Transceiver Location Research Articles

Joint Illumination and Communication Optimization in Indoor VLC for IoT Applications

Visible light communication (VLC) is one of the candidates to realize data rates of up to tera-bps in indoor scenarios, and is a popular topic in Internet of Things (IoT) applications. However, the receiving performance of the VLC channel is affected by relative locations of transceivers directly, while the uniform illumination is also required when the IoT devices can appear anywhere with strong mobility. Consequently, both the illumination uniformity and the average achievable rate are optimized by joint lamp arrangement and power allocation in this article. Moreover, the achievable rate maximization under diverse uniformity constraints is also obtained based on different room sizes and various numbers of lamps. The feasibility and superiority of the proposed algorithms are demonstrated by simulation validations, while the lower and upper bounds of uniformity constraints are explored. Numerical results also show the changing tendency of average achievable rates in multifarious situations, and the proposed schemes realize the tradeoff between uniform illumination and communication performance.

HandGest: Hierarchical Sensing for Robust-in-the-Air Handwriting Recognition With Commodity WiFi Devices

Recent advances in wireless sensing techniques have made it possible to recognize hand gestures using channel state information (CSI) in commodity WiFi devices. Existing WiFi-based gesture recognition systems mainly use learning-based pattern recognition methods to recognize different gestures, however, these methods fail to work well when the locations of transceivers, the relative location and orientation of the hand with respect to transceivers, and/or the hand gesturing size change, leading to inconsistent signal patterns caused by those factors. Although some recent efforts have been made to address the so-called “domain-dependent” gesture recognition problem, they either require prior knowledge on initial locations of the hand and WiFi devices or need to train several classifiers for the specific domains. Different from the state-of-the-art methods, we construct two distinct features from a hand-oriented view (rather than from a transceiver’s view), namely, the dynamic phase vector (DPV) and motion rotation variable (MRV), which are quite consistent in characterizing a big set of handwriting gestures, despite significant change in locations of transceivers, the relative location and orientation of the hand with respect to transceivers, and the drawing sizes. We further incorporate a hierarchical sensing framework and develop HandGest—a real-time handwriting gesture recognition system using commodity WiFi devices, to precisely recognize a great number of “in-the-air” handwritings based on the aforementioned two domain-independent features and a pipeline of specific features. Extensive experiments have been done in practical settings with 20 volunteers, evaluation results demonstrate that HandGest outperforms state-of-the-art methods on a large number of handwritings with different transceivers’ location, different initial hand locations and orientations, as well as different drawing sizes. Given its superior performance, we believe that HandGest paves a new way to enhance the real-world practicality of WiFi-based gesture recognition.

Spatial Loss Field for Outdoor Micro-Cells

In propagation analysis it is assumed that existing shadowing losses are due to obstacles through the propagation path between two transceivers. Although classically modelled as a log-normal random variable, special attention is being recently put into models where shadowing is considered as a consequence of an Underlying Spatial Loss Field (USLF) accounting for attenuation, under Radio Channel Tomography (RCT) framework. In this paper we address the task of making shadowing predictions for transceiver locations, without the need of measurements for those locations. A spatial loss field estimate is produced from measurements for a given set of transceiver locations, and used as an input to predict the shadowing at another set of transceiver locations. Moreover, new weighting functions are proposed and developed from channel parameter estimates of the propagation paths.

Relay Placement Algorithms for IoT Connectivity and Coverage in an Outdoor Heterogeneous Propagation Environment

A vast majority of the Internet of Things (IoT) devices will be connected in a topology where the edge-devices push data to a local gateway, which forwards the data to a cloud for further processing. In sizeable outdoor deployment regions, the edge-devices may experience poor connectivity due to their distant locations and limited transmission power. Repeaters or relays must be placed at a few locations to ensure reliable connectivity to either a gateway or another node in the network. A big challenge in achieving reliable connectivity and coverage is the outdoor propagation environment being heterogeneous. Engineers often deploy networks based on resource-intensive field visits, detailed surveys, measurements, initial test deployments, followed by fine-tuning. For scalability to large scale IoT deployments, automated network planning tools are essential. Such tools should predict connectivity based on the edge-device locations using available Geographical Information System (GIS) data, identify the need for relays/repeaters, and, if needed, suggest the number of relays needed with their locations. Furthermore, such tools should also be extended to suggest the minimum number and locations of base stations that maximise coverage. In this paper, we propose an automated network deployment framework using a black box received signal strength estimation oracle that provides signal strength estimates between candidate pairs of transceiver locations in a heterogeneous deployment region. Our proposed methodology uses either Ant Colony Optimisation (ACO) or Differential Evolution (DE) to identify the number and locations of relays for meeting specified quality of service constraints. We discuss adaptations of our techniques to handle scenarios with multiple gateways. Further, we show the effectiveness of these algorithms to find suitable candidate base station locations to provide coverage in a heterogeneous propagation environment that meets the specified quality of service constraints. We then demonstrate the effectiveness of our algorithms in two deployment regions.

IoT-Based Tracking System of Transceiver Location

Object mapping based on location tracking methods has been widely used in various types of applications. Most tracking systems recently use existing technology and infrastructure such as satellite, cellular and wireless (RF) technology. These existing technologies are high-cost technology that needs authorized permission to be integrated to the novel technology. This research proposed a cheap point to point device technology to track a location of a transceiver using GPS in a portable infrastructure using Line of sight radio communication. The tracking system design is connected to the IoT system in order to be more accessible. The proposed system using GPS as an identifier of the transceiver coordinate location and 433MHz radio module as media communication between transmitter and receiver. The use of a 433MHz radio frequency module which is free-license adds value to the system so that it will be easily accessed. The design of portable and internet-based devices also gives a positive value in which the system does not have to depend on existing infrastructure and the system can also be reached even if it is placed in remote areas. The system test results show that the system can be well accessed up to a distance of 6.8 km.

Deterministic 3D Ray-Launching Millimeter Wave Channel Characterization for Vehicular Communications in Urban Environments.

The increasing demand for more sensors inside vehicles pursues the intention of making vehicles more “intelligent”. In this context, the vision of fully connected and autonomous cars is becoming more tangible and will turn into a reality in the coming years. The use of these intelligent transport systems will allow the integration of efficient performance in terms of route control, fuel consumption, and traffic administration, among others. Future vehicle-to-everything (V2X) communication will require a wider bandwidth as well as lower latencies than current technologies can offer, to support high-constraint safety applications and data exhaustive information exchanges. To this end, recent investigations have proposed the adoption of the millimeter wave (mmWave) bands to achieve high throughput and low latencies. However, mmWave communications come with high constraints for implementation due to higher free-space losses, poor diffraction, poor signal penetration, among other channel impairments for these high-frequency bands. In this work, a V2X communication channel in the mmWave (28 GHz) band is analyzed by a combination of an empirical study and a deterministic simulation with an in-house 3D ray-launching algorithm. Multiple mmWave V2X links has been modeled for a complex heterogeneous urban scenario in order to capture and analyze different propagation phenomena, providing full volumetric estimation of frequency/power as well as time domain parameters. Large- and small-scale propagation parameters are obtained for a combination of different situations, taking into account the obstruction between the transceivers of vehicles of distinct sizes. These results can aid in the development of modeling techniques for the implementation of mmWave frequency bands in the vehicular context, with the capability of adapting to different scenario requirements in terms of network topology, user density, or transceiver location. The proposed methodology provides accurate wireless channel estimation within the complete volume of the scenario under analysis, considering detailed topological characteristics.

A Unified Spatial Framework for UAV-Aided MmWave Networks

For unmanned aerial vehicle (UAV) aided millimeter wave (mmWave) networks, we propose a unified three-dimensional (3D) spatial framework in this paper to model a general case that uncovered users send messages to base stations via UAVs. More specifically, the locations of transceivers in downlink and uplink are modeled through the Poisson point processes and Poisson cluster processes (PCPs), respectively. For PCPs, Matern cluster and Thomas cluster processes, are analyzed. Furthermore, both 3D blockage processes and 3D antenna patterns are introduced for appraising the effect of altitudes. Based on this unified framework, several closed-form expressions for the coverage probability in the uplink and downlink, are derived. By investigating the entire communication process, which includes the two aforementioned phases and the cooperative transmission between them, tractable expressions of system coverage probabilities are derived. Next, three practical applications in UAV networks are provided as case studies of the proposed framework. The results reveal that the impact of thermal noise and non-line-of-sight mmWave transmissions is negligible. In the considered networks, mmWave outperforms sub-6 GHz in terms of the data rate, due to the sharp direction beamforming and large transmit bandwidth. Additionally, there exists an optimal altitude of UAVs, which maximizes the system coverage probability.

Towards a Diffraction-based Sensing Approach on Human Activity Recognition

In recent years, wireless sensing has been exploited as a promising research direction for contactless human activity recognition. However, one major issue hindering the real deployment of these systems is that the signal variation patterns induced by the human activities with different devices and environmental settings are neither stable nor consistent, resulting in unstable system performance. The existing machine learning based methods usually take the "black box" approach and fails to achieve consistent performance. In this paper, we argue that a deep understanding of radio signal propagation in wireless sensing is needed, and it may be possible to develop a deterministic sensing model to make the signal variation patterns predictable. With this intuition, in this paper we investigate: 1) how wireless signals are affected by human activities taking transceiver location and environment settings into consideration; 2) a new deterministic sensing approach to model the received signal variation patterns for different human activities; 3) a proof-of-concept prototype to demonstrate our approach and a case study to detect diverse activities. In particular, we propose a diffraction-based sensing model to quantitatively determine the signal change with respect to a target's motions, which eventually links signal variation patterns with motions, and hence can be used to recognize human activities. Through our case study, we demonstrate that the diffraction-based sensing model is effective and robust in recognizing exercises and daily activities. In addition, we demonstrate that the proposed model improves the recognition accuracy of existing machine learning systems by above 10%.

Joint data transmission and dimming control optimization for MIMO–VLC systems with channel-adaptive spatial constellation design

In the field of indoor wireless communications, visible light communications (VLCs) have attracted great attention for synergistically providing both illumination and data transmission. Meanwhile, multiple-input multiple-output (MIMO) technique has been applied in VLC systems to boost data rate by utilizing spatial resources. However, different geometrical locations of transceivers provide distinct optical channels which may effect the performance of the conventional MIMO–VLC techniques severely. In this paper, we propose the channel-adaptive spatial constellation (CASC) design for the MIMO–VLC systems by fully taking advantage of the channel state information (CSI), where the optimal transmitted signal constellation can be constructed via maximizing the minimum Euclidean distance (MED) of the received signal constellation. Meanwhile, the practical lighting constraints are taken into consideration with the non-linearity characteristic of light-emitting diode (LED) and the dimming requirements to maintain a specific indoor illumination level. Finally, simulations results indicate that the proposed CASC design can achieve significant improvement of error performance compared with the conventional MIMO–VLC schemes.

Modeling and Analysis of D2D Millimeter-Wave Networks With Poisson Cluster Processes

This paper investigates the performance of millimeter wave (mmWave) communications in clustered device-to-device (D2D) networks. The locations of D2D transceivers are modeled as a Poisson Cluster Process. In each cluster, devices are equipped with multiple antennas, and the active D2D transmitter (D2D-Tx) utilizes mmWave to serve one of the proximate D2D receivers. Specifically, we introduce three user association strategies: 1) uniformly distributed D2D-Tx model; 2) nearest D2D-Tx model; and 3) closest line-of-site (LOS) D2D-Tx model. To characterize the performance of the considered scenarios, we derive new analytical expressions for the coverage probability and area spectral efficiency (ASE). Additionally, in order to efficiently illustrating the general trends of our system, a closed-form lower bound for the special case interfered by intra-cluster LOS links is derived. We provide Monte Carlo simulations to corroborate the theoretical results and show that: 1) the coverage probability is mainly affected by the intra-cluster interference with LOS links; 2) there exists an optimum number of simultaneously active D2D-Txs in each cluster for maximizing ASE; and 3) the closest LOS model outperforms the other two scenarios but at the cost of extra system overhead.

Node Positioning and Lifetime Optimization for Wireless Body Area Networks

Wireless communication networks may be categorized based on the extent of the geographical area that they cover. The latest trend in this assortment is wireless body area network (WBAN), which is standardized by IEEE 802.15.6 and is defined as a network composed of intelligent, miniaturized, low-power nodes that are implanted in, placed on, or in close proximity to the human body for certain healthcare applications. In this paper, we will start with some assessments on applicable channel models for a typical WBAN. Considering various scenarios with different carrier frequencies, bandwidths, body movements, and transceiver locations, the well-known Bayesian Information Criterion is used to check an available channel data set against 11 different statistical models. Having the channel models as the tools of the trade, we have chosen symbol error rate as the desired metric to find the best node location among the predefined options that results in the most reliable performance. Apart from the positioning of individual nodes, the reliability concept can be utilized in the context of a more general problem, giving rise to useful applications beyond a single node level. Here, we introduce the network lifetime as the performance indicator that can be evaluated for any scenario of interest. Moreover, the network lifetime may be treated as the cost function of an optimization problem. By following the requirements mentioned in the standard, we have found the optimum values for different node attributes that result in the network lifetime maximization.

Aspect-dependent efficient multipath ghost suppression in TWRI with sparse reconstruction

In through-the-wall radar imaging, multipath propagation can create ghost targets, which can adversely affect the image reconstruction process. However, unlike genuine targets, ghost positions are aspect-dependent, which means their position changes with the transceiver location. This paper proposes efficient ghost suppression methods exploiting aspect dependence feature under compressive sensing framework. This paper proposes a generalized signal model that accommodates for the reflections of the front-wall and target-to-target interactions, making the scheme more practical, yet the knowledge of the location of reflecting geometry is not a requirement as in most of the recent literatures. In addition, the sensing matrix is greatly reduced making the methods more attractive. Moreover, this paper investigates the influence of array configurations by examining two antenna array configurations: multimonostatic, and single-view bistatic configurations. Results based on synthesized data and real experiment show that the proposed method can greatly suppress multipath ghosts and hence increase signal-to-clutter ratio.

Energy harvesting assisted cognitive radio: random location-based transceivers scheme and performance analysis

We consider spectrum-sharing scenario where coexist two communication networks including primary network and secondary network using the same spectrum. While the primary network includes directional multi-transceivers, the secondary network consists of relaying-based transceiver forwarding signals by energy harvesting assisted relay node. In cognitive radio, signals transmitted from secondary network are sufficiently small so that all of primary network receivers have signal to noise ratio (SNR) greater than a given threshold. In contrast, the transmitted signals from primary network cause increasing noise which is difficult to demodulate at secondary network nodes and hence it leads to the peak power constraint. In this paper, we focus on the influence of random location of transceivers at primary network using decode-and-forward protocol. Specifically, we derive closed-form outage probability expression of the secondary network under random location of transceivers and peak power constraint of primary network. This investigation shows the relationship between the fraction of energy harvesting time $$\alpha $$ of time switching-based relaying protocol on outage probability of secondary network and throughput. In addition, we analyse the influence of the number of primary network transceivers as well as primary network’s SNR threshold on secondary network. Furthermore, the trade-off between increasing energy harvesting and rate was investigated under the effect of energy conversion efficiency. The accuracy of the expressions is validated via Monte-Carlo simulations. Numerical results highlight the trade-offs associated with the various energy harvesting time allocations as a function of outage performance.

Convex Space Building Discretization for Ray-Tracing

This paper describes a point-to-multipoint 3-D convex space-based ray-tracing technique. This visibility list is calculated and stored and can be reused as needed. What distinguishes our method is that the visibility list is transmitter location-independent, is a 3-D implementation, and is highly computationally efficient. The division of the building into free and filled convex spaces leads to an efficient Method of Images reflection and diffraction path generation algorithm. This technique can be used to optimize the locations of base transceivers in a highly efficient manner. The first step in producing this tool is the generation of efficient ray-tracing algorithms. The ray-tracing algorithm was specifically designed for later incorporation into a transmitter optimization algorithm. This requires a fast ray-tracing method because of its computationally intensive needs—running multiple times over a point-to-multipoint grid. Our algorithm is executed for sample building environments and then for a real building and compared with measurements to confirm its validity. It is clear that the results are in good agreement but do indicate that a highly accurate spatial modeling of the building is required.

Optimal Placement of Cellular Transceiver for Transmission Line Monitoring Using Genetic Algorithm

In recent decades, automation and modernization inhabit a vital role in the electric power industry. For reliable operation, the transmission network has to be continuously monitored and smarter decisions could be executed to satisfy the real time needs. In this respect, electrical transmission towers are installed with wireless sensor network (WSN) to gather the information from the transmission line network. The collected information is transmitted to the control centre for further actions through hybrid hierarchical network architecture. The hybrid architecture consists of a combination of wired, wireless and cellular technologies. WSNs are facing the bottleneck problem during transmission of data due to the bandwidth and latency of low data rate devices. Installation of cellular transceiver in transmission towers can reduce bottleneck problems remarkably. Whereas the installation of cellular transceivers cause high cost. Hence, this paper explains the optimistic ways for optimal placement of cellular transceivers with minimum cost. The objective is to define cellular node locations in order to improve network performance in terms of bandwidth and end-to-end delay. To attain the cost optimistic location of cellular transceivers, a heuristic algorithm based on genetic strategy is developed and applied to a benchmark set of problems. Experiments by simulations are conducted to evaluate the performance of the proposed algorithm in this paper. Model solutions specify both where to place the cellular transceivers and the optimal data paths to route the data. The optimization problem is carried with the objective of minimizing the installation cost. Through a comprehensive evaluation in simulation we show that our approach is effective in accomplishing the desired objectives for corridor of several hundreds of towers.

수조에서 MIMO 수중음향통신의 실험적 성능 고찰

본 논문에서는 수조에서 실험을 통해 획득한 데이터를 이용하여 MIMO (Multi-Input Multi-Output) 수중음향통신의 성능을 분석하였다. 이를 위하여 먼저 여러 송수신 위치에서 채널 전달 특성을 측정하였다. 송신신호는 QPSK (Quadrature Phase Shift Keying)로 변조하였으며, 수신신호는 Zero Forcing 등화기 등을 포함하는 검출기를 거쳐 복원되었다. 실험이 이루어진 수조 환경이 물리적으로 폐쇄된 매우 심한 다중 경로 전달 환경이어서 최대 30~40 ms의 지연 현상이 나타났다. 실험 결과 송신 및 수신 센서가 각각 두 개인 <TEX>$2{\times}2$</TEX> MIMO 시스템을 사용하였을 때 채널 특성으로 인해 비트 오차율이 비교적 크게 나타났지만 SISO (Single-Input Single-Output) 시스템에 비해 약 15% 정도 향상된 성능을 갖는 것을 확인하였다. In this paper, we have analyzed the performance of MIMO (Multi-Input Multi-Output) underwater acoustic communication by using the acquired data via the experiments in water tank. First of all, in the pursuit of this aim, we have measured the channel transfer characteristics at several transceiver locations. The transmitted signal was modulated by QPSK(Quadrature Phase Shit Keying) and the received signal was recovered through the detector that contains the zero forcing equalizer. A maximum 30~40 ms delay was appeared because of physically closed water tank environment that has the harsh multi-path transmission conditions. In result of experiment, even though the bit error rate showed comparatively large when <TEX>$2{\times}2$</TEX> MIMO system with two transmitters and receivers was considered. However, we confirmed it has approximately 15% enhanced performance compared with SISO (Single-Input Single-Output) system.

Designing four multi-objective models for dispersion facilities location problems considering Data Envelopment Analysis and maximum covering

Dispersion facilities location problem is one of the facility location problems. Possible applications include the location of shops and service-stations (for minimizing competition among them), the location of transceivers (for minimizing interference among them), and the location of undesirable facilities. Four different models of dispersion exist. In this paper we develop four different dispersion facilities location modeling formulations that utilize simultaneous data envelopment analysis (SDEA) efficiency measures to find optimal and efficient facility location patterns, and maximize total demands of satisfied demand points. Also these models consider existing facilities. These models with three objectives, match the real world problems a lot. Since these four models are multiobjective, a fuzzy goal programming approach was applied to solve problem. In this paper, after introducing the proposed model, an example, with the results of numerical calculations is provided.

Optimal Relay Antenna Location in Indoor Environment Using Particle Swarm Optimizer and Genetic Algorithm

An optimization procedure for the location of the relay transceiver in ultra-wideband wireless communication system is presented. The impulse responses of different transceiver locations are computed by shooting and bouncing ray/image (SBR/Image) techniques and inverse fast Fourier transform (IFFT). By using the impulse responses of these multi-path channels, the bit error rate (BER) performance for binary pulse amplitude modulation (BPAM) impulse radio UWB communication system are calculated. Based on the BER performance, the outage probability for any given relay location of the transceiver can be computed. The optimal relay antenna location for minimizing the outage probability is searched by genetic algorithm (GA) and particle swarm optimizer (PSO). The transmitter is in the center of the whole indoor environment and the receivers are uniform distributed with 1.5 meter intervals in the whole indoor environment. Two cases are considered as following: (I) Two relay transceivers with two different cases are employed. First, the whole space is divided into two areas and one relay transceiver is used in each area. The optimal relay antenna locations are searched in each area respectively. Second, the two optimal relay locations are searched in the whole space directly without any prior division. (II) Four relay transceivers with two different cases are employed. First, the whole space is divided into four areas and one relay transceiver is used in each area. The optimal relay antenna locations are searched in each area respectively. Second, the four optimal relay locations are searched in the whole space directly without any prior division. Numerical results have shown that our proposed method is effective for finding the optimal location for relay antenna to reduce BER and outage probability.

System and method for cardiac imaging

Ultrasound systems and methods are described to measure changes in cardiac chamber volumes and organ wall areas, thicknesses, volumes and masses between the cardiac chambers using computer readable media employing image processing algorithms applied to 3D data sets acquired at systole and diastole. The systems for cardiac imaging includes an ultrasound transceiver configured to sense the mitral valve of a heart by Doppler ultrasound, an electrocardiograph connected with a patient and synchronized with the transceiver to acquire ultrasound-based 3D data sets during systole and diastole at a transceiver location determined by Doppler ultrasound affected by the mitral valve, and a computer readable medium configurable to process ultrasound imaging information from the 3D data sets communicated from the transceiver.

Spatio-temporal ultrawideband indoor propagation modelling by reduced complexity geometric optics

A simple and efficient virtual-source ray-tracing technique for the simulation of indoor wideband radio and optical propagation channels is proposed. The parametric deterministic model considers the room geometry, transceiver locations, material properties and probe signal types. It is applied to the indoor ultrawideband channel in the FCC-allocated 3.1–10.6 GHz band, and a range of novel results are presented to illustrate several possible applications. The channel small-scale fading statistics and spatial variability are examined by synthesising a densely sampled aperture. Multiple-antenna array systems are simulated to evaluate multiple-input multiple-output performance. The multipath angular characteristics are analysed from the simulated azimuth-delay profile. The simulation results closely match previous channel measurement studies and statistical models, validating the proposed technique. It is shown that specular reflection is dominant, and power convergence is achieved with three reflections in a typical indoor environment. Thus, it is demonstrated that despite its simplicity, the model yields reliable and accurate results, and can therefore be a useful tool for indoor wireless network planning and performance prediction.