3D pSLC NAND Bridges the Gap to DDR5 for 5G Base Station Designers

June 25, 2020


So is DDR5 the answer for today's 5G base station developers? For now, the answer is "not yet." One alternative appears to be advanced DDR4 technology, 3D pSLC NAND flash.

Compared to 4G, there’s no argument that 5G performance far exceeds its predecessor. It provides higher peak data speeds (up to 20Gbps), super-low latency, greater reliability, massive network capacity, increased availability, and a more uniform user experience.

But with the benefits of 5G come certain setbacks. For instance, Daryl Schoolar, Practice Leader for Next Generation Infrastructure at research firm Omdia notes that 5G’s “higher spectrum bands like 3.5 GHz or mmWave … don’t penetrate buildings as well as lower spectrum bands.”

The poor diffraction capability, easy loss, and decreased coverage area that result from these higher frequency radio waves means that the number of 5G small cells will be two to three times that of the 4G era. Indeed, Schoolar is projecting a 74.8 percent compound annual growth rate for 5G base stations over the next five years.

The deployment of more small cells necessarily means that more large-capacity memory will be needed to manage the massive amounts of temporarily stored data generated by increased network loads and the real-time computing requirements of 5G applications such as vehicle-to-everything (V2X) connectivity, robotic control, and augmented/virtual reality; and the subsequent temporarily stored data.

The small file sizes of 5G network data, along with frequent write requirements, means that 5G base station memory will have to provide fast speeds and a high number of program/erase (P/E) cycles at competitive price points. With its higher density, 3D NAND flash is emerging as the technology of choice in these deployments, explains Anthony Spence of Silicon Power Computers & Communications, Inc.

“Normally we have [network] customers looking to acquire products with P/E cycles in the ranges of 60K, like the ones provided by traditional SLC,” Spence says. “However, as traditional 2D Flash becomes scarce and prices begins to rise, both customers and suppliers are adapting to the circumstances and this is where pSLC 3D NAND flash comes in.

“pSLC is able to provide high levels of durability, which near the ones for SLC, at a cheaper cost,” he adds.

Pseudo single-level cell (pSLC) flash is a multi-level cell (MLC) memory derivative that provides a middle ground between SLC and TLC solutions. The technology is faster, more reliable, and delivers a significantly higher number of P/E cycles than traditional MLC or TLC memory, with pSLC 3D NAND devices from Silicon Power delivering 30K write/erase cycles (more than 10 times that of 3D TLC NAND). Meanwhile, it is also much less costly than SLC flash memory, with Silicon Power quoting at least an 86 percent cost savings (Figure 1).

Figure 1. Comparison of  SLC, MLC, TLC, and pSLC memory characteristics.

pSLC, Where the “p” is for Performance Density

From a 5G base station design perspective, Spence explains that the performance density of 3D pSLC NAND flash provides the advantage of being able to add capacity without sacrificing area.

“5G base stations have higher requirements than 4G predecessors meaning that density is important,” he says. “NAND flash is able to provide higher storage capacity so, for example, if you were looking to somewhat equal the 60K P/E durability of a 16 GB SLC solution you would use 32GB of 30K pSLC.”

“Small form factors such as ECC-SODIMM or higher-end SORDIMM DRAM modules allow [network engineers] to meet their performance needs without the tradeoff of taking up too much space.”

Silicon Power offers a range of high-speed, industrial-grade DDR4-2666 DRAM modules in UDIMM, SODIMM, ECC-SODIMM, and other form factors (Figure 2).

Figure 2. Silicon Power offers memory in a variety of DDR4 DRAM module form factors.

To increase the reliability of its 3D pSLC NAND flash solutions even further, Silicon Power offers wide temperature memory variants, as well as customization options such as sulfur resistance for base stations deployed in or near manufacturing and other noxious environments.

Its memory products are also supported by the company’s SMART IoT toolbox, an application that allows network engineers to remotely monitor the health and status of memory devices. This allows them to intervene before a component fails and maintain network uptime.

Does 5G Need DDR5? It Probably Can’t Wait.

The next generation DDR5 specification is slated to be published by JEDEC sometime this year, but currently is still undergoing revisions. The new standard promises to double bandwidth while reducing overall power consumption, which would certainly be a boon for 5G base station developers.

But even with standard publication drawing near, industry will require years to refine the technology to meet the reliability, performance, and price envelopes required by 5G base stations. And as Schoolar notes, the APAC region, which is projected to represent approximately 64 percent of the 5G market, is already moving rapidly behind initiatives like Made in China 2025 that define 5G as a “strategic emerging industry.”

So is DDR5 the answer for today’s 5G base station developers? For now, the answer is “not yet.”

One good alternative appears to be selecting the right balance of advanced DDR4 technology, 3D pSLC NAND flash.

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Perry Cohen, associate editor for Embedded Computing Design, is responsible for web content editing and creation in addition to podcast production. He also assists with the publication?s social media efforts which include strategic posting, follower engagement, and social media analysis. Before joining the ECD editorial team, Perry has been published on both local and national news platforms including KTAR.com (Phoenix), ArizonaSports.com (Phoenix), AZFamily.com, Cronkite News, and MLB/MiLB among others. Perry received a BA in Journalism from the Walter Cronkite School of Journalism and Mass Communications at Arizona State university. He can be reached by email at [email protected]. Follow Perry?s work and ECD content on his twitter account @pcohen21.

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