Optimization of MIMO systems under the influence of Antenna Mutual Coupling
Speaker: Shiyang Lu, ITEE
When: 2007-09-20 11:00:00
Venue: 78-622
Host: Dr. Hon Tat Hui
Abstract:With the increasing demand of high data-rate transmission in
wireless communications, the combining of the multiple-input
multiple-output (MIMO) technique has been suggested as a very
promising method for future broadband wireless communication
systems. One of the major challenges that designers of MIMO systems
face is the reliably conveying information from the transmitting
sides to the receivers in the presence of signal fading caused by
destructive addition of multipath components and correlation effects
in the hostile radio propagation medium. Previous works on analysing
the performance of MIMO system with correlation model are mostly in
the field of signal processing or information theory, without
considering about antenna mutual coupling (MC) effect. However, away
from the spatial correlation, when inner antenna separation in the
receiving or transmitting antenna is small due to the limitation on
the size of the mobile/wireless terminals, the previous channel
models ignoring the presence of antenna MC are not held.
This research aims to model the antenna mutual coupling (MC) into
the channel correlation of the MIMO systems strictly. By using the
unconventional concepts of receiving/transmitting mutual impedances
to incorporate measuring the antenna MC effect, this model is more
accurate comparing with the traditional model employing conventional
mutual impedances.
Via investigating two indicators, the bit-error-rate (BER)
performance and channel capacity of MIMO/MIMO-OFDM systems, we
firstly obtain the analytical model of system performance under the
influence of antenna MC effect. Numerical results prove that with
the presence of antenna MC, the performance shows an obviously
different case comparing with the case ignoring the MC, especially
when inner antenna spacing is smaller than 0.4 carrier wavelength.
With this in mind, a transmission strategy incorporating antenna MC
into power allocation scheme for MIMO systems is derived. The scheme
involves that transmitters knowing the perfect or partial knowledge
of channel state information (CSI), i.e., statistical information of
transmit and receive correlation matrixes. By our optimum
transmission strategy, computer simulation results show that we
could maximize channel capacity under the influence of antenna MC.
Similarly, we also build the antenna MC into training based channel
estimation algorithms of MIMO-OFDM system and derive the
close-formed expressions to calculate the MMSE channel estimation
error. The optimal training sequences are designed rigorously due to
the existence of antenna mutual coupling.
Biography:(biography unavailable)
Type: MPhil confirmation
Contact:Dr. Hon Tat Hui, seminar host (hthui@itee.uq.edu.au)
or Guido Governatori (ITEE seminar co-ordinator)
(guido@itee.uq.edu.au)