A user communication device for cellular communication with a base station and device-to-device, D2D, communication with at least one further user communication device, wherein the user communication device comprises: a communication interface configured for cellular communication with the base station and D2D communication via a D2D communication channel between the further user communication device and the user communication device, wherein the D2D communication with the further user communication device comprises receiving channel state information from the further communication device, wherein the channel state information comprises channel state information of a cellular communication channel between the further user communication device and the base station; and a processing unit configured to adapt a feedback vector on the basis of a quality measure of the D2D communication channel between the further user communication device and the user communication device and to provide information about the adapted feedback vector via the communication interface to the base station; wherein the quality measure of the D2D communication channel between the further user communication device and the user communication device is a noise σ kj of the channel state information of the D2D communication channel between the further user communication device and the user communication device; wherein the processing unit is configured to adapt the feedback vector on the basis of the noise σ kj of the channel state information of the D2D communication channel between the further user communication device 102-2 and the user communication device by determining a feedback vector from a codebook C of feedback vectors, which satisfies the following equation: û k = arg max u ∈ C h k H u 2 ∑ j ≠ k 1 − σ kj 2 h ^ j k H u 2 + ∑ j ≠ k σ kj 2 + K P, wherein û k denotes the feedback vector, h k denotes the downlink channel of the user communication device, h ^ j k denotes the quantized downlink channel of the further user communication device as known by the user communication device, K denotes number of user communication devices, and P denotes a total transmission power of the base station; and wherein σ kj is the variance of CSI quantization error due to a finite rate D2D communication. a communication interface configured for cellular communication with the base station and D2D communication via a D2D communication channel between the further user communication device and the user communication device, wherein the D2D communication with the further user communication device comprises receiving channel state information from the further communication device, wherein the channel state information comprises channel state information of a cellular communication channel between the further user communication device and the base station; and a processing unit configured to adapt a feedback vector on the basis of a quality measure of the D2D communication channel between the further user communication device and the user communication device and to provide information about the adapted feedback vector via the communication interface to the base station; wherein the quality measure of the D2D communication channel between the further user communication device and the user communication device is a noise σ kj of the channel state information of the D2D communication channel between the further user communication device and the user communication device; wherein the processing unit is configured to adapt the feedback vector on the basis of the noise σ kj of the channel state information of the D2D communication channel between the further user communication device 102-2 and the user communication device by determining a feedback vector from a codebook C of feedback vectors, which satisfies the following equation: û k = arg max u ∈ C h k H u 2 ∑ j ≠ k 1 − σ kj 2 h ^ j k H u 2 + ∑ j ≠ k σ kj 2 + K P, wherein û k denotes the feedback vector, h k denotes the downlink channel of the user communication device, h ^ j k denotes the quantized downlink channel of the further user communication device as known by the user communication device, K denotes number of user communication devices, and P denotes a total transmission power of the base station; and wherein σ kj is the variance of CSI quantization error due to a finite rate D2D communication.