This paper presents an interference suppression and signal restoration technique that can create the clean signals required by automotive frequency-modulated continuous wave radar systems. When a radar signal from another radar system interferes with own transmitted radar signal, the target detection performance is degraded. This is because the beat frequency corresponding to the target cannot be estimated owing to the increase in the noise floor. In this case, advanced weighted-envelope normalization or wavelet denoising can be used to mitigate the effect of the interference; however, these methods can also lead to the loss of the desired signal containing the range and velocity information of the target. Therefore, we propose a method based on an autoregressive model to restore a signal damaged by mutual interference. The method uses signals that are not influenced by the interference to restore the signal. In experiments conducted using two different automotive radar systems, our proposed method is demonstrated to effectively suppress the interference and restore the desired signal. As a result, the noise floor resulting from the mutual interference was lowered and the beat frequency corresponding to the desired target was accurately estimated.

Various co-sited wireless communication systems may share the same frequency band. This causes mutual interference between the wireless communication systems, and degrades the performance of each wireless communication system. In this paper, we analyze the effect of mutual interference between WiFi and WiMAX systems sharing the same frequency band. We propose novel methods based on a proposed coexistence zone within the WiMAX frame structure and a modified power saving mode of the WiFi system to solve the problem. We evaluate the performance of the proposed methods by computer simulation.