TRUY N THÔNG SỀ Ố
DIGITAL COMMUNICATION
Tu n 8ầ
Mã hóa kênh p3
1
Reference
•“Digital communications: Fundamentals
and Applications” by Bernard Sklar
•Catharina Logothetis’s Lecture, Uppsala
University
2
3
Last time
•Mã ch p (Convolutional codes).ậ
•C u trúc c a b mã hóa (structure of the ấ ủ ộ
encoder).
•Các ph ng pháp bi u di n b mã hóa.ươ ể ễ ộ
4
Block diagram of the DCS
Information
source
Rate 1/n
Conv. encoder Modulator
Information
sink
Rate 1/n
Conv. decoder Demodulator
sequenceInput
21
,...),...,,(
i
mmm
=
m
bits) coded ( rdBranch wo
1
sequence Codeword
321
,...),...,,,(
n
nijiii
i
,...,u,...,uuU
UUUU
=
=
=G(m)U
,...)
ˆ
,...,
ˆ
,
ˆ
(
ˆ
21 i
mmm
=
m
dBranch worper outputs
1
dBranch worfor
outputsr Demodulato
sequence received
321
,...),...,,,(
n
nijii
i
i
i
,...,z,...,zzZ
ZZZZ
=
=Z
Channel
5