SAN JOSE, Calif.— Three service providers are working on plans to deploy cloud radio access networks (C-RANs), a new approach to building cellular networks. The radical concept uses banks of x86 servers to connect cellular calls rather than traditional wireless base stations.
China Mobile, the world's largest carrier with 700 million subscribers, has been spearheading trials and plans to deploy systems as early as 2015. Japan's NTT Docomo said it will follow in 2016, and a third unnamed carrier is now preparing plans for C-RANs, said Gilad Garon, chief executive of Asocs Ltd. which sells silicon cores for modems.
"In last few months any doubts whether C-RAN would happen have gone away," said Garon, whose company was chosen in February to supply baseband technology for China Mobile's trials, in an interview. "Korea Telecom is involved, and we see interest in Europe primarily from Deutsche Telekom."
China Mobile aims to lower the cost of C-RANs to less than $30 per LTE sector, down from about $10,000 two years ago. It will start a second round of trials later this year using servers equipped with PCI Express cards to handle baseband processing. Each card will pack four FPGAs using Asocs cores, each FPGA capable of handling 12 LTE sectors, said Garon.
The trial also will test Asocs' MPL, a programming language for baseband chips. MPL lets developers call C-language libraries that will run jobs on ARM, Mips or x86 processors.
The next trial will use only Intel servers, but emerging low power ARM servers could be used in C-RANs in the future. "There's still the cost of optics, software and servers, but the sheer DSP processing will be cheap," said Garon.
C-RANs will likely take their place beside traditional base stations and emerging small-cell base stations as another tool for building cellular nets, said Gordon Mansfield, chairman of the Small Cell Forum and executive director of small cell solutions and radio access network delivery at AT&T Mobility.
"C-RANs' biggest challenge is backhaul," said Mansfield. "It requires extreme low latency and that requires fiber" which is expensive and not widely deployed in many parts of the world where traditional and small cells will be a better fit, he said.
With the exception of Intel, C-RANs also lack the support of the major chip makers, Mansfield, said. "Having general purpose hardware and software is the ultimate goal, and all the big, heavy-processing silicon providers will end up there I believe, but right now it's too early to see who will come out as leaders," he added.