Embodiments of the present disclosure provide a signal retransmission apparatus and method and a communication system. The method includes: a first UE determines a resource for retransmitting a signal according to a resource for initially transmitting the signal and a frequency hopping pattern; and retransmits the signal to a second UE according to the determined resource. With the embodiments of the present disclosure, interference between UEs may be randomized as possible, and complexity of blind detection by receiver end UE may be lowered as possible.