Energy-detection is appealing for IEEE 802.15.4a receivers as it allows to exploit the ranging capabilities and the multipath resistance of impulse-radio UWB at a reasonable complexity. IEEE 802.15.4a receivers operate with interference created by uncontrolled piconets and an uncoordinated medium access control. Prior work showed that the performance of an energydetection based receiver is greatly degraded in such scenarios. Hence, we present an interference mitigation algorithm based on statistical interference modeling for energy-detection receivers. This combines a low complexity architecture and robustness to interference. Our performance evaluation shows that our solution decreases the packet error rate significantly.