Microwave Link Design Process Five Critical Issues

In microwave link design for mobile backhaul, a variety of factors must be considered. Eirik Nesse, vice president of product strategy for microwave backhaul provider Ceragon, gave RCR Wireless his perspective on the top five factors in microwave link design planning.

Frequency planning and spectrum are the highest priority in microwave link design, he said. “Finding available channels could be a challenge, and finding available spectrum to deploy the link can also be a challenge,” he said.
Ability to re-use spectrum. Spectrum constraints are a major feature that comes into play in microwave link design. How much spectrum is available for the microwave link? In what bands?
Although the use of microwave for backhaul is currently much more common in Europe than in the North America, the technology is expected to play a larger role in heterogeneous networks (HetNets) as LTE deployments progress and small cells are used in larger numbers. In small cell topology, a number of potential topologies can be used, including a wing structure, hub-and-spoke, or mesh.
“There’s no single answer. There’s no golden rule here,” Nesse said. In certain scenarios, different topologies are going to fit operators’ needs or the limitations of a specific geographic location, and that factors into the microwave link design.
And, he added, challenges remain for figuring out just how all of the small cells in HetNets are supposed to be connected to the rest of the network.
“Small cells are require backhaul. It’s just a different type of cell, but they still have the same challenges,” Nesse added.
Redundancy. Building resiliency and redundancy into microwave link design is critical. Operators need their networks running reliably to collect revenue and retain positive relationships with their customers.
“If you lose a base station, that’s not a big problem,” Nesse said. “If you lose a whole city, it’s a big problem, because all of the revenue is gone.”
Capacity planning for future growth of the network also is important in microwave link design. Nesse noted that the expectations for data growth are enormous, and that operators want to future-proof their networks as much as possible. He also pointed out that in the cellular industry, technology standard releases are becoming increasingly numerous — which means that base stations and other pieces of network equipment are expected to be replaced faster than in the past. The technology cycle for 3G was on the scale of 10 years, but now the life cycle of base station equipment is likely to be closer to five years.
“The things that we deploy now may be obsolete in five years,” Nesse said. “And it’s not just the backhaul network, they may change out the base stations, because there’s a new technology that has a lower cost of ownership, which may have different requirements for backhaul.”
And that total cost of ownership (TCO) is another factor that must be considered in microwave link design, he added. TCO “is not just about the cost of the equipment, but can we save on the power bill? On the spectrum license?”
As network technologies’ lifespans decrease, operators are ever more interested in gaining back a return on investment as quickly as possible and looking for the most efficient network with the lowest total cost of ownership.
“Over that five-year lifespan, the operational cost of the equipment can easily be more than the cost of the equipment itself,” Nesse notes.
He said that in particular, operators are committing to reduce their environmental footprint by reducing the power consumption of their networks – which also saves them money. So power usage must be balanced within the design of the microwave link.