Chip discrimination for large near far power ratios in UWB networks

A simple chip discrimination technique is presented for use with ultra wide band (UWB), impulse radio (IR) that improves performance for large near/far interference ratios. A typical spread-spectrum IR that employs a matched filter sum for bit decisions is susceptible to small numbers of large power pulses that can dominate the bit decision threshold statistics. This paper describes a technique for chip discrimination prior to the spreading summation that can greatly reduce the effects of large near/far interferers. The technique exploits the unique time domain characteristics that only UWB systems can provide. A statistical model is developed that predicts bit error performance for binary offset pulse position modulation (PPM) as a function of near/far density and power for varying discrimination thresholds. We find that even a small number of very near interferers can greatly reduce the performance of a system without blanking or discrimination. Results show substantial improvement using this method for near interferers with near/far power ratios greater than 20 dB.