I've to implement a wireless communication system. Details are as follows.

 - Range is about 600m
 - Point-to-point communication
 - No LoS is available. (but not highly obstructed)
 - Won't need much higher data rates.
 - Should be reliable.
 - No constraints with supply power, size etc...
 - Intended to handle with PICs of Arduinos.

Please point me to a proper transceiver module that can be used for the purpose. Don't have prior experience with wireless modules (so, you can assume fine details and then let me know of them), **a straight answer is much appreciated..**

Thanks!