While all the commotion is in the small cell domain, let’s look at a traditional tail site and see what are the main ideas for capacity coverage improvement.
Just seven years ago, a tail site was connected with a single DS1 or E1. With LTE, we went up to 100-150 Mbps per site. Now we’re pitching 1Gbps per tail site. Mainly because LTE-Advanced can deliver 1Gbps using 100 MHz of spectrum with carrier aggregation.
The first question that arises in the minds of network engineers is, “Where am I supposed to get 100 MHz of spectrum?” The main option today is to re-farm old 2G and 3G spectrum to gain better spectral efficiency with new gear. The second option is to bid for new channels such as LTE3500. Upon release, 3.5GHz LTE will bring with it a potential 400 MHz for distribution in many countries. In the meantime, the eco-system is not there yet but with 200MHz in FDD, 200 MHz in TDD – it is safe to say that it is likely to happen.
Higher spectrum is not very efficient for coverage but it is the right choice for small cells and tail sites. We can reuse this spectrum many times due to its short range. This spectrum was sub-optimal for WiMAX because it didn’t go very far but for small cells or a tail site that is covering a small area, 3.5GHz is an excellent spectrum.
But this does not conclude all my capacity requirements in this particular location. I am likely to have a RAN sharing model one way or another, with more than one mobile operator. This sharing concept requires a short explanation. The obvious trends are whole operations sharing such as EE in UK or a backhaul joint venture such as NetShare in Ireland. However the case of backhaul service provides (Carriers of Carriers – CoC or alternate access vendors – AAV) is very similar – it its about transparency and service differ nation. But it also means a need to serve additional spectrum slices per site in terms of capacity or marinating a more sophisticated timing scheme
And even more interesting, this is considered to be the best place to aggregate all my other small cells. My offload, integrated, coordinated models, not to mention more sectors connected to a tail site – aka, Distributed Base Station as we discussed in my past post.
All of these capacity requirements surface as this is my point of presence. However, when we start talking about coordinated multi-point capabilities and carrier aggregation (CoMP). More coordination between the sites means higher capacities and lower latencies. Though it has yet to be seen how to implement these concepts in an ideal or non-ideal backhaul environment. So in essence, it’s easy to see that 1 Gbps is going to be the new E1 for a tail site.
Stay tuned for part three of this conversation where I will discuss taking the distribution concept to the extreme with a move to Cloud-RAN (C-RAN).
In the meantime, for more information on how to increase capacity coverage, feel free to take a moment to view Ceragon’s new white paper on Capacity Coverage or feel free to reach out to me with any questions at email@example.com.