Long range and global solution, a tough equation, or…?
Many products and applications target a global market and therefore are looking for solutions in the 2.4 GHz ISM band, as this is the lowest frequency band available for a true global solution. However, an issue with 2.4 GHz band is its limited range, typically around 100 feet / 30 meters for practical purposes. There are a few solutions to resolve this issue, such as mesh networking or simply giving up on global support and have different products with unique hardware for different markets.
There is a middle ground that is attractive when you want the scale of manufacturing for a global solution and the longer communication range of a 915/868 MHz solution. These frequency bands give approximately 4x the range compared to a 2.4 GHz, i.e. well over 300 feet / 100 meters which is a requirement for many products. The 4x increase is admittedly a simplification as the radio range in real life is also driven by the environment (inhouse, outdoors etc), modulation and other factors. Still, the formula gives a good first level approximation of what to expect.
The solution is based on radio modules with a standardized footprint. The modules contain all the RF specific design needed, which means that all other hardware can be the same for an 868 MHz product and for a 915 MHz product. Even the antenna can be the same as an antenna on these frequencies typically has sufficient bandwidth to support both frequencies. The Radiocrafts modules share the same footprint, so there is no need to change the PCB. The only difference between the two products is a line in the BoM, where one uses an 868 MHz module and the other use a 915 MHz module.