| 摘要 |
A robust IP/UDP/RTP header compression mechanism is provided to correctly reconstruct IP/UDP/RTP headers in the presence of packet losses and errors o f unreliable networks. The header compression mechanism may include a compressor/de-compressor implemented for operation similarly to RFC 2508 but designed specifically to address robustness when employed in lossy and error - prone networks. The robust header compression scheme requires that, when a second-order difference of a field is non-zero, not only a particular RTP packet whose second-order difference is non-zero is sent with the new first- order difference, but also those following packets are also sent with the ne w first-order difference as long as: (a) a pediod pre-determined by factors su ch as channel characteristics (e.g., link round-trip time RTT/inter-packet separation); or (b) a positive confirmation is received by the compressor th at the new first-order difference has been correctly received. In addition, during a period of communicating with the new first-order difference, if the corresponding RTP field changes again with non-zero second-order difference, the "new" first-order difference is combined with the original first-order difference such that the two first-order differences may be appended togethe r as a simple means of communicating the two-order differences reliably.</SDOA B>
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