Hi Oscar,
BTS(Base transceiver System)is a set of equipment to handle a cell in GSM. BTS consists of transmitters, receivers, CDUs,power supplies and antennae. Each GSM site may be configured in two or three sectors and each sector is provided with four hannels.For GSM, RBS200 series and 2000 series were used. Now 2206 is extensively used. For WCDMA RBS300 series is introduced.