An In-Building Cellular Enhancement System, commonly implemented in conjunction with a distributed antenna system (DAS), is a telecommunications solution which is used to extend and distribute the cellular signal of a given mobile network operators (hereafter abbreviated as an MNO) within a building. In the United States, operators commonly supported by such solutions are include AT&T Mobility, Verizon Wireless,Sprint
Corporation, T-Mobile US, in addition to smaller regional carriers as required. Below ground level, large buildings and high rises are examples where mobile phones are unable to properly reach the carrier's macro or outdoor network.
In these environments, the in-building cellular enhancement system will connect to the carrier's signal source which is typically a bi-directional amplifier or a base transceiver station. This signal source transmits (and receives) the mobile network operator's licensed radio frequency. This frequency is then transported within the building using coaxial cable, optical fiber or Category 5e/Category 6twisted pair cable. In-building coverage antennas are strategically placed to provide the best overall coverage for users.