Coded
Modulation
- It is a
technology of combining bandwidthefficient modulation and
coding to achieve coding gain without bandwidth expansion
or reducing data rate.
- The basic
concept of this technology is to perform coding onto an
expanded modulation signal set (relative to that needed
for uncoded transmission).
- The
redundancy needed for error control comes from signal
expansion (or from both signal expansion and coding).
- Coding is
used to from structured signal sequences with large
minimun Euclidean distance.
- This
combination of coding and modulation into an integral
part in called coded modulation.
- It finds
applications on bandlimited channels such as voiceband
telephone, terrestrial microwave, satellite and mobile
channels.