Rakuten Mobile to use an optical mesh network for backhaul

Rakuten Mobile will use Nokia's Photonic Service Switch to power its optical mesh backhaul network. That backhaul network will be used to transmit traffic between the operator's cell sites and its switch for Rakuten's 5G service.

Rakuten is in the process of building a 4G mobile network in Japan from scratch – a "greenfield" network – and has touted it as the world's first end-to-end, fully virtualized, cloud-native network. The company plans to launch that 4G network April 8 and quickly migrate to 5G sometime later this year.

Rakuten said that it will use Nokia's optical component technologies and wavelength routing technology to build a nationwide optical backhaul network covering all 47 prefectures (similar to a state) in Japan.

Kyle Hollasch, product marketing director for optical networking at Nokia, said that Rakuten's deployment is unique because it's the first time a reconfigurable optical network will be used for mobile backhaul. This technology is more commonly used in core networks and metro networks, Hollasch said. "What is unique here is that they are building this from the ground up and want all the capabilities that you see in an optical core network," he said.

One of the advantages of a photonic mesh mobile backhaul network is that the operator can move wavelengths around and respond to events on the fly. "Generally, you can add and move capacity around," Hollasch said.

And while it's possible to use an optical mesh backhaul network for traditional wireless networks that aren't fully virtualized, Hollasch said that it's much easier to combine this technology with a cloud-native 5G network. "It's harder for existing networks that aren't greenfield," he said, adding that this technology initially was used in core networks and now – as the technology becomes smaller, cheaper and denser – it can be used in smaller metro networks.

Also, an optical mesh backhaul network is likely to be more critical for 5G networks because these networks are expected to handle much bigger volumes of data traffic and therefore need more bandwidth.

— Sue Marek, special to Light Reading. Follow her @suemarek.