Cell Sites: Coverage vs. Capacity

I have heard quite a few people complaining lately about their cellular coverage.  Some claim it has gotten worse.  While that is actually possible, it is probably unlikely.  While I am not a Radio Frequency (RF) engineer, I would argue that the problem is not an issue of coverage, but rather capacity.

What’s the Difference?

In a cellular network, coverage refers to the amount of area or land that a signal from a cellular network reaches.  Every carrier offers “coverage maps online or in their retail stores and you see the vast majority of the United States colored to reflect the carrier’s service area.  On the other hand, capacity refers to the amount of bandwidth for a cellular network within that service area.

Think of it is simple, hypothetical terms.  One cell site on top of the Empire State Building turned up to full power would radiate a signal covering most, if not all, of Manhattan.  But that does not mean that every person walking on the streets in NYC will be able to get a call through that single cell site. Instead, RF engineers design wireless networks with multiple cell sites at heights much lower than the top of the Empire State building so that each unique site covers a smaller area, thereby increasing the chances for each individual user to have his/her call go through.

So why does it seem like I drop more calls?

I don’t know if you are actually dropping more calls or not.  There is a reasonable claim that we have become more dependent on our cell phones thus we are less patient when calls are interrupted or fail to go through, thus we complain more. But we are definitely experiencing a capacity problem in modern cellular networks.  With the advent of more and more powerful smart phones we are not only using them to talk but to also download and upload music, video, photos as well as web surfing.  Thus each cell site must not only process voice, but also data – LOTS OF DATA! This is stressing the capacity of each cell site and thus the cellular network as a whole.  More cell sites are continually being built to increase capacity.

In short, future cellular networks will need thousands more small cell sites (called microcells and picocells) much lower to the grounds to manage our data crazy smart phones.  More to follow…

 

Verizon iPhone has sparked the public race for “4G”

After all the speculation, all the anticipation, it is official – Verizon has begun selling the CDMA iPhone.  While I am a loyal Blackberry guy with no intention of switching, I must admit I am excited about the announcement.  You see, if you listened closely around the time of the announcement, you may have heard the shot fired from the starting gun for the race for the next generation of wireless coverage.  Actually it started long before that in the “war rooms” of each of the nationwide cellular operators but now the race is being run in public view – just watch one NFL football game for the ads they are running.

What is generally being marketed as “4G” will bring with it a massive expansion in the cellular networks – the largest infrastructure boom in the wireless industry since 1996 when the FCC auctioned off the PCS licenses releasing a lot of spectrum and networks began to upgrade from analogue to digital.  There is speculation that some iPhone users will jump from AT&T to Verizon because of the frustrations they experienced with AT&T coverage (actually it was a capacity problem, not a coverage problem). And some will wait to see if Verizon is prepared.  Regardless of your expectations or loyalties to one operator or another, one thing is sure – AT&T, Sprint, T-Mobile and Verizon all are in the process of upgrading their respective networks.  And, these upgrades will have two large impacts on their respective networks. 

First, each network will be substantially faster.  WiMAX, LTE, and HSPA+, will take each system to another level and that is great for consumers.  Whether you use the iPhone, Blackberry or Droid you are about to see an increase in speed which will in turn facilitate an explosion of even cooler apps and eventually machine-to-machine communication.

Second, the number of cell sites are about to significantly increase.  At first they will be overlaid on top of already existing sites and tower companies will see a big early bump in leasing revenue.  This initial overlay will establish 4G coverage nationwide.  But then the number of smartphones will quickly increase and so will consumers data usage and these initial sites will not offer adequate capacity because you can’t shove ten pounds of data through a five pound cell site.  While they can’t build ten pound cell sites, they can build two five pound sites.  Or go even further to manage capacity by building ten one-pound sites – one on every street corner and cul-de-sac.  All this because our appetite for data is about explode!!!