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Millimeter wave technology will be dominating the fifth-generation networks due to the clear advantage of higher frequency bands and hence wider spectrum. In this paper, the indoor radio wave propagation at 28 GHz is studied by developing an efficient three-dimensional ray tracing (ETRT) method. The simulation software based on the ETRT model has been verified by measurement data. The received signal strength indication and path loss have shown significant agreement between simulation and measurement. Compared with the conventional shooting bouncing ray tracing method, the proposed ETRT method has better agreement with measurement data.

Temporal fault trees (TFTs), an extension of classical Boolean fault trees, can model timedependent failure behaviour of dynamic systems. The methodologies used for quantitative analysis of TFTs include algebraic solutions, Petri nets (PN), and Bayesian networks (BN). In these approaches, precise failure data of components are usually used to calculate the probability of the top event of a TFT. However, it can be problematic to obtain these precise data due to the imprecise and incomplete information about the components of a system. In this paper, we propose a framework that combines intuitionistic fuzzy set theory and expert elicitation to enable quantitative analysis of TFTs of dynamic systems with uncertain data. Experts' opinions are taken into account to compute the failure probability of the basic events of the TFT as intuitionistic fuzzy numbers. Subsequently, for the algebraic approach, the intuitionistic fuzzy operators for the logic gates of TFT are defined to quantify the TFT. On the other hand, for the quantification of TFTs via PN and BN-based approaches, the intuitionistic fuzzy numbers are defuzzified to be used in these approaches. As a result, the framework can be used with all the currently available TFT analysis approaches. The effectiveness of the proposed framework is illustrated via application to a practical system and through a comparison of the results of each approach. INDEX TERMS Fault tree analysis, reliability analysis, fuzzy set, intuitionistic fuzzy set theory, expert judgement, temporal fault trees.

Abstract-Omni-directional antennas are useful for variety of wireless communication devices as well as capable of handling the additional different frequency bands since the radiation pattern allows good transmission and reception from a mobile unit. However, to implement the two frequencies on a single antenna with wide bandwidth can be significant because of the presence of mutual coupling and interference effects between the two radiating elements. In this paper, a novel method of combining dual-band frequencies onto a single layer board with wide bandwidth is described. A dual-band printed dipole antenna is designed in this study by combining a rectangular and two "L" shaped radiating elements and are embedded on a single layer structure with relatively small size. The obtained results show that the proposed dual-band omni-directional microstrip antenna achieves high antenna efficiency and provides better bandwidth while maintaining the structural compact size.

One of the biggest challenges in RFID (radio frequency identification) large scale deployment, such as in warehouse RFID deployment, is the positioning of RFID reader antennas to efficiently locate all the tagged objects distributed at RFID reader environment. This paper has investigated a novel location sensing system based on geometric grid covering algorithm that can use any passive or active RFID standard for positioning or tracking objects inside buildings. This study involves design of RFID reader antenna network which focuses on placing the reader antennas on a grid to cover all the tags distributed at two dimensional planes and position calculation using statistical averages algorithm. The statistical averages algorithm simply computes the location coordinates of the tagged object by statistical average of the reader antenna's location. The proposed grid of reader antennas can assist in minimizing the actual number of reader antennas required for RFID large scale deployment. The proposed prototype system is a simpler positioning system which presents the solution of placement pattern of RFID reader antennas, gives less complicated mathematical calculation, and is able to provide a high degree of accuracy. The obtained results show that the proposed location sensing system can achieve better positioning accuracy as compared to existing positioning system and in some cases accuracy improvement of about 50% can be reached.

The indoor positioning system (IPS) is becoming increasing important in accurately determining the locations of objects by the utilization of micro-electro-mechanical-systems (MEMS) involving smartphone sensors, embedded sources, mapping localizations, and wireless communication networks. Generally, a global positioning system (GPS) may not be effective in servicing the reality of a complex indoor environment, due to the limitations of the line-of-sight (LoS) path from the satellite. Different techniques have been used in indoor localization services (ILSs) in order to solve particular issues, such as multipath environments, the energy inefficiency of long-term battery usage, intensive labour and the resources of offline information collection and the estimation of accumulated positioning errors. Moreover, advanced algorithms, machine learning, and valuable algorithms have given rise to effective ways in determining indoor locations. This paper presents a comprehensive review on the positioning algorithms for indoors, based on advances reported in radio wave, infrared, visible light, sound, and magnetic field technologies. The traditional ranging parameters in addition to advanced parameters such as channel state information (CSI), reference signal received power (RSRP), and reference signal received quality (RSRQ) are also presented for distance estimation in localization systems. In summary, the recent advanced algorithms can offer precise positioning behaviour for an unknown environment in indoor locations.

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