Every new wireless network technology – from 3G to 4G to 5G – requires an upgrade to the backhaul network, which is the term used for carrying network traffic from the cell site to the mobile core. But in a 5G world, where network performance is expected to take a huge leap in capacity and bandwidth, backhaul becomes even more critical.

In fact, in the 5G network nomenclature, backhaul is no longer the term of choice. It's been replaced by either IP transport or anyhaul. "Everyone called it backhaul but it is now transport," said Shane McClelland, VP and head of transport at Ericsson North America. "And there's a good reason for that."

But Houman Modarres, senior director of IP product marketing at Nokia, said that he prefers the term "anyhaul" because it includes backhaul, fronthaul and even midhaul (which are all used for transporting traffic amid various network configurations). Modarres explained that anyhaul is independent from the 3G, 4G and 5G standards, but is nonetheless very important because if operators don't upgrade this portion of the network they may end up with bandwidth and latency issues in their 5G networks.

Upgrade early
Nokia recently inked a deal with South Korean operator LG Uplus to upgrade the operator's IP transport and core network. In fact, Nokia's Modarres said that many operators are upgrading their anyhaul part of the network before they deploy all of their 5G offerings because they learned from the initial iPhone 3GS launch that it's important to have excess backhaul capacity to avoid traffic bottlenecks that can occur if a certain use case or device becomes a big hit with consumers.

"It's important for the enhanced mobile broadband, which is one of the use cases for 5G," he said.

Nokia isn't the only vendor signing IP transport deals with operators. Ericsson also recently signed a deal with Taiwanese operator Chunghwa Telecom to provide the operator's 5G network equipment. The deal covers basestations, 5G evolved packet core as well as the fronthaul and IP backhaul transport.

RAN tied to transport
Ericsson's McClelland said that the 5G radio access network (RAN) must be closely coordinated with transport because the architecture of the RAN is becoming disaggregated.

In 3G and 4G networks, McClelland explained, RAN sites were homogenous, meaning that the radio, the tower and the basebands were contained in one place and then connected to fiber or microwave backhaul. But in a 5G world, the elements of the RAN can be spread around a given geographic area. And when that happens, backhaul will look very different depending upon the type of RAN architecture and interface.

"All will have new interfaces and different requirements for capacity and latency," McClelland said, adding that's why the term IP transport is a better fit for the 5G environment.

He added that if operators don't match the RAN architecture with the correct IP transport, the transport portion of the network could become a bottleneck. "If you don't have the transport coordinated with the RAN, then you won't get the right efficiency, latency and bandwidth."

Ericsson is encouraging operators to consider the IP transport when they are determining the RAN portion of the network. McClelland said that Ericsson wants operator RAN and IP transport teams to work more closely together, particularly if the operator is considering using a certain spectrum band for its 5G deployment. "You need to calculate the bandwidth for the transport and it will differ depending on whether you are using highband or midband spectrum," he said.

No room at the cell site
Interestingly, McClelland noted that with some 5G deployments, such as those in the millimeter wave (mmWave) bands, operators need more cell sites and many of the sites are at street level. This can make it difficult to fit all the basebands, power connections and fiber connections all together. "Sometimes you can't put the baseband next to the radio," he said.

In that type of scenario, the transport piece often has to fit inside a structure like a light pole.

McClellan said that this is why it is so critical for the RAN team and the transport team to work together to better manage all the cell sites and ease any deployment challenges.

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