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Chapter 17 Performing RFoOBSAI Testing
JD700B Series User’s Guide
645
Introduction
Cell sites today have a distributed architecture of the radio that consists of the baseband (BB) module or
baseband unit (BBU) installed at the bottom of the tower and the remote RF unit (RRU) or remote radio
head (RRH) installed at the top of the tower. These two elements interface with each other for data transfer
over fiber links via the Reference Point 3 (RP3) protocol, which is specified by Open Base Station
Architecture Initiative (OBSAI).
This distributed architecture provides the benefit of replacing coax-based feeders with fiber- based feeders,
significantly reducing the problems of signal loss and reflections. However, since all the RF modules reside
on the RRU, any RF maintenance or troubleshooting requires climbing to the top of the tower to access the
RRU, increasing operational cost and unnecessary safety issues.
JD700B series analyzers provide the option of RFoOBSAI that allows you to perform RF maintenance and
troubleshooting activities on the ground via the fiber interfaces at the BB module, significantly reducing
maintenance time and operational expenses. Thanks to the RFoOBSAI technology, you can verify the
OBSAI RP3 protocol and extracts the RP3 messages transmitted between the BBU and RRU to monitor and
analyze the uplink interferences and the downlink signals.
The RFoOBSAI testing provides following measurements and analysis:
◼
Layer 2 monitoring of link maintenance errors and optical power
o
Loss of Signal (LOS)
o
Loss of Frame (LOF) – Frame synchronization or alignment
o
Optical Rx and Tx power levels
o
Line Code Violation
o
Rx K30.7 words
o
RP3 address/message counts
◼
Layer 2 terminate testing
◼
Interference analysis
o
Spectrum
o
Spectrogram
o
Received Signal Strength Indicator (RSSI)
o
Spectrum replayer
◼
PIM detection of single or multiple carrier(s)
◼
LTE-FDD downlink signal analysis over OBSAI
o
Spectrum
o
RF analysis – Channel Power and Occupied Bandwidth
o
Power vs. Time (Frame)
o
Modulation analysis – Constellation, Data Channel, Control Channel, Subframe, Frame,
Time Alignment Error, and Data Allocation Map
o
Power Statistics CCDF
Display overview
Figure 388 provides descriptions for each segment of the measurement screen.