How to transmit data wireless to 1km distance?

i'm working on transmitting data using wireless transmission and i want my signal to travel a distance of 1 km..... can someone suggest me some modulation schemes and other things related to that..... especially i need the power and frequency i would be needing....

Anand,
Please provide greater details. You need to explain the requirement and the environment in which your devices will work. Otherwise, generic replies, based on the info provided by you, will not be of any use to you.

A generic answer would be the use of IEEE 803.11 (wifi) to your aplication.

Good Luck.

can we transmit the data in form of signals using Radio Frequency signals..?
plz rly.....
Thanks in advance