Broadcom joins small-cell basestation fray
Small cells are widely seen as the answer to the flood of mobile data congesting today’s traditional macro base stations. But creating a new tier of cells that use a mix of 3G, 4G and Wi-Fi links is a costly and complex task that carriers are still testing this year in trials.
Initial deployments will probably start next year, focusing on High Speed Packet Access nets, which form the brunt of most carrier traffic today, said Hanna Maurer Sibley, a director of mobile broadband at Ericsson. Unfortunately so far each carrier seems to have different requirements, she added.
Last year, carriers used the Super Bowl, London Olympics and the U.S. Republican and Democratic national conventions as testing grounds for small-cell concepts. AT&T put out a request for information on small cells, and Sprint has shared some plans for the approach.
Small cells pose challenges for carriers in managing both licensed (cellular) and unlicensed (Wi-Fi) spectrum in cells. They also need to support a range of wireless and fibre-optic backhaul links.
The need to install more fibre carries regulatory and cost hurdles, said John Georges, who led a startup pioneering distributed antenna systems (DAS), a forerunner of small cells. His startup installed as many as 10,000 DAS devices in the United States. Japan and Korea also have deployed early versions of small cells, he said.
Chip, system vendors scramble for position
The promise of a market for four to eight small cells for every macro base station has chip and system vendors scrambling for position. Freescale and Texas Instruments rolled new SoC architectures for small cells last year, and LSI announced its own recently, following an industry trend of shifting to ARM cores.
TI announced at MWC physical-layer software for small cells
running on its SoCs.
In the competition for customers, LSI claims Nokia Siemens Networks will use its new Axxia chips. TI said China’s ZTE has adopted its Keystone SoCs for 3G/4G small cells. Freescale is working with The Technology Partnership, which is building small cells using TV white-space spectrum.
There’s also a scramble to create small-cell ecosystems. Broadcom partnered with Radisys, which is contributing its LTE software to Broadcom’s reference designs. The chip maker also rolled out its own integrated development platform.
For its part, TI announced a software package handling all physical-layer software for 3G/4G small cells on its chips. It announced a separate package for transport functions for base stations and edge networks.
Meanwhile a handful of top OEMs are duking it out for a slice of the basestation market. Ericsson and Huawei each claim about 24 percent of the radio access segment, followed by Nokia Siemens Networks, Alcatel-Lucent, ZTE, Samsung and NEC, according to market-watcher ABI Research. The sector grew 17.4 percent sequentially in the fourth quarter of 2012 to reach almost $8.5 billion last year, ABI estimated.
Broadcom joins the fray
Broadcom is a late comer to integrated basestation chips, but it has significant strengths including battle-hardened 3G as well as Wi-Fi silicon that it can integrate when the time is right. The company also has been a player in chips for residential femtocells, a related and still-growing market.
Ultimately small cells on carrier networks may rise to volumes as great as femtos, but there’s likely more margin and revenue in small cells, said Greg Fischer, general manager of Broadcom’s broadband group that deals with everything from femtos to fibre optics.
The new BCM 617xx SoCs support LTE at a low cost and with less silicon area than competitors, Fischer claims. The SoC also includes an undisclosed set of MIPS processors at a time when some OEMs are converging on the x86 and ARM.
"Some OEMs prefer [ARM], but others don’t care or are agnostic because we bring a solid underpinning of the software they need," he said.
The chips also pack multiple Gbit Ethernet ports, Broadcom’s Firepath DSP and PCI Express interfaces to external Wi-Fi chips. They support 40-MHz LTE bands and both FDD and TDD flavors of LTE.
The SoCs support both the physical and transport layer needs for small cells for up to 256 users. Larger macro cells typically separate the two functions, often using OEM modem ASICs, FPGAs or third party DSPs, he noted.
The chips come in three versions for different sizes of small cells and are sampling now. Broadcom also updated its femto cell offering with the BCM61630, now supporting HSPA rates up to 21.6 Mbits/s and in volume production by June.
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