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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.

60GHz communication technology is a type of short-range and high-speed wireless communication technology, which is currently considered the most promising one because it has a very high time and multi-path resolution. Therefore, it has the potential to achieve high-precision ranging and positioning. At present, carrier communication system like orthogonal frequency division multiplexing (OFDM) or single carrier techniques using frequency domain equalization (SC-FDE), etc., are mostly used in 60GHz communication system. Furthermore, accurate wireless positioning systems is mostly based on impulse radio. We propose a pulse positioning system in 60GHz band to meet the requirements of high-precision positioning. A pulse waveform suitable for 60GHz positioning is presented, meanwhile the positioning process of pulse transmitting, channel transmission, pulse receiving and coordinates calculation using positioning algorithm is also designed and simulated. The results show that the 60GHz pulse system has millimeter-level ranging accuracy and centimeter-level positioning accuracy in line-of-sight (LOS) channel, in addition the accuracy is much higher than that in ultra-wide band (UWB) pulse system.

In this paper we use UWB measurements for bandwidths up to 3 GHz to present a framework for statistical modeling of the indoor radio channel propagation characteristics that are pertinent to precise indoor geolocation using time-of-arrival (TOA) estimations. Accuracy of indoor geolocation systems relies on the strength and TOA of the direct path (DP) in the channel profile. Based on UWB measurements in a typical office building, we introduce empirical models for the path-loss and TOA of the DP. Path-loss model for the DP is used to analyze the occurrence of the undetected direct path (UDP) conditions which cause large errors in indoor geolocation systems. We then introduce a novel statistical model for the ranging or distance measurement error (DME) which is needed for comparative performance evaluation of the indoor positioning algorithms. The DME is a function of the bandwidth of the system, occurrence of the UDP conditions, and the distance between the transmitter and the receiver.

We are developing a robust, compact, and affordable photonic proximity sensor for munition fuze applications. Successful implementation of this sensor will provide a new capability for direct fire applications. The photonic component development exploits pioneering work and unique expertise at ARDEC, ARL, and Sandia National Laboratories by combining key optoelectronic technologies to design and demonstrate components for this fuzing application [Ruff, et al. 1994; Stann, et al. 1996; Simonis, et al. 2000; Liu, et al. 2000]. The technologies employed in the optical fuze design are vertical cavity surface-emitting lasers (VCSELs), the p-i-n or metal-semiconductor-metal (MSM) photodetectors, and miniature lenses optics. This work will culminate in a robust, fully integrated, g-hardened component design suitable for proximity fuzing applications. This compact sensor will replace costly assemblies that are based on discrete lasers, photodetectors, and bulk optics. It will be mass manufacturable and impart huge savings for such applications. The specific application under investigation is for gun-fired munitions. Nevertheless, numerous civilian uses exist for this proximity sensor in automotive, robotics and aerospace applications. This technology is also applicable to robotic ladar and short-range 3-D imaging.