A Review Investigation on Outdoor and Indoor Propagation Models

Journal of Materials Science Research and Reviews

1(1): 1-11, 2018; Article no.JMSRR.41658

V. O. A. Akpaida1, F. I. Anyasi1, S. I. Uzairue2*, A. I. Idim3 and O. Alashiri2

1Department of Electrical and Electronics Engineering, Ambrose Alli University, Ekpoma, Edo State, Nigeria. 2Department of Electrical and Information Engineering, Covenant University, Ota, Ogun State, Nigeria. 3Department of Electrical and Electronics Engineering, Petroleum Training Institute, Effurun Delta State, Nigeria.

Authors’ contributions

This work was carried out in collaboration between all authors. Author VOAA designed the study, performed the statistical analysis. Author SIU wrote the protocol and first draft of the manuscript. Authors FIA and AII managed the analyses of the study. Author OA managed the literature searches. All authors read and approved the final manuscript.

Article Information

DOI: 10.9734/JMSRR/2018/41658 Editor(s): (1) Dr. Madogni Vianou Irenee, Departement de Physique, Laboratoire de Physique du Rayonnement LPR, Cotonou, Universite d’Abomey-Calavi (UAC), Benin. (2) Dr. Anjanapura V. Raghu. Professor, Department of Basic Science, Centre for Emerging Technology, Jain Global Campus, Jain University, India. (3) Dr. Suraya Hani Bt Adnan, Associate Professor, Department Civil Engineering Technology, Faculty of Engineering Technology, Universiti Tun Hussein Onn Malaysia, Malaysia. Reviewers: (1) Vikram Puri, DuyTan University, Vietnam. (2) S. Sridhar, S. A. Engineering College, India. (3) Muhammad Faheem, Abdullah Gul University, Turkey. Complete Peer review History: http://www.sciencedomain.org/review-history/25560

Received 25th April 2018 Accepted 10th July 2018 Review Article Published 14th July 2018

ABSTRACT

Path loss exponent has turned out to be one of the key challenges that are been faced in the telecommunications sector both in Nigeria and other countries. There is a great need to take a critical look at the various mathematical methods and techniques that have been developed by many researchers of which are used in the calculation of signal loss in telecommunication industry. This article draws the conclusion that all the methods are accurate depending on the condition(s) or factors after reviewing over fifty (50) journals. It was therefore concluded that the method that is applied to a particular situation depends on the surrounding environments.

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*Corresponding author: E-mail: [email protected];

Akpiada et al.; JMSRR, 1(1): 1-11, 2018; Article no.JMSRR.41658

Keywords: Path loss; propagation; models; signal strength.

1. INTRODUCTION Path loss is typically communicated in dB. In its most straightforward shape, the path loss can be Path loss is the decrease in power density computed utilizing the equation. (attenuation) of an electromagnetic wave as it travels through space. Path loss is a noteworthy L = 10 n + C (1) part of the investigation and plan of the connection spending plan of a Where L is the path loss in decibels, n is the path telecommunication framework. The term is loss exponent, d is the separation between the generally utilized as a part of wireless transmitter and the receiver, normally estimated communication and signal spread. Path loss in meters, and C is a consistent which represent could be due to impacts such as: free-space framework losses. loss, absorption, reflection, diffraction, aperture- medium coupling loss and refraction. Path loss is The estimation of C typically fluctuates and is also affected by shapes, territory, condition ordinarily reliant on the kind of demonstrating (urban or provincial, vegetation and foliage), under thought. A rundown of run of the mill path spread medium (dry or wet air), the separation loss exponents acquired in different versatile between the transmitter and the receiver, and the situations has appeared in Table 1. stature and area of the antennas [1-5,6]. Path loss typically incorporates propagation losses Table 1. Path Loss Exponents for Different caused by the regular development of the radio Environments [11,12,13,14,15] wave front in free space, absorption losses (aka infiltration losses), when the signal goes through Environment Path loss media not straightforward to electromagnetic exponent, n waves, diffraction losses when part of the radio Free space 2 wave front is discouraged by a hazy deterrent, Urban area cellular radio 2.7 to 3.5 and losses caused by other wonders [7,8,9,6]. Shadowed urban cellular radio 3 to 5 In building line-of-sight 1.6 to 1.8 The multipath effect is a process in which a Obstructed in building 4 to 6 signal emanated by a transmitter may travel Obstructed in factories 2 to 3 along a wide range of paths to a receiver concurrently. Multipath waves join at the receiver 2. PATH LOSS PREDICTION antenna, bringing about a resulting signal that TECHNIQUES may fluctuate generally, contingent upon the circulation of the force and relative engendering The process of calculating the path loss is time of the waves and bandwidth of the usually called prediction. Exact prediction is transmitted signal. The aggregate power of plausible only for less complex cases, such as meddling waves in a Rayleigh fading situation the previously mentioned free space propagation differs rapidly as a component of space (which is or the flat-earth model. In practical cases the known as a small-scale fading). Small-scale path loss is calculated by using a number of fading alludes to the fast changes in radio signal approximations. Statistical methods (likewise abundancy in a brief timeframe or travel separate called stochastic or empirical) depend on [10] estimated and arrived at the midpoint of losses along typical classes of radio connections. Some 1.1 Path Loss Experiment of the most commonly utilized methods are Hata, Okumura-Hata, the COST Hata model, In wireless communication studies, path loss is W.C.Y.Lee etc. which are otherwise known as spoken to by the path loss exponent, whose radio wave propagation models and are typically esteem is regularly in the scope of 2 to 4, where 2 utilized as a part of the plan of cellular networks is for propagation in free space, 4 is for and public land versatile networks (PLMN). The moderately lossy conditions and for the instance Okumura-Hata as refined by the COST-231 of full specular reflection from the earth surface project is the method employed for wireless alluded to as the level earth display. In a few communications in the very high frequency conditions, the path loss exponent can achieve (VHF) and ultra-high frequency (UHF) frequency values in the scope of 4 to 6. Then again, a band (the bands utilized by walkie-talkies, police, passage may go about as a waveguide, bringing maneuvers and cellular telephones). For FM about a path loss exponent under 2. radio and the TV broadcasting, the path loss is

Akpiada et al.; JMSRR, 1(1): 1-11, 2018; Article no.JMSRR.41658

most commonly predicted utilizing the ITU model extraordinary for a similar distance along two as described in ITU-R P.1546 recommendation. unique paths and it can be distinctive even along Other well-known models are those of Walfisch- a similar path if estimated at various Ikegami, W.C.Y Lee, and Erceg. circumstances.

Ray tracing is one of the deterministic methods in In radio wave condition for versatile antennas is view of the physical laws of wave propagation close to the ground. Viewable pathway that are additionally utilized as they are expected propagation (LOS) models are highly altered. to produce more accurate and solid predictions The signal path from the BTS antenna normally of the path loss than the empirical methods but raised over the rooftop tops is refracted down are considerably more costly in computational into the local physical condition (slopes, trees, exertion and rely upon the definite and accurate houses) and the LOS signal only here and there description of all objects in the propagation reaches the antenna. Nature will produce a few space, such as structures, rooftops, windows, deflections of the direct signal unto the antenna, entryways and walls. They are therefore where typically 2-5 deflected signal components employed predominantly for short propagation will be vectorially included. These refraction and paths. Among the most commonly employed deflection processes cause loss of signal methods in the plan of radio gear such as strength, which changes when the versatile antennas and bolsters is the limited difference antenna moves (Raleigh fading), causing quick time-space strategy. varieties of up to 20 db. The network is therefore intended to give an excess of signal strength Comparable methods are employed in predicting compared to LOS of 8-25 db relying upon the the path loss in other frequency bands (medium idea of the physical condition, and another 10 db wave (MW), short wave (SW or HF), micro wave to maintain a strategic distance from the fading (SHF) although the actual calculations and because of development. [16] equations may slightly be dissimilar to those for VHF/UHF. Dependable prediction of the path 2.1 Propagation Models loss in the SW/HF band is particularly difficult, and its accuracy is comparable to weather A radio propagation model, otherwise called the predictions [16]. Easy approximations for Radio Wave Propagation Model or the Radio calculating the path loss over distances Frequency Propagation Model is an empirical significantly shorter than the distance to the radio mathematical plan for the characterization of skyline: In free space the path loss increases radio wave propagation as a function of with 20 dB every decade (one decade is when frequency, distance and other conditions. The the distance between the transmitter and the conduct of propagation for every single receiver increases ten times) or 6dB for every comparable connection under comparable octave (one octave is when the distance between constraints is usually predicted with a solitary the transmitter and the receiver pairs). This can model is usually created with the objective of be utilized as a very harsh first request guess for formalizing the way radio waves are proliferated (microwave) communication joins. The path loss starting with one place then onto the next, such increases with roughly 35-40 dB for each decade models typically predict the path loss along a (10-12 dB for each octave) for signals in the connection or the effective coverage region of a UHF/VHF band spreading over the surface of the transmitter. As the path loss encountered along Earth which can be utilized as a part of cellular any radio connection fills in as the predominant networks as a first figure. The estimation of the factor for characterization of propagation for the path loss in developed regions can reach 110- connection, radio propagation models typically 140 dB for the main kilometer of the connection focus on the acknowledgment of the path loss between the base transmitter station (BTS) and with the auxiliary undertaking of predicting the the versatile in cellular networks, such as UMTS territory of coverage for a transmitter or modeling and GSM, which work in the UHF band. The path the conveyance of signals over various areas. loss for the initial ten kilometers may be 150-190 Because each individual telecommunication dB. These qualities are very inexact and are interface needs to encounter distinctive given here only as a delineation of the range in landscape, path, obstructions, atmospheric which the numbers used to express the path loss conditions and other marvels, it is intractable to esteems can eventually be; these are not detail the exact loss for all telecommunication authoritative or restricting figures. Studies have systems in a solitary mathematical condition. shown that the path loss may be very Accordingly, extraordinary models exist for

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various types of radio connections under various category of Foliage or Vegetation models with conditions. The models rely on computing the profundity of foliage of up to 400 m, for the cases middle path loss for a connection under a certain of observable pathway propagation as utilized as probability that the considered conditions will a part of microwave transmission. This model is occur. only applicable when there is an obstruction made by some foliage in the connection i.e. in Radio propagation models are empirical in between the transmitter and receiver. nature. For any model, the collected information must be sufficiently extensive to give enough It is perfect for application in the circumstance likeliness (or enough scope) to all sort of where the LOS path is blocked by thick, dry and circumstances that can occur in that specific leafy trees. It is appropriate for application in the scenario. Like every single empirical model, radio frequency scope of 230 MHz to 95 GHz [17]. propagation models don't call attention to the Defined in 1982, this model is an improvement of exact conduct of a connection, rather, they the ITU Model for Exponential Decay (MED). predict the no doubt conduct the connection may Weissberger's model is formally communicated show under the specified conditions. as:

Diverse models have been created to address the issues of understanding the propagation conduct in various condition. Types of models for (2) radio propagation include the under recorded: where, (i) Models for indoor applications

(ii) Models for outdoor applications L = The loss due to foliage in decibels (dB). (iii) Ground wave propagation models f = The transmission frequency in gigahertz (iv) Sky-Wave propagation models (GHz). (v) Environmental Attenuation models d = The depth of foliage along the path in (vi) Point-to-Point propagation models meters (m). (vii) Terrain models

(viii) City models Unfortunately, this model has the following 3. MODELS FOR OUTDOOR ATTENUA- limitations. TIONS (i) The equation is scaled for frequency Outdoor attenuations models are classified into specified in GHz range. four groups namely, Near-earth propagation (ii) Depth of foliage must be specified in models, Terrain models, City models and Band- meters (m). specific models. (iii) It is significant for the frequency range of 230 MHz to 95 GHz only, as pointed out by 3.1 Near-Earth Propagation Models Blaunstein [17] (iv) The model does not define the operation if Under this model, there are two distinct groups the depth of vegetation is more than 400m. namely, Foliage and updated ITU model. (v) The model predicts the loss due to foliage; hence the path loss must be calculated 3.1.1 Foliage models with the inclusion of the free space loss [17] Foliage models are sub divided into

Weissberger’s modified exponential decay model (b) Early ITU Model and Early ITU model.

(a) Weissberger’s Modified Exponential Decay The ITU vegetation model is a radio propagation Model model that gauges the path loss encountered because of the presence of at least one trees Weissberger's adjusted exponential decay inside a point to point telecommunication model, or simply, Weissberger's model is a radio connect. The predictions found from this model is wave propagation model that gauges the path congruent to those found from Weissberger's loss because of the presence of at least one adjusted exponential decay model in low trees in a point-to-point telecommunication frequencies. It was subsequently embraced late connect. This model has a place with the 1986.

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The model is applicable to the circumstances located inside some backwoods or manor and where the telecommunication interface has a few the term profundity applies to the distance obstructions made by trees along its way; it is, from the terminal inside the ranch to the finish therefore, reasonable for point-to-point of estate along the connection. It is microwave connects that has vegetation in additionally appropriate for frequencies below 5 their path. The typical application of this model is GHz [25-30] to predict the path loss for microwave joins. Below is the mathematical expression of the 3.3 Single Vegetative Obstructive Model model: The ITU Single Vegetative Obstructive Model is a (3) Radio propagation model that quantitatively approximates the attenuation because of the Where, vegetation amidst a telecommunication connect. The model is relevant to scenarios where no L = The path loss in decibels (dB). finish of the connection is totally inside foliage, f = The frequency of transmission in yet a solitary plant or tree remains amidst the megahertz (MHz). connection. It is discovered valuable in the d = The depth of foliage along the link in recurrence go beneath 3GHz and more than meters (m). 5GHz. Below is the mathematical expression of the model; Equation (2.3) is scaled for frequency specified in megahertz (MHz) only while the depth of foliage must be in the units of meter. Unfortunately, the result of this model gets impractical at high frequencies [18-24] (5)

3.2 Updated ITU Model Where,

The Early ITU model described above was A = The Attenuation due to vegetation in updated in early 2002; this gave rise to two other decibel (dB) models described below. D = Depth of foliage in meter (m) Γ = Specific attenuation for short vegetations 3.2.1 One woodland terminal model in decibel/meter (dB/m).

R = The initial slope of the attenuation curve The ITU earthly model for one terminal in i R = The final slope of the attenuation curve woodland is a proportion propagation model f f = The frequency of operations in gigahertz having a place with the class of foliage models. (GHz) This model is a successor of the early ITU k = Empirical constant model. It is applicable to the scenario where one terminal of a connection is inside foliage and the 3.3.1 The calculation of slopes flip side is free. It is very valuable for frequencies below 5 GHz. Below is the mathematical For the calculation of slopes, the initial slope is expression of the model; calculated as:

f AV = A (4) Ri = a (6) where And the final slope as:

c AV = Attenuation because of vegetation in decibel Rf = bf (7) (dB) A = Maximum attenuation for one terminal where a, b and c are empirical constants given in caused by a certain foliage in decibel (dB) Table 2.2. D = Depth of foliage along the path in meter (m) Γ = Specific attenuation for short vegetations in 3.3.2 Calculation of k decibel/meter (dB/m). For the calculation of k, it is computed as: The estimation of γ is reliant on the frequency and is an empirical constant. The model k = k – 10log (8) expects that exactly one of the terminals is 0

Akpiada et al.; JMSRR, 1(1): 1-11, 2018; Article no.JMSRR.41658

where, the connection. The aggregate path loss incorporates different components like free k0 = Empirical constant given in Table 2.2 space loss which is excluded in this model. More Rf = Empirical constant for frequency than 5 GHz and beneath 3 GHz, the conditions all dependent attenuation of a sudden turn out to be greatly perplexing in A0 = Empirical attenuation constant is given in light of the conditions. Likewise, this model does Table 2.2 not work for frequency between 3 GHz and 5 Ai = Illumination area GHz.

3.3.3 Calculation of Ai Table 2. Empirical constants a, b, c, k0, Rf and A0 used for Single Vegetation Obstruction Ai is computed in utilizing any of the conditions Model [35] 2.9 and 2.10, taking note of that, the terms h, hT, hR, w, wT and wR are characterized opposite to Parameter Inside leaves Out of leaves the expected level line joining the transmitter and A 0.20 0.16 recipient. The initial three terms are estimated B 1.27 2.59 vertically and the other three are estimated on a level plane [31-34] C 0.63 0.85 k0 6.57 12.6 R 0.002 2.1 (9) f A0 10 10

3.4 Terrain Models

(10) Terrain models are generally subdivided into three models, namely Egli Model, Longley-Rice

Model and ITU terrain loss model. where,

3.4.1 Egli Model w = Width of illuminated area as seen from the T transmitter in meter (m). The Egli model is a terrain model for radio w = Width of illuminated area as seen from the R frequency propagation. The model was gotten receiver in meter (m). from true information on UHF and VHF TV w = Width of the vegetation in meter (m). transmission in a few expansive urban h = Height of illuminated area as seen from the T communities. It predicts the aggregate path loss transmitter in meter (m). for a point to point interface. The model is h = Height of illuminated area as seen from the R regularly utilized for outdoor observable pathway receiver in meter (m). transmission and it gives the path loss as a h = Height of vegetation in meter (m). solitary amount. It is ordinarily reasonable for α = Azimuth beam width of the transmitter in T cellular communication scenarios where one degree or radian. radio wire is settled and another is portable. The α = Azimuth beam width of the receiver in R model is likewise relevant to scenarios where the degree or radian. transmission needs to go over a sporadic terrain. e = Elevation beam width of the transmitter in T Shockingly, the model has two noteworthy degree or radian. impediments: e = Elevation beam width of the receiver in R degree or radian. (a) It does not consider travel through some d = Distance of the vegetation from transmitter T vegetative obstruction, such as trees or in meter (m). shrubbery [36-40] d = Distance of the vegetation from receiver in R (b) It predicts the path loss all in all and does meter (m). not subdivide the loss into free space loss

and different losses. Below is the The empirical constants a, b, c, k , R and A are 0 f 0 mathematical expression of the model; used as tabulated in Table 2.

Tragically, the model predicts the express path P (11) loss because of the presence of vegetation along T

Akpiada et al.; JMSRR, 1(1): 1-11, 2018; Article no.JMSRR.41658

where, focuses, the area variable has an estimation of zero. th PR50 = 50 percentile receive power (W). PT = Transmit power (W). The reference attenuation characterized as an GB = Absolute gain of base station antenna. element of separation additionally includes 3 GM = Absolute gain of mobile station antenna. territories for expectation: I) observable pathway; hB = Height of the base station antenna (m). ii) diffraction; iii) diffuse. For every one of these hM = Height of the mobile station antenna reaches, there are attenuation coefficients (m). characterized by connecting geometry. These d = distance from the base station antenna factors additionally consider the geology that (m). is characterized as terrain sporadically f = frequency of transmission (MHz). parameter Δh(d) for a reference separate (D0). A few applications utilize the Longley-Rice 3.4.2 Longley-Rice Model Model. Illustrations are CRC-COVWEB, SPLAT!, Radio Mobile, QRadioPredict, Pathloss5 The Longley-Rice model (LR) is a radio [44-45] propagation model: a strategy for foreseeing the attenuation of radio signs for a telecommunication 3.4.3 ITU Terrain Loss Model link in the frequency scope of 20MHz to 20 GHz (Seybold, 2005). Longley-Rice is otherwise called The ITU terrain loss model is a radio propagation the irregular terrain model (ITM). It was made for model that gives a technique to anticipate the the requirements of frequency arranging in TV middle path loss for a telecommunication broadcasting in the United States in the 1960s connection. The model was produced based on and was widely utilized for setting up the tables of diffraction hypothesis and it predicts the path loss channel designations for VHF/UHF broadcasting as an element of the stature of path blockage and there. the First Fresnel zone for the transmission connect (Seybold, 2005). The model records for Longley-Rice has two sections: a model for hindrances amidst the telecommunication expectations over a zone and a model for point to connection. It is in this manner reasonable to be point interface forecasts. The Longley-Rice model utilized inside urban areas and in open fields. The was proposed for frequencies between 20 MHz model has the benefit of being reasonable for use and 40 GHz for various scenarios and distinctive in any terrain and any frequency. Below is the statures of transmitting and accepting receiving mathematical expression of the model; wires. The model displays a speculation of the got signal control without an itemized portrayal of the channel, which relies upon the factors of every (12) situation and condition [41-43] Where, The variety of the signal is dictated by the forecast model as indicated by the air changes, A = Additional loss (in excess of free-space topographic profile and free space. These loss) due to diffraction (dB) varieties are depicted with the assistance of C = = Normalized terrain clearance factual evaluations which have deviations that N add to the aggregate attenuation of the signal. h = hL – h0 The statistical appraisals or attenuation factors of F = 17.3 this forecast model are: I) Situation inconstancy 1 (YS); II) Location changeability (YL). The reference attenuation (W) is resolved as an 3.4.4 City models element of the separation, attenuation factors and an urban factor for a region or point-to-point. In City models include Young Model, Okumura light of this fluctuation, there could be deviations Model, Hata Model for Urban Areas, Hata (δ) pretty much huge to the attenuation of the Models for Suburban Areas, Hata Model for Open transmitted signal. The got signal (W) is acquired Areas, COST Hata Model, Area to Area signal level constricted in free space (W0) Lee Model and Point to Point Lee Model. Some weakened by the aggregate of the lessened of these models that are close to the area shaped by irregular factors. On the off chance under study are selected for presentation in this that transmitter and beneficiary are at known section.

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3.4.4.1 Young Model

The young model is a proportion propagation (14) model that was based on the information gathered on New York City in 1952. It regularly For small or medium sized city, models the conduct of cellular communications in urban communities. It is perfect for modeling the (15) conduct of cellular communications in substantial urban areas with tall structures. The model gives And for large cities a valuable device in the frequency scope of 150 MHz to 3700 MHz. Below is the mathematical expression of the model;

(16) (13) where, where, L = Path loss in urban areas in decibel (dB). hB = Height of base station antenna in meter L = Path loss in decibel (dB) (m). GB = Gain of base transmitter in decibel (dB) hM = Height of mobile station antenna in meter GM = Gain of mobile transmitter in decibel (dB) (m). hB = Height of base station antenna in meter f = Frequency of transmission in Megahertz (m). (MHz). hM = Height of mobile station antenna in meter (m). Though based on Okumura model, the Hata d = Link distance in kilometer (km). model does not provide coverage to the whole β = Clutter factor range of frequencies covered by Okumura model. Hata model does not go beyond 1500 MHz while 3.4.4.2 Hata Model for Urban Areas Okumura provides support for up to 1920 MHz.

The Hata model for urban zones, otherwise 3.4.4.3 Hata Model for Suburban Areas called the Okumura-Hata model for being an advancement adaptation of the Okumura model, The Hata model for rural territories, otherwise is the most generally utilized radio frequency called the Okumura-Hata model for being a propagation model for anticipating the conduct of created adaptation of the Okumura model, is the cellular transmissions in developed territories. most broadly utilized model in radio frequency This model fuses the graphical data from propagation for anticipating the conduct of cellular Okumura model and creates it further to transmissions in city edges and other rustic understand the impacts of diffraction, reflection regions. This model fuses the graphical data from and disseminating caused by city structures. This Okumura model and creates it further to better model additionally has two more assortments for suit the need. This model additionally has two transmission in rural territories and open zones more assortments for transmission in urban [46,47,8,9,6,48] zones and open territories; these are not investigated in this work [50,10] This specific adaptation of the Hata model is relevant to the radio propagation inside urban The Hata model predicts the aggregate path loss zones. It is suited for both point-to-point and along with a connection of earthbound microwave communicates transmissions and it depends on or other sort of cellular communications and is a broad experimental estimations taken. It is component of transmission frequency and the appropriate to be connected in the frequency normal path loss in urban zones. The Hata model scope of 150 MHz to 1500 MHz. The model was for rural zones, otherwise called the Okumura – created for Mobile Station Antenna Height of Hata model, for being a created form of the between 1 to 10km, and Base Station Antenna Okumura model is the most generally utilized as a Height of range 30 to 200 meters [46, 49]. part of radio frequency propagation for foreseeing Equation 14 shows the mathematical expression the conduct of cellular transmission in city edges of the model: and other rustic zones. This model consolidates

Akpiada et al.; JMSRR, 1(1): 1-11, 2018; Article no.JMSRR.41658

the graphical data from Okumura model and (18) creates it further to better suit the need. It additionally has two more assortments for where, transmission in urban zones and open zones.

The Hata model predicts the aggregate path loss L = The total path loss in decibel (dB) along with a connection of earthly microwave or f = Frequency of transmission in megahertz other sort of cellular communications. It also (MHz) serves as a function of transmission frequency d = Distance between base station and and the average path loss in urban areas. Below portable terminal in meter (m). is the mathematical expression of the model; [45] N = The distance power loss coefficient n = Number of floors between the transmitter and portable terminal (n ≥ 0), Lf = 0 dB for (17) n = 0 Lf(n) =The floor loss penetration factor where, 4. CONCLUSION LSU = Path loss in suburban areas in decibel (dB) From these models analysis both the outdoor LU = Average path loss in urban areas for and indoor, it was observed that all models can small sized city in decibel (dB) perform better depending on the condition(s) that f = Frequency of transmission in Megahertz is involved. That is, the type of model used in (MHz) analysis depends on the area where the experiment is to be carried out and as such, 3.5 Models for Indoor Attenuations model A could perform better than model B, etc. Therefore, it is highly recommended that before a In indoor radio channels, the propagation is firmly mathematical model can be chosen for any impacted by the format of structures, experiment, the surrounding environment have to development materials and building compose, be considered. e.g. kind of parcels, delicate or hard segments and multi-floor structures. As a rule, it is hard to COMPETING INTERESTS foresee the correct model for indoor conditions where infiltration from outside is included. Thus, a speculation is generally made, e.g. the flag Authors have declared that no competing quality got inside building increments with height, interests exist. because of urban group impact [46-47] REFERENCES 3.5.1 ITU Model for Indoor Attenuation 1. Ajakaye TA. Telecommunication business The ITU indoor propagation model, otherwise in Nigeria University of Lagos. 2005;1:37- called ITU model for indoor attenuation, is a radio 51. propagation model that gauges the path loss 2. Ajay Mishra. Advance cellular network inside a room or a shut zone inside a building planning and optimization. John Wiley and delimited by dividers of any shape. Appropriate Sons. 2007;28:402-411. for machine intended for indoor utilize, this model 3. Amitay N. Modeling and computer approximates the aggregate path loss an indoor simulation of wave propagation in lineal connection may understanding. The model is line-of sight microcell. IEEE Trans. Veh. pertinent to just the indoor situations. Normally, Tech. 1992;337-342. such apparatuses utilize the lower microwave 4. Anderson JB, Rappaport TS, Yoshida S. groups around 2.4 GHz. Nonetheless, the model Propagation measurements and models applies to a significantly more extensive territory, for wireless communication channels. with better outcomes between the frequencies of IEEE Communication Magazine. 1995;42- 900 MHz to 5.2 GHz. [20-22, 8-9,6]. The model is 49. also found suitable for multi floor attenuation 5. Anderson HR. A ray-tracing propagation predictions when the number of floors less than or model for digital broadcast systems in equal to 3 (ITU-R, 2001). The ITU indoor path urban area. IEEE Trans. Broadcasting. loss model is formally expressed as (ITU-R, 2001;39:309-317. 2001):

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