Handbook

ClearFill Star CDMA
1100187 Rev. 1.0
Page 18 of 152
2.2 Unit description
2.2.1 Base Station Interface (BSI)
The connection to the BTS is established through an RF interface. The RF interface allows
ClearFill®Star to support any manufacture’s BTSs. The central task of the BSI is to convert
the downlink radio signals into outgoing Ethernet packets and to convert incoming Ethernet
packets into uplink radio signals.
The BSIs RF interface processes the downlink RF signal with a down-converter and an
analogue-to-digital converter (ADC) to generate a digital base band signal.
The uplink data is processed by a digital-to-analogue converter (DAC) and an up-converter.
To support multiple sectors a ClearFill®Star network can easily support multiple BSIs.
For the uplink, multiple packet streams from multiple RRHs are combined by summation to
form a single IQ signal stream for the BTS receiver. This feature is called summing. A
summing function is included in the BSI, an example for the summing function is shown in
Figure 9.
RRH RRH RRH
GES
RRH + sum
(
Level 4
)
RRH RRH RRH
GES
RRH + sum
(
Level 4
)
GES
GES
GES
BSI + Sum
of Sums
Transport Network of a 4 Cascade Configuration
Level 1
Level 2
Level 3
Level 4
NMS
Figure 9 Example of a cascaded transport network.
The BSI described in this manual is the CFS-BSI-2S-819-1, a simplexed twin BSI rack.
It consists of two BSIs, which are independent units in a single housing. All connections (RF,
Ethernet, power supply) are realized for each BSI independently.