Performance evaluation of IEEE 802.11a WLAN interfered by spread spectrum noises from a PC clock system

The OFDM-based WLAN systems, such as IEEE 802.11a system, have been widely used and their terminals are usually placed very close to personal computers (PCs). However, PCs radiate clock harmonics over a wide frequency band that may cause interference with the WLAN systems. Recent PC clock frequency is intentionally swept with time (spread spectrum clocking; SSC). Hence BER performance of IEEE 802.11a WLAN systems is investigated applying frequency modulated harmonic interferences. Theoretical analysis and numerical simulations are carried out in order to discuss the BER degradation and the effectiveness of forward error correction (FEC). It is found that, if the FEC is not applied, the average BER improves as the frequency variation rate of the harmonic increases. On the contrary, the error correction becomes less effective.