Efficient RF Front-End Non-Linear Multi Antenna Coupling Cancellation Techniques

Abstract

One of the recent trends in mobile communication industry is the use of multiple antennas in transmitter and at the receiver in order to gain diversity and achieve high bit rates. At the same time, as the mobile terminals are getting smaller, the number of electronic elements squeezed inside of them increases. Inside this hostile environment the coupling, which can considerably alter the overall system performance, is bound to emerge.To combat the multi antenna RF front-end coupling a DSP software module, positioned between the output of AD converter and any further digital signal processing is proposed. The coupling is modelled with polynomials limited to third order nonlinear behaviour. The inverse nonlinear coupling function of the 9 th degree is solved using simulated annealing (SA) approximation method. The proposed coupling cancellation algorithm is analyzed under different system conditions with different processing power requirements. A trade off between the guaranteed precision and speed is made, and the simplified algorithm version, showing good coupling cancellation characteristics, is presented.

Simulated Quenching for Cancellation of Non-Linear Multi-Antennas Coupling

“…The ranks of polynomials, controlled with (N 1 , N 2 ), are determined as a trade off between the acceptable system performance and the required computational power. In [2], the approximation with 20 coefficients for the coupling cancellation fitting surface is proven to be accurate enough.…”

RF- Front-End Non-Linear coupling cancellation = Cancelación de acoplo no lineal en frontales de RF

“…Actually, even very complex surface with 20 coecients can guarantee excellent decoupling performance in every strong coupling environment, and it would not be logical to expect much simpler surface to cover the whole coupling distortion area with the same precision. This conclusion is also reached in [Ara07a] where SA approach is implemented with dierent surface forms. The corresponding coupling distortions in this article use dierent coupling strength measurements taking into account only numerical coecient ratios, hence from the numerical point of view, coupling of amplitudes [−20, −30, −40]dB in [Ara07a] is equal to approximately [−10, −9, −7]dB coupling strength calculated in this thesis.…”

“…This conclusion is also reached in [Ara07a] where SA approach is implemented with dierent surface forms. The corresponding coupling distortions in this article use dierent coupling strength measurements taking into account only numerical coecient ratios, hence from the numerical point of view, coupling of amplitudes [−20, −30, −40]dB in [Ara07a] is equal to approximately [−10, −9, −7]dB coupling strength calculated in this thesis.…”