WIth Mobile Networks, what is an umbrella cell?

WIth Mobile Networks, what is an umbrella cell?

• A slang term used for a waterproof mobile phone with folding display.
• Large mobile phone network covering smaller cells.
• Coverage area of a transmitter in a television network
• A cell infected by a virus developed by an international conglomeration. 

 

EXPLANATION

There are five different cell sizes in a GSM (mobile telephone) network: macro, micro, pico, femto and umbrella cells.
Umbrella cells are used to cover shadowed regions of smaller cells and fill in gaps in coverage between those cells.

SOURCE

http://4g5gworld.com/wiki/global-system-mobile-communications-gsm