The scale of the take-up of smartphones has increased traffic and put unprecedented pressure on networks. Consequently, European carriers, in particular, are facing significant capacity crunch and spectral efficiency challenges. Explaining that limited spectrum and spectral congestion were key issues, Alan Solheim, VP of Product Management at DragonWave, told Microwave Journal, “For a long time European regulators have recognised that the spectrum is a non-renewable resource, so licensing regimes have been geared towards preserving that spectrum. Because of the pricing regime and the usage patterns of microwaves, European operators are looking at either new spectrum or ways to use their existing spectrum more efficiently.”

He elaborated, “One of the problems that carriers are facing is that as they increase the capacity on the microwave backhaul they can only do so much—going to higher modulation, or adaptive modulation to get higher throughputs over the existing infrastructure but eventually you hit a wall. A lot of the last mile links have been connected with 7 or 14 MHz channels, which can typically deliver a few tens of Mbits over conventional systems.

“What DragonWave has done is to address the fact that in order to deliver the capacities that are needed in those channel sizes, you need to get a factor of two improvement in the spectral efficiency of the product. We have done many things—higher modulation rates, cross-pole interference cancellation to allow true polarisation multiplexing, adaptive modulation—and then we have added a suite of baseband optimisation techniques that take a look at the lossless compression, etc. So, using conventional microwave techniques we can get up to about 100 Mbits out of a 7 MHz channel and using baseband techniques we can get almost 200 Mbits out of that baseband channel.”

Explaining how European carriers in particular can benefit, he commented, “A whole new realm of possibilities is opened up. Instead of operators having to redesign their networks, go back to their regulators and try to re-engineer their spectrum allocation in the backhaul segment they can simply deploy new equipment and upgrade the technology to LTE-style capacity without having to re-engineer and deal with all of the churn.”