Right now for my IOT project I use an antenna that has a gain of about -2.2dBi. It can connect to the cellular network fine, but this often takes a long time and can easily total to several minutes.
However, looking at the talk about antennas leaves me very confused regarding what would be best to have for my project. I want to deploy my sensor device out in the environment, but won't have control over the positioning of the antenna (hence directional antennas wouldn't work well). Cost of the antenna isn't too important.
Considering it needs to connect to 850/1900MHz cellular bands and needs to be reliable regardless of positioning, what kind of dBi gain should I aim for to achieve a substantial improvement over my current -2.2dBi antenna?