Abstract: Operating unmanned aerial vehicle (UAV) over cellular networks would open the barriers of remote navigation and far-flung flying by combining the benefits of UAVs and the ubiquitous availability of cellular networks. In this letter, we provide an initial insight on the radio propagation characteristics of cellular-to-UAV (CtU) channel. In particular, we model the statistical behavior of the path-loss from a cellular base station toward a flying UAV. Where we report the value of the path-loss as a function of the depression angle and the terrestrial coverage beneath the UAV. The provided model is derived based on extensive experimental data measurements conducted in a typical suburban environment for both terrestrial (by drive test) and aerial coverage (using a UAV). The model provides simple and accurate prediction of CtU path-loss that can be useful for both researchers and network operators alike.

Abstract: Fifth-generation (5G) wireless networks are expected to operate at both microwave and millimeter-wave (mmWave) frequency bands, including frequencies in the range of 24 to 86 GHz. Radio propagation models are used to help engineers design, deploy, and compare candidate wireless technologies, and have a profound impact on the decisions of almost every aspect of wireless communications. This paper provides a comprehensive overview of the channel models that will likely be used in the design of 5G radio systems. We start with a discussion on the framework of channel models, which consists of classical models of path loss versus distance, large-scale, and small-scale fading models, and multiple-input multiple-output channel models. Then, key differences between mmWave and microwave channel models are presented, and two popular mmWave channel models are discussed: the 3rd Generation Partnership Project model, which is adopted by the International Telecommunication Union, and the NYUSIM model, which was developed from several years of field measurements in New York City. Examples on how to apply the channel models are then given for several diverse applications demonstrating the wide impact of the models and their parameter values, where the performance comparisons of the channel models are done with promising hybrid beamforming approaches, including leveraging coordinated multipoint transmission. These results show that the answers to channel performance metrics, such as spectrum efficiency, coverage, hardware/signal processing requirements, etc., are extremely sensitive to the choice of channel models.

Abstract: The Global Navigation Satellite System (GNSS) cannot achieve accurate positioning and navigation in the indoor environment Therefore, efficient indoor positioning technology has become a very active research topic Bluetooth beacon positioning is one of the most widely used technologies Because of the time-varying characteristics of the Bluetooth received signal strength indication (RSSI), traditional positioning algorithms have large ranging errors because they use fixed path loss models In this paper, we propose an RSSI real-time correction method based on Bluetooth gateway which is used to detect the RSSI fluctuations of surrounding Bluetooth nodes and upload them to the cloud server The terminal to be located collects the RSSIs of surrounding Bluetooth nodes, and then adjusts them by the RSSI fluctuation information stored on the server in real-time The adjusted RSSIs can be used for calculation and achieve smaller positioning error Moreover, it is difficult to accurately fit the RSSI distance model with the logarithmic distance loss model due to the complex electromagnetic environment in the room Therefore, the back propagation neural network optimized by particle swarm optimization (PSO-BPNN) is used to train the RSSI distance model to reduce the positioning error The experiment shows that the proposed method has better positioning accuracy than the traditional method

Abstract: Millimeter-wave communication systems require many innovative antennas adapted for future application scenarios such as the upcoming 5G cellular networks. Due to the strong path loss in free space at the millimeter-wave frequency range, high gain and low-cost antennas are in great demand. Also, advanced features such as multi-beam for multiple user, dual-polarization, or even complete phased arrays with enormous degrees of freedom in beamforming are some of the key research lines for antenna designers nowadays. In this article an overview of a new type of family of low-loss antennas and components based on the recently developed gap waveguide technology is presented. With the advent of new millimeter-wave applications, this low-cost and low-loss waveguide technology can be considered as a good candidate to be used as the core RF building block.

Abstract: More people prefer to using rail traffic for travel or for commuting due to its convenience and flexibility. As the record of the maximum speed of rail has been continuously broken and new applications are foreseen, the high-speed railway (HSR) communication system requires higher data rate with seamless connectivity, and therefore, the system design faces new challenges to support high mobility. Millimeter-wave (mmWave) technologies are considered as candidates to provide wideband communication. However, mmWave is rarely explored in HSR scenarios. In this paper, channel characteristics are studied in the 5G mmWave band for typical HSR scenarios, including urban, rural, and tunnel, with straight and curved route shapes. Based on the wideband measurements conducted in the tunnel scenario by using the “mobile hotspot network” system, a 3-D ray tracer (RT) is calibrated and validated to explore more channel characteristics in different HSR scenarios. Through extensive RT simulations with 500-MHz bandwidth centered at 25.25 GHz, the power contributions of the multipath components are studied, and the dominant reflection orders are determined for each scenario. Path loss is analyzed, and the breakpoint is observed. Other key parameters, such as Doppler shifts, coherence time, polarization ratios, and so on, are studied. Suggestions on symbol rate, sub-frame bandwidth, and polarization configuration are provided to guide the 5G mmWave communication system design in typical HSR scenarios.

Abstract: Wireless communication environments are unaware of the ongoing data exchange efforts within them. Moreover, their effect on the communication quality is intractable in all but the simplest cases. The present work proposes a new paradigm, where indoor scattering becomes software-defined and, subsequently, optimizable across wide frequency ranges. Moreover, the controlled scattering can surpass natural behavior, exemplary overriding Snell's law, reflecting waves towards any custom angle (including negative ones). Thus, path loss and multi-path fading effects can be controlled and mitigated. The core technology of this new paradigm are metasurfaces, planar artificial structures whose effect on impinging electromagnetic waves is fully defined by their macro-structure. The present study contributes the software-programmable wireless environment model, consisting of several HyperSurface tiles controlled by a central, environment configuration server. HyperSurfaces are a novel class of metasurfaces whose structure and, hence, electromagnetic behavior can be altered and controlled via a software interface. Multiple networked tiles coat indoor objects, allowing fine-grained, customizable reflection, absorption or polarization overall. A central server calculates and deploys the optimal electromagnetic interaction per tile, to the benefit of communicating devices. Realistic simulations using full 3D ray-tracing demonstrate the groundbreaking potential of the proposed approach in 2.4GHz and 60GHz frequencies.

Abstract: Owing to the rapid growth in wireless data traffic, millimeter-wave (mm-wave) communications have shown tremendous promise and are considered an attractive technique in fifth-generation (5G) wireless communication systems. However, to design robust communication systems, it is important to understand the channel dynamics with respect to space and time at these frequencies. Millimeter-wave signals are highly susceptible to blocking, and they have communication limitations owing to their poor signal attenuation compared with microwave signals. Therefore, by employing highly directional antennas, co-channel interference to or from other systems can be alleviated using line-of-sight (LOS) propagation. Because of the ability to shape, switch, or scan the propagating beam, phased arrays play an important role in advanced wireless communication systems. Beam-switching, beam-scanning, and multibeam arrays can be realized at mm-wave frequencies using analog or digital system architectures. This review article presents state-of-the-art phased arrays for mm-wave mobile terminals (MSs) and base stations (BSs), with an emphasis on beamforming arrays. We also discuss challenges and strategies used to address unfavorable path loss and blockage issues related to mm-wave applications, which sets future directions.

Abstract: In this letter, we study the physical layer secrecy performance of the classic Wyner’s wiretap model over double Rayleigh fading channels for vehicular communications links. We derive novel and closed-form expressions for the average secrecy capacity (ASC) taking into account the effects of fading, path loss, and eavesdropper location uncertainty. The asymptotic analysis for ASC is also conducted. The derived expressions can be used for secrecy capacity analysis of a number of scenarios including vehicular-to-vehicular (V2V) communications. The obtained results reveal the importance of taking the eavesdropper location uncertainty into consideration while designing V2V communication systems.

Abstract: This paper focuses on giving a simplified molecular absorption loss model for a 275–400 GHz frequency band, which has significant potential for variety of future short and medium range communications. The band offers large theoretical data rates with reasonable path loss to theoretically allow even up to kilometer long link distances when sufficiently high gain antennas are used. The molecular absorption loss in the band requires a large number of parameters from spectroscopic databases, and, thus, the exact modeling of its propagation characteristics is demanding. In this paper, we provide a simple, yet accurate absorption model, which can be utilized to predict the absorption loss at the above frequency band. The model is valid at a regular atmospheric pressure, it depends on the distance, the relative humidity, and the frequency. The existing simplified model by ITU does not cover frequencies above 350 GHz and has more complexity than our proposed model. The molecular absorption loss increases exponentially with the distance, decreasing the utilizable bandwidth in the vicinity of the absorption lines. We provide a model to approximate the window widths at the above frequency band. This model depends on the distance, the relative humidity, the frequency, and the maximum tolerable loss. It is shown to be very accurate below one kilometer link distances.

Abstract: Recently, unmanned aerial vehicle (UAV) plays an important role in many applications because of its high flexibility and low cost. To realize reliable UAV communications, a fundamental work is to investigate the propagation characteristics of the channels. In this paper, we propose path loss models for the UAV air-to-air (AA) scenario based on machine learning. A ray-tracing software is employed to generate samples for multiple routes in a typical urban environment, and different altitudes of Tx and Rx UAVs are taken into consideration. Two machine-learning algorithms, Random Forest and KNN, are exploited to build prediction models on the basis of the training data. The prediction performance of trained models is assessed on the test set according to the metrics including the mean absolute error (MAE) and root mean square error (RMSE). Meanwhile, two empirical models are presented for comparison. It is shown that the machine-learning-based models are able to provide high prediction accuracy and acceptable computational efficiency in the AA scenario. Moreover, Random Forest outperforms other models and has the smallest prediction errors. Further investigation is made to evaluate the impacts of five different parameters on the path loss. It is demonstrated that the path visibility is crucial for the path loss.

Abstract: In this paper, an optimal model is developed for path loss predictions using the Feed-Forward Neural Network (FFNN) algorithm. Drive test measurements were carried out in Canaanland Ota, Nigeria an...

Abstract: Distance-based attenuation is a critical aspect of wireless communications. As opposed to the ubiquitous power-law path loss model, this paper proposes a stretched exponential path loss model that is suitable for short-range communication. In this model, the signal power attenuates over a distance $r$ as $e^{-\alpha r^{\beta }}$ , where $\alpha$ and $\beta$ are tunable parameters. Using experimental propagation measurements, we show that the proposed model is accurate for short to moderate distances in the range $r \in ~(5,300)$ meters and so is a suitable model for dense and ultradense networks. We integrate this path loss model into a downlink cellular network with base stations modeled by a Poisson point process, and derive expressions for the coverage probability, potential throughput, and area spectral efficiency. Although the most general result for coverage probability has a double integral, several special cases are given, where the coverage probability has a compact or even closed form. We then show that the potential throughput is maximized for a particular BS density and then collapses to zero for high densities, assuming a fixed signal-to-interference-plus-noise ratio (SINR) threshold. We next prove that the area spectral efficiency, which assumes an adaptive SINR threshold, is nondecreasing with the BS density and converges to a constant for high densities.

Abstract: In Intelligent Transportation Systems, visible light communication (VLC) has emerged as a powerful candidate to enable wireless connectivity in vehicle-to-vehicle (V2V) and vehicle-to- infrastructure (V2I) links. While VLC has been studied intensively in the context of indoor communications, its application to vehicular networking is relatively new. In this paper, we carry out a comprehensive channel modeling study to quantify the effect of rain and fog on a V2V link with a high-beam headlamp acting as the transmitter. Taking advantage of advanced ray tracing features, we first develop a path loss model for V2V link as a function of distance under different weather conditions. Then, we use this expression to determine the maximum achievable distance to ensure a given bit error rate. We further investigate the deployment of relay- assisted systems to extend transmission ranges. Extensive numerical results are presented to corroborate our findings.

Abstract: In this paper, we propose a dual-hop radio-frequency (RF)/free-space optical system with multiple relays employing the decode-and-forward and amplify-and-forward with a fixed gain relaying scheme. The RF channels are subject to a Rayleigh distribution while the optical links experience a unified fading model emcopassing the atmospheric turbulence that follows the Malaga distribution (or also called the $\mathcal {M}$ -distribution), the atmospheric path loss, and the pointing error. Partial relay selection with outdated channel state information is proposed to select the candidate relay to forward the signal to the destination. At the reception, the detection of the signal can be achieved following either heterodyne or intensity modulation and direct detection. Many previous attempts neglected the impact of the hardware impairments and assumed ideal hardware. This assumption makes sense for low data rate systems but it would no longer be valid for high data rate systems. In this paper, we propose a general model of hardware impairment to get insight into quantifying its effects on the system performance. We will demonstrate that the hardware impairments have small impact on the system performance for low signal-to-noise ratio (SNR), but it can be destructive at high SNR values. Furthermore, analytical expressions and upper bounds are derived for the outage probability and ergodic capacity while the symbol error probability is obtained through the numerical integration method. Capitalizing on these metrics, we also derive the high SNR asymptotes to get valuable insight into the system gains, such as the diversity and the coding gains. Finally, analytical and numerical results are presented and validated by the Monte Carlo simulation.

Abstract: Large antenna arrays and millimeter- wave (mmWave) frequencies have been attracting growing attention as possible candidates to meet the high requirements of future 5G mobile networks. In view of the large path loss attenuation in these bands, beamforming techniques that create a beam in the direction of the user equipment are essential to perform the transmission. For this purpose, in this paper, we aim at characterizing realistic antenna radiation patterns, motivated by the need to properly capture mmWave propagation behaviors and understand the achievable performance in 5G cellular scenarios. In particular, we highlight how the performance changes with the radiation pattern used. Consequently, we conclude that it is crucial to use an accurate and realistic radiation model for proper performance assessment and system dimensioning.

Abstract: Ultra-reliable and low-latency communications (URLLC) have stringent requirements on quality-of-service and network availability. Due to path loss and shadowing, it is very challenging to guarantee the stringent requirements of URLLC with satisfactory communication range. In this paper, we first provide a quantitative definition of network availability in the short blocklength regime: the probability that the reliability and latency requirements can be satisfied when the blocklength of channel codes is short. Then, we establish a framework to maximize the available range, defined as the maximal communication distance subject to the network availability requirement, by exploiting multi-connectivity. The basic idea is using both device-to-device (D2D) and cellular links to transmit each packet. The practical setup with correlated shadowing between D2D and cellular links is considered. Besides, since processing delay for decoding packets cannot be ignored in URLLC, its impacts on the available range are studied. By comparing the available ranges of different transmission modes, we obtained some useful insights on how to choose transmission modes. Simulation and numerical results validate our analysis and show that multi-connectivity can improve the available ranges of D2D and cellular links remarkably.

Abstract: Considering both non-line-of-sight (NLoS) and line-of-sight (LoS) transmissions, the transitional behaviors from noise-limited regime to dense interference-limited regime have been investigated for the fifth generation (5G) small cell networks (SCNs). Besides, we identify four performance regimes based on base station (BS) density, i.e., 1) the noise-limited regime, 2) the signal-dominated regime, 3) the interference-dominated regime, and 4) the interference-limited regime . To characterize the performance regime, we propose a unified framework analyzing the future 5G wireless networks over generalized shadowing/fading channels, in which the user association schemes based on the strongest instantaneous received power and the strongest average received power can be studied, while NLoS/LoS transmissions and multislop path loss model are considered. Simulation results indicate that different factors, i.e., noise, desired signal, and interference, successively and separately dominate the network performance with the increase of BS density. Hence, our results shed new light on the design and management of SCNs in urban and rural areas with different BS deployment densities.

Abstract: Unmanned aerial vehicles, i.e., drones, have recently caught attention for providing on-demand capacity to wireless networks as drone-base-stations (drone-BSs). Many studies assume simplified channel models based on average characteristics of the environment to estimate the placement of drone-BSs. However, especially in urban areas, positioning of drone-BSs with respect to intersections and roof-top heights of buildings can severely change the path loss characteristics. To address this issue, we adopt an ITU channel model utilizing more information about the environment, such as the shapes of the buildings. We optimize parameters of the selected ITU model, so that it can be used for altitudes both strictly lower and higher than building roof-tops. Using ray-tracing simulations as a benchmark, we compare the proposed model with a widely used simpler model. Results show that the proposed model can reduce the root-mean-squared error from 35 to 10 dB, which may have critical implications for drone-BS operations, such as planning for the required number of drone-BSs to cover outdoor urban users, as demonstrated with simulations.

Abstract: In this paper, we provide a performance analysis for practical unmanned aerial vehicle (UAV)- enabled networks. By considering both line-of- sight (LoS) and non-line-of-sight (NLoS) transmissions between aerial base stations (BSs) and ground users, the coverage probability and the area spectral efficiency (ASE) are derived. Considering that there is no consensus on the path loss model for studying UAVs in the literature, in this paper, three path loss models, i.e., high- altitude model, low-altitude model and ultra-low- altitude model, are investigated and compared. Moreover, the lower bound of the network performance is obtained assuming that UAVs are hovering randomly according to homogeneous Poisson point process (HPPP), while the upper bound is derived assuming that UAVs can instantaneously move to the positions directly overhead ground users. From our analytical and simulation results for a practical UAV height of 50 meters, we find that the network performance of the high-altitude model and the low-altitude model exhibit similar trends, while that of the ultra-low-altitude model deviates significantly from the above two models. In addition, the optimal density of UAVs to maximize the coverage probability performance has also been investigated.

Abstract: Machine-Type Communications are meeting a growing interest on the consumer market. Dedicated technologies arise to support more robust communications involving a massive number of low cost, low energy-consuming devices. This paper discusses the coverage extension of a Low-Powered Wide Area Network using a Low Earth Orbit satellite constellation, benefiting from the improved performance of a recent standard. The transmission complies with the user equipment specifications standardized as NB-IoT by 3GPP in Release 13. This radio technology is an update on LTE standard with enhanced performances: the supported path loss can be 20 dB higher than with legacy LTE. This improvement makes satellite- compatible the small and energy-constrained devices. A specific unidirectional system is defined, and a link budget is derived. Also, a receiver architecture is presented, that takes into consideration satellite channel specific impairments.

Abstract: In this paper, we investigate the coverage probability improvement of a millimeter wave network due to the deployment of spatially random decode-and-forward (DF) relays. The source and receiver are located at a fixed distance and all the relay nodes are distributed as a 2-D homogeneous Poisson point process (PPP). We first derive the spatial distribution of the set of decoding relays whose received signal-to-noise ratio (SNR) are above the minimum SNR threshold. This set is a 2-D inhomogeneous PPP. From this set, we select a relay that has minimum path loss to the receiver and derive the achievable coverage due to this selection. The analysis is developed using tools from stochastic geometry and is verified using Monte-Carlo simulation. The coverage probabilities of the direct link without relaying, a randomly chosen relay link, and the selected relay link are compared to show the significant performance gain when relay selection is used. We also analyze the effects of beam misalignment and different power allocations at the source and relay on coverage probability. In addition, rate coverage and spectral efficiency are compared for direct and selected relay links to show impressive performance gains with relaying.

Abstract: In this paper, the channel characteristics and cell coverage of the 28 GHz millimeter wave (mmWave) band outdoors are investigated by developing an efficient 3-D ray-tracing simulation. First, the accuracy of the simulation is verified by comparing its results with actual measurements. The path loss (PL) agrees well in both line-of-sight (LOS) and non-LOS (NLOS) regions, whereas the shadowing factor exhibits differences in the NLOS regions. Additional simulations are conducted for downtown Gangnam, a representative high-rise urban area in Seoul, South Korea. The simulated and measured coverages of 300 base stations operating in 900 MHz long-term evolution band are compared and analyzed. For the LOS regions, PL of 28 GHz is 30 dB higher because of the free-space PL gaps, whereas PL varied in the NLOS regions because of multipath fading. In addition, the outage probability is determined to evaluate the validity of mmWave cell deployment and coverage for high-rise urban microcell environments. The contributions of this paper include LOS and outage probability models with low root-mean-square errors, indicating improvement over previously developed models.

Abstract: In the nonline of sight (NLOS) ultraviolet (UV) scattering communication, the received signals exhibit the characteristics of discrete photoelectrons due to the extremely large path loss. We design and demonstrate an NLOS UV scattering communication system in this paper, where the receiver-side signal detection is designed based on a discrete-time Poisson channel model. In our system, a laser and multiple photomultiplier tubes are employed as the optical transmitter and detector, respectively. Furthermore, we design algorithms for pulse-counting, synchronization, channel estimation, and ${\rm{LLR}}$ computation for hardware realization in field-programmable gate array board. Simulation results are provided to evaluate the proposed system design and specify the system key parameters for real-time implementation. We perform field tests for real-time communication with the transmission range over 1 km, where the system throughput reaches 1 Mbps.

Abstract: The paths loss propagation model is an important tool in wireless network planning, allowing network planner to optimize the cell towers distribution and meet expected service level requirements. However, each type of path loss propagation model is designed to predict path loss in a particular environment that may be inaccurate in other different environment. In this research different propagation models (Hata Model, ICC-33 Model, Ericson Model and Coast-231 Model) have been analyzed and compared based on the measured data. The measured data represent signal strength of two cell towers placed in two different environments which obtained by a drive test of them. First one in AL-Habebea represents an urban environment (high-density region) and the second in AL-Hindea district represents a rural environment (low-density region) with operating frequency 0.8 GHz. The results of performing the analysis and comparison conclude that Hata model and Ericsson model shows small deviation from real measurements in urban environment and Hata model generally gives better prediction in the rural environment.

Abstract: Smart parking management systems need to keep up with the state of parking spots at all times. This is efficiently accomplished via sensor nodes that detect vehicles and update the system’s state as it changes in real time. When sensor nodes use wireless communication as their primary communication link, the deployment approach becomes important, since it directly affects network connectivity, cost, and lifetime. The main factor to consider when deploying wireless sensor networks (WSN) in parking environments is the prediction of radio frequency (RF) signal propagation. Inaccurate propagation models lead to systems that under- or over-perform, both of which negatively affect WSN performance. Most of the existing RF propagation models are created to support cellular systems environments, which drastically differ from indoor/outdoor parking environments—few or no model exists that accurately predict RF signal propagation in parking environments. Therefore, there is a need for models that accurately characterize RF signal propagation in these environments. This paper proposes empirical path loss models for WSN deployment in indoor and outdoor car parking lots. The proposed models are compared with theoretical models. Theoretical models deviate from the proposed models and the measured values by 10% to 46%. The provided models, as well as the measured data, can be used for efficient planning and deployment of WSN in various proposed smart cities, intelligent transportation, and parking lot systems.

Abstract: To overcome considerable path loss in millimeter‐wave propagation, high‐gain directional beamforming is considered to be a key enabling technology for outdoor 5G mobile networks. Associated with beamforming, this paper investigates propagation power loss characteristics in two aspects. The first is beamwidth effects. Owing to the multipath receiving nature of mobile environments, it is expected that a narrower beamwidth antenna will capture fewer multipath signals, while increasing directivity gain. If we normalize the directivity gain, this narrow‐beamwidth reception incurs an additional power loss compared to omnidirectional‐antenna power reception. With measurement data collected in an urban area at 28 GHz and 38 GHz, we illustrate the amount of these additional propagation losses as a function of the half‐power beamwidth. Secondly, we investigate power losses due to steering beam misalignment, as well as the measurement data. The results show that a small angle misalignment can cause a large power loss. Considering that most standard documents provide omnidirectional antenna path loss characteristics, these results are expected to contribute to mmWave mobile system designs.

Abstract: LTE V2X is the response of the 3GPP standardization body to the high market expectations related to vehicular communications for safety and infotainment services. To fulfill the stringent requirements in terms of reliability associated with safety applications, geolocation-based access (GLOC) has been proposed for direct vehicle-to-vehicle (V2V) communication. Such a scheme aims at maximizing the distance of co-channel transmitters (i.e., transmitter that use the same resources) while preserving a low latency when accessing the resources and a low overhead. In this paper, we analyze, with the aid of stochastic geometry, the delivery of periodic and nonperiodic broadcast messages with GLOC, taking into account path loss and fading as well as the random locations of transmitting vehicles. Analytical results include the average interference, average binary rate, capture probability, i.e., the probability of successful message transmission, and energy efficiency (EE). Mathematical analysis reveals interesting insights about the system performance, which are validated through extensive Monte Carlo simulations. In particular, it is shown that the capture probability is an increasing function with exponential dependence with respect to the transmit power and it is demonstrated that an arbitrary high capture probability can be achieved, as long as the number of access resources is high enough. Finally, to facilitate the system-level design of GLOC, it is obtained the optimum transmit power, which fulfill a given minimum capture probability constraint while maximizing the EE of the system.

Abstract: The exploitation of mm-wave bands is one of the key-enabler for 5G mobile radio networks However, the introduction of mm-wave technologies in cellular networks is not straightforward due to harsh propagation conditions that limit the mm-wave access availability Mm-wave technologies require high-gain antenna systems to compensate for high path loss and limited power As a consequence, directional transmissions must be used for cell discovery and synchronization processes: this can lead to a non-negligible access delay caused by the exploration of the cell area with multiple transmissions along different directions The integration of mm-wave technologies and conventional wireless access networks with the objective of speeding up the cell search process requires new 5G network architectural solutions Such architectures introduce a functional split between C-plane and U-plane, thereby guaranteeing the availability of a reliable signaling channel through conventional wireless technologies that provides the opportunity to collect useful context information from the network edge In this article, we leverage the context information related to user positions to improve the directional cell discovery process We investigate fundamental trade-offs of this process and the effects of the context information accuracy on the overall system performance We also cope with obstacle obstructions in the cell area and propose an approach based on a geo-located context database where information gathered over time is stored to guide future searches Analytic models and numerical results are provided to validate proposed strategies

Abstract: Fifth generation wireless communications will exploit the enormous chunk of bandwidth available at millimeter-wave frequency bands. Accordingly, an accurate and simple path loss model is critical for indoor environments, where deployment is likely to occur. We conducted measurement campaigns in the 14 and 22 GHz frequency bands in a typical indoor corridor environment on 5th floor of the Discipline of Electrical, Electronic and Computer Engineering building, University of KwaZulu-Natal, Howard Campus, South Africa. This paper presents details of measurement campaigns with unique transmitter-receiver combinations using a costume-designed channel sounder. The acquired measurement results provide large-scale path loss statistics in an open-plan indoor environment in line-of-sight and non-line-of-sight conditions. An effective application of dual slope single-frequency directional large-scale path loss model is evaluated based on the acquired measurement data. The application of dual slope large-scale path loss model is supported by a comprehensive analysis and consideration of propagation mechanisms, such as reflection and diffraction resulting in modal attenuation. Validated results show that dual slope large-scale path loss model applied in this paper outperforms close-in reference distance model that assumes the impact of propagating wave guiding effect in indoor corridors.