Goodbye base station: Rebuilding radio access network architecture

Alcatel-Lucent has proposed a bold new product portfolio for radio access network architecture that it claims will lower expenses, improve performance and eliminate base stations.

From car phones to cell phones to smartphones, mobile operators have always rolled with the latest mobile gadgets, but basic radio access network (RAN) architecture hasn't changed a bit. Operators still encumber their cell towers with bulky and costly base stations.

With the range and impact of mobile services, applications and devices escalating exponentially, mobile operators are recognizing that decades-old RAN architectures are in desperate need of an update. Alcatel-Lucent (ALU) has proposed a new product portfolio that claims to lower RAN expenses and improve performance by downsizing and eliminating base stations.

I've been frustrated for years by the fact that … equipment vendors haven't come up with an affirmative response to the [radio access network] equipment problems operators face.

Tom Nolle
President, CIMI Corp.

ALU claims its new lightRadio portfolio can eliminate the need for carriers to purchase and deploy separate sets of RAN equipment for each generation of wireless technology. Used together, the lightRadio products also eliminate the need for base stations at a cell site by consolidating some of their functions into antennas and distributing other functions to a central, cloud-like processing center. 

This new radio access network architecture would lower the total cost of ownership (TCO) of the RAN by 51% for carriers, said Tom Gruba, senior director of product marketing at ALU. Mobile operators would spend less on equipment, reduce power consumption and lower rack space and cell site rental requirements, he said.

"It's just like having a 30-year-old refrigerator, air conditioner or car. It's not as efficient. They're not as green. We can do better," Gruba said. "If we cut even a small percentage [of base stations], it's a big number."

"Anything that makes the radio network more cost-effective is good for operators and more importantly, it's good for the market because it keeps operators from having to generate revenue solely from increases in price," said telecom consultant Tom Nolle, president of CIMI Corp. "This could mark the beginning of a real shift."

Radio access network architecture: More is not better

Radio access network architecture is "the most important but most problematic part of mobile broadband," Nolle said.

Operators have traditionally responded to increased mobile traffic consumption by adding more cell sites and deploying more efficient technologies, such as HSPA+ and Long-Term Evolution (LTE). But there are only so many bits that can be crammed into a pipe and so much that carriers can spend on building cells, Nolle said.

Additionally, each generation of technology often requires carriers to deploy a separate set of radio and base station equipment.

"The largest single issue in mobile broadband is how in the heck the operator is ever going to be able to afford the costs of [continually adding] cells," Nolle said. "I've been frustrated for years by the fact that … equipment vendors haven't come up with an affirmative response to the [RAN] equipment problems operators face. They've always assumed operators will have to pay what they [charge]."

To some extent, vendors have struggled with radio access network architecture innovation because the infrastructure has become heavily standardized to address a wide range of needs, said Peter Jarich, research director at Current Analysis.

"If you think about any of those other technologies, you have to put some bounds on the endpoint. If I buy a DSLAM [Digital Subscriber Line Access Multiplexer], I know those DSLAMs work with a certain number of modems," Jarich said. "For mobile, who knows what phones are going to be out there next, so [vendors] have to make sure it's standardized."

Virtualization, consolidation simplify new radio access network architecture

ALU initially built the lightRadio product portfolio to fit a "cloud RAN" or C-RAN architecture proposed last year by China Mobile, according to Gruba. Alcatel-Lucent "didn't invent the architecture, but we're providing the products to suit the architecture," he said.

The lightRadio cube is the core product of the portfolio. This 2.5"x2.5" cube consolidates multiple generations of antennas into one array. The cube, which was developed by Bell Labs, contains diplexer, radio, amplifier and passive cooling components. A mobile operator can stack multiple cubes in different columns to accommodate different frequencies, and the cubes can support multiple new generations of wireless technology through software upgrades.

 The lightRadio cube is powered by ALU's system-on-a-chip, new silicon chip that Bell Labs developed in conjunction with chipset manufacturer Freescale Semiconductor. This chip enabled ALU to remove the amplifier and baseband functionalities from the base station and consolidate them directly into the cube, Gruba said.

ALU's new radio access network architecture also virtualizes signal processing and load balancing, which has also traditionally lived in the base station, into a centralized "cloud-like architecture," Gruba said. Multiple cells can pool processing power and share it as needed. Gruba said this is an appealing alternative for operators whose powerful base stations only use these features during peak hours.

"Think about New York City and think about Wall Street. During the day, the cell tower is very loaded," he said. "At night, there are crickets … [so] you've got that tower with all those electronics and no one using the system. That's not efficient."

Operators can run fiber directly from the antenna to backhaul data to that processing cloud. Bell engineers are working to support more types of backhaul connectivity, such as microwave, Gruba said.

The lightRadio portfolio also includes beam-forming technology for antennas, stronger compression algorithms, more resilient remote radio heads and advanced features that enable antennas to "work in harmony instead of fighting with one another," Gruba said.

ALU will stagger its release of lightRadio products from 2012 through 2014. No carriers have fully deployed the products today, but ALU is trialing the technology with China Mobile and other operators worldwide.

Can new radio access network architecture be too flexible?

Although the concepts behind lightRadio are sound, carriers may struggle to decipher the complex and multifaceted portfolio, Jarich said. Carriers want flexibility, but too much of it can be paralyzing.

"If I'm an operator, it's sometimes a little bit easier to say, 'Here's what I'm deploying in my network and what I'm going to train everyone on' … as opposed to, 'Here's a bunch of building blocks and go build whatever you want,'" Jarich said. "With so many moving parts, [the ability for] an operator to understand what this means may be difficult."

 Other major wireless network equipment vendors -- Ericsson, Nokia Siemens Networks, Huawei -- have also inched toward phasing out physical base stations and adding multimodal support, but represent a more standardized offering, he said.

"We ding them from time to time, saying operators may want more options, but the value is the operator knows what [it's] getting," Jarich said.

Even in ALU's promotional materials, one large carrier that was quoted in the press release struck a slightly noncommittal tone.

In a written statement, Tom Sawanobori, vice president of technology planning at Verizon Wireless, said the carrier "looks forward to learning more about the benefits of lightRadio technology and how they could be applied."

Let us know what you think about the story; email: Jessica Scarpati, News Writer.

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