Copper based ADSL (asymmetric digital subscriber lines), FTTC (fibre to the cabinet), and G.fast cannot provide gigabit speeds, although performance between these services varies. ADSL is capable of delivering maximum download speeds of 24Mbps, compared to FTTC (VDSL/virtual digital subscriber line) which can deliver download speeds of up to 80Mbps and G.fast which is currently capable of providing speeds of up to 330Mbps. However, with all these services, the speed achievable declines with distance, with the highest speeds only available to premises closest to the cabinet.
FTTP (fibre to the premises or full fibre) and DOCSIS (data over cable service interface specification) 3.1 are both capable of gigabit download speeds. However, unlike DOCSIS 3.1, FTTP can also offer symmetrical upload speeds, and can therefore deliver gigabit upload as well as download. High upload speeds are especially important to businesses in sectors where large files need to be transferred e.g. media production, as well as for certain domestic uses, such as online gaming.
All gigabit capable networks also offer increased reliability and resilience compared to copper, with FTTP providing the most reliable and resilient service. As well as improved quality of service, full fibre networks requires much lower maintenance compared to copper networks, with five times fewer faults. The reduction in fault rate means FTTP networks are cheaper to run than copper, and the National Infrastructure Assessment estimated that this could save £5bn in operating costs over 30 years.
The department has not made specific assessments of the differences in energy efficiency. However, FTTP has lower energy requirements than copper and cable technologies and requires the use of fewer exchanges, and will therefore likely lead to reduced emissions for similar bandwidths.
Fibre is a key requirement for 5G networks, providing high speed and capacity mobile backhaul to match the capacity of 5G mobile networks. It is important that mobile operators and infrastructure providers have access to the key inputs for network densification, including sufficient fibre backhaul capacity.