Analysis of an Adaptive Nonlinear Interference Suppressor for Wireless Multimode Transceivers

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In multimode transceivers, the transmitter for one communication standard may induce strong interference in the receiver for another standard, often exceeding the desired signal by many tens of decibels. To linearly suppress this interference, the receiver requires a very large linear dynamic range, resulting in excessive power consumption. In a recent paper, a nonlinear block, which requires an adaptation signal proportional to the envelope of the received interference, has been used to strongly suppress the interference. In that work, the required adaptation signal for the nonlinear block has been determined analytically. In this paper, we quantify the required accuracy for the adaptation signal to properly suppress the interference while keeping the degradation to the receiver symbol error rate (SER) negligible. To provide the required accuracy, we propose a closed-loop method that calculates the adaptation signal based on a model, which describes the received interference in terms of the locally available baseband interference. We propose a method to adapt this model during the operation of the transceiver such that the power of the residual interference at the output of the nonlinear block is minimized. Our analysis shows that the proposed method can strongly suppress the interference while a SER close to that of an exactly linear receiver is achieved. Simulation results for a practical scenario validate this analysis.