Wavecom W-BitView V2.5.00 - Manual (Page 43)

BitView Manual V2.5.00 WAVECOM W-BV Function Library
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Decoding/Equalizer
Viterbi-Decoding
In: Bit stream
Out: Bit stream
Function:
Decode the incoming bit stream using the Viterbi algorithm - a maximum-likelihood decoding procedure
for convolutional codes.
Parameter
Constraint length Equals K, where K is the number of memories of the shift register in the encoder
Decision best state Use best state or not
Last decoder state Initial state of the decoder
Metric Select hard or soft decision
Mode Select whether the input data should be treated as a continuous stream or a stream of
bursts.
Soft decision bits If soft decision is used, enter the number of soft decision bits
De-Puncturing
In: Bit stream
Out: Bit stream
Function:
This function adds de-puncturing and probability bits to the input bit stream.
Parameter Value
Frame Bits are inserted according to the entered bit pattern. The length of the bit pattern corre-
sponds to the frame length. At positions marked with a ‘0’, a bit is inserted. Additionally, for
every input bit, a probability bit is added. For received bits (marked with a ‘1’ in the frame
pattern), a ‘1’ probability bit is added - for inserted bits, a ‘0’ probability bit is added (equals
a probability of 0.5)
Example with a frame pattern of “110”:
The frame pattern “110” means that after two input bits, a de-puncturing bit must be inserted so “1111”
becomes “111100111100”.