Uplink and downlink signalling
In the uplink path, the BTS receives signals from the MS. In the downlink path, the BTS sends signals to the MS. Uplink and downlink signals travel through the Air interface on different frequencies, with the higher frequency carrying downlink signals.
The uplink signal path involves the following actions:
The antenna picks up a signal from the MS through the Air interface.
The antenna passes the signal to the optional Masthead Amplifier (MNxx) and Bias Tee (BPxx) units or to the optional Dual Band Diplex Filter (DU2A) unit.
The signal passes through either the Dual Variable Gain Duplex Filter (DVxx) or Remote Tune Combiner (RTxx) unit to the Receiver Multicoupler (M2xA or M6xA) and Transceiver RF (TSxx) units.
The Transceiver module (TRX) on the TSxx unit converts the received signal to Intermediate Frequency (IF) levels and filters the signal.
The TSxx unit then sends the signal to the Transceiver Baseband (BB2x) unit for digital signal processing.
The BB2x unit sends the processed signal to the Transmission (VXxx) unit, which transmits the signal to the BSC utilizing standard transmission technologies.
The downlink signal path involves the following actions:
The BSC receives a signal from the core network and sends the signal to the VXxx unit utilizing standard transmission technologies.
The VXxx passes the signal to the BB2x unit for digital signal processing.
The BB2x unit sends the processed signal to the TSxx unit.
The TRX module on the TSxx unit filters the signal, raises it to the carrier frequency, and amplifies it.
The TSxx unit then sends the signal either to the RTxx unit or through the optional Wideband Combiner (WCxA) unit to the DVxx unit.
The DVxx or RTxx unit sends the signal through either the optional DU2A unit or the BPxx and MNxx units to the antenna, which passes the signal through the Air interface to the MS.