Ultra-wideband (UWB) technology is very suitable for indoor wireless localization and ranging. IEEE 802.15.4a is the first physical layer standard specifically developed for wireless ranging and positioning. While malicious devices are not typically present, snoopers, impostors and jammers can exist. The data link and network layers in standards such as Wi-Fi, IEEE 802.15.4 and 802.11 mainly provide authentication and encryption support, but security about ranging or location is rarely considered. Ranging can be achieved using just the preamble and start of frame delimiter (SFD), so in this case malicious devices can easily obtain position information. Therefore, the security of ranging or positioning protocols is very important, which differs from the case with data exchange protocols. To provide secure location services, a protocol is presented which is based on a pseudo-random turnaround delay. In this protocol, devices use different turnaround times so that it is difficult for a snooper to figure out the location of sensor devices in protected areas. At the same time, in the period of Hello frame transmission, together with the authentication mechanism of IEEE 802.15.4, an impostor cannot easily engages its deception attack.
Pedestrian Path Prediction with Recursive Bayesian Filters: A Comparative Study