Alcatel-Lucent has developed an element that sits in between its Baseband Units and DAS elements from any vendor, to create a new way of distributing radio capacity across wireless networks.
The element, called the Radio Frequency Manager, acts as an LTE interface card that can then provide a simplified RF signal from Alcatel-Lucent’s BBU to a DAS, removing the need for equipment that is deployed to refine signal for DAS, such as signal duplexers and attenuators. Alcatel-Lucent has said that its research has shown the RFM card produces large savings on space, cost, and power requirements compared to normal DAS deployments. The RFM unit is half rack size, with versions for high band and low band radios.
The RFM can connect to any Alcatel-Lucent BBU via the CPRI interface, distributing RF signal to any vendors’ anallogue DAS element, thereby ensuring that neutral host models can be maintained, where necessary. The unit can be configured to align uplink and downlink power to achieve improvements in signal to noise ratios across a system – Alcatel Lucent claims live tests have achieved 10dB improvement in uplink noise, for example.
Last year Alcatel-Lucent achieved integration between its BBUs and TE Connectivity (now Commscope) DAS elements so that Alcatel-Lucent radios could be used to “feed” existing Commscope DAS elements. That solution was called the CPRI Digital Interface Unit (CDIU).
Tristan Barraud De Lagerie, Director of Product Marketing (Wireless) at Alcatel-Lucent, told TMN that the new RFM was “an extension of the work to optimise the deployment cost and space required to feed DAS.”
However, he added, “The CDIU approach goes one step further though, and moves the generation of RF altogether into the DAS Head-End but it works only with one specific vendor (Commscope). DAS RFM allows the support of the other vendors’ DAS.”
The RFM can also be seen as extending the flexibility of the architectures that a BBU can support. So for instance Alcatel Lucent’s recent 9926 Digital BBU can support up to 24 cells, which means it can connect up to 24 DAS RFM and/or cellular remote radio heads. Of course, where the connection is between a BBU and cellular RRH, the RRHs must be Alcatel Lucents, as CPRI is not an open interface.
