ELEDIA

Dr. ANSELMI won the YOUNG SCIENTIST Award @ ACES-2018
The ELEDIA Research Center is pleased to announce that Dr. Nicola ANSELMI has been awarded the "YOUNG SCIENTIST AWARD" at…
Prof. Oliveri named Associate Editor of IEEE JMMCT
The ELEDIA Research Center is pleased to announce that Prof. Giacomo Oliveri has been named Associate Editor of the IEEE Journal…
R. J. Mailloux has joined ELEDIA
The ELEDIA Research Center is pleased to announce that Dr. R. J. Mailloux is member of the ELEDIA Research Staff.…

 

Logo Smart Antenna Eledialab

The term adaptive antenna (or smart antenna) is used for an antenna array when the weighting on each element is applied in a dynamic fashion. The amount of weighting on each channel is not fixed at the time of the array design, but rather decided by the system at the time of processing the signals to meet required objectives. In other words, the array pattern adapts to the situation and the adaptive process is under control of the system.

 

Smart Architecture
Figure 1: block diagram of the ELEDIALab Fully Adaptive Antenna System

 

The smart antennas offer substantial benefits to the design of wireless mobile communications systems, which can be summarized as follows:
• Increased antenna gain: this helps increase the base station range and coverage, extends battery life, and allows for smaller and lighter handset designs.
• Interference rejection: antenna pattern nulls can be generated toward interference sources. 
• Diversity: composite information from the array can be used to minimize fading and other undesirable effects of multipath propagation. In addition to spatial and polarization diversity, antenna arrays also allow the use of angular diversity. As with any other adaptive antennas application, the nature of the system in which they are employed, the conditions under which they operate, and the results they are intended to achieve all have to be considered when a smart antenna system design is incorporated in a specific wireless system.

The main advantage of adaptive antenna arrays compared with switched beam antennas is their ability to steer beams towards desired users and nulls toward interfering signals as they move around a sector.

 

The fully adaptive antenna system developed by the ELEDIALab Group works in the 2.4GHz-2.5GHz frequency range and it is composed by the following devices (see Fig. 1):

- n. 8 radiating elements: in the first protoype we employ a printed version of a dipole antenna with an integrated balun. Moreovere, it is possible to change this element in a easy way;

- n. 8 electronically managed RF Attenuator/Phase shifter: the ELEDIALab Group have develop a high precision Attenuator and Pahse Shifter controlled by a voltage signal that in a single devices combines a 0-360° phase shifter and an a 3 to 35 dB RF signal attenuator;

- n. 1 RF power splitter.

Smart Eledia -  Top View
Figure 2: top view of the Smart Antenna.
 
Smart Eledialab - Front
Figure 3: front view of the Smart Antenna.

Conventional beamformer or delay-and-sum beamformer has all the weights of equal magnitudes. To steer the array in a particular direction, the phases are selected appropriately. Withr ours smart antenna is also possible to dinamically change the magnitude of the weights so more degree of fredom are introduced (in Fig. 2 and 3 you can see the first prototype).

Both hardware and software modules have been separately tested and then integrated to assess the adaptive behaviour of the antenna system. Moreover, the smart antenna system have been tested in a anechoich chamber and also in a real scenario.

In a typical application, the antenna pattern has the main beam pointed in the desired signal direction, and has a null in the direction of the interference. Assume that the interference is not stationary but moving slowly. If optimal performance is to be maintained, the antenna pattern needs to adjust so that the null position remains in the moving interference direction (see Fig. 4).


Figure 4: the GUI of the optimization alghoritm to manage the smart antenna configuration.

The smart antenna prototype was validated at the Eledialb's Anechoic Chamber and in a unsupervised real scenario.

Figure 5: the experimental validation.

The SW Control Unit (based on the PSOM) performs the optimization of the array weights of the HW Control Unit in order to maximize the SINR Signal to Noise plus Interference Ratio (Figure 6). The resulting beam patterns in some TimeSteps are shown in the Figure 7.

fitness

Figure 6: the SINR behaviour resulting from some TimeSteps.

Finally, in the Figure 8 it is easy to observe that, as expected, in every TS the antenna array adapt his radiating pattern in order to minimize the signal received from the interference source.

result

Figure 7: the beam patterns (simulated in red and measured in green) resulting from the TS1, TS2 and TS5.