디지털통신

제14주

Signal Processing Lab., http://signal.korea.ac.krDept. of Elec. and Info. Engr., Korea Univ.

2016년 6월 27일2 page

Example of Hard-Decision Viterbi Decoding Summary (cont’d)

Signal Processing Lab., http://signal.korea.ac.krDept. of Elec. and Info. Engr., Korea Univ.

2016년 6월 27일3 page

Signal Processing Lab., http://signal.korea.ac.krDept. of Elec. and Info. Engr., Korea Univ.

2016년 6월 27일4 page

Path Memory Length h: (4 or 5) times K

Required Path Storages u = h2K-1

Signal Processing Lab., http://signal.korea.ac.krDept. of Elec. and Info. Engr., Korea Univ.

2016년 6월 27일5 page

Soft-Decision Viterbi Decoding

Signal Processing Lab., http://signal.korea.ac.krDept. of Elec. and Info. Engr., Korea Univ.

2016년 6월 27일6 page

Free Distance of Convolutional Codes Distance properties:

Since the code is linear, the minimum distance of the code is the minimum distance between each of the codewords and the all-zero codeword.

This is the minimum distance in the set of all arbitrary long paths along the trellis that diverge and remerge to the all-zero path.

Signal Processing Lab., http://signal.korea.ac.krDept. of Elec. and Info. Engr., Korea Univ.

2016년 6월 27일7 page

Free Distance of Convolutional Codes (cont’d)

Signal Processing Lab., http://signal.korea.ac.krDept. of Elec. and Info. Engr., Korea Univ.

2016년 6월 27일8 page

Performance Bounds for Convolutional Codes (cont’d)

Error correction capability of convolutional codes is given by

For a given code rate, increasing the constraint length usually increases the free distance.

For a given constraint length, decreasing the coding rate usually increases the free distance.

But the coding gain is upper bounded

2/)1( fdt

)(10loggain coding 10 fcdR

Signal Processing Lab., http://signal.korea.ac.krDept. of Elec. and Info. Engr., Korea Univ.

2016년 6월 27일9 page

Signal Processing Lab., http://signal.korea.ac.krDept. of Elec. and Info. Engr., Korea Univ.

2016년 6월 27일10 page

Comparison of Free Distance

Signal Processing Lab., http://signal.korea.ac.krDept. of Elec. and Info. Engr., Korea Univ.

2016년 6월 27일11 page

Performance Bounds for Convolutional Codes (Hard-Decision Decoding)

1/3

Signal Processing Lab., http://signal.korea.ac.krDept. of Elec. and Info. Engr., Korea Univ.

2016년 6월 27일12 page

Performance Bounds for Convolutional Codes (Soft-Decision Decoding)

Signal Processing Lab., http://signal.korea.ac.krDept. of Elec. and Info. Engr., Korea Univ.

2016년 6월 27일13 page

Path Memoryh = 32