So far we have derived the probability of symbol error for a data
system whereas in practice the user is more concerned with the probability of bit error
for the communications link.
For a binary system, bit and symbol error are identical as each symbol error corresponds
to a single bit error. For M-ary systems (M > 2), however, this does not hold true.
For example, the 8-ary ASK scheme shown here can convey
three bits per symbol and may incur anything from one bit error to three bit errors for
each incorrectly decoded symbol, depending on which symbol was mistakenly identified.
|
 |