In
telecommunication,
Intersymbol Interference (
ISI) is a form of
distortion of a
signal in which one
symbol interferes with subsequent symbols. This is an unwanted phenomenon as the previous symbols have similar effect as
noise, thus making the communication less reliable. The spreading of the pulse beyond its allotted time interval causes it to interfere with neighboring pulses. ISI is usually caused by multipath propagation or the inherent non-linear frequency response of a
channel causing successive symbols to "blur" together.