Terabit Broadband – Terabit DSL

Extreme high frequency sub-millimeter waves may increase single-line data rates to terabits/second at 100-meter lengths on ordinary twisted pair phone wire. It has been projected that speeds of 100 Gigabits/second can be achieved at distances over 300 meters, and speeds of 10 Gigabits/second can be achieved at distances over 500 meters.

The Waveguide Over Copper Method

According to Dr. John Cioffi, Chairman and CEO of ASSIA and Emeritus Professor at Stanford, fiber-like speeds of 10 – 1000’s of gigabits/second (Gbps) are possible by using the previously unexploited waveguide modes of current copper infrastructure. Waveguide-mode use is similar to use of millimeter-wave transmissions in advanced wireless and 5G. Waveguides can enable use of frequencies above 100 GHz for extraordinary speeds.

The new waveguide over copper method was introduced by Dr. Cioffi during his keynote at the Paris G.fast Summit conference on May 10, 2017 titled Terabit DSL”. He introduced multiple IEEE papers and ITU and Broadband Forum contributions that have further elaborated on it. Dr. Cioffi explained how 5G wireless can already run at 70 GHz and 90 GHz, in the frequencies of waveguide over copper. Wireless above 300 GHz (sub-millimeter wave) is being actively researched.  Early designs suggest link latency of 50-100 microsec is readily achievable, which would easily allow even the most stringent 5G latency specifications of 1ms or less to be achieved with these Terabit DSLs.

Today’s fastest DSL (G.fast) uses only 200 MHz, while wireless uses 25 times as much spectrum.

Initial Value for Phone and Internet Company Data Centers 

While at this time, no one really needs terabits/s (Tbps) to their home, terabits/s will be most valuable to the data centers controlled by phone companies, as well as, to internet companies such as Google and Microsoft. While Tbps demand may be a few years into the future, 10-100 Gbps speeds are important to networks today and will be a big market. Rapid advances in the Internet of Things (IoT), including autonomous vehicles, means the number of connected devices requiring high-speed ubiquitous connectivity will increase dramatically in the next decade. ASSIA believes that Terabit DSL will play a critical role in serving the needs of that ecosystem with ultra-high-throughput and ultra-low-latency connectivity.

Terabit DSL and 5G

Further driving the demand for bandwidth, hundreds of thousands of 5G small cells and DOCSIS 3.1 cable nodes will require 5-20 gigabit backhaul. Most 5G cells will connect to a Cloud RAN controller that can use 100 gigabits/s to support dozens of cells.

AT&T and other telcos around the world are also deploying G.fast to apartments. G.fast speeds of 300 megabits to a gigabit can be supplied to every apartment. This differs from cable, which has shared connections that require multi-gigabit backhaul.

Fiber is and always will be expensive to deploy. There are a billion phone lines around the world which could be able to deliver fiber-like speeds over existing copper infrastructure. Using the existing wires in place can dramatically reduce the cost of 5G networks.

There are a few years of work ahead in the industry to refine the system. LTE and now 5G wireless have proven that major advances can evolve from concept to deployment in five to seven years. Data centers at Google and Facebook can leverage such new technologies in only a few years.

Brown University Work

Work is now underway at Brown University under the direction of Professor Dan Mittleman to further advance waveguide over copper. A portion of this work was funded by the United States National Science Foundation with ASSIA as the industry sponsor.