What is AISG ?

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The AISG or Antenna Integrated Services Group, a UK based group --www.aisg.org.uk, sets standards for various remotely controlled services that are located up on top of (cellular) antenna towers and buildings roof-tops. For example, the electrical control of Antenna Tilt (--and Azimuth); using a electric-motor driven device called RET (Remote Electrical Tilt) --see below. The other prominent device along with RETs in the Antenna Line Device (ALD) family; is the Tower Mounted Amplifier or TMA. The ALDs need power and communications for control, which is defined by the AISG Standard, AISG 2.0 (2006) and accepted by all ALD manufacturers as well as the Wireless Base-Station Equipment Manufacturers. The Base-Station (Radio) Equipment, in particular has embedded AISG Controller acting as Master while the ALDs on that same AISG network become (AISG) slaves. The AISG Master can service all ALDs in the Base-Station (Cell).

Often field deployments of AISG hardware, share the antenna cable carrying the wireless traffic for distributing AISG Communications & DC Power --. The 3GPP (3rd Gen Partnership Project) stepped in to define the TS25.461 for 3GPP compliance of AISG ALD --.

 

        AISG definitions:

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AISG (--aisg.org.uk) current standard AISG 2.0 (2006) and extensions AISG 2.1.0 (2013), adding new parameters such as Temp, Voltage, Position and more.

 

AISG Cable, Connector:

         

 Cases are connected over the cable shield.

 

Pin #  Pin Function
1 +13V DC (+12V Nominal)
2  - not used
3 RS-485 B
4   - not used
5 RS-485 A
6 +29V DC (+24V Nominal)
7  DC Return
8  - not used

 

AISG Signal Repeater: a passive device splitting an (input) AISG cable multiple ways so that several AISG devices can be copied in a 'star' configuration.

 

ALD or Antenna Line Devices, family members include:

- RET (Remote Electrical Tilt; single/dual)

- TMA (Tower Mounted Amplifier; dual, multi-band)

- Smart Bias-T

- Signal Splitter (passive device)

- Lightning Protection Devices

- Mounting Hardware; grounding plates, brackets, cable clamps

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RET: an electric-motor driven device that turns a worm-gear, which in turn is mechanically coupled to the Antenna mount (top or bottom); such that the motor turning in one direction (clockwise; anti-clockwise), pushes the linkages of the movable end out, while the other end of antenna remains pivoted. The overall effect being that the Antenna may be tilted through a small (5-10) angle. The motor turning in the reverse direction produces the opposite effect; pulling the Antenna mount in and reducing the tilt.

 

TMA: is a single- or pair-, RF Low Noise Amplifiers (LNA), with a switchable gain of 12dB. The TMA is placed close to the Antenna up on the tower, and offsets the Antenna RF Cable loss which otherwise would reduce the Receiver Sensitivity (Si) dB for dB. For Example Rx Si of -100dBm, will be reduced by a long cable running from Antenna over the length of the tower, over ground all the way into the equipment hut, where the Radio may be located. The loss can add up to 4-6dB or more, depending on cable spec; and reduces the receiver sensitivity by that amount. In turn the lower sensitivity reduces the coverage distance on ground by 2-4 times or even more; of what an original -100dBm Sensitivity Rx might deliver, for the given Antenna tower height.

The TMA of fixed 12dB (switchable to 0dB); requires that the left over gain such as 6dB for a -6dB cable loss; must be compensated (dropped to 0dB) before hitting the Rx internal input, which otherwise would bring on Receiver's Front-End saturation early, and end up in Inter-Modulation (IM) distortion. The uncompensated TMA gain therefore reduces the Third-Order Input Intercept Point or Rx IIP3, shrinking the Receiver Dynamic Range (DR), the most important Receiver attribute.

The other TMA criterion is the faithful transfer of DC supply (24-30V by AISG spec), usually residing in the Radio, and which also powers the other ALDs, RET(s) and all, in the AISG network. The DC is sent either over the AISG Cable or routed over AISG and Rx Antenna Cable in a way that the wireless traffic is not obstructed.

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Smart Bias-T: is a (plain) Bias-T along with embedded AISG Signal Modem (AISG carrier 2.176MHz; using OOK or On-Off Keying Modulation) for communications. The Bias-T helps both in adding and separating the Modulated AISG Carrier Signal to and from, the wireless traffic (hi-frequency carrier) going over the same RF cable.

 

Lightning Protection: a means for providing a (quick; DC) path to ground for lightning induced potential on exposed conductors. Electronic equipment with inputs coming in over exposed conductors or cables are usually protected internally; such as Antennas, TMAs, and Smart Bias-Ts.

 

AISG 2.1.0: Extensions (2013) providing more parameters such as Temp, Voltage, Alignment, and more.

AISG Carrier 2.176MHz

OOK Modulated AISG Carrier; (On-Off-Keying)

RS-485: AISG communications is carried over a twisted-pair using a differential RS-485 (higher speed RS-232 type) HDLC signaling conforming.

HDLC: a communications protocol commonly used in Serial Communications.

RAS: Remote Azimuth Steering; an acronym associated with Antenna Beam Steering; also RAB Remote Azimuth Beamwidth; standard AISG-ES-RAS, and AISG-ES-RAB v2.1.0 (2007), Vienna.

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