Ultra narrow band: Ultra-narrow band systems feature cheap tags that chirp out weak, wideband signals that are received by three or more readers. Since the signal is wideband, the accuracy is usually outstanding. This makes the indoor positioning systems using this technology to be the most accurate in the industry.
Infrared: Here infrared light pulses are used to locate signals inside a building. A professional installs infrared readers in every room of the house, and when they create a pulse, the pulse is read by a reader device. When properly installed, this system is highly accurate. Unfortunately, you have to install a reader in every room, which can be expensive if you have a large building.