Why RPMA Unabashedly Loves the 2.4 GHz ISM Band
Ingenu’s RPMA utilizes the 2.4 GHz ISM band. There, we said it. And we love it! The 2.4 GHz band offers many reasons why it is a practical choice for M2M communication if you are savvy enough to use it right.
At first glance some think that the 2.4 GHz band is inferior to the sub GHz band due to propagation. But this is trivially overcome with antenna diversity. In plain English, we put two antennae on our modules rather than one, because we can. The 2.4 GHz band wavelength is shorter than the 900MHz so we are able to place two antennae and still have flexible and practical small form factors. And just like that, propagation issues are overcome.
As with many things, government regulations are the largest hurdle for most frequency bands, including the 900 MHz family of bands. However, the 2.4 GHz band has very favorable government regulations in both the US and Europe. For example, in the US, narrowband transmissions are restricted to 400ms (or 0.4 seconds), but this doesn’t affect RPMA as it utilizes direct-sequence spread spectrum (DSSS) modulation. +1 RPMA!
Another advantage of the 2.4 GHz band is the enormous amount of bandwidth available in the 2.4 GHz band. We have 80 MHz of bandwidth in the US. That means in the US we have 40 completely independent channels to choose from. And in Europe we have an enormous amount compared to only 500 kHz for the 900 MHz band.
What’s more is the 2.4 GHz band is truly available worldwide cost-free. It’s as if some worldwide organization back in the mid 20th century decided that the 2.4 GHz band should be available worldwide. Wait, they did! The 900 MHz family has the ‘family’ in its name because in Europe it is actually 868 MHz and in the US it is 915 MHz; so it isn’t actually available worldwide as a single continuous band.
RPMA was designed to utilize the 2.4 GHz band because it is available worldwide, has more bandwidth, is cost free, and has extremely favorable regulatory conditions. In the end, it isn’t just the frequency band that matters; it’s what you can do with it. And what RPMA does is simply genius.
Get a more detailed comparison of the 2.4 GHz band and 900 MHz band by reading our forthcoming white paper, Unlicensed Spectrum: 2.4 GHz and 900 MHz Compared.