Setting the standards for 3G and beyond

The avenue for growth in remote electrical tilt antenna technology has been cemented with the collaborative development of an open communications protocol by 3GPP and the AISG advisory group, supported by Radio Frequency Systems.

Third-generation networks that were in their infancy only a few years ago, have today become a commercial reality. As carriers implement wideband code division multiple access (W-CDMA) networks, the economic advantages of applying remote electrical tilt (RET) have moved into the limelight.

Equipment manufacturers are looking for the support of an open market to facilitate the evolution of RET technology. OEMs are asking for assurance that current equipment will retain its value with each development in technology.

In essence, interoperability and backwards-compatibility have become must-haves.

In a bid to create a globally accepted antenna control interface standard, manufacturers from around the world - including wireless technology group, Radio Frequency Systems (RFS) - have joined forces under the banner of the Antenna Interface Standards Group (AISG).

The latest version of this standard, Standard AISG 2.0, defining the specification for means of communication between antenna line equipment and the base station (or node B), is likely to be published soon.

Importantly, the technical solution proposed by the AISG has been selected by the '3rd Generation Partnership Project' (3GPP) as a basis for four technical specifications stipulating the requirements for the physical, data link and application layers of RET technologies.

As a global initiative for the creation of technical specifications for a 3G mobile system, 3GPP has effectively set in stone the requirements for signalling software.

According to AISG chairman, Brian Collins, the AISG specification is currently the de-facto global standard for tower-top monitoring and control.

"Our goal has been to draw attention to the issues concerning RET and determine an open standard," said Collins.

"3GPP took into consideration version 1.1 of the AISG standard and from this developed its own specifications. Working in parallel with 3GPP, we've taken on board these new specifications to generate AISG version 2.0."

What currently differentiates the technical specifications advocated by the 3GPP and Standard AISG 2.0 are requirements regarding tower-mount amplifiers (TMA).

André Doll, RFS vice president product management RF conditioning, who represents RFS as a founding member of AISG, explained that AISG version 2.0 is a replication of 3GPP, with an expanded scope of interest.

"It has been an iterative process between AISG and 3GPP to ensure that the final specifications meet everyone's needs," said Doll.

"Now, if a product is AISG 2.0-compliant, then it is 3GPP-compliant. However, AISG 2.0 also incorporates TMAs and a common communications protocol between the TMA and ACU, whereas 3GPP hasn't accounted for these at all."

With the 3GPP finalising its RET technical specifications in late 2005, RFS is releasing the first series of its AISG 2.0-compliant products. These include a new control network interface combined with a power distribution unit - resulting in a 'CNI-P' control network interface designed to support up to three double TMAs and nine ACUs.

In addition, RFS has developed an AISG 2.0-compliant modem bias-tee to combine the RF and digital control signals and an AISG-compatible TMA.

"Although 3GPP has not yet considered the TMA in its framework, AISG has already developed a set of specifications that standardises communication between the Node B, RET antenna and TMAs," said Collins.

"The next step for AISG will be to continue developing the standard and ensuring that manufacturers interpret and understand it correctly - after all it's to be used as a design tool providing direction and momentum to the development of technology."