Error detection/correction and fault detection/recovery – Pulse or data error handling – Memory testing
Patent
1999-03-04
2000-10-31
Chung, Phung M.
Error detection/correction and fault detection/recovery
Pulse or data error handling
Memory testing
375225, 714701, G01R 3128
Patent
active
061417815
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method for processing data via a channel with a variable channel bit rate.
BACKGROUND INFORMATION
The standard H 324 M for mobile video telephone applications admits all possible mobile radio systems so that the requirement for an available data rate (channel bit rate) can be different. Even within a communications system, the available bit rate for speech and video channel codecs can be different.
German Patent Application No. 41 37 609 describes, a method for decoding binary signals from binary signals transmitted via a channel and processed using an error-correcting code is known. The bit error probability is evaluated and a decision made whether the received bits are correct or errored.
European Patent Application No. 0 643 493 describes an error correction method for a digital cellular radio system. This European Patent Application describes that data are divided into three different bit classes with different error protection. For the division into the different bit classes, evaluation of the speech sampled values takes place based on "A-factor analysis" and using speech intelligibility tests.
SUMMARY OF THE INVENTION
An adaptation of a channel codec for any transmission method can be achieved.
Unlike conventional transmission methods, a specific channel codec, e.g., a channel codec especially for GSM or DECT, does not need to be provided for each communications system, e.g., a mobile radio system. The method according to the present invention works reliably even if the available channel bit rate is unknown. According to the present invention, the configuration of a channel encoder and a corresponding channel decoder depends only on the available channel codec bit rate. Transmission according to G.723.1 Standard via mobile radio channels with different channel bit rates is possible without changing the channel encoder or decoder. The channel encoders or rather decoders only need be designed to be scalable, i.e., the code rate is changed in steps as a function of the channel bit rate.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a block diagram for data processing according to the present invention.
FIG. 2 shows exemplary embodiments for a bit distribution among bit classes and weighting factors of the bit classes.
FIG. 3 shows the bit distribution among the bit classes and a code rate for different channel bit rates.
FIG. 4 shows another embodiment of the bit distribution for a different transmission method.
DETAILED DESCRIPTION
As is shown in FIG. 1, the information bits of a source coder 1 to be processed, e.g., according to communications standard G.723.1, are arranged in a unit 2 as a function of their error sensitivity. The most sensitive bit is placed at the first location of the arranged data stream and the least sensitive bit at the last position. Determination of the error sensitivity of information bits is based on known measurement techniques that were proposed in conjunction with G.723.1. The data stream arranged in this manner is now divided into different bit classes c [i] (--block 3--) where, say, i=0, . . . , 4, with c [0] containing the most error-sensitive bits and c [4] the least error-sensitive bits. Then, a weighting factor w [i], i=0, . . . , 4 (--block 4--) is assigned to each bit class to control the allocation of the bit rate (code rate) r for the individual bit classes. The weighting factor w [i] is chosen as a function of the average error sensitivity of the respective bit class c [i]. Here, the code rate r indicates the ratio of the number of information bits k to the number of transmission bits n as described in Furrer, "Fehlerkorrigierende Block-Codierung fur die Datenubertragung", [Error-Correcting Block Encoding for Data Communications] Birkhauser-Verlag, Basel, 1981, p. 270):
If r=1, the information bits are transmitted unprotected. For r=1/2, each information bit is provided with a redundant error protection bit. The bits in class 4 receive no protection. Class c [0] contains c [0] -3 informatio
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F.J. Furrer, "Fehlerkorrigierende Block-Codierung fur die Datenubertragung", Birkhauser-Verlag, Basel, 1981, p. 270.* (No translation).
Chung Phung M.
Robert & Bosch GmbH
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