Abstract:
Cooperative communication has become one of the fastest growing domain
of wireless communication and is likely to become one of the mainstream
technologies in future due to its e cient use of spectrum. This interest in
cooperation is not undeserved since it o ers advantages of diversity and multiplexing
which make it highly desirable for use in wireless channels.
A three node network known as relay channel forms the basic building
block of cooperative networks. Therefore a large body of research specially
in the realm of information theory has been dedicated to relay channel. Since
its inception, several coding schemes have been proposed to enable cooperation
between nodes. They can mainly be classi ed into Decode and Forward,
Compress and Forward and Amplify and Forward.
This monologue presents a multi-level compress and forward coding scheme
for a three-node relay network in which all transmissions are constrained to
be from an M-ary PAM constellation. The proposed framework employs a
uniform scalar quantizer followed by Slepian-Wolf coding at the relay. We
rst obtain a performance benchmark for the proposed scheme by deriving
the corresponding information theoretical achievable rate. A practical coding
scheme involving multi-level codes is then discussed. At the source node, we
use multi-level low-density parity-check codes for error protection. At the
relay node, we propose a multi-level distributed joint source-channel coding
scheme that uses irregular repeat-accumulate codes, the rates of which are
carefully chosen using the chain rule of entropy. For a block length of 2 105
symbols, the proposed scheme operates within 0:56 and 0:63 dB of the theoretical
limits at transmission rates of 1:0 and 1:5 bits/sample, respectively.
