High rise office buildings proliferate in every crowded city. Signal strength tends to get weaker the higher you go, demonstrated by the fact that many operators refuse to guarantee their service above the 12th floor.
Ironically, the problem stems from the large number of basestations normally found in crowded cities, as operators strive to guarantee outdoor service in places where most of their subscribers demand it.
Increased basestation density forces the need for antenna tilts, which significantly reduce signal strength on the highest floors. In addition, as power is cranked up, interference from many BTS leads to poor signal quality.
Unfortunately for operators, many companies locate their senior executives on the top floors of high rise buildings, precisely the people who are most sensitive to signal strength and quality. And, critically, these are the people who make the decisions about corporate mobile contracts.
Picocells can be used to target specific floors quickly and easily: