Jammer Sensing and Performance Analysis of MC-CDMA Ultrawideband Systems in the Presence of a Wideband Jammer

Abstract

Jamming, either intentional or unintentional, is a big, and increasingly prevalent, problem for many wireless communications systems. A well-known countermeasure is the application of spread spectrum techniques that spread the information over a bandwidth possibly larger than that of the jammer thereby exploiting processing gain for jammer suppression; an especially attractive spreading technique is multi-carrier code division multiple access (MC-CDMA), due to its flexibility to shape transmit spectra, resilience to inter-symbol interference, and ease of implementation. Such spreading needs to be combined with spectral notching at the receiver RF frontend, to avoid saturation of the low-noise amplifiers. Such notching, in turn, requires the receiver to sense the band over which the jammer is operating. In this paper, we consider an MC-CDMA transceiver that is being jammed by a wideband non-stationary jammer. For a Rayleigh fading channel, we derive the symbol error rate for the case that the jammer parameters are available at the receiver. We derive the Maximum-Likelihood-based and Log-Likelihood Ratio-based jammer parameter estimators for both the case where channel state information is available during jammer sensing and when it is not. The performance of various jammer parameter estimation schemes is studied using Monte Carlo simulations and with the channel impulse responses collected from the wireless propagation measurements conducted in the 10–12 GHz band.