John Cioffi theorizes that 1 Terabit/s over 100m is possible. Several world-class engineers have confirmed the theory appears correct. The same higher-order waveguide modes could deliver 10 Gbps at 500 meters, which is exciting some of the most important companies in the industry. It could drastically reduce the cost of backhauling 5G small cells in the required millions of locations.
Some are using the name Surface Wave over Copper (SWoC) instead of TDSL as the system moves closer to test. Building a test system and proving the real challenges can be met will be expensive. The frequencies involved are at 50 GHz and higher, 200 times higher than the new 212 MHz G.fast.
The signal would not run over copper wires and the performance is far beyond the Shannon Law limit of the copper. Instead, transmission is in the gaps (presumably air, but could also be at times plastic sheathing) between and around the wires. The wires act as guides rather than carrying the current directly like they do in conventional DSLs
Everyone needs tests results before we are convinced, myself included. But Cioffi, a friend, has at least twice delivered results "everyone thought impossible." 20-some years ago, the best in the business thought 1.5 megabits was the practical limit using 1 MHz of spectrum for ADSL. John theorized that 6 megabits was possible. No one believed enough to support him, so he raised the money and built the first DMT modem. Hundreds of millions are in homes today. A decade later, vectoring was also dismissed. It is now a mass market product and at the heart of G.fast.
Some of the largest companies in the industry are ready to back the development and John is confident real products are only a few years away.
John is presenting at the Broadband Access Summit in Berlin on Oct 24. See you there.
|The DSL roadmap from G.fast to Terabit-fast|
|Use of higher-order waveguide modes are explored for increasing the speeds of twisted-pair data rates to levels as high as 1 Terabit/s over 100m. A path to significantly improve DSL speed/range is reviewed in terms of significantly advance beyond the lengths for G.fast and G.mgfast through these modes use. 1 Gbps symmetric speeds at the low end at ranges of 600-700 meters and 10 Gbps at 500 meters are reviewed as intermediate steps to the eventual Terabit DSL. The steps and complexities of advancing to these capabilities are suggested and reviewed.|