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4 BTS3900 Components
Functions
The GRFU performs modulation and demodulation of baseband signals and RF signals,
processes data, and combines or divides signals.
The GRFU has the following functions:
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The GRFU consists of the high-speed interface unit, signal processing unit, power amplifier,
and duplexer.
Figure 4-32 Logical structure of the GRFU
The High-speed interface unit has the following functions:
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The signal processing unit consists of two UL RX channels and one DL TX channel.
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Implements the direct frequency conversion technique in the transmit channel, modulates
the baseband signals to GSM RF signals; then sends the signals to the antenna for
transmission through the duplex filter after filtering, amplifying, and combining the RF
signals (the combining can be performed as required)
Receives RF signals from the antenna and performs down-conversion, amplification,
analog-to-digital conversion, digital down-conversion, matched filtering, and Automatic
Gain Control (AGC), and then transmits the signals to the BBU for further processing
Provides power control and Voltage Standing Wave Ratio (VSWR) detection
Provides reverse power detection
Provides frequency synthesis and loopback test
Generates the CPRI clock, recovers the CPRI clock of lost synchronization, and detects
alarms
Figure 4-32
shows the logical structure of the GRFU.
Transmits the signals received from the BBU to the signal processing unit
Transmits the signals received from the signal processing unit to the BBU
The UL RX channel has the following functions:
– Performs down-conversion of the RF signals to IF signals
– Amplifies the IF signals and performs IQ demodulation
– Performs analog-to-digital conversion through the ADC
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Copyright © Huawei Technologies Co., Ltd.
BTS3900
Hardware Description
Issue 04 (2011-02-15)
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