Abstract: A printed circuit board includes a substrate portion including a first insulating layer, and a first wiring layer disposed on or in the first insulating layer, and a connection structure disposed on or in the substrate portion, the connection structure including a plurality of first dielectric layers, first and second metal layers respectively disposed on the plurality of first dielectric layers, a second insulating layer disposed on the plurality of first dielectric layers, and a second wiring layer disposed on the second insulating layer. Each of the plurality of first dielectric layers includes an organic material. A distance between the first metal layer and the second metal layer is less than a distance between the first metal layer and the second wiring layer.

Abstract: A head-end device according to an embodiment includes: a plurality of base station interfacing units configured to interface each of transmission/reception signals that are exchanged between the head-end device and a plurality of base stations; and a head-end control unit configured to receive an upper interfacing unit signal transmitted from an upper base station interfacing unit from among the plurality of base station interfacing units, and sequentially transmit the received upper interfacing unit signal to a lower base station interfacing unit.

Abstract: A head-end device according to an embodiment includes: a plurality of base station interfacing units configured to interface each of transmission/reception signals that are exchanged between the head-end device and a plurality of base stations; and a head-end control unit configured to receive an upper interfacing unit signal transmitted from an upper base station interfacing unit from among the plurality of base station interfacing units, and sequentially transmit the received upper interfacing unit signal to a lower base station interfacing unit.

Abstract: A head-end device according to an embodiment includes: a plurality of base station interfacing units configured to interface each of transmission/reception signals that are exchanged between the head-end device and a plurality of base stations; and a head-end control unit configured to receive an upper interfacing unit signal transmitted from an upper base station interfacing unit from among the plurality of base station interfacing units, and sequentially transmit the received upper interfacing unit signal to a lower base station interfacing unit.

Abstract: A head-end device according to an embodiment includes: a plurality of base station interfacing units configured to interface each of transmission/reception signals that are exchanged between the head-end device and a plurality of base stations; and a head-end control unit configured to receive an upper interfacing unit signal transmitted from an upper base station interfacing unit from among the plurality of base station interfacing units, and sequentially transmit the received upper interfacing unit signal to a lower base station interfacing unit.

Abstract: A remote device of an optical relay system includes first and second remote driving units each extracting transmission signals of different frequency bands from downlink Radio Frequency (RF) signals provided from an optical conversion unit and outputting the transmission signals; and a downlink path control unit receiving the downlink RF signals from the optical conversion unit and transmitting the downlink RF signals to the second remote driving unit through the first remote driving unit, or transmitting the downlink RF signals to the second remote driving unit by bypassing the first remote driving unit.

Abstract: A remote device of an optical relay system includes first and second remote driving units each extracting transmission signals of different frequency bands from downlink Radio Frequency (RF) signals provided from an optical conversion unit and outputting the transmission signals; and a downlink path control unit receiving the downlink RF signals from the optical conversion unit and transmitting the downlink RF signals to the second remote driving unit through the first remote driving unit, or transmitting the downlink RF signals to the second remote driving unit by bypassing the first remote driving unit.