Path Loss

In this paper we present theoretical data in support of the unified indoor geolocation channel model namely: path loss and multipath distribution models. First, the path loss model is currently accepted to be a function of the transmitter and receiver geometry and frequency of operation. Second, the most widely used and accepted indoor channel multipath distribution models are Nakagami with m degrees of freedom, Rayleigh, Rician, and lognormal. The purpose of this paper is twofold: to provide a better interpretation of the sets of theoretical data for the indoor channel model; and, to explain the lack of fitting of the well-known multipath distribution models from the previous measurement data sets reported in the literature; thus, providing support for the unified indoor channel model theory. The unified path loss model consists of an approach for linking together the path loss models of the three geolocation systems (macro-cellular, microcellular, and indoor) with the distance between the transmitter and receiver, R, and the frequency of operation, f. The path loss caused by the increase of the transmitter receiver distance is much more severe than the path loss caused by the increase of the frequency of operation. The bottom line here is that we need to design future receivers or propose a signal structure i that will account for 40 to 80 dB of signal degradation indoors. The unified multipath distribution consists of a linear transformation of the well-known multipath distribution models such as Nakagami with m degrees of freedom, Rayleigh, Rician, and lognormal. While it is rather straight forward to prove the unified geolocation multipath distribution model when only the contributing individual distributions are Rayleigh, Rician, and lognormal, if we assume that we have a fourth distribution such as Nakagami with m degrees then the process is not straight forward any more. We will investigate this and report the results in the future. The main purpose of the unified multipath distribution model is to enable the calculations of reflections' gain. Assuming that the channel is composed of individual distributions such as Rayleigh, Rician, and Lognormal we have perform reflection gain calculations.

Millimeter wave (mmWave) frequencies have been selected to provide the high data rates and capacity targeted by the next generation (5G) of mobile communication networks. Compared to the sub 6-GHz bands that have been historically exploited by popular communication systems, mmWave bands suffer from adverse radio propagation degradations such as higher path loss and blockage, however they provide significantly larger bandwidths and lower levels of usage than sub 6-GHz bands. Mobile operators can employ Carrier Aggregation (CA) techniques to combine the newly acquired spectrum in mmWave bands with their already allocated spectrum in sub 6-GHz bands. The use of CA as a technique to combine chunks of spectrum in a transparent manner for higher layers of the protocol stack has been widely researched. In this paper, a different focus is considered by exploring the use of CA as a diversity technique in order to further improve the network capacity under various radio propagation scenarios. The obtained results indicate that CA can effectively be exploited as a diversity technique to optimize the overall system performance and increase the network capacity, with the optimum number of component carriers depending on the radio propagation distance.

Investigation of the effect of beam alignment for milimeter wave (mmWave) transmission in the case of Vehicle-to-Infrastructure communication (V2I) is carried out. The investigation covered varying transmission-reception (TX-RX) distances. The effect of carrier frequency variation using different antenna angles and gains is also analyzed. The results showed convergence of path loss (PL) values regardless of angle or antenna gain (dBi). The investigation also proved that shadow fading (SF), which is related to standard deviation () and exponent number (n) is a main contributor to the observed high path loss values in the case of misalignment. It is also noted that the path loss values decreases as a function of frequency per same travelled distance, which is related to the exponent number. This work highlights the importance of antenna alignment and that V2I communication can be very much optimized if and when auto-antenna alignment is used, and the importance of multi-antenna arrays.

LoRa, or Long Range, is an increasingly popular wireless communication technology for Internet of Things (IoT) applications, offering long-distance connectivity with low power consumption. Radio channel propagation plays a critical role in determining the performance of a LoRa system. This paper provides a comprehensive review of radio channel propagation in the context of LoRa communications. It introduces various factors influencing LoRa signal propagation and examines recent research efforts aimed at understanding the propagation characteristics of LoRa radio channels and addressing the associated challenges. In conclusion, selecting an appropriate propagation model for LoRa, the propagation model requires consideration of environmental variations ranging from urban to rural settings. The Free Space Path Loss model is suitable for open areas and short distances, while the Log-Distance Path Loss provides flexibility across various conditions. The Okumura-Hata model is well-suited for urban and suburban environments, the ITU-R P.1546 model offers broad coverage across a wide range of environmental types, and the SUI model presents a comprehensive solution to a wide range of conditions. The appropriate model selection depends on the deployment of location, frequency of operation, and specific environmental conditions in which LoRa is implemented.

In this study a comparative analysis of various empirical models for estimating radio wave propagation path losses with those measured experimentally for the rural area in Erbil city is presented. In Gazna village near the center of the Erbil city, one of the Korek telecommunication towers is selected for the purpose of comparative analysis and seven different empirical models were utilized. The implemented models are free space model, Electronic Communication Committee (ECC-33), Stanford Interim University (SUI), Optimization Cost-231, Okumura-Hata, Egli, and Ericson models. The data were collected at operating frequencies of 1800 MHz and 2100 MHz using drive test equipment with Sony-Ericson mobile phone to measure received signal strength. Generally, the analyzed results, which are based on the Mean Absolute Percentage Error (MAPE) values, shows that the Egli and ECC-33 overestimated while both FSPL and Okamura-Hata are underestimated path loss values. In addition, the SUI and Optimized-Cost-231 models are providing minimum MAPE path loss values which are 0.49 and 0.55 at 1800 MHz and 0.07 and 0.16 at 2100 MHz, respectively. Therefore, in order to improve network performance and accurate estimation of financial feasibility, these two models especially SUI model can be used successfully and confidently in the design of the wireless communication system in the rural area of Erbil city in Kurdistan region of Iraq.

The ability to interconnect and communicate wirelessly in and around the built environment with sufficient aptitude is becoming progressively important as the array of consumer-grade portable devices with broadband wireless functionality flourishes. These devices provide incredible functionality, much of which is dependent on broadband internet connectivity which, from a user perspective, is frequently sub-optimal. With almost a hundred percent of today's communication and data consumption happening within the domain of wireless technology, it is surprising that for the built environment in Nigeria, codes/guidelines do not yet exist in the building industry to guide and enhance their deployment and use within our built environment. The knowledge to limit, or eliminate and enhance these wireless waves as needed through spatial and material manipulations is virtually non-existent amongst our built environment practitioners. Design solutions and developments are all of the time made without recourse to the proper placement of communication infrastructure, educated use of building materials and spatial organization. This paper provides a structural guideline or formwork for the creation of codes of practice and conduct with the purpose of optimizing wireless communication in our built environment. It concludes that for wireless systems, the learned ability to compensate for the dynamics of radio propagation within the built environment is crucial for achieving optimal performance.

A novel, multi-slope dual breakpoint model for predicting path-loss in Ultra-Wideband (UWB) off-body communication channels, is proposed. This model is based on real-body measurements, carried out in the frequency range between 3.5GHz-6.5GHz, in an anechoic chamber. New parameters that describe this specific propagation environment are presented and evaluated. Results show that the first breakpoint point angle lies in the lit region of the transmitter and increases exponentially with distance until it rises to its threshold value. Based on this finding the near and far field areas for BAP (Body to Access Point) channels are defined. In addition, newly estimated decay coefficients suggest severe degradation as the receiver moves in between the two critical angles. Finally, techniques for model expansion in two dimensions are discussed.

In this contribution, a narrowband radio channel model is proposed for rural scenarios in which the radio link operates under near-ground conditions for application in wireless sensor networks dedicated to smart agriculture. The received power attenuation was measured for both transmitter and receiver antennas placed at two different heights above ground: 0.2 and 0.4 m. Three frequency ranges, proposed for future 5G-IoT use case in agriculture, were chosen: 868 MHz, 2.4 GHz and 5.8 GHz. Three ground coverings were tested in a rural scenario: soil, short and tall grass fields. The path loss was then estimated as dependent of the radio link range and a three-slope log-normal path loss model was tailored. Results are explained in terms of the first Fresnel zone obstruction. Commercial Zigbee sensor nodes operating at 2.4 GHz were used in a second experiment to estimate the link quality from the experimental Radio Signal Strength Indicator (RSSI) received values. Two sensor nodes were p...

The characterization of different vegetation/vehicle densities and their corresponding effects on large-scale channel parameters such as path loss can provide important information during the deployment of wireless communications systems under outdoor conditions. In this work, a deterministic analysis based on ray-launching (RL) simulation and empirical measurements for vehicle-to-infrastructure (V2I) communications for outdoor parking environments and smart parking solutions is presented. The study was carried out at a frequency of 28 GHz using directional antennas, with the transmitter raised above ground level under realistic use case conditions. Different radio channel impairments were weighed in, considering the progressive effect of first, the density of an incremental obstructed barrier of trees, and the effect of different parked vehicle densities within the parking lot. On the basis of these scenarios, large-scale parameters and temporal dispersion characteristics were obta...

In this contribution, we present a narrowband radio channel model for a scenario wherein the radio link operates under near-ground conditions, occurring on a ZigBee wireless sensor networks applied to smart agriculture. A near-ground network deployment can be useful to avoid tall antenna masts, or once crops grow. Among the examined scenarios, we analyzed path loss caused when placing sensor nodes in soil, short and tall grass fields. We measured the received power when locating both transmitter and receiver antennas at two different heights. The path loss was then estimated as dependent of the radio link range. In another scenario, RSSI were obtained to analyze the communication quality between sensor nodes using same antennas heights as the previous scenarios, only for the case of a short grass field.

The characterization of different vegetation/vehicle densities and their corresponding effects on large-scale channel parameters such as path loss can provide important information during the deployment of wireless communications systems under outdoor conditions. In this work, a deterministic analysis based on ray-launching (RL) simulation and empirical measurements for vehicle-to-infrastructure (V2I) communications for outdoor parking environments and smart parking solutions is presented. The study was carried out at a frequency of 28 GHz using directional antennas, with the transmitter raised above ground level under realistic use case conditions. Different radio channel impairments were weighed in, considering the progressive effect of first, the density of an incremental obstructed barrier of trees, and the effect of different parked vehicle densities within the parking lot. On the basis of these scenarios, large-scale parameters and temporal dispersion characteristics were obta...

In this contribution, a narrowband radio channel model is proposed for rural scenarios in which the radio link operates under near-ground conditions for application in wireless sensor networks dedicated to smart agriculture. The received power attenuation was measured for both transmitter and receiver antennas placed at two different heights above ground: 0.2 and 0.4 m. Three frequency ranges, proposed for future 5G-IoT use case in agriculture, were chosen: 868 MHz, 2.4 GHz and 5.8 GHz. Three ground coverings were tested in a rural scenario: soil, short and tall grass fields. The path loss was then estimated as dependent of the radio link range and a three-slope log-normal path loss model was tailored. Results are explained in terms of the first Fresnel zone obstruction. Commercial Zigbee sensor nodes operating at 2.4 GHz were used in a second experiment to estimate the link quality from the experimental Radio Signal Strength Indicator (RSSI) received values. Two sensor nodes were p...

The attenuation due to vegetation can limit drastically the performance of Wireless Sensor Networks (WSN) and the Internet of Things (IoT) communication systems. Even more for the envisaged high data rates expected for the upcoming 5G mobile wireless communications. In this context, radio planning tasks become necessary in order to assess the validity of future WSN and IoT systems operating in vegetation environments. For that purpose, path loss models for scenarios with vegetation play a key role since they provide RF power estimations that allow an optimized design and performance of the wireless network. Although different propagation models for vegetation obstacles can be found in the literature, a model combining path loss and multipath propagation is rarely considered. In this contribution, we present the characterization of the radio channel for IoT and 5G systems working at 2.4 GHz, focusing on the radio links blocked by oak and pine trees modelled from specimens found in a real recreation area located within a dense forest environment. This specific forest, composed of thick in-leaf trees, is called Orgi Forest and it is situated in Navarre, Spain. In order to fit and validate a radio channel model for this type of scenarios, both measurements and simulations by means of an in-house developed 3D Ray Launching algorithm have been performed, offers as outcomes the path loss and multipath information of the scenario under study. A geometrical and dielectric model of the trees were created and introduced in the simulation software. The path loss was then estimated as dependent of the radio link range for two species of trees at 2.4 GHz. We concluded that the scattering produced by the tree can be divided into two zones with different dominant propagation mechanisms: a freespace zone far from the tree and a diffraction zone around the edge of the tree. 2D planes of delay spread value are also presented which similarly reflects the proposed two-zone model.

Machine learning, which is a branch of Artificial Intelligence (AI), is a method where computers or learning machines can learn from and get information from a large amount of data. The machine learning approach involves data collection and storage, and its transformation into a large knowledge database for different applications and different domains. Machine learning can be used in the education sector to save time in non-school-related activities. For example, teachers can use virtual assistants to work from home for their students. This can help to enhance student learning and improve retention and success. Another use of machine learning in education is to enable personalised learning. Through the development of artificial intelligence, teachers can understand the learning process of their students and are able to develop an individualised curriculum to suit their learners. AI can also allow the moderation of intelligence when applied to the education industry.