AISG protocol is based on half-duplex communication and HDLC protocol. The AISG bus is a single master multi-slave bus. Communication media can be either RS-485 based using a dedicated cable specified in the AISG standard or an OOK carrier injected into the RF antenna feeder cable of a base station site.
The master controlling the communication is called a primary and the slave devices on the bus are called secondaries and ALDs (Antenna Line Devices). Primary functionality can be integrated into a base station. Primary can also be a stand-alone controller installed on the BTS site or a handheld/portable controller typically used during the installation of a base station site. Secondary device types include a RET (actuator tilting antenna beam electronically), a TMA (Tower Mounted Amplifier), a GLS (Geographic Location Sensor) or an ASD (Alignment Sensor Device).
