Binary PSK with a rectangular pulse-shape

In BPSK, the data symbols are real and thus only modulate the in-phase component of the carrier, i.e.  cos(2πfct). The transmit signal is thus

Where 

s[n] = {+1,−1} are the transmit symbols (bits) and pT(t − nTb) is the transmit filter/pulse-shape. If we replace pT(t − nTb) by the rectangular pulse