Mobile, or cellular, backhaul describes both the infrastructure responsible for and the process of carrying voice and data communications traffic from the access network (cell sites) to the core network. Backhaul is a primary component in all cellular networks, whether 2G, 3G or 4G (LTE).
Mobile backhaul traffic is carried over a variety of physical transmission media, including microwave, fiber, copper and, occasionally, satellite. Backhaul distances can be very short (< 1 km), in the case of cell sites that are located near a mobile switching center (MSC) that serves as a gateway to the core network or very long (> 100 km), in the case of remote rural cell sites.
Historically, backhaul capacity requirements have been limited to less than 10 Mbps per cell site and the choice of backhaul medium has been driven by cost, availability and geography. Microwave has been the leading backhaul approach in Europe, where the heavily urbanized topology makes copper and fiber difficult to deploy. In North America, on the other hand, the ready availability of low capacity, low cost leased lines has made that medium the leading backhaul approach.
But the underlying dynamics of the mobile network have changed dramatically since the widespread rollout of 3G access network technology such as HSPA and EV-DO and the rapid subscriber uptake of mobile broadband data services. Even prior to the deployment of LTE, mobile operators are now contending with the following backhaul challenges:
- A dramatic increase in required capacity per cell site, projected to increase by as much as 5x or more over the next few years, is creating a widely reported backhaul bottleneck;
- For those using leased copper lines, the increase in required backhaul capacity makes those leased lines a money-losing proposition due to the fact that their cost increases in linear fashion with capacity;
- The vast majority of all backhaul is TDM-based yet there is a clear need to migrate from TDM to IP/Ethernet over time; it’s difficult to determine the best way to accommodate both.
In addressing these challenges, operators are faced with the reality that leased copper lines can be, at best, only a stop-gap measure for lightly loaded cell sites. And although fiber offers no shortage of capacity, its availability is limited and the costs associated with the installation of new fiber are extremely high.
Exalt radio systems, including the new ExtendAir® and ExploreAir™, are designed with these mobile network trends and backhaul challenges in mind, offering:
- An array of options designed to support the different requirements edge, aggregation and core backhual;
- Systems that support both native TDM and native Ethernet in any combination, providing operators the ability to simultaneously support both 2G voice and 3G and LTE data with the same backhual infrastructure;
- Software upgradeable capacity ensures that the radio can accommodate both current and future capacity requirements while allowing a “pay as you grow” approach when it comes to turning up new capacity;
- A rapidly declining cost per bit as capacity increases, driving payback times versus leased lines as low as months in some cases (see Economics of Backhaul).
Exalt offers a full line of microwave backhaul radio systems from 2 to 40 GHz.