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Tags | Blog, Mobile, Wireless broadband |

Everyone knows that mobile broadband traffic is going through the roof. So how much spectrum do you really need? While spectrum policy and regulation is constantly being developed, debated, and revised this simple question – oddly – seems to go unanswered most of the time. But the answer can certainly be determined.

Contrary to common belief it

is certainly possible to answer this question without having to resort to teams

of engineers and enormously complicated simulations models. As a technology

strategy consultant, I’ve worked on spectrum strategy questions like this for decades.

It turns out that there are only three parameters you really need to worry

about: The mobile or wireless technology that you want to apply, the distance

between base station sites (the inter-site distance), and the volume of

end-user traffic.

If know these three, you can

calculate your spectrum need using what amounts to kitchen math – but of course

you do need to know the right method. I’ve spent a number of years refining and

simplifying an Excel-based spectrum model that does exactly that. Since it is

remarkable simple, **I’ve called it the SSM: The **

**Simple Spectrum Model****.**I believe that any engineer or tech-savvy

economist can understand and apply this model without difficulty. It also

happens to represent the current de-facto industry standard for doing spectrum

calculations.

Let’s look have a look at the

inputs: Any mobile technology can be defined in terms of its spectral

efficiency, i.e. how many bits you can transfer per unit spectrum. The values

for spectral efficiency are well-documented and easy to source (most of them). If

you know that you are working off an existing base station grid, the inter-site

distance is often known or at least it can be estimated. The traffic per user –

for example in GB per month – is also known from public sources, such as Cisco’s

VNI. In addition to this you need a value for the mobile broadband user density

per unit area but this is also quite easy to derive based on demographics.

If you’re looking to boost

your network capacity – and most network operators are these days – you can

essentially do three things: Increase your spectrum holdings, improve your

technology, or densify your grid. Many operators are doing all of the above at

the same time and continuously – which is the right approach. As spectrum

becomes more and more scarce, grid densifications are becoming more important

and thus the current hype surrounding small cells.

What about the technologies

available? Well, LTE will boost your capacity by a factor of at least two

compared to 3G (if the bandwidth stays the same) and up to 4 times if you also

double your bandwidth. You can also improve your technology by introducing

smart antenna techniques including MIMO. One very important new factor is how

unlicensed spectrum (e.g. for WiFi) will impact your business. I personally

believe that WiFi is a superb complement to 3G and LTE.

But to make an informed

decision, you still need to *calculate*

what kind of traffic your spectrum can support. And I don’t know of any better

or more efficient way than the SSM. Find it here – and don’t hesitate to

contact me if you have questions.

Claus Hetting