Analysis of platform noise effect on WWAN performance

With the advance of semiconductor and wireless communications technologies in recent years, the systems of highly integrated high-speed digital circuits and multi-radio modules have paved the way to mobile communications and networking. While notebook computers become more and more powerful in all respects, many RF modules such as Wi-Fi, Bluetooth, WWAN with GSM and WCDMA have been put together inside notebook computer to enhance mobile communications. The system design becomes more difficult due to the design complexity and stringent requirement for platform noise. Since the in-bands EMI emitted from CPU, LCD, memory and CCD camera will degrade the wireless communication performance and even severely affect the project development, we have to take into account of platform noise problem during the system design and integration stage. In order to study the effect of digital platform noise on the receiving performance of wireless communications, we use the popular Netbook to evaluate its TIS (Total Isotropic Sensitivity) following OTA test procedure of CTIA. From the measurement result, we found that when the noise level increases 1 dB, the receiving sensitivity degrades 2 dB accordingly. Therefore we will further analyze the relationship between TIS and the platform noise from different devices in this paper.