> I have came across a so-called soft symbol mapper in OFDM system, which I
> understand it is modulation by soft values, but how to do it? for example,
> QPSK modulation will make [0 0] [0 1] [1 0] [1 1] to [-0.7071-0.7071i]
> [-0.7071+0.7071i] [+0.7071-0.7071i] [+0.7071+0.7071i], how about soft
> symbol mapper?
Perhaps they're implementing some sort of predistortion?
--
% Randy Yates % "And all that I can do
%% Fuquay-Varina, NC % is say I'm sorry,
%%% 919-577-9882 % that's the way it goes..."
%%%% <yates@ieee.org> % Getting To The Point', *Balance of Power*, ELO
http://www.digitalsignallabs.com
Reply by cpope●December 31, 20072007-12-31
"totohaha" <wuxianguk@hotmail.com> wrote in message
news:r46dnXdaDqH-eOranZ2dnUVZ_h2pnZ2d@giganews.com...
> I have came across a so-called soft symbol mapper in OFDM system, which I
> understand it is modulation by soft values, but how to do it? for example,
> QPSK modulation will make [0 0] [0 1] [1 0] [1 1] to [-0.7071-0.7071i]
> [-0.7071+0.7071i] [+0.7071-0.7071i] [+0.7071+0.7071i], how about soft
> symbol mapper?
Usually it is just a look up table. If the I and Q values are 16 bit, for
example, a 4x32 memory can implement this function for you.
Typically it is a dual port memory so that the values can be reloaded on one
port while the data is processed on the other port.
-Clark
Reply by totohaha●December 31, 20072007-12-31
anybody answer me?
>I have came across a so-called soft symbol mapper in OFDM system, which
I
>understand it is modulation by soft values, but how to do it? for
example,
>QPSK modulation will make [0 0] [0 1] [1 0] [1 1] to [-0.7071-0.7071i]
>[-0.7071+0.7071i] [+0.7071-0.7071i] [+0.7071+0.7071i], how about soft
>symbol mapper?
>
Reply by totohaha●December 30, 20072007-12-30
I have came across a so-called soft symbol mapper in OFDM system, which I
understand it is modulation by soft values, but how to do it? for example,
QPSK modulation will make [0 0] [0 1] [1 0] [1 1] to [-0.7071-0.7071i]
[-0.7071+0.7071i] [+0.7071-0.7071i] [+0.7071+0.7071i], how about soft
symbol mapper?