G.fast is now being rolled out by several operators to provide ultra-fast broadband. G.fast can deliver nearly one Gigabit per second (Gbps) on telephone lines and over one Gbps on coax. G.fast provides an economical alternative to Fiber to the Home (FTTH), eliminating the high cost of fibering the last few hundred meters, while still pulling fiber deeper to provide ultra-fast service.
G.fast has many capabilities which enable robust high-speed service over existing and in-home telephone wiring; including:
- Vectoring to cancel crosstalk
- Retransmission and coding to correct errors
- Low-power modes and reverse-power feed (RPF)
- Many on-line reconfiguration capabilities, including:
- Seamless Rate Adaptation (SRA)
- Fast Rate Adaptation (FRA)
- Robust Management Channel Parameter Adjustment (RPA)
- RMC recovery (RMCR).
ASSIA works throughout the standards communities to ensure that equipment vendors provide open interfaces for operators to manage such capabilities. Each of these capabilities can be configured in many ways via many operator-configurable parameters. And, these are in addition to the margin, data rate, re-initialization and many other configurations common to DSLs. Further, the downstream:upstream asymmetry ratio of G.fast is configurable and can vary with real-time traffic loads. The G.fast environment is highly variable line-by-line, and to configure each G.fast line for best performance is impossible (unless perhaps an operator recruits an army of Ph.Ds in communication theory). But there is a solution: ASSIA DSL Expresse® is now adapted to automatically configure G.fast for the highest customer satisfaction and fewest trouble calls.
Multi-Gigabit fast (MGfast)
After G.fast, the ITU-T is now defining multi-gigabit fast (MGfast) for applications such as fiber-to-the building, fiber-to-the curb, and feeding small cells. MGfast is expected to have all the capabilities of G.fast and more, while running at multi-gigabit speeds. New duplexing and frame structures are being defined to provide wireline and 5G applications on a single backhaul or fronthaul MGfast line, including ultra-reliable and low-latency communications, and ultra-fast broadband. These traffic types should be supported on separate virtual network slices with the operator-configured boundaries. MGfast management will be even more challenging than that of G.fast.
Waveguide over copper
Beyond MGfast lies a new concept now being studied by a group of ASSIA® researchers: Waveguide over copper, which enables the Terabit DSL (TDSL). This exploits waveguide transmission modes, in particular transmission modes that are efficiently transported on the surface of a conductor such as copper wire. Waveguide over copper runs at millimeter frequencies (about 30 GHz to 1 THz) and is synergistic with 5G/6G wireless. A type of vectoring is applied to effective separate the many modes that can propagate within a telephone cable. Preliminary analyses project that waveguide over copper should support about the following per-home data rates:
|100 meters||300 meters||500 meters|
|1 Tbps (=1000 Gbps)||100 Gbps||10 Gbps|