In this paper, indoor localization using the Bluetooth low energy (BLE) system is explored. The range estimation is performed using the phase-based measurements of the commercially available off-the-shelf BLE devices and employing different range estimation methods. The unknown coordinates of the BLE node are computed via the analytical multilateration method based on the estimated range information at each anchor. The localization performance of the analytical multilateration utilizing different range estimation methods is experimentally examined and compared with the maximum likelihood (ML) localization, which serves as the best benchmark for localization performance. The experimental results demonstrate that the high-precision range estimation using the phase-based measurements outperforms other range estimation approaches and gives the least absolute localization error. In particular, the mean of the absolute localization error of the high-precision method approaches that of the ML localization and is within 12 cm for the selected trajectory in the measurement setup.

This paper demonstrates an IEEE 802.15.4z/ab compatible Impulse Radio Ultra-Wideband (IR-UWB) time-division-duplexing (TDD) multiple-input-multiple-output (MIMO) radar system for in-cabin monitoring for automotive applications. The proposed system supports two in-cabin use cases running in real-time: occupancy detection and breathing rate estimation. The IR-UWB TDD MIMO radar system detects if the driver and/or front passenger seats are occupied. Furthermore, the our system estimates the breathing rates of persons sitting in a car’s driver and/or front passenger seat. The experimental results confirm achieving a high precision for estimating the angle-of-arrival (AoA) and breathing rate. Particularly, for a measurement scenario where both passenger and driver seats are occupied, our system achieves a standard deviation of less than 1.90 degree and 2.95 bpm, for AoA and breathing rate estimations, respectively.

This paper proposes a real-time localization method, which estimates the tag’s location and updates the estimated measurement noise model without relying on offline measurements. The unique feature of our method is that it can update the measurement noise model using limited range measurements between a tag and anchors at each localization step. Simulation and measurement setups confirm that the performance of the proposed localization is close to the optimal maximum-likelihood (ML)-based localization, requiring the prior knowledge of the measurement noise model. In particular, the mean of the absolute localization error of the proposed algorithm is within 12 cm with respect to the ML-based localization in both simulation and measurement setups.

The IEEE 802.15.4z standard enabled secure ranging based on introducing a ciphered sequence called Scrambled Time Sequence (STS) in the Ultra-Wideband (UWB) packet. The channel impulse response (CIR) estimated by the STS sequence of the UWB packet has some side lobes due to STS sequence pseudo-random structure. The side lobes of a strong Non-Line-of-Sight (NLoS) in the CIR may obscure/distort the weak Line-of-Sight, leading to degradation of the ranging performance. In this paper, we propose an algorithm based on a structured bit flipping, referred to as bit flipping-based digital side lobe mitigation (BP-DSM), that reduces the magnitude of the side lobes in the estimated CIR of STS. BP-DSM improves the precision of the range estimation using the CIR of STS by up to 10 times. Additionally, BP-DSM is fully feedforward, avoiding the need for the time-consuming and computationally expensive re-computation of side lobes for each bit flipping trial, as required by an exhaustive search scheme. Consequently, BP-DSM is well-suited for secure UWB range estimation with limited processing time and power consumption.

Releasing the IEEE 802.15.4z standard enhanced de-ployment of the Ultra- WideBand (UWB) system in many chipsets for various emerging secure location and proximity applications. Accurate and precise range estimation is necessary in such applications. This paper improves the range estimation between two UWB nodes using a two-way range estimation principle in both Line-of-Sight (LOS) and Non-LOS (NLOS) channels. We provide a method based on the Maximum Likelihood principle to efficiently estimate the peak position of the first path in the estimated Channel Impulse Response (CIR) from the UWB packet. Our method works when there is an unknown phase offset in the CIR samples due to e.g., hardware nonidealities. The proposed method improves the standard deviation (STD) of range error by more than 1 order of magnitude with respect to the state-of-the-art technique, while only incurs an extra 4% computational complexity increase. Simulations show that with 40ppm of crystal offset between two devices, the STD of range error for our method is 3.5mm in the LOS channel. Furthermore, with Oppm of crystal offset between two devices, the STD of range error for our method is 0.5mm in the LOS channel simulation compared with 1.3mm in the LOS measurement setup.

The leading edge of a transmitted pulse shape plays an important role in the estimation of the Time of Arrival (ToA) of the pulse by a receiver. This is particularly the case for indoor, multipath environments, in which the trailing edge and to some extent the peak of the pulse may well be corrupted by following multipath components. It is therefore proposed that an asymmetric Ultra-Wide Band (UWB) pulse shape is used with a steep leading edge, generated by a modest precursor pulse with the opposite carrier phase to improve close-in multipath robustness. An integrated circuit implementation and experiments show such a pulse can meet the spectrum mask and improve the ToA measurement performance.

This paper demonstrates an IEEE 802.15.4z compliant Impulse Radio Ultra-Wideband (IR-UWB) radar system for in-cabin monitoring for automotive applications. The presented system demonstrates three in-cabin use cases running in real-time: occupancy detection, breathing rate estimation, and gesture detection. The IR-UWB radar system detects occupancy and estimates the breathing rates of persons sitting in a car's driver and/or front passenger seat. Furthermore, the radar system detects if the passenger is performing a pre-defined gesture. The experimental results demonstrate the effectiveness of the system in a real-time platform, confirming its potential for enhancing automotive safety and comfort. In the presented demo, we achieve a false alarm probability of lower than 10–3, a breathing rate accuracy of less than 1 beat per minute (bpm), and gesture detection accuracy of more than 90%.

The growth in the number of low-cost narrow band radios such as, Bluetooth low energy (BLE) enabled applications, such as asset tracking, human behavior monitoring, and keyless entry. The accurate range estimation is a must in such applications. Phase-based ranging has recently gained momentum due to its high accuracy in multipath environment compared to traditional schemes such as ranging based on received signal strength. The phase-based ranging requires tone exchange on multiple frequencies on a uniformly sampled frequency grid. Such tone exchange may not be possible due to some missing tones, e.g., reserved advertisement channels. Furthermore, the IQ values at a given tone may be distorted by interference. In this article, we proposed two phase-based ranging schemes which deal with the missing/interfered tones. We compare the performance and complexity of the proposed schemes using simulations, complexity analysis, and measurement setups. In particular, we show that for small number of missing/interfered tones, the proposed system based on employing a trained neural network (NN) performs very close to a reference ranging system, where there is no missing/interference tones. Interestingly, this high performance is at the cost of negligible additional computational complexity and up to 60.5 KB of additional required memory compared to the reference system, making it an attractive solution for ranging using hardware-limited radios such as BLE.

Cyberloafing has received increasing research interest in recent years and from a diversity of research streams. The implications of cyberloafing have proved to be significant, stronger and costly as compared to other less knowledge-based settings. Among other antecedents, the interrelationship of knowledge-workers’ personality traits and their inclinations to cyberloaf has not been studied to date. This survey investigates the relationship between the mentioned factors within and across a number of knowledge-intensive professional services firms in Iran. The findings show the significant positive impact of neuroticism, extraversion and openness to experience on both types of cyberloafing (namely activities and behaviours) and the negative impact of agreeableness on only cyberloafing activities.

We propose a novel binary message passing decoding algorithm for product-like codes based on bounded distance decoding (BDD) of the component codes. The algorithm, dubbed iterative BDD with scaled reliability (iBDD-SR), exploits the channel reliabilities and is therefore soft in nature. However, the messages exchanged by the component decoders are binary (hard) messages, which significantly reduces the decoder data flow. The exchanged binary messages are obtained by combining the channel reliability with the BDD decoder output reliabilities, properly conveyed by a scaling factor applied to the BDD decisions. We perform a density evolution analysis for generalized low-density parity-check (GLDPC) code ensembles and spatially coupled GLDPC code ensembles, from which the scaling factors of the iBDD-SR for product and staircase codes, respectively, can be obtained. For the white additive Gaussian noise channel, we show performance gains up to 0.29 dB and 0.31 dB for product and staircase codes compared to conventional iterative BDD (iBDD) with the same decoder data flow. Furthermore, we show that iBDD-SR approaches the performance of ideal iBDD that prevents miscorrections.

In this study, two diversity achieving schemes in two‐way relay channel (TWRC) under Nakagami‐ m fading are proposed. A general network of N r relays is considered where each relay is equipped with N a antennas. It is also assumed that the relays operate in decode‐and‐forward (DF) mode. The data transmission is divided into two phases, multiple access (MAC) phase and broadcast (BC) phase. In the MAC phase, the sources send their data to the relays simultaneously and after decoding, one relay is selected with MAX–MIN relay selection criterion and then in the BC phase retransmit the decoded symbols using the proposed transmission schemes at the selected relay. With evaluating the asymptotic behaviour of the bit error rate (BER) of the proposed schemes, it is proved that the diversity order of them is N r N a m . As a result, the proposed schemes achieve full diversity order.