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Introduction |
Future wireless communication systems will require higher and higher data rates. Hence need arises for increasingly powerful transceiver schemes. Multi transmit and receive antennas enhance the system's degrees of freedom, which can be used to increase the link reliability via space-time coding or the data rate via spatial multiplexing in a very efficient way. However the achievable increase depends largely on the propagation environment and diminishes with increasing channel correlation.
For frequencies beyond 5 GHz, which will be used for future Wireless Local Area Networks (WLAN), the channel equals more and more the line-of-sight (LOS) propagation due to the increasing wave attenuation in free space. Consequently the correlation of the channel paths will increase, which poses a problem for the practical exploitation of MIMO technology. |
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Possible scenario for a multihop transceiver scheme
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Recent works in the field of cooperative MIMO Systems use distributed relays as active scatterers. These nodes, which can have one or more antennas, process and forward or simply amplify and forward the received signal. Thus, artificial multipath propagation is created and the correlation of the channel paths is reduced. An example of such a scenario can be seen in the illustration above. |
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To investigate the behavior of different transceiver schemes, including cooperative relaying, a mobile simulation laboratory (Radio Access with Cooperative Nodes) has been installed at the Wireless Communications Group. The equipment consists of ten single antenna relays which can be combined arbitrarily making RACooN an extremely adaptive and highly flexible laboratory. |
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Background
Features |
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