Alcatel-Lucent 9500 MXC User Manual page 860

Backplane
TDM Bus
RAC 30
RAC 30 Transmit
Vol. VI-F-4
The backplane carries signal and power interconnection between INU/INUe
plug-ins. It is a multi-layered PCB with connectors positioned for each plug-in.
The TDM bus enables traffic interconnect between plug-ins. It comprises two
high-speed parallel buses, each divided into time slots, the timing (bus timing) of
which can be user-selected for E1, DS1, E3, DS3, or STM1/OC3 rates. In this
way, an INU/INUe can be configured as an E1, DS1. E3, DS3 or STM1/OC3
platform.
Slot traffic includes payload and overhead. Each plug-in has access to the entire
bus, but slot access depends on its function and configuration.
Bus timing and frame synchronization are provided by the NCC, which can be
protected by the installation of the NPC option.
RAC 30 supports the ODU 300 for bandwidth options to 28/30 MHz using
modulation options from QPSK to 128QAM.
Operation of the transmit and receive paths are described in turn for the RAC 30
diagram shown in Figure F-1 on page F-2.
The Bus Demux extracts the payload and overhead traffic from the TDM bus and
passes it to FiFo (First-in, First out) buffer and Mux stages, which accepts,
synchronizes and frames:
• Up to 64xE1, 84xDS1, 4xE3, 3xDS3, or STM1/OC3 channel capacities.
• One NMS channel, plus the INU-to-INU communication overhead.
• Up to six auxiliary data channels.
The framed data stream is passed to the Vantex modulator, where:
• Reed-Solomon FEC check data and associated block interleaving is inserted.
• It is rate modulated for the selected (in CT) capacity and bandwidth/modulation
options.
• 90 degree phase-shifted I and Q data streams are generated.
The I and Q streams are converted to analog signals in the D/A converter, and
passed to the quadrature modulator, which impresses the data onto a 311 MHz IF
carrier. This IF is passed to the N-Plexer, where it is combined with telemetry and
reference oscillator signals, plus 48Vdc power, to go to the ODU.
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