To check and correct errors in the transmission of redundant data and information derived from the data are added to the current so as to increase the bit rate. For voice, the length of these codes is 456 bits every 20 ms.
The bit rate of the code stream output from the vocoder is 13 kbit / s, which is divided into several continuous segments 20ms each segment containing 260 bits. They can be classified as follows:
Redundancy treatment is carried out, as shown in the diagram above.
The block encoder is applied to three-bit redundancy code, while the excited encoder applies with double redundancy, then added 4 tail bits in the data stream.
There are three methods of channel coding in the GSM system convolution coding, block coding and parity coding.
The bit rate of the code stream output from the vocoder is 13 kbit / s, which is divided into several continuous segments 20ms each segment containing 260 bits. They can be classified as follows:
- Very significant 50 bits;
- 132 important pieces;
- 78 ordinary pieces
Redundancy treatment is carried out, as shown in the diagram above.
The block encoder is applied to three-bit redundancy code, while the excited encoder applies with double redundancy, then added 4 tail bits in the data stream.
There are three methods of channel coding in the GSM system convolution coding, block coding and parity coding.
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