@Oli yeah you are right that up1=up4. In the pic number of channel also specified. if you look at the print for up4.conv_trans1.weight torch.Size([1152, 384, 2, 2]) is 1152 channel but in the pic up1 is 384. I think the concatenation shouldn’t be in the self.conv_trans1 . Also in the pic connection specified in front of conv col. is that right?