Effects of finite weight resolution and calibration errors
on the performance of adaptive array antennas

Mattias Wennström, Tommy Öberg, and Anders Rydberg

IEEE Transactions on Aerospace and Electronic Systems.
Vol.37, No.2, April 2001, pp.549-562

Abstract:

Adaptive antennas are now used to increase the spectral efficiency in mobile telecommunication systems. In this paper, a model of the received carrier to interference plus noise ratio (CINR) in the adaptive antenna beamformer output is derived, assuming that the weighting units are implemented in hardware. The finite resolution of weights and calibration is shown to reduce the CINR. When hardware weights are used, the phase or amplitude step size in the weights can be so large that it affects the maximum achievable CINR. It is shown how these errors makes the interfering signals ``leak'' through the beamformer and we show how the output CINR is dependent on power of the input signals. The derived model is extended to include the limited dynamic range of the receivers, by using a simulation model. The theoretical and simulated results are compared to measurements on an adaptive array antenna testbed receiver, designed for the GSM-1800 system. The theoretical model was used to find the performance limiting part in the testbed as the 1 dB resolution in the weight magnitude. Furthermore, the derived models are used in illustrative examples and can be used for system designers to balance the phase and magnitude resolution and the calibration requirements of future adaptive array antennas.

Related publications:

Auto-Calibrating Adaptive Array for Mobile Communications
IEEE Transactions on Aerospace and Electronic Systems publication, April 2000

Source:

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