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标题: CDMA2000 1X接收端滤波器的设计 [查看完整版帖子] [打印本页]
时间: 2015-4-21 16:06
作者: 天山苍雪
标题: CDMA2000 1X接收端滤波器的设计
CDMA2000 滤波器有三部分:
1.发送端基带滤波器
文献4 对基带滤波器的要求及系数:(p450)
该滤波器系数已知,为h_k。
2.发送端均衡滤波器
求解he(先用的已知的y)
根据文献2:
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% 此处用的四倍,由频域转到Z域代码:
w0=2*pi*3.15*100000;
[b, a] = bilinear([-1,1.36*w0,-w0*w0],[-1,-1.36*w0,-w0*w0],1.2288*4*10e5);
[he,n]=impz(b,a);
生成的he为36阶。
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
3.接收端补偿滤波器
文献1给出了接收端滤波器的设计方法,介绍了求补偿滤波器hc的方法。三个滤波器卷积之后应满足:
hk*he*hc=RC filter
先求前两个卷积:y=hk*he。文献1介绍了方法。此处先用已知的y。
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
http://www.edaboard.com/thread127909.html
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
h_k=[ -0.0253
-0.0342
-0.0358
-0.0167
0.0216
0.0649
0.0910
0.0819
0.0371
-0.0220
-0.0607
-0.0512
0.0079
0.0844
0.1269
0.0945
-0.0128
-0.1435
-0.2118
-0.1405
0.0946
0.4414
0.7859
1.0000
1.0000
0.7859
0.4414
0.0946
-0.1405
-0.2118
-0.1435
-0.0128
0.0945
0.1269
0.0844
0.0079
-0.0512
-0.0607
-0.0220
0.0371
0.0819
0.0910
0.0649
0.0216
-0.0167
-0.0358
-0.0342
-0.0253];
%%%%%%%%%%%%%%%%
w0=2*pi*3.15*100000;
[b, a] = bilinear([-1,1.36*w0,-w0*w0],[-1,-1.36*w0,-w0*w0],1.2288*4*10e5);
[he,n]=impz(b,a);
Hk=fft(h_k,128);
He=fft(he,128);
Y1=Hk.*He;
y1=ifft(Y1,128);
y=y1(1:70);
%%%%%%% RC
z=rcosine(1,4,'normal',0,14);
%%%%%%% Kaiser window using matlab built-in function kaiser()
N=113; beta = 6.65;
w = kaiser(N, beta);
w = w';
% Apply Kaiser window w to RC filter z
zw = z.*w; zw=zw.';
Hz=fft(zw,128);
Hy=fft(y,128);
H=Hz./Hy;
hc=ifft(H,128);
%%%%%%%%%%%%%验证
% a=conv(y,hc);
% b=1;
% figure(2)
% plot(a);hold on;
% plot(b:4:length(a),a(b:4:end),'+r');
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
文献4对性能要求(p116):
验证过程:(时域/用fvtool(a)看幅度,相位,群延时)
三个滤波器卷积之后验证是否满足奈奎斯特定理。
RC = hk*he*hc = y*hc
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% a=conv(y,hc);
% b=1;
% figure(2)
% plot(a);hold on;
% plot(b:4:length(a),a(b:4:end),'+r');
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
用fvtool(a)看幅度,相位,群延时。
参考文献:
1.《Complementary Filter Design for Testing of IS-95 Code Division Multiple Access Wireless Communication Systems》
2.《Receiver Architectures for CDMA2000 1 xEV-DV Mobile Terminals including Phase Compensated Filtering》
3.《Recommended Minimum Performance Standards for cdma2000 Spread Spectrum Base Stations》
4.《Physical Layer Standard for cdma2000 Spread Spectrum Systems》
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