The small cell backhaul has been a bit quiet recently… but now it’s back with a vengeance, as operators demand affordable gigabit backhaul to meet next generation capacity requirements everywhere.
The principle market for small cell backhaul is urban densification. Initially we saw relatively small deployments as operators used them tactically as a precision tool to fix isolated problem areas in their network. Operators are now urgently scaling up deployments to become part of their densification strategy. And this is where backhaul is needed. According to consultants IHS Technology, backhaul connections for urban small cells are set to multiply by 20 times between 2016 and 2020, driving cumulative spending of $6.4bn in the same period.
At a recent Small Cell Forum webinar, operators didn’t mince words when describing the challenges they’re facing, and how they’d like things to change. There were calls to unify planning which differs from city to city, let alone country to country. At the same time, there is great interest in using higher frequency spectrum for 5G access. However, this places uncertainty around the microwave and millimeter wave backhaul solutions which currently use these bands.
As the road to 5G beckons, the essential role of automation in deploying and operating dense HetNets becomes increasingly evident. SON today is largely RAN centric – automating cell ID and neighbor list allocations. In future, operators need to automate all aspects of end to end service delivery, including backhaul. Operators need small cells and backhaul to be plug, play and forget to avoid high and unexpected O&M costs.
Virtualization of small cells is also changing the game for backhaul. The Small Cell Forum has now published its nFAPI interface which enables C-RAN benefits over packet Ethernet type connections, unlike CPRI based C-RAN which generally needs fiber. Other so-called ‘functional splits’ of the small cell are possible, each providing a different tradeoff between the benefits of centralization and the required backhaul performance. In the longer term, virtualized functions can be moved around according to transport performance, allowing operators to squeeze the most from their deployed assets. This is why the need for guidelines on transport performance requirements for different splits is an early priority.
So after the hype and the disillusionment, small cell backhaul is once again re-asserting its place as an essential ingredient in the future HetNet.
