i am writing a code for ofdm generation, and I have a question regarding the same

[EDIT: 20110615 22:33 CDT - reformat - WDR]

after these lines

clear all;close all;echo off;tic;

clc;

para=128;
fftlen = 128 ;
noc = 128;
nd = 6 ;
ml = 2 ;
sr = 250000 ;
br = sr .* ml ;
gilen= 32; 
ebn0 = 10;

nloop = 100;
noe = 0; 
nod = 0 ;
eop = 0 ;
nop = 0;

Y2 = zeros(para,1);

%h = modem.pskmod (4,0);

seridata = rand ( 1, para*nd*ml)>0.5 ;

paradata = reshape( seridata, para,nd*ml)

x=paradata(1,:)
%in = mat2str(x)

%paradata(1,:)
h = modem.qammod(16);
y2= modulate(h,x)

i get an error

??? Undefined function or method 'ceil' for input arguments of type 'logical'.

_**Error in ==> modem.abstractMod.checkModInput at 13
if isempty(x) || ~isreal(x) || any(any(ceil(x) ~= x)) ...

Error in ==> modem.abstractMod.modulate at 10
checkModInput(h, x);

Error in ==> ofdmbook at 36
y2= modulate(h,x)**

Can someone please tell me what is wrong with my code ??

Answer 1

[Walter Roberson]

Change

seridata = rand ( 1, para*nd*ml)>0.5 ;

to

seridata = 0 + rand ( 1, para*nd*ml)>0.5 ;

[Swapna Iyer]

thanks . I changed it. But I am still getting this error :

??? Undefined function or method 'ceil' for input arguments of type 'logical'.

Error in ==> modem.abstractMod.checkModInput at 13

if isempty(x) || ~isreal(x) || any(any(ceil(x) ~= x)) ...

Error in ==> modem.abstractMod.modulate at 10

checkModInput(h, x);

Error in ==> ofdmbook at 36

y2= modulate(h,x)

Answer 2

[Yella]

>> h = modem.qammod(16); >> h

h =

             Type: 'QAM Modulator'
                M: 16
      PhaseOffset: 0
    Constellation: [1x16 double]
      SymbolOrder: 'Binary'
    SymbolMapping: [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15]
        InputType: 'Integer'

h isnt a matrix of values its just information of the modem. I think h is a transfer function(channel coefficients). i would suggest u first to modulate the input X = qammod(x,16) and convolute the 'h' with 'X' to get the tranmitter data.

[Swapna Iyer]

qammod(x,16) wont work on my matlab. I think it is obsolete. As you said, h is just used to construct a modulator object and the modulate is used for the modulation process.

[Yella]

Ms Swapna which version of matlab r u using?

[Yella]

What about BPSK and QPSK?