Samsung Mobile WiMAX Outdoor RAS SPI-2331, Описание системы

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CHAPTER 3. Outdoor SPI-2331 Architecture
3-4 © SAMSUNG Electronics Co., Ltd.
3.2.1 ULDB
The ULDB is the uppermost board in the outdoor SPI-2331. The main processor of the
outdoor SPI-2331 is installed on this board and it provides system operation and a
maintenance function. In addition, the ULDB is an integrated digital board providing a
modem, GPS signal receiving and clock distribution, and network interface functions.
Main Processor Function
The ULDB is the board that carries out the role as the highest layer in the outdoor SPI-
2331 and is equipped with the main processor. The main processor of the ULDB performs
the functions, such as communication path setting between MS and ACR, Ethernet switch
function in the outdoor SPI-2331 and system operation and maintenance.
The ULDB manages the status of all hardware and software in the outdoor SPI-2331 and
reports each status information to WSM via ACR. In addition, the ULDB allocates and
manages the resources of the outdoor SPI-2331 and the connection of the ULDB and a PC
for the Web-EMT enables to maintain the outdoor SPI-2331 with no interworking with ACR.
Modem Function
The ULDB is equipped with the modem supporting IEEE 802.16e standard physical layer
and the modem performs the OFDMA channel processing function.
The ULDB modulates the packet data received, and transmits the modulated data to the ULRB
as digital baseband I/Q(LVTTL) signal. In the contrary, the ULDB demodulated the data
received from the ULRB, converts the data into the format defined in the IEEE 802.16e Mobile
WiMAX physical layer standard and then transmits the converted data to the ACR via Ethernet
interface.
Network Interface Function
The ULDB interfaces with an ACR in Fast Ethernet method and the ULDB can provide
maximum two Fast Ethernet ports. Then the service provider can choose the copper or
optic for the network interface.
GPS Reception and Clock Distribution Function
The Universal Core Clock Module(UCCM), which is installed as ULDB mezzanine, generates
a system clock [Pulse Per 2 Second(PP2S), Reference Clock(44.8 MHz), Analog 11.2 MHz]
by using the GPS signal from the GPS and distributes the clock to each board and module.
Therefore, each device of the outdoor SPI-2331 runs under the synchronized clock system.
The UCCM provides a holdover function(24-hour) which maintains its normal clock for a
specific time period based on its prior learning capability when there is no GPS signal
because of any accidents.