I'm asking about some details about using the Walsh matrix as spreading sequence code. For example, suppose I'm using a $4\times 4$ Walsh matrix given by
$$H = \begin{pmatrix} 1 & 1 & 1 & 1 \\ 1 & -1 & 1 & -1 \\ 1 & 1 & -1 & -1 \\ 1 & -1 & -1 & 1 \end{pmatrix}$$ and I have data $x$ which will be spread on that Walsh matrix.
My question: what is the length of $x$ supposed to be? Must it be less than 4? Or can it be more than 4 too? In other words, suppose I have a signal $x = 10$ , it's supposed that is easy to spread the signal $x$ on the first column of $H$. The question is, What's about if the signal $x = 101101$ , can we do the spread on the first column too? where the signal $x$ has length larger than the first column.