ADCP-75-110
•
Issue 2B
•
July 2001
Page 17
©
2001, ADC Telecommunications, Inc.
The
LIU is rack or wall mountable and is powered by 120–240 Vac (50–60 Hz) power. Refer
to
the Digivance Local Interface Unit User Manual (ADCP-75-113) for a complete description
of
the LIU.
2.1.2 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 the DHU and antenna. The correct levels
at
the DHU and antenna can be provided using the Remote Interface Unit (RIU). The RIU is
an
accessory item that provides adjustable gain or attenuation in both the RF forward and
reverse
paths. The RIU connects to a directional antenna through a duplexer which provides
separate
forward and reverse path connections for the DHU. In the forward path (downlink),
the
RIU provides the DHU with the recommended composite maximum RF input signal level
of
–20 dBm. When the level of the RF input signal at the DHU is –20 dBm, the level of the
RF
output signal at the DRU is +13 dBm which is the maximum allowed.
In
the reverse path, the required RF output signal level to 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 is –30 dBm. Therefore, it may be necessary to add gain or
attenuation
to the reverse path signal in order to achieve the required output signal level at the
RIU
antenna port. A block diagram showing a typical remote DHU to BTS interface is
provided
in Figure 9.
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 a complete
description
of the RIU.
DIRECTIONAL
ANTENNA TO/FROM
CELL SITE BTS
16425-A
REMOTE
INTERFACE
UNIT
FORWARD
(DOWNLINK)
REVERSE
(UPLINK)
+13 dBm
(COMPOSITE
MAX)
-40 dBm
(COMPOSITE
MAX)
-20 dBm
(COMPOSITE
MAX)
-30 dBm
(COMPOSITE
MAX)
DIGITAL
HOST
UNIT
OPTICAL LINK
OPTICAL LINK
DIGITAL
REMOTE
UNIT
DIRECTIONAL ANTENNA
TO/FROM HANDSETS
Figure 9. Remote BTS Interface Block Diagram
Summary of Contents for Digivance
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