Docomo and NGMN boost active antenna standards

The further vendors and operators move along up 3GPP release ladder, the more antennas emerge from the shadows to become strategically important to the success of an LTE or LTE-Advanced network. MIMO arrays with more and more elements, and active antenna technologies for flexible multimode, multiband base stations, are increasingly vital, and operators are looking for standards work to be accelerated to ensure affordability and interoperability.

In the run-up to Mobile World Congress, NTT Docomo took the lead in showing off the way advanced cellcos will harness new antennas, while the NGMN (Next Generation Mobile Network) alliance supported standards for base station antennas.

Docomo talked about a five-band LTE antenna it had developed itself, looking to add its new 700MHz spectrum to its existing 3G and 4G bands in the coming couple of years. It followed that up with news that it had successfully connected an active antenna to a commercial LTE base station.

Such demonstrations are important because active antenna (AAS) technology is in its infancy and some carriers remain nervous of deploying it, despite its ability to reduce the cost and complexity of rolling out multiband 2G/3G/LTE systems. Docomo's antenna was jointly developed by Japanese antenna maker Dengyo Kosaku and Ubidyne of Germany, the latter a pioneer in active antenna chips, and a platform that allows radios to be distributed along the antenna to reduce power.

Most significantly, Docomo connected its antenna to its base station via an interface based on ORI, the emerging standard which carriers hope will lower costs and allow them to implement multivendor networks (for this reason, some major base station OEMs have not been over-supportive of ORI, as they cling to the old lock-ins). Currently active antennas and base stations need to be made by the same vendor because of the lack of a standard interface between the elements.

ORI is an ETSI specification already supported in Docomo's heavily customized base stations, but winning NGMN backing is an important step to seeing it universally adopted by BTS vendors. The Japanese carrier said ORI will allow it to install active antennas quickly and inexpensively without having to set up new base stations.

Docomo said that it would submit the results of its test to the 3GPP to contribute to the standardization of future active antennas.

Dengyo had contracted Ubidyne to adapt its existing 700MHz active antenna platform for 800MHz LTE, 3GPP band 19 requirements, along with the integration of an operator defined CPRI interface and full RF system testing. The complete 800MHz AAS system is expected to be deployed with a major regional network operator in 2013, said the Japanese company. Dengyo developed an advanced antenna housing, while Ubidyne implemented the operator proprietary CPRI interface. This is based on a Ubidyne specific framework that supports fast adoption of CPRI integration.

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