Hi Zsliu,
It looks like you are on a right track with the answer to your question. As you said, the number of symbols will be defined by the number of bits (length of bit sequence) and the number of bits per symbol (depends on your modulation scheme). However, I am not exactly sure what do you mean by “output signal and time have same samples”. Are you relating this question to the clocking scheme or you are planning to adjust the sampling rate?