Backhauling

Backhauling is the provision of the transport links that connect the access network with the core network. It aggregates traffic from end-user access points such as mobile base stations, fixed wireless access nodes, or enterprise VPN gateways and transports it to the central switching or routing infrastructure. Backhaul is the middle part of the network path, distinct from both the access network and the core network.

In mobile networks, backhaul connects base transceiver stations to the operator's core network; in fixed networks, it connects customer premises or local aggregation points to the backbone. Common backhaul media include fiber optic cables, microwave radio links, copper leased lines, and, in remote areas, satellite links. With the growth of 4G and 5G, high-capacity backhaul links are required, often using fiber or high-capacity microwave.

Key design considerations include capacity, latency, availability, and cost. Backhaul must support quality of service for voice and data, provide redundancy, and cope with traffic growth and weather or interference in wireless links. Deployment can be constrained by geography, fiber access, spectrum licensing, and regulatory requirements; operators may lease backhaul services from wholesale providers or build their own networks.

Related terms include fronthaul, which connects distributed radio units to centralized processing within the RAN, and midhaul, which sits between fronthaul and backhaul in some architectures. The term middle mile is sometimes used in other contexts to describe backhaul-like links.