Yes / Beamforming in multi-user MIMO (MU-MIMO) systems is a vital part of modern wireless communication systems. Researchers looking for best operational performance normally optimize the problem and then solve for best weight solutions. The weight optimization problem contains variables in numerator and dominator: this leads to so-called variable coupling, making the problem hard to solve. Formulating the optimization in terms of the signal to leakage and noise ratio (SLNR) helps in decoupling the problem variables. In this paper we study the performance of the SLNR with variable numbers of users and handset antennas. The results show that there is an optimum and the capacity curve is a concave over these two parameters. The performances of two further variations of this method are also considered.

No / In this work we have studied the performance of MIMO-DWT based multicarrier system using the feedback circuit from the receiver to the transmitter to understand the channel state information (CSI) and to create a steering matrix in order to constructively combine the received signal at the receiver which provides the advantage of keeping the burden of processing at the transmitter which has more power and less constraints.

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<p>We examine the robust downlink beamforming design from the point of outage probability constraint. We further reason that since the estimated downlink channel correlation (DCC) matrices form a manifold in the signal space, the estimation error should be measured in terms of Riemannian distance (RD) instead of the commonly used Euclidean distance (ED). Applying this concept of measure to our design constraint, we establish approximated outage probability constraints using multidimensional ball set and multidimensional cube set. We transform the design problem into a convex optimization problem which can be solved efficiently by standard methods. Our proposed methods apply to both Gaussian distribution assumption and uniform distribution assumption. Simulation results show that the performance of our design is superior to those of other robust beamformers recently developed.</p> / Master of Applied Science (MASc)