License-free ISM Band
License-free Industrial, Scientific, and Medical (ISM) band wireless technologies provide low-power, low-cost access to designated radio frequencies for specific uses, making them good options for closed-loop detection networks. While originally designated for fire, HazMat, and law enforcement, the same frequencies are also used by remote-controlled consumer devices and home-automation products. While interference from other ISM devices is common, because sensor applications are typically low-power, they tend not to interfere with other ISM network users. This enables reliable transmissions for threat-detection information.