Backhaul is the part of a telecommunications network that connects local access points, like cell towers or Wi-Fi hotspots, back to the core internet infrastructure. Think of it as the middle mile: your phone talks to a nearby cell tower (the last mile), and that tower needs its own high-capacity connection running back to the provider’s main network. That connection is the backhaul. Without it, a cell tower is just a tall piece of metal with no link to the outside world.
How Backhaul Fits Into a Network
Every telecommunications network has a layered structure. At the edges, you have small local networks: your phone connecting to a cell tower, your laptop connecting to a router. At the center sits the core network, sometimes called the backbone, which routes traffic across cities, countries, and continents. Backhaul is the set of links in between, carrying aggregated traffic from the edge inward to the core.
In a mobile network, which is the most common place you’ll encounter backhaul, it works like this: dozens or hundreds of phones communicate with a single cell tower. That tower then sends all of that combined traffic over a backhaul link to a point of presence, which is the provider’s gateway to the wider internet. The tower handles the wireless connection to your device. The backhaul handles everything after that.
Fiber, Microwave, and Satellite Options
Not all backhaul links use the same technology. The three main options are fiber optic cables, microwave radio links, and satellite connections, each with tradeoffs in speed, cost, and where they can be deployed.
Fiber is the gold standard. It offers the highest capacity and lowest latency, making it the preferred choice for connecting critical network components and aggregating large volumes of traffic. The downside is cost and time: running fiber requires physical construction like trenching, drilling, or hanging cables on poles. In a dense city, that infrastructure often already exists. In a rural area, the civil work can be prohibitively expensive.
Microwave links use radio signals transmitted between dish antennas mounted on towers or rooftops. This is a well-proven, low-cost technology that can be deployed in days rather than months, with a range of several miles per link. The catch is that microwave requires a clear line of sight between the sending and receiving antennas. Hills, tall buildings, or dense tree cover can block the signal entirely.
Satellite backhaul fills in where neither fiber nor microwave can reach. It’s typically deployed in remote or rural communities where ground-based infrastructure simply doesn’t exist. Traditional satellite backhaul using geostationary (GEO) satellites has historically suffered from high latency and limited bandwidth. Newer low-Earth orbit (LEO) constellations like Starlink and OneWeb have improved the picture significantly. Starlink satellites orbit at around 550 km altitude, producing typical one-way delays of 18 to 36 milliseconds in suburban conditions. OneWeb orbits higher at 1,200 km, with one-way delays closer to 54 to 58 milliseconds. Those numbers are dramatically better than traditional satellite, though still slower than fiber or microwave.
Why Backhaul Costs More Than You’d Expect
Backhaul is one of the most expensive parts of running a mobile network, and the costs aren’t where most people assume. The upfront hardware and construction (capital expenditure) accounts for only about 10 to 12% of the total cost of ownership over a ten-year period. The remaining 88 to 90% is ongoing operational spending.
The biggest single expense is leasing space for antennas and equipment at tower sites. In North America, antenna leases make up roughly 41% of the ten-year total cost, with site leases adding another 25%. Installation and maintenance account for about 19%. In Western Europe, the cost profile shifts: spectrum licensing fees for wireless backhaul consume around 30% of the total, while antenna and site leases are somewhat lower. Either way, the ongoing costs of keeping backhaul running dwarf the initial investment in equipment.
Urban vs. Rural Challenges
Deploying backhaul in a city and deploying it in a rural area are fundamentally different problems. In urban environments, the challenge is density. Thousands of cell sites packed into a small area all need high-capacity connections, but existing fiber infrastructure and short distances between sites make this manageable. The physical space for equipment is expensive, but the technology is straightforward.
Rural deployments flip those priorities. Sites are separated by long distances, traffic volumes are lower and grow unevenly, and physical access to tower locations can be limited. Power availability is often constrained in remote areas. Fiber, while ideal from a performance standpoint, is expensive to deploy and slow to extend, and the low traffic volumes of an early-stage rural site rarely justify the construction costs. Fixed hardware configurations that work well in cities quickly become inefficient when you’re covering vast areas with scattered demand. This is why rural networks tend to rely more heavily on microwave and satellite backhaul, at least initially.
What 5G Demands From Backhaul
Each new generation of mobile technology puts greater pressure on backhaul capacity. 5G is no exception. A single 5G cell site can require backhaul speeds of 25 Gbps, and looking ahead, dense deployments using millimeter-wave spectrum for future 6G networks may need over 100 Gbps per cluster of cells, with latency requirements dropping below 100 microseconds. For context, 100 microseconds is one ten-thousandth of a second, far tighter than what older networks demanded.
This is a major reason fiber remains so critical. Microwave and satellite can handle many 4G backhaul scenarios, but meeting 5G’s full capacity and latency requirements over wireless links is a much harder problem.
Self-Backhauling With 5G Small Cells
One innovation helping solve the 5G backhaul bottleneck is called Integrated Access and Backhaul (IAB). Instead of requiring every small cell to have its own fiber connection, IAB lets a small cell use the same wireless spectrum to serve users and relay traffic back to a fiber-connected base station. In practice, this means a carrier can deploy a dense grid of small cells with only a handful of fiber connections per square kilometer (fewer than 10 per square kilometer in some scenarios) while still delivering strong performance, including uplink speeds above 100 Mbps at the cell edge.
This matters most for millimeter-wave 5G deployments, which need many closely spaced small cells to cover an area. Running fiber to each one would be slow and expensive. IAB lets carriers roll out coverage quickly, using wireless self-backhauling to fill the gaps until fiber can be extended over time.