Collin Arocho
29 August

As demand for broadband internet network capacity skyrockets, DSL – the legacy phone line system – is headed straight into a brick wall. For this dilemma, the Imec spin-off Pharrowtech is proposing a new take on an old technology: fixed wireless access.

Since 2005, Imec has made big strides in the development of RF, analog and mixed-signal designs for both radar and high-speed wireless communications. In 2015, under the guidance of Wim Van Thillo, the Belgian research and development powerhouse started a number of R&D programs spanning multiple frequencies from 140 GHz, for applications in radar, down to 28 GHz for 5G wireless. By 2017, Van Thillo saw an emerging business opportunity in the field of millimeter-wave-based fixed wireless access. Together with Imec, they decided that the 60 GHz technology, used for wireless communications, was both mature and robust enough that it was ready to be spun out. The result: Pharrowtech, run by Van Thillo, the company’s co-founder and CEO.

By capitalizing on the years of cutting-edge R&D, the Leuven-based start-up believes it can utilize Imec’s millimeter-wave technology to offer high-speed wireless internet to the masses and can do so in a cost-effective manner. Now, several months after the company’s creation and thanks to a successful 6 million euro round of seed investment from Imec.Xpand, Bloc Ventures and KBC’s Focus Fund, the millimeter-wave fixed wireless access experts at Pharrowtech are ready to bring their next-generation solution for broadband internet access into production.

Currently, Pharrowtech has fully operational prototypes, but not yet a product. Credit: Pharrowtech

Physical limitations

Currently, the top two methods for broadband access are through coax cable and legacy telephone line systems, like DSL. In fact, according to the 2018 EU Digital Economy and Society Index (DESI) report, the market share for DSL internet in the Netherlands is just under 40 percent, while in Germany, DSL accounts for almost 75 percent of broadband service. Though DSL has had a good run over the last few decades, as network capacity needs continue to skyrocket in the current digital age, it’s simply no longer going to cut it.

“DSL has had a very, very nice track record. Technologically speaking, it’s an amazing product and what this industry has managed to pull over a copper cable is incredible,” praises Van Thillo. “But now, the technology is really running into a brick wall of physical limitations in terms of bandwidth and crosstalk. You simply cannot pull much more through a twisted pair of copper wires, it’s running out of capacity.”

In addition to the capacity issues of DSL, there’s the problem of connection speed. In the coming years, the general standard speed for broadband companies just to stay relevant in the industry, is going to need to be one gigabyte per second – a task DSL, even in good circumstances, isn’t going to meet. Of course, there’s an alternative. Fiber-optic internet connections are tremendously fast and have an extremely low cost of maintenance, but there are two big issues. One: the cost of deployment is prohibitively high, as high as 2,000 euros per house in urban environments, and for houses in rural areas, even higher. Two: the logistics are next to impossible.

“Let’s use Germany’s 40 million households as an example. If German operators could successfully connect 10,000 houses every single day, it would still take more than a decade to get to full deployment. By then, as a business you’re no longer competitive,” explains Van Thillo.

In 2005, Wim Van Thillo started his PhD as a KU Leuven doctoral student at Imec, working on system and algorithm design for 60 GHz wireless communications. In 2015, he took over as program director at the research institution for a number of similar projects before moving on in 2018 to become the founder and CEO of the Imec spin-off Pharrowtech. Credit: Imec

High-end Wi-Fi

Fixed wireless technology itself is nothing new. It’s been used on LTE-like technologies for years and more recently, it’s being used in the upcoming 5G cellular network. But, while the mobile-based technologies continue to struggle with bandwidth, that’s not a problem for Pharrowtech. In terms of bandwidth, with the new IEEE 802.11ay standard and the most recent FCC and ETSI channel allocations, there are six channels of approximately 2 GHz wide – meaning more than 12 gigs of available bandwidth. Van Thillo: “That’s huge, that’s more in just that single 60 GHz band than anywhere else in the spectrum and more than all of the other bands added up together,” continuing, “In terms of spectrum, it’s like a factor of 10x or more compared to what traditionally is considered to be very wide band.”

Compared to DSL and fiber, Pharrowtech’s fixed wireless solution has a couple advantages. First, unlike DSL, it can easily offer customers the one gigabyte per second speeds that are required. Second, in contrast to fiber, it can be deployed much faster – it’s just a matter of installing wireless access points on the street. To give an idea, think of a high-end Wi-Fi access point, both in terms of price and power consumption. Once these connection points are installed, it’s then up to the consumer to subscribe to the service, after which they’ll receive customer premises equipment (CPE), like a router, in order to connect.

“If only 10 percent of the homes sign up for service, the telecom company simply sells these 10 percent CPEs and can start making their investment back immediately. In contrast to fiber deployments that require the 100 percent investment all at once, they won’t need to sink huge investments into the 90 percent who don’t connect yet,” suggests Van Thillo.

Secret sauce

There are some potential drawbacks for the 60 GHz system. By nature, the signals are spatially constrained. In other words, they don’t travel very far. They operate primarily in line of sight. At a distance beyond a kilometer, there’s absorption in the atmosphere, which degrades the signal. However, this can also be an advantage. For instance, if you want to reuse a frequency on a very dense local scale, that’s possible. The same band can be used on one street and then used again on the next street, and so on. Van Thillo: “This is because of our customized, power-effective beamforming transceivers, which is really the core of our technology and is something that Imec has long been developing.”

Similar to the fixed wireless access, beamforming transceivers are also not a new idea. Beamforming radars have existed for some time, but at these high frequencies, they were typically implemented in expensive semiconductors technologies. Initially, that consisted of compound semiconductors like gallium arsenide, but recently there’s been a shift toward silicon-germanium – which is often used in automotive radar.

Utilizing techniques from Imec, Pharrowtech’s system is designed in plain digital CMOS, allowing for extremely high-volume processes with very high yields and relatively low cost, in terms of technology. Van Thillo: “That’s the hard thing about CMOS, it’s not typically a process suited for these high frequencies, it’s not a process specifically suited for analog and mixed signals. And that’s the essence of what we have been designing. That’s our secret sauce.”

Credit: Pharrowtech

Final phase

With this secret sauce and the support of the recent investment, the next step for Pharrowtech is to ramp up production and get the system ready for the market. To do this, the start-up is focused on growing its team, having already attracted semicon and telco industry veteran board directors with backgrounds in Broadcom, Huawei, Vodafone, Arm, Cadence, Synopsys and several high tech start-ups. With this, the company still expects to have the mm-wave fixed wireless access ready for deployment within the next two years.

Before this can happen, there are still a number of steps to be taken. “Currently, we have fully operational prototypes, not yet a product. To get to the final phase, we have to design for high-volume manufacturing, for reliability and for qualification,” discusses Van Thillo. “We’re establishing a support organization for customers, like field application engineers. We need to ensure proper integration with the baseband support for the embedded software. So, there’s still plenty to do.”