User Manual

ADCP-75-192 • Issue 1• December 2005 • Section 1: Overview
Page 1-3
 2005, ADC Telecommunications, Inc.
In the reverse path, the antenna receives RF signals from a mobile and sends those signals into
the RFA which contains a diplexer and Low Noise Amplifier. The output of the RFA is
connected the RAN Down Converter (RDC) which down converts the RF back to IF and
digitizes the signals. The DIF signals are passed to the SIF, which sends digital optical signals
from the RAN to the HUB SIF. The Hub SIF combines with DIF signals from the other RAN’s
that are in that simulcast cluster through the Reverse Simulcast Card (RSC). The Hub Up
Converter (HUC) takes the RSC output and translates the digital optical signals back to RF
signals for transmission to the BTS.
Figure 1-2 shows the RF signal path through the Digivance CXD system. In the forward
direction, the signal starts from the base station sector on the left and moves to the right. In the
reverse direction, the RF path starts at the antenna and then flows from the RAN to the Hub
and to the base station sector receiver(s).
20800-A
HDC FSC
HUC RSC
HDC FSC
HUC RSC
STF
CPU
RDC
RUC
RDC
STF
CPU
SIF SIF
RFA
800/
900
800 MHz
BTS
900 MHz
BTS
800/900
DUPLEXED
OUTPUT
CXD Hub CXD RAN
Figure 1-2. Digivance CXD Block Diagram
2.3 Local Service Interface
Local communications with the Digivance CXD system is supported through an IP interface
capability. The Hub Digital Chassis and RAN Chassis both contain CPU modules with
Ethernet ports that act as nodes in an Ethernet-based network similar to that of a computer
local area network (LAN). Each RAN in the Digivance network contains one CPU, while the
Hub contains multiple CPUs within the Digital Chassis units depending on the number of
tenant sectors supported in the system. A local user is able to gain access to the CXD network
by the DHCP server resident on the Hubmaster CPU.