However, the interaction, with a selective impairment of visual discrimination for motor preferential ellipses when participants mobilized their dominant hand, makes an interpretation in terms of a simple interference between the direction of presented ellipses and the hand mobilized unlikely.
It can be seen that each beampattern has minimum interference at the directions of the mainlobes of the other beampatterns, but they do not affect beamforming directions at SU. Fig. 5 Normalized beam pattern power for the proposed algorithm.
Further suppose there are one interference located at the direction angle θ i =10° and range R i =10 km.
In the environment where the desired signal is stronger or not significantly weaker than the interferences, nulling in the direction of interest becomes a problem for conventional zero tracking algorithm.
The design problem of imposing deeper nulls in the interference direction of uniform linear antenna arrays under the constraints of a reduced side lobe level (SLL) and a fixed first null beam width (FNBW) is modeled as a simple optimization problem.
While directional antennas can perform interference mitigation by estimating the direction of the incoming signals at the receiver, we show that reconfigurable MIMO antennas can achieve a similar result, with lower system complexity, by only estimating the channel matrix.
In the case of the random antenna selection scheme, on the other hand, the interference from random direction of the grating lobes are averaged out so that other users who are located on different directions can receive their desired signals.
Numerical validation illustrates the possibility to suppress interference without actually forming a spatial null in the direction towards interference, and the necessity to design transmit filters that are robust to uncertainties in the given scenario.
This is because the system reacts much more sensitive w.r.t uncertainty in the interference directions as compared to the signal direction, since nulls in the beamforming pattern are commonly very narrow whereas peaks are comparatively broad in the angular domain (see also the example in Fig. 2).
Also it seems that in Figure 3B, the middle panel "Interference:B1" has the directions marked incorrectly.
