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H.324M: Overview & Update

H.324M: Overview & Update. Marko Luomi, Senthil Sengodan Nokia. Outline. H.324M Motivation & Requirement H.324M Standard Future Directions. H.324M in ITU-T. H.324M has been developed in the ITU-T SG16 Q11 Mobile Group The members of the group have been: universities,

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H.324M: Overview & Update

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  1. H.324M: Overview & Update Marko Luomi, Senthil Sengodan Nokia

  2. Outline • H.324M Motivation & Requirement • H.324M Standard • Future Directions

  3. H.324M in ITU-T • H.324M has been developed in the ITU-T SG16 Q11 Mobile Group • The members of the group have been: • universities, • mobile network operators, • mobile terminal manufacturers as well as • PSTN H.324 vendors etc.

  4. Why H.324M? • H.324 is a bandwidth efficient solution for circuit-switched multimedia communications. • Increasing data rates enable the usage of H.324 in "2G mobile networks (such as GSM, IS-136, and IS-95), 3G mobile networks, DECT, etc." • However, other characteristics of the networks like bit error rate and delay differ from PSTN. • Therefore changes were required to adopt H.324 to mobile environment.

  5. What H.324M Is? • In terms of standards: • It is an extension to H.324. • Annex C of ITU-T Recommendation H.324: “Terminal for low bit rate multimedia communication”. • ITU-T Recommendation H.223 - Annex A: “Multiplexing protocol for low bit rate multimedia mobile communication over low error-prone channels”. • ITU-T Recommendation H.223 - Annex B: “Multiplexing protocol for low bit rate multimedia mobile communication over moderate error-prone channels”. • ITU-T Recommendation H.223 - Annex C: “Multiplexing protocol for low bit rate multimedia mobile communication over highly error-phone channels”. • ITU-T Recommendation H.223 — Annex D: “Optional multiplexing protocol for low bit rate multimedia communication over highly error-prone channels”. • The relevant parts of the ITU-T Recommendation H.245, version 3: “Control protocol for multimedia communication”.

  6. What H.324M Is? • H.324M is backward compatible with H.324. • In terms of functionalities: • H.324M provides a toolbox to enhance the error robustness of the H.223 multiplexer. • In the Annex A the HDLC flag used to delimit multiplex packets in H.223 is replaced with a longer flag and HDLC bit stuffing is not used. • In addition to previous, the multiplex header is more error robust and packet length field is introduced in Annex B. • In addition to previous, forward error correction is applied to the payload in the Annexes C and D.

  7. What H.324M Is? • At the beginning of the connection terminals select the highest common level. • Later the used level can be changed dynamically. • Addition to changes to the multiplexer a Control Channel Segmentation and Reassembly Layer (CCSRL) was introduced to ensure the faster transfer of control information in error prone environment. • Possibility to use codecs suitable for mobile environment like GSM AMR speech codec and MPEG4 visual.

  8. Related Activities • Co-operation with ITU-T SG16 Q15: • support error resilience improvements to the H.263 video codec, and • create a realistic simulation model for video error resilience experiments. • Interoperability experiments: • Interoperability group has tested all new main functionalities introduced by H.324M. • Initiative has been done to sift these tests under the IMTC H.324 test group. • 3rd Generation Partnership Project (3GPP) uses H.324M as a basis for circuit-switched multimedia telephony service.

  9. Current Status of Standards • Annex C of H.324, decided • Annexes A, B, and C of H.223, decided • Annex D of H.223, determined • H.245 version 5, determined

  10. Future Activities • Continue improvements to video quality in the mobile environment in coordination with ITU-T SG16 Q.15. • Work on new methods for unequal error protection strategies between systems and video. • Develop Mobile Multilink

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