Small Cell ChipsetsSeveral key chipset functions are needed to build a small cell. These provide the same capabilities as found in larger macrocells but at a fraction of the cost, consuming little power and taking up minimal space.
Three major elements can be physically integrated or combined into a common solution:
These chips would be supported by separate memory chips, typically a read/write chip for transient data (called RAM) and a read only chip which holds the program (called ROM). These are standard components used in many electronic devices.
Small cells have achieved tremendous reduction in component count by integrating much of the functionality into a few critical chipsets. Each new revision of vendor chipsets integrates more capability as we move closer to a complete system on a chip (SoC).
There is still a distinction between the baseband processing chipset (which are digital) and the RF front end (which is analog), although recent iterations from some vendors have combined the two especially for lower power (indoor) products.
Separate small cell chipsets have been developed specifically for 3G and LTE technologies, but more recently we have seen powerful products capable of running either (or both) simultaneously.
The 3G residential small cell market was initially dominated by Picochip (since acquired by Mindspeed, then Intel) and later overtaken by Percello (acquired by Broadcom) whose latest hardware can run 3G and/or LTE. Qualcomm who offer both CDMA and UMTS chipset variants, are newer to the market. It's now a two horse race between Broadcom and Qualcomm, especially for emerging new designs for LTE and/or 3G/LTE multimode products. A few older products continue to ship using the picochip design.
Higher capacity Enterprise and Urban small cells have attracted investments and specific product variants from the larger vendors who already supplied macrocell parts: specifically TI (Texas Instruments), Freescale and Cavium.
Intel appear to be refocussing on Cloud RAN solutions where the baseband processing hardware is centralised although do continue to support earlier picochip/Mindspeed customers.
MAXIM have been the major supplier of RF front end components for 3G residential femtocells, and continue to be a major player. Other vendors including ADI and Lime Microsystems also have market share.
Qualcomm take a slightly different approach and incorporate the RF front end into their solution set, so a separate vendor RF front end chipset isn't required. Broadcom have also integrated the RF in some of their latest products, such as the BCM616x0
For some insights about how these vendors are approaching the market, read our interview with Jerry Wei, Business Manager for Wireless RF transceivers at MAXIM and Dr Busheri, CEO of Lime Microsystems.
The wide range of frequency spectrum options which could potentially be used for LTE brings a requirement for a single but adaptable design. Some RF components can be easily tailored by selecting alternative passive components during the final stages of product assembly.
TDD mode requires a different circuit design but can often use the same standard components.
Reports from multiple sources have indicated that Broadcom are downsizing their activities in the Small Cell market. While this doesn’t immediate affect products shipping today based on their design, we consider the implications and point to other recent developments.
Cavium’s CEO reckons they’ve got silicon that covers all the architecture options for small cells and Cloud RAN. They’ve even proposed a new middle ground with smarter radio heads. He shares opinions on timescales, architectures and equipment vendors.
A lot of investment has gone into development of specialist silicon for small cells in recent years. In this article, we've taken a step back and reviewed the landscape, talked to many of the major players, and developed our view of what's going on. It might be controversial for some, but should help navigate through the plethora of press releases and announcements.
Powerful chipsets developed for use in Small Cells have evolved dramatically over recent years, as have those for macrocells. Clear market segmentation is evolving associates specific silicon vendors to the different system architectures. We look at how these critical components are shaping up for the future.
One of the best ways to find out what products are likely to be appearing soon is to ask the component vendors. They can often tell you what requirements are being seen in the market, and have a good idea of what development work is ongoing. Although they can't divulge details about their individual customers, it helps to sense the priorities and focus of the industry.
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