Mitigation techniques for RFI due to broadband noise

Mobile computing devices such as Laptops, tablets, smartphones and the like mostly have GPS, WLAN, and cellular capabilities whose performance could be degraded in the presence of broadband noise in the receiver antennas vicinity due to integrated high speed buses and digital circuitry. Shielding, as a passive technique, has become a convention in the mobile wireless industry and we present here a study of its effectiveness particularly in the near-field (as inside a smartphone for instance). We also present some novel active techniques such as bus activity control and RFI data encoding. In the former one, the correlation that exists between the activity level of the bus and its noise coupled to the radio is used in an adaptive algorithm that indirectly estimates the noise affecting the data transmission and controls the bus activity level to meet some require SNR. In the latter one, line encoding is used to reduce the spectral contribution to RFI of a data bus at some specific frequency band. Using K to N (K <; N) codes, simulations show a reduction of the noise of more than 10dB.