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Update of header compression state in packet communications

A head and communication station technology, applied in the direction of security communication devices, digital transmission systems, electrical components, etc., can solve problems such as not being used by voice decoders, loss of specific packets, and destruction of soft state cycles

Inactive Publication Date: 2004-08-18
TELEFON AB LM ERICSSON (PUBL)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] (1) A bit error in part 13 of Figure 1 (the least significant speech codec bit) will result in a slight degradation of the speech quality carried by a particular packet
[0010] (2) A bit error in part 12 of Figure 1 (the most significant speech codec bit) will result in a severe degradation of the speech quality, so that the packet is judged useless and not used by the speech codec
Therefore, bit errors in 12 parts of a packet will cause a particular packet to be lost
[0011] (3) The bit error (header, compressed or uncompressed) of part 11 in Figure 1 may cause the loss of a specific packet because it cannot be transmitted to the upper layer of the protocol stack
However, this approach requires a duplex channel with a short round trip time to keep the corrupted soft-state period small

Method used

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  • Update of header compression state in packet communications
  • Update of header compression state in packet communications
  • Update of header compression state in packet communications

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Embodiment Construction

[0034] The exemplary implementation of the present invention cooperates with the DTX technology used in most traditional digital voice services. DTX (Discontinuous Transmission) includes techniques to detect periods of non-speech (silence) and to send only silence descriptors (SID frames) during these periods in order to generate comfort noise at the receiving end. This comfort noise provides the illusion that the sound is being sent continuously. Therefore, during the non-speech period, the transmitted packet has a format similar to that shown in FIG. 1 except for the payload part (parts 12 and 13) with the SID frame. Figures 2 and 3 show the traditional DTX schemes, namely the original DTX (Figure 2) and the so-called soft DTX (Figure 3).

[0035]According to an exemplary embodiment of the present invention, header update information may be added to the SID frame of FIG. 2 or replace the SID frame of FIG. 2 . For example in GSM, a SID frame (see 21 in Fig. 2) is sent perio...

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Abstract

The soft state of a header compression scheme in a communication system carrying packet traffic including a real time communication signal can be updated (63) during periods of communication signal inactivity, during which there is no need to transmit the communication signal. The header compression soft state can also be updated by stealing bits (83, 84) from the communication signal to carry the header update information (73). If the communication signal includes source encoded data, the header compression soft state can be updated selectively (126) based on the bit rate (122, 124) of a codec that produced the source encoded data.

Description

technical field [0001] The present invention relates generally to packet communications, and more particularly to header compression in packet communications. Background technique [0002] The term header compression (HC) refers to techniques for minimizing the bandwidth required to carry information in packet headers on a per-hop basis in point-to-point links. Header compression is usually implemented initially by sending only static information. Semi-static information is then sent by sending only changes to previous headers and completely random information is sent without compression. Therefore, header compression is usually implemented by a state machine. [0003] A traditional VoIP packet (Voice over IP) basically includes three parts with different quality requirements, as shown in FIG. 1 . The three parts are: [0004] (1) A compressed or uncompressed header 11. For example, traditional IP / UDP / RTP headers are often used for real-time voice;...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L1/00H04L12/56H04L29/06
CPCH04L29/06095H04L29/0653H04L29/06102H04L29/0604H04L29/06H04L69/04H04L69/16H04L69/22H04L69/161H04L9/40
Inventor L·维斯特贝里K·斯万布罗J·松德奎斯特
Owner TELEFON AB LM ERICSSON (PUBL)