Dr Robert Soni, CTO, Small Cell Program at Alcatel-Lucent, told TMN, “We will be building new metro radios that take on multiple personalities – that either can be a metro cell with distributed baseband alone, an MRO (MetroCell Radio Outdoor) or something in between to support the use case.”
“We are looking at an asset that takes on the personality that’s required according to what the backhaul actually supports. So if you can do full CPRI [on the backhaul/fronthaul], you want to centralise all your asset base in one particular place and you don’t want to be dependent on anything at the end point then the box is an MRO. If the backhaul is constrained or shared or doesn’t meet CRPI restrictions on delay, distance, jitter, then we are looking at an all-in-one base station architecture.”
However, he described another scenario that would see some processing carried out on the device, and some in the cloud.
“There’s something in between where potentially the backhaul may have an ability to scale beyond supporting typical IP requirements, in which case we look at splitting the processing between the edge node and the cloud,” Soni said.
This sort of product would work in conjunction with Alcatel-Lucent’s work with Intel on virtualising its RAN portfolio, and making sure that the company can scale support for inter-layer and inter-frequency management.
Soni is sceptical of the edge services gateway/node approach (see Huawei Service Anchor, Spidercloud SSN, Nokia FlexiZone, Airvana Onecell baseband controller unit) that controls distributed small cells from a controller node at the edge of the network.
“The real question is do you gain a lot from having the interference management capability that is bandied about by SpiderCloud and Airvana. There are a lot of dependencies on release type and terminal types, particularly with the Airvana solution. And maturity with SpiderCloud is yet not clear, specifically with regards to eICIC which is not commercial yet in any network. So there’s lots of dependency on interference cancellation techniques that are available on a per-release, per UE type. It’s not clear you can leverage that today.”
Soni added that other approaches, such as Ericsson’s Radio Dot, which are claimed to work over shared backhaul on Cat5/6/7 cabling, also have limitations.
“While we see the value of having a standard interface across shared backhaul… there’s always something. When people tell you that it can operate on shared backhaul, don’t always believe it. When somebody’s trying to push so much data across Cat5/6/7 cable there’s very little else that can go across at the same time. And more importantly when something else does go across it disrupts. So I think there’s a lot of talk, but no-one ever really talked about the fact that there’s nothing else you could do with that cable.”
Soni added that the total cost of ownership of fibre vs cable was insignificant.
“Sure the cost differential between the fibre and cable itself is significant but the total cost is dominated by the cost of labour to install – that’s where I struggle a little bit with those solutions.
Alcatel-Lucent, Soni said, is exploring the possibility of scaling down its gateway product to work as a local solution, as well as using its “Core in a Box” [virtualised EPC] providing full EPC functionality at the large enterprise, bypassing the need to wait for R12 SIPTO local breakout functionality.
“We are looking at this in addition to our existing gateway architecture and whether it can be scaled down and be localised. Operators are giving different requirements for what they expect and need. As we already have a commercial gateway an enterprise could do a local gateway solution or potentially do a full EPC. I tend to think operators like standardised interfaces and boxes, if we can show them the value of having a core in a box in the enterprise that will create a lot of value from them.”