User Manual

User Reference and Installation Manual 2-13

MDS 5800 II

The 64-QAM Modem performs the modulation and demodulation of the payload/wayside/SNMP

data and forward error correction using advanced modulation and coding techniques. Using all-

digital processing, the 64-QAM Modem uses robust modulation and forward error correction

coding to minimize the number of bit errors and optimize the radio and network performance.

The 64-QAM Modem also scrambles, descrambles and interleaves/deinterleaves the data stream

in accordance with Intelsat standards to ensure modulation efficiency and resilience to sustained

burst errors. The modulation will vary by application, data rate, and frequency spectrum. The

highest order modulation mode supported is 64 Quadrature Amplitude Modulation (QAM).

The SDIDU

also provides the physical interface for the user payload and network management.

In transmit mode, the Framer merges user payload with radio overhead-encapsulated network

management data. This combined data stream is transmitted without any loss of user bandwidth.

In the receive mode, the Framer separates the combined data stream received from the 64-QAM

Modem. The SDIDU

supports Scalable Ethernet data rates, such as 25 or 50 Mbps via the

100BaseT data interface port. The SDIDU

provides network management data on 10 Mbps

ports accessible via the 10/100BaseTX port. The Central Processor Unit (CPU) provides the

embedded control and network element functionality of the OAM&P. The CPU also

communicates with other functions within the SDIDU

for configuration, control, and status

monitoring. The CPU passes appropriate status information to the SDIDU

front panel display.

In Ethernet models, the payload of each user Ethernet data packet and all T1 can be encrypted

using an AES encryption algorithm. In addition, the encryption engine is re-seeded with a new,

randomly generated key stream every 10 seconds, in order to provide enhanced security. The

initial key is based off of a pass phrase entered into each MDS 5800 II unit by the network

administrator. Consult factory for the availability of this encryption function.

The power supply converts -48 Vdc to the DC voltage levels required by each component in the

system.

2.6 Consecutive Point Architecture

The consecutive point network architecture is based upon the proven SONET/SDH ring.

Telecommunications service providers traditionally use the SONET/SDH ring architecture to

implement their access networks. A typical SONET/SDH network consists of the service

provider’s Point of Presence (POP) site and several customer sites with fiber optic cables

connecting these sites in a ring configuration (see Figure 2-5). This architecture lets providers

deliver high bandwidth with high availability to their customers.