Jun 26, 2007 - h(l): i.i.d Rayleigh fading (Broadband, frequency interleaver). Wei Jiang .... survivor path at each stag
Convolutional Multi-code Multiplexing for OFDM Systems Wei Jiang, Daoben Li School of Information Engineering Beijing University of Posts and Telecommunications
[email protected]
June 26, 2007
Wei Jiang (BUPT)
OFDM-CMM
ICC 2007
1 / 25
Outline
1
Multiplexing in Multicarrier Systems
2
OFDM-CMM System Model
3
Maximum Likelihood Detection
4
Code Design
5
Simulation Results
Wei Jiang (BUPT)
OFDM-CMM
ICC 2007
2 / 25
Outline
1
Multiplexing in Multicarrier Systems
2
OFDM-CMM System Model
3
Maximum Likelihood Detection
4
Code Design
5
Simulation Results
Wei Jiang (BUPT)
OFDM-CMM
ICC 2007
3 / 25
Multiplexing in Multicarrier Systems Orthogonal Frequency Division Multiplexing(OFDM/OFDMA): High spectrum efficiency Immune to inter-symbol interference Simple implementation ... Flat fading on each subcarrier, have to use error correcting codes or power/rate adaptation
...
Frequency
Code-Division Multiplexing(OFDM-CDM) Spread symbol onto multiple subcarriers Achieve frequency diversity gain, limited Wei Jiang (BUPT)
OFDM-CMM
ICC 2007
4 / 25
Outline
1
Multiplexing in Multicarrier Systems
2
OFDM-CMM System Model
3
Maximum Likelihood Detection
4
Code Design
5
Simulation Results
Wei Jiang (BUPT)
OFDM-CMM
ICC 2007
5 / 25
Convolutional Multi-code Multiplexing: System Model d1
Symbol Mapper
d2
S2
Convolutional Spreader1
X
Convolutional Spreader2
Interleaver
IFFT
CP
D/A
...
Symbol Mapper
S1
dK
Symbol Mapper
SK
Convolutional Spreader
K
Figure: OFDM-CMM System Model Ck (1) ×
S1
S3
S1
S2
SL
S3
SL
...
Ck ( 2 ) ×
S2
Ck ( N ) ×
S1
S2
S3
SL Frequency
Figure: OFDM-CMM Symbols in Frequency Wei Jiang (BUPT)
OFDM-CMM
ICC 2007
6 / 25
Convolutional Spreader
S k (l)
S k (l-1 ) D
C k (1)
C k (2)
S k (l-N+2 )
D
..
S k (l-N+1 )
..
D
C k (N-1 )
C k (N)
X (k ,l)
Figure: Convolutional Spreader with transversal filter implementation
X(l) =
K X N X
Ck (n)Sk (l − n + ), < l ≤ L,
k= n=
The spreading code Ck = [Ck (), Ck (), · · · , Ck (N )] , ≤ k ≤ K is the designing freedom. Wei Jiang (BUPT)
OFDM-CMM
ICC 2007
7 / 25
Channel Model
AWGN channel Y (l) = X(l) + n(l),
