Journal of the Institute of Electronics Engineers of Korea SP (대한전자공학회논문지SP)

The Institute of Electronics and Information Engineers (대한전자공학회)
권호 표지

Low-Delay LSF FEC Technique Robust in Lossy VoIP Environment

VoIP 손실 환경에 강인한 저지연 LSF FEC 기법

  • Yang, Hae-Yong (Aplication Technology Research Department, National Security Research Institute) ;
  • Lee, Kyung-Hoon (Aplication Technology Research Department, National Security Research Institute) ;
  • Hwang, In-Ho (Aplication Technology Research Department, National Security Research Institute)
  • 양해용 (國家保安技術硏究所 應用技術硏究部) ;
  • 이경훈 (國家保安技術硏究所 應用技術硏究部) ;
  • 황인호 (國家保安技術硏究所 應用技術硏究部)
  • Published : 2002.11.01
Download PDF
⟨ Previous Next ⟩

Abstract

Media-specific FEC techniques, suggested to confront with VoIP speech packet loss, improve speech quality at the expense of generating additional one-frame delay. In this paper, we suggest new media-specific FEC, i.e, LSF FEC technique which is able to improve speech quality with much shortened additional delay. In the proposed technique, the LSF parameters of the future frame are utilized to recover a lost packet. To evaluate performance of the proposed technique, we use ITU-T G.723.1 and G.729 Codec and apply Gilbert packet loss model and estimate MOS per every packet loss rate using PESQ speech quality estimation algorithm. The proposed technique has effect of shortening delay over from 6.5ms to 27ms compared with existing media-specific FEC techniques. Simulation results for comparison of reconstructed speech quality show this novel technique improves the MOS over 0.1 in practical lossy environment of 5 % packet loss rate.

VoIP 음성 패킷 손실에 대한 대응 방안으로 제시되고 있는 매체 종속 FEC 기법은 통화 품질을 개선시키는 효과를 갖는데 반하여 한 프레임에 해당하는 추가지연이 발생하는 단점을 갖는다. 본 논문에서는 패킷 손실 복원에 사용되는 잉여 정보로 미래 프레임의 LSF 성분을 사용함으로써, 전송 지연을 줄이고 통화 품질을 개선할 수 있는 LSF FEC 기법을 제안하고 그 성능을 평가한다. 성능 평가를 위해서 VoIP에서 사용하는 ITU-T G.723.1, G.729 코덱을 Gilbert 손실 모델에 적용하고, PESQ 음질 측정 알고리즘을 사용하여 각 손실률 별로 MOS를 추정하는 방법을 사용한다. 본 논문에서 제안한 기법은 기존의 매체 종속 FEC 기법에 비해서 6.5ms∼27ms 이상의 지연 감소 효과를 가지고 있는 것으로 나타났으며, FEC를 적용하지 않은 경우와의 복원 음성 품질 비교 시뮬레이션 결과, 5% 정도의 현실적인 손실 환경에서 MOS 0.1 이상의 음질 개선 효과를 보였다.

Keywords

References

  1. B. Duysburgh, S. Vanhastel, B. De Vreese, C. Petrisor, P. Demeester, 'On the influence of best-effort network conditions on the perceived speech quality of VoIP connections,' Proceedings of IEEE International Conference on Computer Communications and Networks, 2001, pp. 334-339 https://doi.org/10.1109/ICCCN.2001.956284
  2. C. Perkins, O. Hodson, V. Hardman, 'A Survey of packet loss recovery techniques for Streaming Audio,' IEEE Network, Sep./Oct., 1998 https://doi.org/10.1109/65.730750
  3. N. Erdol, C. Castelluccia, A. Zilouchian, 'Recovery of missing speech packets using the short-time energy and zero-crossing measurements,' Trans. Speech and Audio Processing, Vol. 1, No. 3, pp. 295-303, Jul. 1993 https://doi.org/10.1109/89.232613
  4. V. Hardman et al., 'Reliable audio for use over the Internet,' Proc. INET 95, 1995
  5. J. -C. Bolot and A. Vega-Garcia, 'The case for FEC based error control for packet audio in the Internet,' to appear, ACM Multimedia Sys.
  6. S. M. Lee, S. Park, Y. Jang, 'Cost-effective implementation of ITU-T G.723.1 on a DSP chip,' Proc. of the 1997 IEEE Int. Sym. on Cons. Elec., pp. 31-34 https://doi.org/10.1109/ISCE.1997.658344
  7. R. Salami, C. Laflamme, B. Bessette, J-P. Adoul, 'Description of ITU-T recommendation G.729 ANNEX A: reduced complexity 8 Kbps CS-ACELP codec,' ICASSP-97, 1997 IEEE International Conference on ASSP, Vol. 2, pp. 775-778, 1997 https://doi.org/10.1109/ICASSP.1997.596039
  8. T. Miyata, H. Fukuda, S. Ono, 'Characteristics of successive loss process,' Proc. 15th IEEE Int. Conf. on Information Networking, 2001 https://doi.org/10.1109/ICOIN.2001.905536
  9. D. Veitch, 'Understanding end-to-end Internet traffic dynamics,' IEEE Globecom 98, Nov. 1998 https://doi.org/10.1109/GLOCOM.1998.776
  10. Dan Rubenstein, Jim Kurose, Don Towsley, 'Real-time reliable multicast using proactive forward error correction,' UMASS CMPSCI Technical Report pp. 98-99, 1998
  11. A. W. Rix, J. G. Beerends, M. P. Hollier, A. P. Hekstra, 'Perceputal evaluation of speech quality (PESQ)-a new method for speech quality assessment of telephone networks and codes,' ASSP 2001, Vol 2, pp. 749-752 https://doi.org/10.1109/ICASSP.2001.941023
  12. ITU-T Rec. P.862, 'Perceptual evaluation of speech quality (PESQ), an objective method for end-to-end speech quality assessment of narrowband telephone networks and speech codecs,' Jan. 2002