G.fast

To limit interference to those radio services, the ITU-T G.9700 recommendation, also called G.fast-psd, specifies a set of tools to shape the power spectral density of the transmit signal;[9] G.9701, codenamed G.fast-phy, is the G.fast physical layer specification.

[3] The discontinuous nature of TDD can be exploited to support low-power states, in which the transmitter and receiver remain disabled for longer intervals than would be required for alternating upstream and downstream operation.

GigaDSL remains a transitional technology, and traditional TDD-based G.fast is expected to dominate larger post-VDSL growth.

To that end, the impulse noise protection (INP) data unit retransmission scheme specified for ADSL2, ADSL2+, and VDSL2 in G.998.4 is also present in G.fast.

[3][23] Performance in G.fast systems is limited to a large extent by crosstalk between multiple wire pairs in a single cable.

[20][24] On older, unshielded cable, aggregate data rates of 500 Mbit/s were achieved at 100 m.[20] The Broadband Forum is investigating architectural aspects of G.fast and has, as of May 2014, identified 23 use cases.

In FTTdp deployments, a limited number of subscribers at a distance of up to 200–300 m are attached to one fiber node, which acts as DSL access multiplexer (DSLAM).

[31] Former FCC chief of staff Blair Levin has expressed skepticism that US ISPs have enough incentives to adopt G.fast technology.

Bell Labs, Alcatel-Lucent proposed the system concepts of XG-FAST, the 5th generation broadband (5GBB) technology capable of delivering a 10 Gbit/s data rate over short copper pairs.

[36][37] The XG-FAST technology will make fiber-to-the-frontage (FTTF) deployments feasible, which avoids many of the hurdles accompanying a traditional FTTH roll-out.

Project objectives include:[25] On October 15, 2019, Broadcom announced the BCM65450 series xDSL modems with support for upcoming G.mgfast modes with up to 424 MHz bandwidth.

[42] Beyond MGfast lies a new concept now being studied by a group of Brown University and ASSIA researchers:[43][44] Waveguide over copper, which enables the Terabit DSL (TDSL).

Preliminary analyses project that waveguide over copper should support about the following per-home data rates: As of 2017, this technology remains an interest of research teams, as a working implementation is yet to be demonstrated.