Mustafa S. Bakr

Using DecaWave UWB transceivers for high-accuracy multipath-assisted indoor positioning

Robust indoor positioning and location awareness at a sub-meter accuracy typically require highly accurate radio channel measurements to extract precise time-of-flight measurements. Emerging UWB transponders like the DecaWave DW1000 chip offer to estimate channel impulse responses with reasonably high bandwidth and excellent clock stability, yielding a ranging precision below 10 cm. The competitive pricing of these chips allows scientists and engineers for the first time to exploit the benefits of UWB for indoor positioning without the need for a massive investment into experimental equipment. This work investigates the performance of the DW1000 chip concerning position related information that can be extracted from its channel impulse response measurements. We evaluate the signal-to-interference-plus-noise ratio of the line-of-sight and reflected multipath components which is a key parameter determining the Cramér-Rao lower bound on the ranging error variance. We propose a novel and highly efficient positioning algorithm, which requires information from a single anchor only. Results demonstrate reliable and robust positioning at an accuracy below 0.5 m.

SALMA: UWB-based Single-Anchor Localization System using Multipath Assistance

Setting up indoor localization systems is often excessively time-consuming and labor-intensive, because of the high amount of anchors to be carefully deployed or the burdensome collection of fingerprints. In this paper, we present SALMA, a novel low-cost UWB-based indoor localization system that makes use of only one anchor and that does neither require prior calibration nor training. By using only a crude floor plan and by exploiting multipath reflections, SALMA can accurately determine the position of a mobile tag using a single anchor, hence minimizing the infrastructure costs, as well as the setup time. We implement SALMA on off-the-shelf UWB devices based on the Decawave DW1000 transceiver and show that, by making use of multiple directional antennas, SALMA can also resolve ambiguities due to overlapping multipath components. An experimental evaluation in an office environment with clear line-of-sight has shown that 90% of the position estimates obtained using SALMA exhibit less than 20 cm error, with a median below 8 cm. We further study the performance of SALMA in the presence of obstructed line-of-sight conditions, moving objects and furniture, as well as in highly dynamic environments with several people moving around, showing that the system can sustain decimeter-level accuracy with a worst-case average error below 34 cm.

Dataset: single-anchor indoor localization with decawave DW1000 and directional antennas

Highly-accurate localization of wireless devices is a critical feature of future Internet-of-Things applications. Due to its superior time-domain resolution, ultra-wideband (UWB) technology allows centimeter-level positioning accuracy. Still, setting up an anchor-based UWB localization system requires extensive labour and costs. Recent works have shown that, instead of multiple physical anchors, the exploitation of multipath reflections from walls minimizes the required infrastructure to a single anchor. This dataset contains an extensive measurement campaign in two complex indoor environments with one anchor. It contains line-of-sight as well as non-line-of-sight situations. Furthermore, we have acquired datasets using directional antennas at the anchor to allow observing the impact of the angular domain on the localization performance.

Multipath-assisted indoor positioning enabled by directional UWB sector antennas

High-accuracy indoor radio positioning can be achieved by using high signal bandwidths to increase the time resolution. Multiple fixed anchor nodes are needed to compute the position or alternatively, reflected multipath components can be exploited with a single anchor. In this work, we propose a method that explores the time and angular domains with a single anchor. This is enabled by switching between multiple directional ultra-wideband (UWB) antennas. The UWB transmission allows to perform multipath resolved indoor positioning, while the directionality increases the robustness to undesired, interfering multipath propagation with the benefit that the required bandwidth is drastically reduced. The positioning accuracy and performance bounds of the switched antenna are compared to an omni-directional antenna. Two positioning algorithms are presented based on different prior knowledge available, one using floorplan information only and the other using additionally the beampatterns of the antennas. We show that the accuracy of the position estimate is significantly improved, especially in tangential direction to the anchor.

UWB-based Single-anchor Low-cost Indoor Localization System

In this demo, we present a low-cost indoor localization system based on the off-the-shelf ultra-wideband transceiver Decawave DW1000. To obtain an accurate position information, the system makes use of a single anchor and of multipath reflections from walls, hence removing the need of installing a network of anchors or any other additional infrastructure. The procedure of determining the position of a tag can be divided in four consecutive stages. First, the location of virtual anchors is computed by mirroring the anchor position at reflective surfaces. Using two-way ranging, the distance and channel impulse response (CIR) between anchor and tag is obtained. This actual CIR is compared with expected CIRs from possible tag locations using a maximum likelihood approach to estimate the tags position. Finally, a switchable directional antenna can be exploited to improve the robustness of the system by suppressing undesired, interfering multipath components. By following this procedure, the proposed system can achieve a decimeter accuracy and react to position updates in real-time.

Triple mode dielectric-loaded cavity band pass filter

This paper presents a compact triple mode band pass filter (BPF) using dielectric-loaded cylindrical cavity that allows the realization of three transmission zeros. This class of triple mode resonator utilizes the degenerate TE11 modes and the single TM01 mode. Coupling structure is based on choosing the proper resonator height and input/output feeding probe position (angle Ø) to achieve the desired perturbation between the degenerate modes. Therefore, no additional space nor coupling screws is needed. A three-pole BPF is designed to verify this approach at 2.08 GHz centre frequency with bandwidth of 42 MHz at -20 dB return loss. The introduced triple mode resonator can be used as a building block in the design of diplexers and sophisticated higher-order filters.

A TE 11 dual-mode monoblock dielectric resonator filter

A novel TE11 monoblock dual-mode dielectric resonator filter is presented in this paper. The proposed filter is made of a single piece of ceramic with silver plated external surfaces and metallic lids for hosting tuning elements. The dominant TE11 dual-mode is supported by H-shape dielectric resonator having εr =45. The resonator is ultra-compact in size and offers a maximized space utilization since no metallic housing is required. In addition, the proposed resonator offers a high unloaded quality factor, reasonably wide spurious window and lend itself to implement tunability. One prototype filter operating at 1.96 GHz with 50-MHz bandwidth is designed.