User's Manual

ADCP-75-132 • Issue 2C • August 2006
Page 18
© 2006, ADC Telecommunications, Inc.
The HPCP is rack or wall mountable. Refer to the Digivance ICS 800 and 1900 MHz High
Power Conditioning Panel User Manual (ADCP-75-175) for additional information.
3.1.2 Remote BTS (Cell Site Base Station) Interface
A remote interface between the DHU and the BTS (cell site base station) via a donor antenna
requires specific RF input and output signal levels at both the DHU and the antenna. The
correct input and output signal levels can generally be provided using the Remote Interface
Unit (RIU). The RIU is an accessory item that is used to adjust both the forward and reverse
path RF signal levels. In the forward path, the RIU provides gain adjustments in 1 dB
increments over a range of +9 to +40 dB. In the reverse path, the RIU provides gain
adjustments in 1 dB increments over a range of +28 to +59 dB. A block diagram of a typical
remote DHU to BTS interface is shown in Figure 9.
DIRECTIONAL
ANTENNA TO/FROM
CELL SITE BTS
17793-B
REMOTE
INTERFACE
UNIT
FORWARD
(DOWNLINK)
REVERSE
(UPLINK)
-40 dBm
(COMPOSITE
MAX)
-30 dBm
(COMPOSITE
MAX)
DIGITAL
HOST
UNIT
OPTICAL LINK
OPTICAL LINK
DIGITAL
REMOTE
UNIT
DIRECTIONAL ANTENNA
TO/FROM HANDSETS
COMPOSITE MAX
PER TABLE 6
COMPOSITE
MAX PER
ADJUSTMENT
PROCEDURE
Figure 9. Remote BTS Interface Block Diagram
The RIU connects to a directional antenna through a duplexer (internal) that provides separate
forward and reverse path connections for the DHU. In the forward path (downlink), the
maximum RF input signal level the DHU will accept is determined by the DHU overdrive limiter.
When the RF signal input to the DHU is set to 1 dB below the DHU overdrive level, the RF signal
output at the DRU will be at the specified maximum level (see Table 6). The level of the RF signal
output at the DRU is dependent on the modulation protocol and the number of carriers.
In the reverse path, the RF output signal level required at the donor antenna will vary
depending on the distance from the BTS. When the level of the reverse path (uplink) signal at
the DRU is at the recommended composite maximum level of –40 dBm, the level of the RF
output signal from the DHU with be –30 dBm. Therefore, it will generally be necessary to add
some gain to the reverse path signal in order to provide the output RF signal level required at
the donor antenna.
The RIU is rack or wall mountable and is powered by 120–240 VAC (50/60 Hz) power. Refer
to the Digivance Remote Interface Unit User Manual (ADCP-75-114) for additional
information.