Wideband Interference in Pilot Symbol Assisted OFDM Systems

Spectrum sharing systems such as cognitive radios must both strive to avoid interference and be tolerant to interference. While pilot symbol assisted systems have previously been shown to have detection and synchronization adversely affected by narrowband interference, the impact of wideband interference has received little attention. This paper shows both analytically and by computer simulation that wideband interference prevents correct pilot symbol assisted detection and synchronization for SIRs of 0 dB and less. An asymptotically optimal detector is derived for pilot symbols in the presence of Gaussian distributed wideband interference. Simulation results are presented to demonstrate that robust detection can be achieved for SIRs as low as −60 dB using a low complexity implementation for a typical OFDM system.