Why Gfast Is About to Come of Age
The latest Gfast chipsets, supporting Amendment 3 functionality, are offering a mature solution for gigabit broadband that is re-igniting the copper-versus-fiber debate.
Since the first Gfast chipsets were introduced in 2014, vendors have worked with network operators and system developers to run trials and experiment with higher performance, longer reach and support for coax. The Gfast specifications have been further developed with three amendments, clarifying issues and adding support for 212MHz operation, coax and dynamic time assignment (DTA). The latest Gfast chipsets implement all this functionality and some additional features for future specifications. Gfast has been demonstrated delivering 4Gbit/s aggregate bandwidth on two bonded pairs of CAT-3 copper telephone wires.
The residential broadband market started when dial-up modems were replaced by ADSL during the 1990s for Internet access. Since then there have been two main approaches to increasing telecom broadband speeds: fiber to the home (FTTH) and fiber to the distribution point (FTTdp) using VDSL. FTTH can potentially deliver the highest bandwidth but requires a fiber connection into every home or business. Installing these fiber connections is both disruptive and expensive. By using FTTdp, network operators can significantly shorten copper loop lengths and avoid the cost of installing fiber onto the customer premises. The DP can either be a roadside cabinet or a box located near the customer.
Gfast dramatically increases broadband speeds for short loops; however, like VDSL, Gfast does not significantly improve performance over long loops. VDSL2 works best over loops shorter than 1km, although some benefits are seen up to 2km and work is ongoing to support long reach VDSL. Gfast works best over distances of 100-250m, although longer distances can be achieved in specific applications. Gfast supports reverse powering of the DP from the customer premises equipment (CPE), making it easier and cheaper for network operators to provision Gfast from DPs on poles or at other locations close to the user.
Heavy Reading's new report, Gfast Rollout Starts With Amendment 3 Chipsets, identifies and analyzes vendors developing Gfast chipsets for DP and CPE equipment. The report profiles the leading vendors and analyses both Gfast and VDSL2 chipsets, identifying their key features and highlighting the advantages they hold for service providers and telecom solution providers. The report includes not only information on the chipsets, but also offers insights into how the overall market for Gfast is developing.
Second-generation Gfast DP chipsets have been introduced by both Broadcom and Sckipio with eight 106MHz Gfast ports. Beyond the basic Gfast functionality there are significant differences in the support for 212MHz Gfast, vectoring and other features. Broadcom has a strong portfolio of DSL solutions and both generations of Broadcom Gfast chipsets also support VDSL2 and ADSL. Some of the latest Gfast DP chipsets can support vectoring on up to 96 ports, a significant improvement on first-generation chipsets.
Broadcom and Sckipio also have two generations of Gfast CPE solutions. The Broadcom CPE chipsets integrate MIPS or ARM gateway processors and support for VDSL2/ADSL. The Sckipio CPE chipsets are standalone Gfast modems for use with separate gateway processors or in SFP modules. Metanoia has been shipping standalone VDSL2 and Gfast chipsets for CPE and single line DP applications, and has developed an SFP module design. Intel has an extensive range of CPE gateway solutions, including gateway processors and separate modem chipsets for Gfast and VDSL2/ADSL.
The Broadband Forum has done a lot of work to support Gfast, including setting up the Gfast Council and developing tests that have been used confirm interoperability. There are now multiple DP and CPE Gfast Certified systems using first-generation Gfast chipsets. This work is ongoing and being extended to include the latest chipsets and 212MHz operation.
Gfast is a worthy successor to ADSL and VDSL. It does not remove the need for fiber deployment further into the access network, but it does enable gigabit broadband without fiber being installed over the last hundred meters into the customer premises. The latest Gfast chipsets are being designed into a wide range of DP and CPE systems, which will allow network operators to start a significant rollout of Gfast during 2018 and into 2019. Chipset vendors and the industry in general are continuing to develop broadband technologies over copper lines with G.mgfast promising 5-10 Gbit/s and initial discussion of significantly higher rates, possibly using waveguide technology, further into the future.
— Simon Stanley, Analyst at Large, Heavy Reading