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…