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.