In Time Hopping Ultra-WideBand Impulse Radio (TH-UWB-IR) communication systems, relay attacks represent nowadays a critical threat to authentication protocols. This risk can be mitigated through the use of Distance Bounding (DB) protocols. Some recent works have discussed many issues on the implementation of distance bounding protocols (DB) on UWB communication was considered in the context of single Prover and a single Verifier. In our work, we adapt the THSKI protocol to privacy Group Distance Bounding protocol with NTRU cryptography system. The security and the different merits of the proposed protocol are analyzed.