Samsung Mobile WiMAX Outdoor RAS SPI-2331 System Description page 39

CHAPTER 3. Outdoor SPI-2331 Architecture
Downlink (Tx) Signal Processing
As for the downlink signal, the ULRB performs bandpass filtering of baseband I/Q signal
received from the ULDB and converts the signal into the analog signal through Digital to
Analog Conversion(DAC).
The converted analog signal goes through frequency up-conversion to RF band signal, and
the signal is transferred to power amplifier. The power amplifier amplifies the received RF
band signal and sends it to a filter.
The filter filters out unnecessary frequency components from the received RF signal and
sends out the RF signal through the antenna. The power of the RF transmission signal per
Tx path at the RF output port is 100 mW.
Uplink (Rx) Signal Processing
Out-of-band spurious wave of RF signal received from the antenna is suppressed through
front end analog filter. This signal is low noise amplified in Low Noise Amplifier(LNA),
and it is frequency down converted to the analog signal.
The converted analog signal is converted to the digital baseband signal through Analog to
Digital Conversion(ADC), and it is transferred to ULDB.
TDD Operation
The ULRB has a TDD switch and it switches the sending/receiving path by receiving a
TDD signal from the ULDB to help the outdoor SPI-2331 run as a TDD system.
The TDD switch connects with the transmission path in the DL section and provides a
transmission path for downlink signals amplified in the power amplifier. The TDD switch
connects with the reception path in the UL section and provides a reception path for uplink
signals from the MS.
3-6 © SAMSUNG Electronics Co., Ltd.