Gaussian pulse

the pulse must have these parameters:

Pulse width =3.5 µs
Rise time = 2.5µs
Fall time =2.5µs
level range required= > 80 dB

My problem is how insert the rise and the fall time as well as the level range (instructions), to this gaussian pulse:

t= -30E-3:1/299E3:30E-3;%t: the time
fc=900e3%fc :center frequency =900 khz
bw=0.000035;%Pulse Width= 3.5 µs
yi = gauspuls(t,fc,bw);
plot(t,yi)
grid