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Abstract:
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Network coding is a novel paradigm for multicast relay network. It minimiz es the number of
transmissions required to communicate a given amount of information across the network by
applying processing at relay nodes. Thus, network coding improves network throughput beyond
existing standards based on routing. From first proposition of network coding in 2000 by Ahlswede
et al., a significant number of theoretical results, such as p hysical - layer network coding (PNC), have
been developed but only limited results are available on implementation of network coding on real
channel and real time hardware.
This thesis presents a software- defined radio implementation of two- way relay network, in
which two end nodes exchange information with the help of a relay node. The implementation
model is designed to apply network coding and reduce number of transmissions from four (in
traditional routing scheme) to two (as in physical - layer network codi ng scheme). In the first
transmission (uplink), FDMA is applied to avoid interference between signals sent out from end
nodes; and relay node use a two- branch receiver to get both these signals and decode data
separately, then performs a bitwise XOR on these data. Afterwards, in the second transmission
(downlink), relay node transmits the XORed data to end nodes.
The designed model is verified using GNU Radio (open- source software) and three USRPs
(hardware) in an indoor environment. Simulation and experim ent result show that with short
messages, this model can achieve about 85.2% throughput gain over traditional scheme, which
agrees with PNC theoretical analysis. |