and 7 b into a signal for an intra shelf transmission and a signal for the other shelf transmission and carries out spreading modulation also the respective transmission signal processing circuits 5 a and 5 b are connected through cables to respective transmission signal processing circuit 5 c and 5 d in the other shelf 3 a spread signal for the other shelf transmission hereafter referred to as an inter shelf spread signal is inputted and outputted through this cable when receiving the inter shelf spread signal from the corresponding one of the transmission signal processing circuits 5 c and 5 d the each of the transmission signal processing circuits 5 a and 5 b adds and synthesizes the inter shelf spread signal and the transmission spread signal after the spreading modulation the input output of the inter shelf spread signal between the shelves 2 and 3 is carried out when the transmission baseband signal generated by the intra shelf is desired to be sent at a transmission frequency of the other shelf for example it is supposed that the shelf 2 is short of the resources of the spreading process circuits in the transmission signal processing circuits 5 a and 5 b and the channel coding process circuits 6 a and 6 b or a fault has occurred in a radio transmission processing circuit 8 a or an antenna 9 a in this case each of the transmission signal processing circuits 5 a and 5 b outputs the transmission spread signal to a corresponding one of the respective transmission signal processing circuits 5 c and 5 d in the shelf 3 the radio transmission processing circuit 8 a adds and synthesizes the transmission.