3. Let $\{a_k\}$ be a sequence of data which is multiplied with a pulse shaping function $h(t)$ and sent every $T_s$ seconds. The signal is given by $x(t) = \sum_{k=-\infty}^{\infty} a_k h(t - kT_s)$. We sample this signal every $T_s$ seconds to get the discrete signal $x[n] = \sum_{k=-\infty}^{\infty} a_k h[n - k]$ for every integer $n$.

i) (5%) Derive the condition on \( h(t) \), in time domain, such that there will be no inter-symbol interference?