What Does a Broadband Network look like?
A broadband network is made up of three main parts
- The core network with links to the Internet – sometimes called the Backbone
- The backhaul which connects the backbone network to the community access points
- The local loop – connects the premises to the backhaul delivered within the community
The Core Network
The type of core network or backhaul will vary between suppliers. Some suppliers will have a complete infrastructure with links to the Internet as well as meshing links between node points within the core network that provide load balancing, alternate routing and less exposure to a single point of network failure.
The core may be made up of fibre links, wireless connectivity or a hybrid of both. More than one connection between any core network and the Internet is preferred and ideally these links should provide diversity and be capable of supporting the entire Internet connection requirements for the customer base.
The core network will also include the management and client authentication equipment needed to route the internet to the end users and to match the user service profile to the billing and administration devices.
Connections or backhaul links provide the delivery of Internet services from the core to the community and/or business premises. The backhaul can again be provided by fibre or wireless links.
The Local Loop – Community Connections
The backhaul link is terminated within a community at what may be referred to as a Community Access Point – CAP. There will normally be one main link to the community from the core network (or Internet), however this will be dependent on the supplier, the demand expectation from the community and the willingness to accept a potential single point of failure. The backhaul link should be sized to meet the community demand expectations and the supplier should automatically increase the bandwidth provided as community take up of service increases.
Resident or businesses premises are connected by radio links to a CAP which may be the main link to the community from the core network or an alternate CAP located at a strategic point within the community. Most communities will require multiple CAP’s and typically between six and ten may be required according to the total number of users and the local community geography.
The Economics of a Broadband Network
Whichever network delivery solution is being considered there will always be some trade-off between the cost of delivering the backhaul and local loop, the speed of service provided and the applications that can be delivered to the home or business. These economics generally affect rural communities much more than an urban environment as the distances between the suppliers’ network and the community access points are greater.
The cost of way leaves and the associated “civil works” costs climb dramatically with the distance between locations. In general broadband network economics it is common to have up to 85% of the project cost of supply attributable to laying fibre or cable to a home, business or community access point.
There is much industry debate relating to the total cost of providing backhaul links over fibre to all premises in the UK. Estimates quoted range widely between £25 and £80 billion and even using the lower of these two figures it is clear there is a problem when considering delivering high and super-high speed broadband service to rural communities.
Whilst backhaul link costs will generally be the responsibility of the supplier it follows that few will be prepared to invest heavily in providing fibre delivery to a community unless there is a solid case demonstrating a path to investment recovery.
Other forms of backhaul delivery need to be considered to address this investment imbalance.