Communication system of a vehicle for the communication of the vehicle with a portable ID transmitter , which is set up for UWB communication, for enabling vehicle functions for an operator who carries the portable ID transmitter with him, wherein the communication system comprises at least a first UWB receiver with a first UWB antenna and a second UWB receiver with a second UWB antenna , wherein the first UWB antenna and the second UWB antenna are arranged at a distance from one another on the vehicle , wherein the direction of a maximum reception sensitivity of the first UWB antenna and the direction of a maximum reception sensitivity of the second UWB antenna are oriented at an angle to each other which is at least 30 degrees and/or the direction of a maximum reception sensitivity of the first UWB antenna and the direction of a maximum reception sensitivity of the second UWB antenna are oriented at an angle to each other which is at most 120 degrees, wherein a central UWB control unit of the vehicle is coupled to the first UWB receiver and to the second UWB receiver , wherein the central UWB control unit is set up to evaluate both a first received signal of an ID transmitter UWB signal received from the first UWB antenna and a second received signal of the ID transmitter UWB signal received from the second UWB antenna as a function of one another for authentication of the communication of the vehicle with the ID transmitter , wherein the UWB control unit is set up to determine a first propagation time value of the first received signal and a second propagation time value of the second received signal, the communication between the ID transmitter and the vehicle being discarded as non-authentic communication, if a transit time difference of the first transit time value and the second transit time value exceeds a maximum transit time by more than a tolerated deviation, the maximum transit time being the time required to cover the distance between the first UWB antenna and the second UWB antenna . wherein the communication system comprises at least a first UWB receiver with a first UWB antenna and a second UWB receiver with a second UWB antenna , wherein the first UWB antenna and the second UWB antenna are arranged at a distance from one another on the vehicle , wherein the direction of a maximum reception sensitivity of the first UWB antenna and the direction of a maximum reception sensitivity of the second UWB antenna are oriented at an angle to each other which is at least 30 degrees and/or the direction of a maximum reception sensitivity of the first UWB antenna and the direction of a maximum reception sensitivity of the second UWB antenna are oriented at an angle to each other which is at most 120 degrees, wherein a central UWB control unit of the vehicle is coupled to the first UWB receiver and to the second UWB receiver , wherein the central UWB control unit is set up to evaluate both a first received signal of an ID transmitter UWB signal received from the first UWB antenna and a second received signal of the ID transmitter UWB signal received from the second UWB antenna as a function of one another for authentication of the communication of the vehicle with the ID transmitter , wherein the UWB control unit is set up to determine a first propagation time value of the first received signal and a second propagation time value of the second received signal, the communication between the ID transmitter and the vehicle being discarded as non-authentic communication, if a transit time difference of the first transit time value and the second transit time value exceeds a maximum transit time by more than a tolerated deviation, the maximum transit time being the time required to cover the distance between the first UWB antenna and the second UWB antenna . <EOS>