casestudy1.m

midamble码的生成和基于midamble码的td-scdma信道估计

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% CASE STUDY1
% Construct the midamble code set using the basic midamble codes
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% the basic midamble codes
A=['B';'2';'A';'C';'4';'2';'0';'F';'7';'C';'8';'D';'E';'B';'F';'A';'6';'9';'5';'0';'5';'9';'8';'1';'B';'C';'D';'0';'2';'8';'C';'3'];
% convert hexadecimal string to decimal integer
B=hex2dec(A);
% convert decimal integer to a binary string
C=dec2bin(B);
% change the size of C to 128*1
D=reshape(C,128,1);
% converts a character array representation of a matrix of numbers to a numeric matrix
m0=str2num(D);
% keep '1',change '0'to '-1', the basic midamble codes
for i=1:128
    if m0(i)==0
        m0(i)=-1;
    end
    m0(i)=j^i.*m0(i);
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% P is the size of the basic midamble codes
% Kmax as the maximum number of users that the system can support
% W is the interval of adjacent codes 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
P=128;
Lm=144;
Kmax=16;
W=16;
% periodically extended to the size im=Lm+(Kmax-1)*W，Kmax=16,W=8
im=Lm+(Kmax-1).*W;
for i=1:im
    if i<129
        m(i)=m0(i);
    elseif i>256
        m(i)=m0(i-2*P);
    else
        m(i)=m0(i-P);
    end
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% the number of users K=2,4,6,8,10,12,14,16 
% the value of W is relative to the value of K
% If K<=8, we set W=16. Otherwise(K>8), we let W=8.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
K=8;
if K>8
    W=8;
else
    W=16;
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% use K, as k from 1 to K, intercept the midamble codes from the beginning m1 to mk
% Lm is the size of every midamble code, W is the interval of adjacent codes
% the final results is a circulant matrix (Lm x K) for channel estmation
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Lm=144;
for k=1:K
    for i=1:Lm
        g(i,k)=m(i+(Kmax-k).*W);
    end
end
% show the circulant matrix G
Lm
K
g