Last year, I wrote extensively about small cells. These were a hot topic at MWC 2013, but there were clear signs of froth. This year, there was a lot less marketing around the subject. They remain a subject of interest, but the realities of the marketplace have dampened enthusiasm a bit. This is good news, as it clears the deck for operators and equipment vendors to do the hard work, blocking and tackling, to develop coherent strategies and begin the regulatory grind.
Small cells are an appealing idea for many reasons. Today’s mobile networks are built largely using ‘macro cells’ or base stations. These can cover around a one kilometer radius, with up to a few hundred users. But in almost every market it is getting hard, if not impossible, to install new cell sites. Many people contend that the only way to get the next increase in wireless network speeds is to ‘densify’ the networks – installing smaller base stations, covering a few hundred feet and a few dozen users. These ‘base stations’ come in many sizes and shapes, with each flavor carrying certain implications as to cost and ownership. Since it is now clear that there is no ‘one-size fits all’ solution to densification, we have taken to lumping all these into the catch-all ‘small cell’ term.
There is a true menagerie of options available now. Ericsson is promoting its “Dot” system, which is a neat system of repeaters and distributed antennas that effectively extend existing base station systems. At the other end of the spectrum are advanced femto-cells like those made by privately-held Spider Cloud which are almost entire cellular networks in their own right. In between there are all sorts of combinations of size and features. I will save a full taxonomy for another day.
In my note last year, I pointed out that there are still three key obstacles to wider deployments:
1 – How will small cells interact with each other and the wider network?
2 – How will we physically connect all these cells to the core network?
3 – How will carriers get approval to add all these sites?
All three remain open questions. Some progress has been made, but now that the marketing departments have moved on to new topics, the real work of solving these needs to get underway.
The standards bodies have made some progress in working out the key interference issues around how these cells interact with each other and with the macro network. So far the solutions have not been anything revolutionary. There is still a lot of overhead wasted on handling this problem. There are some clever software solutions coming on the market, but no widespread agreement beyond those.
(A brief side note, privately-held Artemis, unveiled their pCell or DIDO solution last week, not at the show, but at Columbia University. I plan to take a look at this on my website in an upcoming post, so stay tuned. If what they say is true, they may have solved the interference problem in a profound way.)
The backhaul of small cells, or the link between the cell and the wide Internet, remains a key bottleneck. Last year we spoke with a dozen small cell backhaul vendors. For the most part, this remains an undifferentiated field with many solutions on the market. It is hard to stand out in this field, and as a result, the lowest priced products often win. The true standout in this field is privately-held Kumu Networks, who seems to have cracked “full duplex”. Again, a topic for another day, but they have done some really interesting work.
The last issue, finding sites, for all these small cells, is going to take the longest. Technology will only get us so far here. The operators are still going to have to convince municipal governments and building owners to let them deploy and string up all those small cells. There is a pretty good value proposition involved (i.e. let us install a small cell and you will get better mobile service), but common sense and local government do not always go hand in hand.
Regardless of these obstacles, I think the deployment of small cells will plod ahead. Network needs and consumer demand are creating imperatives that cannot be ignored. The industry leaders are promoting these solutions heavily. So break time is over. Time to get laboring.