AISG Products on WWW.NXP.COM
Remote Antenna Site
Failure Detection
by Site Scanning
Using AISG Modems
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Introduction to AISG
AISG setup in basestation tower today
Embedding AISG functionality in Tower Mounted Devices
Using AISG modems for site scanning
Summary & Conclusions
Further reading….
Content
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Purpose of AISG AISG enables remote control of tower mounted devices by a cellular base station
– Remote Electrical Tilt (RET) setting for antennas
– Tower Mounted Amplifier (TMA) parameter setting
– Status monitoring of tower mounted devices (sensors)
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How does it work ? Control is via RS-485 cable
Smart-Bias-Tees (SBTs) to eliminate the RS-485 cable – from bottom to top of the tower
– RS-485 cables and connectors at bottom and top remain !
AISG signals “inserted” on coaxial RF power cable – 9.6kb/s OOK modulation at 2.176 MHz
Complete specification: www.aisg.org.uk
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Avoiding the cable adds many connectors ! Running an RS-485 cable to the tower top is avoided
But 2 extra RS-485 connectors are added
Plus 4 extra RF power coaxial cable connectors
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Optimizing the AISG system by…. Lowering the number of exposed connectors in the tower increases reliability.
“From testing over 2000 feeder lines, 75% of problems are found in
poor quality, poorly assembled, dirty connectors”.* Other contributors are poor component plating, ferromagnetic materials, connectors not torque correctly.
Connectors are also: – Potential cause of installation errors (wrong connections)
– Expensive compared to the actual electronics
* Source: Electro Rent Europe (http://www.electrorent-europe.com/pim-test/faqs.aspx#q3)
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….putting AISG modems inside
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Eliminates the connectors, but also avoids 2 rugged external Smart-Bias-Tees
Inside the RET antenna housing (or TMA) the electronics are safe
‒ Internal AISG modem electronics cost is much lower than cost of 1 single connector
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Step 1 – Embedding the AISG modem
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ANT
RET
Smart Bias Tee AISG
(RS485+DC)
RF
RF +OOK +DC
INTEGRATED ANT
DC-Bias Tee
Power
ASC3011
ANT
RET
RF
RF +OOK +DC
RF & OOK filter
RF+OOK
Power supply
2.176MHzOOK
UART
New solution replacing Smart-Bias Tee
RS485 Transceiver
AISG (RS485+DC)
No changes to existing RET Software
More cost effective than external Smart-Bias Tee
Eliminate RS485 external connectors
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Step 2 – Combining AISG & RET electronics
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INTEGRATED ANT
ANT
RET + MODEM
DC-BiasTee Power
ASC3101
RF
RF +OOK +DC
RF & OOK filter
RF+OOK
Power supply
2.176MHzOOK
New solution replacing Smart-Bias Tee + CPU (in RET) and in Antenna
PWM
Actu
ator
s
GPIO
Alar
ms/
Se
nsor
s
Mot
orD
river
ANT
RET
Smart Bias Tee AISG
(RS485+DC)
RF
RF +OOK +DC
Eliminate internal RS485 interfaces and components
Eliminate separate RET microprocessor
More cost effective than external Smart-Bias Tee and external RET
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Single band HV Polarized integrated antenna (Present solution)
RF(H Pol) +OOK +DC
AISG MODEM
BTS0
Bias Tee
TX Filter
RX Filter
RX Filter
ANT V
LNA Supervision and Control
Bias Tee
TX Filter
RX Filter
RX Filter
ANT H
RF(V Pol) +OOK +DC
BTS0
RET (MCU)
Com
mun
icat
ion
Pow
er S
uppl
yC
omm
unic
atio
nP
ower
Sup
ply
LNA LNA
Single band HV Polarized integrated antenna with ASC3112
ASC3112
RF(H Pol) +OOK +DC
Modem 0
BTS0
Bias Tee
TX Filter
RX Filter
RX Filter
ANT V
RF
LNA
GPIO/ADC
Bias Tee
TX Filter
RX Filter
RX Filter
ANT H
RF
LNA
OOKOOK
RF(V Pol) +OOK +DC
BTS0
GPIO/ADC
Modem 1
Actuators
PWM
Motor Driver
Ala
rms/
Sen
sors
Power SupplyDC DC
Step 3 – Enable all RF ports with AISG Example: Multiband or a single-band HV polarized antenna
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AISG enabled RF ports enable Site Scanning Strictly speaking for AISG communication, a tower device needs only 1 RF
connector “AISG-enabled”.
Adding an internal AISG modem function all RF ports can be done at low cost
Also avoids fixed port assignments that could result in installation errors
And enables checking the status of the RF connectors by AISG !!
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single controller possible single controller possible
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What’s the Problem ?
Connectivity information tower equipment is gathered manually
Mostly once during installation
Based on visual analysis
Bad connections can be overlooked
Wear out almost impossible to detect
Remote tracing not possible
Increasing tower complexity and
increasing number of connectors
drives the need for a (simple) way to
check all these connections (remotely)
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What’s the Solution ?
Automate the gathering of connectivity data
By electronically scanning the connections
Perform the scan any time remotely without affecting tower operation
Detect improper connections and flag it
Detect damages occurring over time (wear-out)
Site Scan provides way to gather connectivity data remotely. It can have a big impact on the cost of network operations Note: It is not (yet) part of the AISG standard
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Site Scanning – How does it work ? RF, AISG and DC power travel over same cable & connector
Use the existing AISG signalling to also check RF connectors
AISG controller will record connection status per tower device
Each tower device indicates number of ports and connections
AISG controller records all the data to make aconnection map
AISG controller can check this mapping check periodically
Request for “Connectivity Check” can be triggered remotely
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Example of a Site Scan Sequence
Site scan can be initiated by the Basestation (BTS)
Blue blocks are NOT detected yet
Black wires are NOT detected yet
Green blocks mean BTS detected this block
Green wires mean connectivity scanned by BTS
Red oval is the targeted connection
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Site Scan Sequence – Initial state
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BTS device_id_00
TMA device_id_10
ANT device_id_20 0 1
2 3
0 1
0 1
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BTS device_id_00
TMA device_id_10
ANT device_id_20 0 1
2 3
0 1
0 1
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Site Scan Sequence – Address 1st device
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BTS device_id_00
TMA device_id_10
ANT device_id_20 0 1
2 3
0 1
0 1
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Site Scan Sequence –1st device responds
Result: – TMA informs BTS it has 4 ports
– 1 out of 2 BTS ports scanned
– 1 out of 4 TMA ports scanned
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ANT device_id_20 0 1
TMA device_id_10
2 3
0 1
BTS device_id_00
0 1
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Site Scan Sequence – Scan next port
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BTS device_id_00
TMA device_id_10
ANT device_id_20 0 1
2 3
0 1
0 1
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Site Scan Sequence – Next port scanned
Result: – 2 out of 2 BTS ports scanned
– 2 out of 4 TMA ports scanned
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BTS device_id_00
ANT device_id_20 0 1
0 1
TMA device_id_10
2 3
0 1
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Site Scan Sequence – Address 2nd device
TMA in AISG repeater mode
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BTS device_id_00
TMA device_id_10
ANT device_id_20 0 1
2 3
0 1
0 1
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Result: – ANT informs BTS it has 2 ports
– 1 out of 2 ANT ports scanned
– 3 out of 4 TMA ports scanned
– 2 out of 2 BTS ports scanned
Site Scan Sequence – 2nd device responds
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BTS device_id_00
TMA device_id_10
ANT device_id_20 0 1
2 3
0 1
0 1
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Site Scan Sequence – Scan next port Horizontal repeater mode
Alternative scan route path
Vertical repeater mode
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BTS device_id_00
TMA device_id_10
ANT device_id_20 0 1
2 3
0 1
0 1
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Site Scan Sequence – All ports scanned
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BTS device_id_00
TMA device_id_10
ANT device_id_20 0 1
2 3
0 1
0 1
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In case of failure…..
If devices support repeater mode,
all connections can be traced
Vertical repeater mode should be
supported at all level
Horizontal repeater mode should
be supported at various levels
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Further notes to Site Scanning The number of layers (2 in the example) can be extended to any number
There can be multiple devices per layer
Site scanning can be performed any time without affecting tower operation
AISG communication runs on different carrier without disrupting RF traffic
The software overhead for the basestation controller is low (simple process),
without real-time requirements
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Summary & Conclusions Integrating AISG into tower equipment saves cost of cabling, connectors, SBT’s
and improved overall tower reliability
AISG enabled RF ports bring the extra benefit of implementing site scanning
Site scanning enables simple and low cost remote connection failure detection
Basestation towers becoming more complex, with more connectors increases
potential failure, downtime, and costly fault-finding
Site scanning is NOT part of the AISG standard; needs definition of commands
and scanning procedure.
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For more information and detailed basestation site scanning proposal
See: http://www.nxp.com/documents/white_paper/75017400.pdf
Or contact: [email protected]
For more information on AISG products
See: http://www.nxp.com/products/interface_and_connectivity/aisg_transceivers_and_controllers/
Further reading…
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