It's been understood for some time that LTE cell sites will be smaller than their 3G counterparts - not just in terms of coverage, but also the size of the base stations themselves. Last year, vendors were talking BTSs the size of an A4 sheet of paper. This year, Alcatel-Lucent is talking about a base station that fits snugly in the palm of your hand.
In February, Alcatel-Lucent (by way of Bell Labs) announced a new product line called "lightRadio" that essentially proposes a new BTS architecture that breaks the BTS down "into its components elements and then distributed into both the antenna and throughout a cloud-like network."
The lightRadio line includes AlcaLu's multiband remote radio head, baseband unit, controller, and 5620 SAM common management solution. But the star of the lightRadio concept, however, is the lightRadio Cube, a 6-cm box sporting SoC technology jointly developed with Freescale Semiconductor that combines a wideband active array antenna with software-defined radio capability to support 2G, 3G and LTE networks at frequency bands ranging from 400MHz to 4GHz.
"This [cube] enables an active antenna as small as 2 watts to an array of typical cellular capacity (30-60 watts)," blogs Wim Sweldens, president of AlcaLu's wireless division. "Big or small cells, it is one continuum, for these cubes can be stacked to build a macro cell or used singularly in a beam formation for targeted coverage."
Sweldens adds that lightRadio cuts site rental costs by 66% and reduces power consumption by over 50%." AlcaLu also intends to leverage the cloud for its lightRadio architecture via virtualization software, saying it will "collaborate with partners like HP to enable a cloud-like wireless architecture for controllers and gateways", to include the baseband processing.
The product line won't be broadly available for another year, but AlcaLu named some big operator names for trials this year, including China Mobile and France Telecom/Orange.
Naturally, lightRadio raises technical issues, such as the impact of its cloud architecture on mobile backhaul networks, notes Caroline Gabriel of Rethink Wireless.
"Radio signals are carried from these boxes to a central location for baseband processing - a heavy burden on the network, which will probably require fiber to connect the cubes to the central platform," Gabriel wrote in a research note. "In time, ALU aims to develop more advanced compression technology to make copper or microwave viable for these links."
There's also the question of what it will mean for AlcaLu's mobile equipment business, Gabriel adds. "The firm needs a radical approach to start to regain market share against Ericsson, Huawei and Nokia Siemens." That said, other vendors are now chasing the small cells concept - notably Ericsson, which has resisted the trend in favor of macro cell equipment.
But at the Mobile World Congress it announced AIR (Antenna Integrated Radio), which integrates the radio and antenna units to reduce power consumption and space on the tower, although it's not as small as lightRadio and the baseband stays at the foot of the mast. Also, Ericsson's solution is aimed more at existing sites whereas lightRadio is more of a greenfield solution, notes Gabriel.
Meanwhile, NSN is reportedly targeting AlcaLu's distributed BTS concept more directly with "Liquid Radio", which will integrate a baseband SoC from Texas Instruments into a distributed radio unit, but with the ability to tap additional baseband capacity from the cloud when cells become overloaded, according to Connected Planet Online.