Backhaul

In a hierarchical telecommunications network the backhaul portion of the network comprises the intermediate links between the core network, or backbone, of the network and the small subnetworks at the "edge" of the entire hierarchical network. For example, while cell phones communicating with a single cell tower constitute a local subnetwork, the connection between the cell tower and the rest of the world begins with a backhaul link to the core of the telephone company's network (via a point of presence).

Visualizing the entire hierarchical network as a human skeleton, the core network would be the spine, the backhaul links would be the limbs, the edge networks would be the hands and feet, and the individual links within those edge networks would be the fingers and toes.

Other examples include:

• Connecting wireless base stations to the corresponding base station controllers.
• Connecting DSLAMs to the nearest ATM or Ethernet aggregation node.
• Connecting a large company's site to a metro Ethernet network.
• Connecting a submarine communications cable system landing point (which is usually in a remote location) with the main terrestrial telecommunications network of the country that the cable serves.

The choice of backhaul technology must take account of such parameters as capacity, cost, reach, and the need for such resources as frequency spectrum, optical fiber, wiring, or rights of way. Backhaul technologies include:

• Point-to-point microwave radio relay transmission (terrestrial or, in some cases, by satellite)
• Point-to-multipoint microwave access technologies, such as LMDS, Wi-Fi, WiMAX, etc., can also be used for backhauling purposes
• DSL variants, such as ADSL and SHDSL
• PDH and SDH/SONET interfaces, such as (fractional) E1/T1, E3, T3, STM-1/OC-3, etc.
• Ethernet

Backhaul capacity can also be leased from another network operator, in which case the choice of technology is generally made by this other network operator.

Vendors

• Ericsson
• Ceragon
• Motorola
• Proxim Wireless
• Harris Stratex Networks
• Nokia Siemens Networks

See also

• Last mile
• Return channel

External links

• Debate: The Backhaul Battle Who Will Win? - Video 40 minutes, wide ranging.
• Over the Backhaul