How Cell Towers Work

[avinayyar]

Whether it's handling simple phone calls or 12Mbps WiMax data, cell sites are organized with more or less the same flow:

• A cellphone or modem radios the nearest towers, saying, basically, "I'm here!" When you make a call or logon, your phone then sends a message via radio that's picked up by the antenna array.

• A wire or fiberoptic line carries the call down to the wireless access point, connected to a multi-port switch.

• The call, along with many others, gets routed to a backhaul, usually down to an underground wired T1 or T3 line, but sometimes back up the mast to a powerful line-of-sight wireless microwave antenna. They resort to wireless either when they don't have a ground connection, or when the ground connection sucks.

• The incoming call or data comes back from the backhaul and up through the switch to the antenna, where it then hits your phone wirelessly, presuming your phone is still communicating with the same site. If you are moving, then there's a handoff—a new but more or less identical cell site transmits the data to your phone, once your phone checks in and says "I'm here."

All of this happens in the blink of an eye.

Full Article + Pictures of the gear