Interference suppression using CPP adaptive notch filters for UWB synchronization in stochastic non-linear channels

For precise synchronization of ultra wide band (UWB) signals in wireless channels, narrow band interference (NBI) suppression is a challenging issue. This is more relevant for real time channels which are non-linear in nature and are coexisted by narrow band wireless systems. An interference suppression scheme coupled to an energy detection based synchronization approach designed using second-order complex adaptive notch filter (ANF) is reported in this paper. This ANF uses a gradient descent algorithm for tracking the filter coefficients. The use of the same exploits the correlation difference property of signals received and suppresses NBIs in UWB signals. Consequently, it significantly reduces the computational complexity compared to the existing adaptive filters and requires lower power for an efficient hardware implementation. The data rate of UWB is usually high, so a combined pipelined-parallelism (CPP) approach is proposed which effectively simplifies the hardware design unlike direct and cascade forms. Detailed analysis suggest that the proposed scheme provides better performance in terms of power, speed, convergence and stability. Moreover, this scheme when used in conjunction with energy detection receivers significantly improves the interference tolerance margin, thereby raising the performance levels of synchronization with energy detection approach in non-coherent energy detection receivers.