Vladica Sark

Configurable software defined radio system for two way time of flight ranging

Many applications rely on precise positioning. For outdoor positioning, GPS, or more generally, Global Navigation Satellite Systems (GNSS) have became a standard. On the other hand, there is no standard solution for indoor positioning. Two favored methods are mainly used. So called “WiFi fingerprinting” is based on the measurement of the received power from WiFi access points. It is interesting, because it can be easily implemented on hand-held devices, like smart phones. Due to the need of an extensive training process for building the fingerprint database and limited precision, this method has limited usability. The other group of indoor localization methods are based on Time of Flight (ToF) measurements. They have better precision, but also higher complexity. No training databases are needed. The deployment of ToF systems is usually very simple.

Reliable wireless communication and positioning enabling mobile control and safety applications in industrial environments

This paper introduces new functionalities for industrial safety applications using the wireless infrastructure of the IEEE 802.11 standard. The new amendments (n/ac/ad) for the 2.4, 5, and 60-GHz-band support additional high data rate modes, for e.g. video applications and device-to-device (D2D) communication. The huge bandwidth in the 60-GHz-band enables precise localization. However, Listen-Before-Talk (LBT) has to be used in order to guarantee fair channel access possibilities and coexistence of many devices. The access requirements are regulated (e.g. by ETSI for the European region). To cope with the uncertainty of coexistence and the special channel conditions in an industrial environment a multi-band PHY and MAC solution with multi-link-connectivity (MLC) support is introduced. This enables highly reliable low-latency wireless communication links for industrial safety applications. The simultaneous Round-Trip-Time-of-Flight (RTToF) ranging measurements enable position based features, like the introduced virtual safe zone.

Multi-Way ranging with clock offset compensation

This paper presents a new approach for reducing the ranging error due to the crystal clock offset. This approach is applicable in cooperative ranging methods like N-Way or Multi-Way ranging, which are mainly used in Wireless Sensor Networks (WSN). Leaving the crystal clock offset error uncompensated leads to propagation of the ranging error through the WSN. In our approach, the crystal clock offset between the nodes is estimated and used to compensate the ranging error. The main advantage of our approach is the smaller number of transmissions compared to other crystal clock offset mitigation techniques. This reduces the energy consumption and minimizes the wireless medium usage for ranging purposes. The simulation results show that, even when a coarse estimation of the clock offset is performed, it has a significant impact (i.e. two orders of magnitude) on the reduction of the ranging error.

Combined high-resolution ranging and high data rate wireless communication system in the 60 GHz band

In this paper, we present a high data rate communication system with an integrated high-resolution ranging feature. The point-to-point communication system is based on an OFDM baseband processor (BB) with data rates up to 3.9 Gbps, a medium access controller (MAC), and an analog frontend (AFE) for the 60 GHz band. The ranging system determines the distance between two stations using the round trip time of flight method (RTToF) in line-of-sight (LOS) environments. The MAC coordinates the channel access between the communication part and the ranging part. The system is integrated in a demonstrator platform based on field programmable gate arrays (FPGA). The ranging performance was simulated and measured in an indoor environment. The resolution is up to centimeter range.

Präzise Lokalisierung und Breitband-Kommunikation im 60-GHz-Band - PreLocate, Teilvorhaben: HF-Chips und Basisbandverarbeitung für Lokalisierung und Kommunikation im 60- GHz-Band (PreLocate-IHP) : Schlussbericht ; Projektlaufzeit: 01.10.2011 bis 31.07.2014

Fur zahlreiche Anwendungen im Bereich mobile drahtlose Kommunikation besteht der Bedarf nach einer genauen Lokalisierung mobiler Terminals. Dabei ist oft eine zentimetergenaue Lokalisierung bei gleichzeitiger Datenubertagung mit Raten von > 1 Gb/s notwendig. Auf Grund der hohen verfugbaren Bandbreite eignen sich dafur Funksysteme im mm-Wellen Bereich und insbesondere im 60-GHz-Band hervorragend. Am IHP wurde ein HF-Chip-Satz fur 60 GHz Ubertragung mit Beamsteering-Funktionalitat entwickelt. Des Weiteren wurde ein OFDM Basisband-Prozessor fur Ubertragungsraten bis zu 3,6 Gb/s entwickelt. Dieser wurde mit einem Verfahren zur Entfernungsmessung erweitert. Die Steuerung von Datenubertragung und Entfernungsmessung erfolgt uber einen speziellen MAC Prozessor. Beide Funktionen laufen im zeitmultiplex quasi-gleichzeitig ab. Zum Nachweis der Funktionalitat der gleichzeitigen Datenubertragung und Lokalisierung wurde ein FPGA-basierter Demonstrator entwickelt und mehrfach ausgestellt.

Modified equivalent time sampling for improving precision of time-of-flight based localization

Applications based on precise indoor and urban area localization are becoming quite popular. The integration of localization in currently existing wireless data communication systems is especially interesting. The popularity comes from the possibility to economically use the same analog front-end for data communication and localization. In indoor environments, where the precision should be under 1 m, because of the limited sample rate of the A/D converters, range binning becomes the main source of errors. Noise is not so much a problem, because for systems used mainly in indoor scenarios, the SNR is usually quite good. One solution, which is used to mitigate range binning is oversampling. Since oversampling requires additional hardware complexity, we propose here a “modified equivalent time sampling” approach. With this approach, no oversampling data converters are needed. The same data converters used for data communication can be used for ranging, but some signal processing before transmission and after reception of the signal is needed. The achieved resolution of the distance measurements is comparable to the solution with oversampling data converters.