With the demanding system requirements for the fifth-generation (5G) wireless communications and the severe spectrum shortage at conventional cellular frequencies, multibeam antenna systems operating in the millimeter-wave frequency bands have attracted a lot of research interest and have been actively investigated. They represent the key antenna technology for supporting a high data transmission rate, an improved signal-to-interference-plus-noise ratio, an increased spectral and energy efficiency, and versatile beam shaping, thereby holding a great promise in serving as the critical infrastructure for enabling beamforming and massive multiple-input multiple-output (MIMO) that boost the 5G. This paper provides an overview of the existing multibeam antenna technologies which include the passive multibeam antennas (MBAs) based on quasi-optical components and beamforming circuits, multibeam phased-array antennas enabled by various phase-shifting methods, and digital MBAs with different system architectures. Specifically, their principles of operation, design, and implementation, as well as a number of illustrative application examples are reviewed. Finally, the suitability of these MBAs for the future 5G massive MIMO wireless systems as well as the associated challenges is discussed.

Multibeam Antenna Technologies for 5G Wireless Communications

A novel deterministic approach to model the radio wave propagation channels in complex indoor environments reducing computational complexity is proposed. This technique combines a neural network and a 3-D ray launching algorithm in order to compute wireless channel performance in indoor scenarios. An example of applying the method for studying indoor radio wave propagation is presented and the results are compared with a very high resolution fully 3-D ray launching simulation as the reference solution. The new method allows the use of a lower number of launched rays in the simulation scenario whereas intermediate points can be predicted using neural network. Therefore a high gain in terms of computational efficiency (approximately 80% saving in simulation time) is achieved.

A Ray Launching-Neural Network Approach for Radio Wave Propagation Analysis in Complex Indoor Environments

In this paper, a convergence analysis to obtain the optimal calculation parameters in an inhouse 3D ray launching algorithm to model the radio wave propagation channel in complex indoor environments is presented. Results show that these parameters lead to accurate estimations with reduced computational time. In addition, simulation results of an indoor complex scenario in terms of received power and power delay profile are presented, showing significant influence of multipath propagation in an indoor radio channel. The adequate election of simulation parameters given by convergence conditions, can aid in optimizing required computational time.

Convergence Analysis in Deterministic 3D Ray Launching Radio Channel Estimation in Complex Environments

Indoor radio frequency positioning systems enable a broad range of location aware applications. However, the localization accuracy is often impaired by Non-Line-Of-Sight (NLOS) connections and indoor multipath effects. An interesting evolution in widely deployed communication systems is the transition to multi-antenna devices with beamforming capabilities. These properties form an opportunity for localization methods based on Angle of Arrival (AoA) estimation. This work investigates how multipath propagation can be exploited to enhance the accuracy of AoA localization systems. The presented multipath assisted method resembles a fingerprinting approach, matching an AoA measurement vector to a set of reference vectors. However, reference data is not generated by labor intensive site surveying. Instead, a ray tracer is used, relying on a-priori known floor plan information. The resulting algorithm requires only one fixed receiving antenna array to determine the position of a mobile transmitter in a room. The approach is experimentally evaluated in LOS and NLOS conditions, providing insights in the accuracy and robustness. The measurements are performed in various indoor environments with different hardware configurations. This leads to the conclusion that the proposed system yields a considerable accuracy improvement over common narrowband AoA positioning methods, as well as a reduction of setup efforts in comparison to conventional fingerprinting systems.

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Indoor Multipath Assisted Angle of Arrival Localization

https://researchrepository.ucd.ie/bitstream/10197/7006/1/Survey_of_WiFi_Positioning_using_Time-Based_Techniques.pdf

Survey of WiFi positioning using time-based techniques

This work presents a new indoor localization method based on the fingerprinting technique. The proposed method uses a ray-tracing model that provides information about multipath effects. This information is stored in a dataset during the first stage of the fingerprinting method. The direction of arrival (DOA) and received signal strength (RSS) are used in the fingerprinting technique as a hybrid system. The localization estimation is calculated while taking into account the Euclidian distance between the DOA and the RSS from each unknown position and the information of the fingerprints. Numerical calculations were performed to show the mean and the standard deviation of the estimated error.

/pdf/the-application-of-ray-tracing-to-mobile-localization-using-34d7r7onlo.pdf

The Application of Ray-Tracing to Mobile Localization Using the Direction of Arrival and Received Signal Strength in Multipath Indoor Environments

A compact dual-band equatorial helical antenna for TTC (telemetry, tracking, and control) applications in satellites is presented. The network feeding system of the antenna was also designed, analyzed, and measured to achieve circular polarization. A Moment Method code was used to evaluate the performance of both the helical antenna and the feed-circuit network. The whole system was optimized to fulfill rather strict specifications, while maintaining quite small size and weight. A prototype of the helical antenna was fabricated and measured. The design process of the geometrical model, and comparisons between the predicted and measured values, are presented. The results led to the conclusion that it is a very suitable antenna for operating at S band.

Optimization of a Dual-Band Helical Antenna for TTC Applications at S Band

The dropout rate of engineering students is a concerning problem at the present time in many countries, resulting in difficulties to follow the demand of professionals in certain technological sectors as well as an associated negative economic impact. This study identifies a number of factors affecting the motivation degree of current electrical and computer engineering students, as well as the main reasons behind the dropout. A survey was completed by 624 students belonging to 8 different Spanish universities, rating the factors that could influence them to abandon their studies and those affecting their motivation to continue studying. Non-parametric analyses were performed in order to test the association of motivation as well as self-reported likelihood of dropping out with several variables. According to the research results, 23 of the 40 analyzed factors are correlated with the degree of motivation and 14 factors are correlated with the self-reported probability of dropping out. About 46% of the students declared to have thought about dropping out at some point in the past. Difficulty, followed by bad academic performance and negative relationships with professors are the main reasons for dropping out given by the students. Lack of vocation and distance to their home address were less frequent reasons.

/pdf/analysis-on-the-lack-of-motivation-and-dropout-in-6ee7ol7oji.pdf

Analysis on the Lack of Motivation and Dropout in Engineering Students in Spain

This communication presents two efficient approaches for the electromagnetic field analysis of complex 3D bodies. The first method can provide a fast and accurate analysis of arbitrary metallic and dielectric/magnetic structures and combines the moment method (MM), the multilevel fast multipole algorithm (MLFMA), physics optics (PO) and the characteristic basis function method (CBFM) to solve very large scattering problems. The second technique is based on a domain decomposition approach that divides the geometry into several parts to minimize the vast computational resources required when applying the MM. A parallelization process was carried out by using the message passing interface (MPI) algorithm to minimize the memory and time requirements for each simulation. A dual-band reflectarray was successfully analyzed to compare the performance of both codes.

Fast Analysis of a Dual-Band Reflectarray Using Two Different Numerical Approaches Based on the Moment Method

This work presents an accurate and realistic positioning approach for indoor environments based on fingerprinting and raytracing techniques. Fading caused by multipath seriously degrades the performance of communication systems operating inside buildings. For this reason, the proposed localization method considers multipath effects due to reflections and diffraction from walls, roof and floor. However, fading in indoor environments can also be caused by the movement of people or the presence of furniture. Because people are the primary absorption agents in indoor channels, their influence on the radio propagation channel must be considered. The proposed localization method takes into account the effects of human body shadowing to provide a realistic estimation of the mobile station position. Numerical calculations in real indoor scenarios show reasonable results.

/pdf/localization-approach-based-on-ray-tracing-including-the-2d80825x9k.pdf

Josefa Gomez

Papers

The Application of Ray-Tracing to Mobile Localization Using the Direction of Arrival and Received Signal Strength in Multipath Indoor Environments

Optimization of a Dual-Band Helical Antenna for TTC Applications at S Band

Analysis on the Lack of Motivation and Dropout in Engineering Students in Spain

Fast Analysis of a Dual-Band Reflectarray Using Two Different Numerical Approaches Based on the Moment Method

Localization Approach Based on Ray-Tracing Including the Effect of Human Shadowing