Given the pervasive challenges associated with network densification, particularly backhaul and site acquisition, and the emergence of 5G at millimeter wave frequencies, what can operators do to deliver the service their customers expect?
Ericsson’s Martin Ljunberg, strategic product manager, small cell solutions, said this new breed of networks requires street-level deployments with inter-site distance of a couple hundred meters. On the backhaul side, he identified the use of both dark and lit fiber as well as the role of microwave. He also noted a potentially “promising future” associated with using millimeter wave frequencies for wireless backhaul, which is set for standardization with 3GPP’s upcoming Release 16. He called site acquisition “a very important aspect of this. A key thing is, of course, to make equipment that is small in size and good looking.”
Ljunberg also discussed centralization of
radio access network equipment which, while not new for 5G, could prove
increasingly beneficial given the need for density and optimizing the use of
network and spectral resources. At a high-level, a C-RAN architecture is marked
by pooling baseband resources and using fronthaul to connect remote radio
units. This decreases equipment footprint and gives operators the ability to
dynamically coordinate multiple radio sites and be more responsive to shifts in
capacity demand.
C-RAN “brings some advantages in coordination
capabilities,” he said. “I think some operators see more importance in the
coordination and see potential of simplified handling. Other operators see that
putting distributed radios in a more D-RAN-type of network, which I must say is
the most common way of building networks today.”
But will 5G prove a boon for C-RAN? “We
certainly see quite a lot of C-RAN deployments and doing C-RAN deployments
offers the possibility to do some coordination features around the network,
everything from carrier aggregation to combined cell and improving the
performance of the network. We see many customers moving toward C-RAN and we
believe also that high-band, low-band and mid-band 5G NR carrier aggregation
will drive need for that. Particularly when we look at the 5G on millimeter
wave, we see those radios are delivering a lot of capacity over a lot of radio
spectrum and even if you do dark fiber, we are starting to see fronthaul
capacity limitations. We believe an integrated street macro with the baseband
processing…in the unit on site makes a lot of sense doing millimeter wave.”
In terms of solving for urban canyons in
millimeter wave deployments, Ljunberg pointed out that propagation
characteristics don’t lend themselves to turning corners, meaning, “There has
to be a denser deployment so you have more line-of-sight and you have to
realize, even with perfect planning, there will not be perfect millimeter wave
coverage.”
To the idea of co-siting LTE and millimeter
wave radios, and as evidenced by what carriers are finding in the field, “For
introducing 5G, use existing sites. But millimeter wave coverage cannot be as
good as with existing LTE bands at the street side. There will be a need to add
millimeter wave-only sites,” Ljunberg said.
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