Distributed Antenna Systems and Linear Relaying for Rank-Deficient MIMO Systems


Boris Rankov, Jörg Wagner, and Armin Wittneben


Chapter in Distributed Antenna Systems: Open Architecture for Future Wireless Communications, Auerbach Publications, CRC Press, 2006, (invited paper).

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The capacity of wireless communication systems can be increased substantially by using multiple antennas at the transmitter and the receiver. In most practical cases a necessary condition to achieve this capacity increase is a channel environment that provides rich scattering. It is expected that future wireless broadband communication systems will operate beyond 5 GHz, for example Wireless Local Area Networks (WLANs) at 17 GHz (Hiperlan) or at 24/60 GHz (ISM bands). In higher frequency bands we expect an increase in correlation because the propagation channel be- comes more and more line-of-sight (LOS). In a line-of-sight dominated channel environment the MIMO channel matrix often becomes rank deficient or ill-conditioned and therefore the capacity increase diminishes. By using ad hoc amplify-and-forward relays or a distributed relay array in order to assist the MIMO communication it is possible to overcome this problem, since the relays can act as active satterers. In this chapter we introduce and study these techniques and show the capacity improvements when MIMO channels are rank deficient.


Distributed antenna systems, relaying, rank-deficient MIMO systems

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