Compressive sensing based NBI mitigation in UWB systems in the presence of multiuser interference

Ultra-wideband (UWB) radios are expected to be the next generation of the transmission systems that can support high data rate and power-constrained applications. Since the UWB signals have wide bandwidth, two problems arise, namely the high speed analog-to-digital-converter (ADC) required at the receiver side and the coexistence with other narrowband interference (NBI) systems that share the same part of the spectrum. The two problems can be addressed using compressive sensing (CS) based on the fact that narrowband signals have sparse representation in the discrete cosine transform (DCT) domain. It becomes more complicated when multiuser case is considered. For training based NBI mitigation with CS, three groups of pilot symbols are used to estimate the NBI signal subspace, the UWB signal subspace and to provide information about the channel. This work aims to evaluate the system performance in the presence of multiuser interference in addition to the NBI. The paper extends the derivations to include the effect of the multiuser interference together with the NBI and the additive white Gaussian noise. Direct sequence combined with time hopping coding is applied for the multiple access technique. Simulation illustrates that as more users being active the performance of the system degrades. Additionally, when the number of the secondary users increases, the multiuser becomes the most dominant factor that affects the system performance irrespective of the NBI.