Lecture 5 : Localization : Angle of Arrival Scribe : Hao

FCC regulations require radiation power of certain devices at some certain level, and the power attenuation of electromagnetic wave though air is P (d) ∝ 1 d2 Psource at far field, thus we can use received power information to know the the distance from a client to the access point (AP). If the distance of the client to at least 3 APs are know, we can then use a method called trilateration[2] to know where the client is. An example application of RSSI is that when you are dialing 911, the base stations will measure their received power and tell the police what is your location. The pros of this method is its easiness in adoption. However, multiple path result in constructively addition and destructively subtraction will make the power distribution much more complex than the equation described above. Thus for the usual indoor application, a lot of start-ups are tying