用matlab进行BPSK调制和解调的仿真

2024-11-05 22:04:56

推荐回答（2个）

回答（1）：

function output_frame = demodulation(input_modu, index)
% demodulation for IEEE802.11a
% Input: input_modu, complex values representing constellation points
% index
% Output: output_frame, output bit stream (data unit is one bit)

% In this version, increase the quatilization levels into 8.
% note: Matlab index starts from 1
Q_length=length(input_modu);
QAM_input_I = real(input_modu);
QAM_input_Q = imag(input_modu);
output_frame = zeros(1,length(input_modu)*index);
switch index
case 1,
BPSK_Demodu_I = [0 1]; %f(m)=(m+1)/2 + 1, so I=-1 ---> 1, I=1 ---> 2
idx = find(QAM_input_I>1);
QAM_input_I(idx) = 1;
idx = find(QAM_input_I<-1);
QAM_input_I(idx) = -1;
output_frame = BPSK_Demodu_I(round((QAM_input_I+1)/2) + 1);
case 2,
QPSK_Demodu_IQ = [0 1]; %f(m)=(m+1)/2 + 1, so I=-1 ---> 1, I=1 ---> 2
idx = find(QAM_input_I>1);
QAM_input_I(idx) = 1;
idx = find(QAM_input_I<-1);
QAM_input_I(idx) = -1;
idx = find(QAM_input_Q>1);
QAM_input_Q(idx) = 1;
idx = find(QAM_input_Q<-1);
QAM_input_Q(idx) = -1;
output_frame(1:2:end) = QPSK_Demodu_IQ(round((QAM_input_I+1)/2) + 1);
output_frame(2:2:end) = QPSK_Demodu_IQ(round((QAM_input_Q+1)/2) + 1);
case 3,
remapping=[0 0 0;0 0 1;0 1 0;0 1 1;1 0 0;1 0 1;1 1 0;1 1 1].';
for i=1:Q_length
phase_det=[2 a=find(phase_det);
output_frame((1+(i-1)*3):(3+(i-1)*3))=remapping((1+(a-1)*3):(3+(a-1)*3));
end
case 4,
QAM_16_Demodu_IQ = [0 1 3 2]; %f(m)=(m+3)/2 + 1, so I=-3 ---> 1, I=1 ---> 3
idx = find(QAM_input_I>3);
QAM_input_I(idx) = 3;
idx = find(QAM_input_I<-3);
QAM_input_I(idx) = -3;
idx = find(QAM_input_Q>3);
QAM_input_Q(idx) = 3;
idx = find(QAM_input_Q<-3);
QAM_input_Q(idx) = -3;
tmp = round((QAM_input_I+3)/2) + 1;
output_frame(1:4:end) = bitget(QAM_16_Demodu_IQ(tmp),2);
output_frame(2:4:end) = bitget(QAM_16_Demodu_IQ(tmp),1);
tmp = round((QAM_input_Q+3)/2) + 1;
output_frame(3:4:end) = bitget(QAM_16_Demodu_IQ(tmp),2);
output_frame(4:4:end) = bitget(QAM_16_Demodu_IQ(tmp),1);
case 5,
remapping=[0 0 0 0 0;0 0 0 0 1;0 0 0 1 0;0 0 0 1 1;0 0 1 0 0;0 0 1 0 1;0 0 1 1 0;0 0 1 1 1;
0 1 0 0 0;0 1 0 0 1;0 1 0 1 0;0 1 0 1 1;0 1 1 0 0;0 1 1 0 1;0 1 1 1 0;0 1 1 1 1;
1 0 0 0 0;1 0 0 0 1;1 0 0 1 0;1 0 0 1 1;1 0 1 0 0;1 0 1 0 1;1 0 1 1 0;1 0 1 1 1;
1 1 0 0 0;1 1 0 0 1;1 1 0 1 0;1 1 0 1 1;1 1 1 0 0;1 1 1 0 1;1 1 1 1 0;1 1 1 1 1].';
for i=1:Q_length
phase_det=[4 2 QAM_input_I(i)<-4&0 -4 QAM_input_I(i)<-4&-2 -4 4 2 a=find(phase_det);
output_frame((1+(i-1)*5):(5+(i-1)*5))=remapping((1+(a-1)*5):(5+(a-1)*5));
end %5+i 3+i 1+i 5+3*i 3+3*i 1+3*i 3+5*i 1+5*i -5+i -3+i -1+i -5+3*i -3+3*i -1+3*i -3+5*i -1+5*i -5-i -3-i -1-i -5-3*i -3-3*i -1-3*i -3-5*i -1-5*i 5-i 3-i 1-i 5-3*i 3-3*i 1-3*i 3-5*i 1-5*i
case 6,
QAM_64_Demodu_IQ = [0 1 3 2 6 7 5 4]; %f(m)=(m+7)/2 + 1, so I=-7 ---> 1, I=1 ---> 5
idx = find(QAM_input_I>7);
QAM_input_I(idx) = 7;
idx = find(QAM_input_I<-7);
QAM_input_I(idx) = -7;
idx = find(QAM_input_Q>7);
QAM_input_Q(idx) = 7;
idx = find(QAM_input_Q<-7);
QAM_input_Q(idx) = -7;
tmp = round((QAM_input_I+7)/2) + 1;
output_frame(1:6:end) = bitget(QAM_64_Demodu_IQ(tmp),3);
output_frame(2:6:end) = bitget(QAM_64_Demodu_IQ(tmp),2);
output_frame(3:6:end) = bitget(QAM_64_Demodu_IQ(tmp),1);
tmp = round((QAM_input_Q+7)/2) + 1;
output_frame(4:6:end) = bitget(QAM_64_Demodu_IQ(tmp),3);
output_frame(5:6:end) = bitget(QAM_64_Demodu_IQ(tmp),2);
output_frame(6:6:end) = bitget(QAM_64_Demodu_IQ(tmp),1);
end

回答（2）：

function
output_frame
=
demodulation(input_modu,
index)
%
demodulation
for
IEEE802.11a
%
Input:
input_modu,
complex
values
representing
constellation
points
%
index
%
Output:
output_frame,
output
bit
stream
(data
unit
is
one
bit)
%
In
this
version,
increase
the
quatilization
levels
into
8.
%
note:
Matlab
index
starts
from
1
Q_length=length(input_modu);
QAM_input_I
=
real(input_modu);
QAM_input_Q
=
imag(input_modu);
output_frame
=
zeros(1,length(input_modu)*index);
switch
index
case
1,
BPSK_Demodu_I
=
[0
1];
%f(m)=(m+1)/2
+
1,
so
I=-1
--->
1,
I=1
--->
2
idx
=
find(QAM_input_I>1);
QAM_input_I(idx)
=
1;
idx
=
find(QAM_input_I<-1);
QAM_input_I(idx)
=
-1;
output_frame
=
BPSK_Demodu_I(round((QAM_input_I+1)/2)
+
1);
case
2,
QPSK_Demodu_IQ
=
[0
1];
%f(m)=(m+1)/2
+
1,
so
I=-1
--->
1,
I=1
--->
2
idx
=
find(QAM_input_I>1);
QAM_input_I(idx)
=
1;
idx
=
find(QAM_input_I<-1);
QAM_input_I(idx)
=
-1;
idx
=
find(QAM_input_Q>1);
QAM_input_Q(idx)
=
1;
idx
=
find(QAM_input_Q<-1);
QAM_input_Q(idx)
=
-1;
output_frame(1:2:end)
=
QPSK_Demodu_IQ(round((QAM_input_I+1)/2)
+
1);
output_frame(2:2:end)
=
QPSK_Demodu_IQ(round((QAM_input_Q+1)/2)
+
1);
case
3,
remapping=[0
0
0;0
0
1;0
1
0;0
1
1;1
0
0;1
0
1;1
1
0;1
1
1].';
for
i=1:Q_length
phase_det=[20QAM_input_I(i)<-2&0-2QAM_input_I(i)<-2&QAM_input_Q(i)<0
QAM_input_I(i)<0&-220a=find(phase_det);
output_frame((1+(i-1)*3):(3+(i-1)*3))=remapping((1+(a-1)*3):(3+(a-1)*3));
end
case
4,
QAM_16_Demodu_IQ
=
[0
1
3
2];
%f(m)=(m+3)/2
+
1,
so
I=-3
--->
1,
I=1
--->
3
idx
=
find(QAM_input_I>3);
QAM_input_I(idx)
=
3;
idx
=
find(QAM_input_I<-3);
QAM_input_I(idx)
=
-3;
idx
=
find(QAM_input_Q>3);
QAM_input_Q(idx)
=
3;
idx
=
find(QAM_input_Q<-3);
QAM_input_Q(idx)
=
-3;
tmp
=
round((QAM_input_I+3)/2)
+
1;
output_frame(1:4:end)
=
bitget(QAM_16_Demodu_IQ(tmp),2);
output_frame(2:4:end)
=
bitget(QAM_16_Demodu_IQ(tmp),1);
tmp
=
round((QAM_input_Q+3)/2)
+
1;
output_frame(3:4:end)
=
bitget(QAM_16_Demodu_IQ(tmp),2);
output_frame(4:4:end)
=
bitget(QAM_16_Demodu_IQ(tmp),1);
case
5,
remapping=[0
0
0
0
0;0
0
0
0
1;0
0
0
1
0;0
0
0
1
1;0
0
1
0
0;0
0
1
0
1;0
0
1
1
0;0
0
1
1
1;
0
1
0
0
0;0
1
0
0
1;0
1
0
1
0;0
1
0
1
1;0
1
1
0
0;0
1
1
0
1;0
1
1
1
0;0
1
1
1
1;
1
0
0
0
0;1
0
0
0
1;1
0
0
1
0;1
0
0
1
1;1
0
1
0
0;1
0
1
0
1;1
0
1
1
0;1
0
1
1
1;
1
1
0
0
0;1
1
0
0
1;1
1
0
1
0;1
1
0
1
1;1
1
1
0
0;1
1
1
0
1;1
1
1
1
0;1
1
1
1
1].';
for
i=1:Q_length
phase_det=[42QAM_input_I(i)<-4&0-4QAM_input_I(i)<-4&-2-442a=find(phase_det);
output_frame((1+(i-1)*5):(5+(i-1)*5))=remapping((1+(a-1)*5):(5+(a-1)*5));
end
%5+i
3+i
1+i
5+3*i
3+3*i
1+3*i
3+5*i
1+5*i
-5+i
-3+i
-1+i
-5+3*i
-3+3*i
-1+3*i
-3+5*i
-1+5*i
-5-i
-3-i
-1-i
-5-3*i
-3-3*i
-1-3*i
-3-5*i
-1-5*i
5-i
3-i
1-i
5-3*i
3-3*i
1-3*i
3-5*i
1-5*i
case
6,
QAM_64_Demodu_IQ
=
[0
1
3
2
6
7
5
4];
%f(m)=(m+7)/2
+
1,
so
I=-7
--->
1,
I=1
--->
5
idx
=
find(QAM_input_I>7);
QAM_input_I(idx)
=
7;
idx
=
find(QAM_input_I<-7);
QAM_input_I(idx)
=
-7;
idx
=
find(QAM_input_Q>7);
QAM_input_Q(idx)
=
7;
idx
=
find(QAM_input_Q<-7);
QAM_input_Q(idx)
=
-7;
tmp
=
round((QAM_input_I+7)/2)
+
1;
output_frame(1:6:end)
=
bitget(QAM_64_Demodu_IQ(tmp),3);
output_frame(2:6:end)
=
bitget(QAM_64_Demodu_IQ(tmp),2);
output_frame(3:6:end)
=
bitget(QAM_64_Demodu_IQ(tmp),1);
tmp
=
round((QAM_input_Q+7)/2)
+
1;
output_frame(4:6:end)
=
bitget(QAM_64_Demodu_IQ(tmp),3);
output_frame(5:6:end)
=
bitget(QAM_64_Demodu_IQ(tmp),2);
output_frame(6:6:end)
=
bitget(QAM_64_Demodu_IQ(tmp),1);
end