Coding and modulation for power and bandwidth efficient communication


Cronie, Harm Stefan (2008) Coding and modulation for power and bandwidth efficient communication. thesis.

Abstract:We investigate methods for power and bandwidth efcient communication.
The approach we consider is based on powerful binary error correcting codes
and we construct coded modulation schemes which are able to perform close
to the capacity of the channel.
We focus on the additive white Gaussian noise channel. For this channel a
Gaussian distribution maximizes mutual information and signal shaping has
to be used to get close to capacity. We investigate a simple method of signal
shaping based on the superposition of binary random variables. With multistage
decoding at the receiver, the original coding problem is transformed into
a coding problem for a set of equivalent binary-input output-symmetric channels.
It is shown that with the method signal constellations can be designed for
high spectral efciencies which have their capacity limit within 0.1 dB of the
capacity of the AWGN channel. Furthermore, low-density parity-check codes
are designed for the equivalent binary channels resulting from this modulation
method. We show how to approach the constrained capacity limit of the signal
constellations we design very closely.
A downside of multistage decoding is that multiple binary error-correcting
codes are used. We show how one can limit the number of error-correcting
codes used by merging bit-interleaved coded modulation and signal shaping.
This results in a coded modulation scheme which is able to approach the capacity
of the AWGN channel closely for any spectral efciency.
These coded modulation methods transform the coding problem for the
original channel into a coding problem for a set of binary channels. Depending
on the design of the modulation scheme these channels are symmetric or
not. We show how to characterize channel symmetry in general and how these
results can be used to design coded modulation schemes resulting in a set of
symmetric binary channels.
Item Type:Thesis
Electrical Engineering, Mathematics and Computer Science (EEMCS)
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