This paper investigates the interference mitigation capability of a millimeter-wave wireless personal area network (WPAN) in a realistic 60GHz channel. The interference mitigation mechanism employs farther-reaching beacon signals and device-relayed synchronization command frames (sync frames) to further extend the protection range of the victim (a.k.a. primary) network. Firstly, it is found that the sync frame is capable of extending the 'interference-free' region as a function of networkcontroller-to-device distance and the location of the interferer. Secondly, it is found that in the interference-free region extended by the beacon/sync frame, the probability of interference is near zero. Finally, interference, when taking place, impacts high speed (3∼5Gbps) links 5∼8dB more significantly than their low speed (1∼3Gbps) counterparts.