

  12. Results: voice quality

  13. Results: Mean Opinion Score

  14. Conclusion • On top of bandwidth savings: Voice quality is improved • ROHC roughly cuts bandwidth for voice transmission in half • ROHC is a very useful complement to third generation mobile systems

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