LAUNCHXL-CC1350: how to achieve up to 3 km distance using LAUNCHXL-CC1350?

Part Number:LAUNCHXL-CC1350

Hello All,

i am working on iot project in sub 1Ghz using 868  MHz and i was test the distance using smart RF with CC1350 Launchpad and select long range setting which is 625 bps but i didn't get more than 1Km , also i found that Texas achieved 20 km using cc1310 i don't remember where i found it ,so i need to know what is all parameters that i need to achieve more than this distance?

also  , i used this in smart meter so i make that with micro strip Antenna , can i achieve this distance with micro strip Antenna?

Thanks a lot