Multi-channel communication in a changing
and disordered world
WZI-UvA and TN-UTwente
Mobile phones, wireless internet and other
wireless applications in modern telecommunication demand more and more
bandwidth and reliability in the already crowded available frequency space.
Furthermore, in a complex urban environment the signal is dispersed, distorted
and continuously changing by reflection from buildings and cars.
Wave propagation in complex systems with
complicated boundary conditions and multiple scattering from internal
structure occurs frequently in nature. Well known examples besides radiowaves
are light in mist and milk, ultrasound in bubbly water, but also e.g. electron
transport in conductors. Despite the complexity of the multiple scattering
process some general features remain that are intricately related to the
fundamental properties of the propagation of waves. Many of these phenomena
are studied in today's condensed matter physics.
Novel developments to enhance wireless
communication exploit the multiple scattering of the signal between receiver
and transmitter. Multiple input multiple output (MIMO) systems use arrays of
transmitters and antennas where the transfer between the communication
channels is enhanced by the multiple scattering of the signal.
The concepts of multi channel communication and
the connection with fundamental problems in physics are discussed. As an
example some acoustic time-reversal experiments will be shown.