# SFBC Alamouti Scheme LTE

A sentence I copied from book.

That a 2$\times$1 Alamouti SFBC is referred to as a rate 1 code, two symbols are sent over two adjacent subcarriers.

This question is regarding this SFBC encoder (Alamouti scheme). I understand how the encoder works for the two transmit antenna case. Below I briefly given an example for convenience.

Assuming a BPSK modulator applied to data input $I$. Then we have

$I$ = 0 0 1 1 0 1 1 1

BPSK symbols= 1 1 -1 -1 1 -1 -1 -1

Then the output of the STBC encoder could be found according to the

\begin{array}{lcr} \mbox{} & Antenna1 & Antenna 2 \\ \mbox{$f_1$} & s_1 & s_2 \\ \mbox{$f_2$} & -s_2^* & -s_1^* \\ \end{array}

and so applying this to the BPSK symbols I get the following symbols

Antenna1 symbols: 1 -1 -1 1 1 1 -1 1

Antenna2 symbols: 1 1 -1 -1 -1 1 -1 -1

My question is next, what do we do with these symbols for LTE system ie OFDM modulation, do we send the symbols 1 and 2 over antenna 1 and antenna 2 respectively over the same subcarrier ? i.e I don't understand how transmission over subcarriers takes place? More precisely I don't undersatnd the assignement of the symbols to the different subcarriers?

Thank you.
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