In my recent discussions with customers, the phrase “software defined radio” has come up. As software increasingly takes over the functions of our electronic devices, it is natural to wonder how deeply we might depend on software to add future functionality. For example, can we use it to add new Wi-Fi physical layers without new hardware?
But I am getting ahead of myself. In the beginning, our regulatory edifice for radio waves was built at the same time as early analog broadcast technology. Regulations were concerned with reserving frequency bands for exclusive use, and getting permission to use a certain frequency generally also came with the right to exclude others. How you used the band was tied to what you were doing. A radio station license didn’t have to state how the radio was being used because if you had a license for an AM radio station, well, what else would you be doing other than AM radio broadcasting?
With increasing computing power, the link between “what I do with my radio spectrum” and “how I do it” does not have to be fixed. Software can change how a radio works. Maybe you change the waveform or modulation, the frequency, or even the protocol. In the extreme case, a generic radio antenna can be used to receive AM radio, Wi-Fi, and protocols yet to be invented, simply by loading new software to interpret the new waveforms (This was previously called a “software defined radio,” but is now often called a “cognitive radio” in recognition of its extraordinary flexibility.) A famous contemporary application of the use of flexible radio programming is the ISEE-3 Reboot Project, which is using newly-modified radios to revive an old satellite that is still in orbit. (Yes, I’m a space geek. You’re not surprised, are you?)
Cognitive radios are still expensive, and indeed, overkill for most applications. In the Wi-Fi industry, we use a very narrow slice of cognitive radio capabilities. As regulations have expanded spectrum, it is possible to update the software that drives Wi-Fi chips to use those new channels. At the end of the day, though, they are still Wi-Fi radios. New software doesn’t change the waveform or protocol. You can have any bit transfer protocol you want, as long as it’s the Wi-Fi you know today.
Does Aerohive use “software defined” radios? Current Wi-Fi chipsets incorporate some SDR/cognitive-type capabilities, but for limited purposes such as making new spectrum available. As an industry, we have not yet been able to come up with a fully software-definable radio that can be reprogrammed on the fly while remaining cost-effective enough for the market that is Wi-Fi. We are still a long way from reprogramming a Wi-Fi chip on the fly.