Innovation: International Journal of Applied Research; ISSN: 2347 9272 (Volume-4, Issue-1) Research Article June 2016

Experimental Determination of Wireless Attenuation Loss of Some Nigerian Roofing and Ceiling Materials Adeniran, .A.O. Ajao, S.O. Obot, S.E. Dept. of Physics, University of Uyo, SLT Dept. The Polytechnic Ibadan, Dept. of Physics, University of Uyo, Nigeria Nigeria Nigeria [email protected] [email protected] [email protected]

Abstract - The Measurement and analysis of radio waves propagation play significant part in the plan and function of Wireless Local Area Network (WLAN) application. In the article research line of light (LOS) was used in determining attenuation loss at various positions. In this work stone coaled Decra with a large thickness of 1.76mm has a high attenuation value of -77dB while aluminum with a low thickness of 0.37mm has a low attenuation value of -72dB. In the categories of ceiling pop sample with a non-uniform thickness has the highest attenuation value of -81dB while sample such as plywood with a thickness of 2.2mm has a low attenuation value of -77dB.

Keywords - Attenuation, wireless, Router, Signal and Roofing.

I. INTRODUCTION Information about the attenuation of various building materials is important for the study of radio frequency (RF) signal propagation in either indoor or outdoor environments (Nowosiriski, 2009). Attenuation is a reduction of signal strength during transmission such as when sending data collected through automated monitoring. Attenuation is represented in decibels (dB), which is ten times the logarithm of the signal power at a particular input divided by the signal power at an output of a specified medium. Attenuation (extinction) occurs with any type of signal, whether digital or analog.The radio energy attenuates as it propagates and when it passes through obstacles like glass, wood, concrete, ceiling and other metal surfaces. The mechanisms that occur when radio waves propagate: non-line of sight reflection, diffraction and scattering. Scattering occurs when radio frequency (RE) can reflect over obstacles which has rough surfaces and after reflecting the signal is dispersed which result in fading of signal. Ultra wideband (UWB) wireless communication has been extensively used in recent years due to its potential application in high rate data transmission as unique capabilities. The propagation of UWB signals as for any electromagnetic wave is governed among other things by the properties of materials in the propagation medium (Daniels, 1996). Attenuation of walls, ceiling and roofing materials dependsamong other things on permittivity of material the wall and roofing materials are made of frequency of incident radiation and thickness.Radio wave propagation of signals is necessary for coming with appropriate design, deployment and management strategies for any wireless network. Radio propagation is to a great extent site-specific and varies considerably depending on the nature of area, frequency of operation, velocity of the mobile terminal, interface, sources and other dynamic factors. Precise classification of the radio channel though main parameters and a mathematical model is important for predicting signal coverage, data rate, effect of obstacles and determining the best position for installing base station (Mark,2003). Propagation measurement means to calculate the field strength value from a transmitter at a given distance with a particular receiver, as every mobile client does not have a wireless utility. Propagation path loss is the loss rate when electromagnetic wave propagates from a transmitter to a receiver as transmitter propagates radio signal to all direction and receiver is located somewhere in the surrounding environment, and the ratio of received power to the transmitted power could be too, meaning that the power of the signal is decreased to one hundredth of its original value at the transmitter (Guillaume, 2012). The fundamental components on which wireless local Area Network Communication is composed of access points (AP) and the mobile clients (MC) typically a laptop or a point direction Access (POA) with a wireless area network card; while for wired network communications Ethernet cables are laid down all over the building and subsequently different buildings are linked to each other by using fiber optics (Dorman, 2001). In wireless local IJAR Journal Page | 32 Adeniran et al., Innovation: International Journal of Applied Research; ISSN: 2347 9272 (Volume-4, Issue-1) Area network, in order to make a network infrastructure access points are positioned at different place all over a building and also if needed in outdoors as well. Then mobile clients communicate with each other by first communicating to the access points and then to the outer world. A major principle of wireless local area network communication is that network data is transmitted as modulated electromagnetic waves using antenna.Therefore, the knowledge of electromagnetic properties of building materials would provide significant insights into the capabilities and limitation of radio frequency (RF) technology indoor and outdoor applications.

II. WIRELESS Wireless communication is the transfer of information between two or more points that are not connected by an electrical conductor. The most common wireless technologies use radio. With radio waves, distances can be short, such as a few meters for television or as far as thousands or even millions of kilometers for deep-space radio communication. It encompasses various types of fixed, mobile and portable applications, including two-way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking. Other examples of application of radio technologies include GPS units, garage door openers, wireless computer mice, keyboards, headsets, headphones, radio receivers, satellite television and cordless telephones.The term “wireless” has been used twice in communications history, with slightly different meaning. It was initially used from about 1890 for the first radio transmitting and receiving technology, as in „wireless telegraphy‟, until the new word radio replaced it around 1920. The term was revived in the 1980s and 1990s mainly to distinguish digital devices that communicate without wires from those that require wires.LTE, LTE-Advanced, Wi-Fi, Bluetooth are some of the most common modern wireless technologies.

Figure 1 : Wireless Communication Network

III. THE SIGNAL STRENGTH In telecommunications, particularly in radio frequency, signal strength (also referred to as field strength) refers to the transmitter power output as received by a reference antenna at a distance from the transmitting antennadBm (decibel-mill watts) is an abbreviation for the power ratio in decibels (dB) of the measured power referenced to one mill watt (mW). High-powered transmissions, such as those used in broadcasting, are expressed in dB-millivolts per meter (dBm/m). For very low-power systems, such as mobile phones, signal strength is usually expressed in dB-microvolts per meter (dB/m) or in decibels above a reference level of one mill watt (dBm).

IJAR Journal Page | 33 Adeniran et al., Innovation: International Journal of Applied Research; ISSN: 2347 9272 (Volume-4, Issue-1) ATTENUATION OF SIGNAL: In physics, attenuation is the gradual loss in intensity of any kind of flux through a medium. Attenuation is a general term that refers to any reduction in the strength of the signal, whether digital or analog. Sometimes called a loss, attenuation is a natural consequence of signal transmission over long distances. The extent of the attenuation is usually expressed in units called decibels (dBs).

IV. FACTORS THAT CAUSE SIGNAL ATTENUATION i. Building Construction: Certain construction materials can cause interference by absorbing or reflecting the radio waves that make up a wireless signal. For example, metals, concrete and ceramics are all known to degrade waves that pass through them, and should be kept out of Wi-Fi signal paths. Sometimes interference- causing materials can be hard to spot, as with the lead paint on the walls in some older buildings. Even a thin layer of lead can cause a severe amount of wireless interference. ii. Electronic Devices: Many common electronic devices emit radio waves, often in the same frequency bands as those used by Wi-Fi routers and access points. This can cause clashes with wireless signals. Some of these devices are designed to communicate wirelessly themselves, like cordless phones and Bluetooth headsets, but devices like microwaves and LCD monitors can also interfere with wireless signals. iii. External Factors: Wireless interference can be generated by factors outside the home or office, often related to the construction or utility industries. Power lines can often interfere with Wi-Fi signals, as can broadcast television masts or cameras. Overhead cranes or scaffolding can also cause wireless disruption, as these are usually made of metal. Even natural phenomena can generate interference trees with large leaves can block Wi- Fi signals due to the signal being broken up by water contained in the plant. iv. Range :Sometimes, wireless signals become distorted because of the sheer distance they travel. This is due to a process known as attenuation, whereby the strength of a signal decreases as it travels through the air. Although Wi-Fi signals travel much better through the air than through solid materials they will still lose power over time, resulting in interference at the signal's destination.

V. MEASUREMENT OF DIELECTRIC CONSTANT Various methods of measuring the electrical constants of building materials have been used. Each method has pros and cons, such as accuracy, cost of equipment, bandwidth of measurements, limitations on material types, etc. A good summary of measurement techniques (not specific to building materials) is given in. Here we focus on the methods generally used for building materials.

FREE SPACE METHODS: These most closely resemble a radio propagation measurement. A parallel-sided slab of material to be measured is placed between a transmitting and a receiving antenna (Figure 4-7). When the angles between the antennas and the slab are set appropriately, the Fresnel transmission and reflection coefficients are measured directly.

VI. THE PHYSICS OF RADIO WAVE PROPAGATION INTO BUILDING As noted in propagation into buildings can involve a large number of paths and different mechanisms that may offer opposing trends of attenuation versus frequency. One example, particularly relevant to the present study, is that longer wavelengths may suffer less absorption due to building materials, but may not couple easily through available apertures such as windows or doors. This may be particularly relevant for the 100 MHz and 200 MHz broadcast bands where the wavelength is comparable with typical aperture sizes. Another complicating factor, that mitigates against simple models for building loss, is that penetration into buildings will often involve multiple paths (e.g, through walls, diffracting around window frames, penetration through thin roofing material and down through wooden floors). This characteristic may cause the overall building entry loss (BEL) to be a very complicated function of the arrival angle of the wanted signal. Many of the studies examined note the difficulty of separating the characteristics of building loss from the clutter around the building. The effects of neighboring buildings are often cited in the literature as the cause of anomalies in the trend of BEL with height.

VII. MATERIALS AND METHOD: Materials used in this work are:Wireless router, Signal analyzer, Micrometer Screw gauge, Tape, Retort stand etc.A wireless signal was produced named: PHYSICS ELECTRONIC RESEARCH GROUP and propagated using a router and distance were measured, measuring tape on the laboratory bench and moved the IJAR Journal Page | 34 Adeniran et al., Innovation: International Journal of Applied Research; ISSN: 2347 9272 (Volume-4, Issue-1) laptop inch by inch away from the access point in all directions first with a line of sight (LOS) and then for non- line of sight (NLOS) areas of same access point. Initially, took reading for every 4m of various types of roofing materials with different thickness. These follow by 6m, 8m and 10m respectively. As all the access points are installed at some height the Pythagoras theorem was used to obtain the exact distance to router. For comparing loss against obstacles, the following table will be used as a reference to see the difference between practical attenuation losses and theoretical value. The TL-WA5210G 2.4Ghz High Power Wireless Outdoor CPE was used as an AP. It was powered by a 12V battery. The AP produced wireless signals which were observable using the Wifi Analyzer. The signal levels dropped with increasing distance between the AP and the Wifi Analyzer and encounter with an obstacle. The aim of the research was to find out the effects the obstacles had on the signals, therefore the distance were varied from 4m to 10m , and hence the need for a measuring tape.The different roofing and ceiling materials were place at 4m, 6m, 8m and 10m and the signal attenuation was measured at a distance to the setup the AP and the wifi Analyzer apart. Two different sets of readings were obtained to ensure accuracy. The Signal Attenuation/loss due to each of the individual walls was calculated as follows Signal loss = Recorded Signal – Threshold signal.

Wi-Fi ANALYSER: Keuwlsoft signal meter is a mobile application meter that measures the wireless signal loss at any range with the IP of 192.189.11. This was used in taking the measurement for the attenuation through the material at every distance away from the obstruction.

Figure 2:2.4GHz High Power Wireless Outdoor CPE Figure 3: Wi-Fi signal Analyzer

VIII. RESULTS AND DISCUSSION Measured values for the attenuation and the calculated attenuation loss is shown in the tables below: the table 1 show the measured for roofing materials and the table 2 show the attenuation loss for the roofing materials while the table 3 and 4 show the attenuation measured calculated attenuation loss in ceiling materials. The calculated values were calculated using Line of Sight method and the measured values for each distance along with the unobstructed signal measurement is shown in Table 4. Attenuation LOS (dBm) -40 -64 -69 -71

Table .1: Measured Attenuation Loss of Roofing Material in dBm. Materials Thickness Loss 4m 6m 8m 10m Aluminium 0.41 -41 -66 -70 -73 Aluminium 2 0.37 -41 -65 -71 -72 Aluminium 3 0.55 -42 -66 -72 -72

Stone Coated Decra 1.76 -43 -67 -75 -77

Cameroun Steel 0.21 -41 -65 -73 -73

Nigeria Swamp 0.32 -42 -66 -72 -74

IJAR Journal Page | 35 Adeniran et al., Innovation: International Journal of Applied Research; ISSN: 2347 9272 (Volume-4, Issue-1) Table .2: Attenuation Loss Measured at different distance to the router Materials 4m dBm) 6m(dBm) 8m(dBm) 10m(dBm)

Aluminium 1 1 2 1 Aluminium 2 1 1 1 2 Aluminium 3 2 2 2 3

Stone Coated 3 3 3 6 Cameroun Steel 1 1 1 4 Nigeria Swamp 2 2 2 3

-69 7 Ttenuation Loss 6m6 6 8m 10m -70 6 5 -71 4 4 3 3 3 3 3 -72 3 -72 -72 2 2 2 2 2 2 2 2 -73 2 1 1 1 1 1 1 1 1 -73 -73 1

-74 Attenua -74 0 -75Attenuati -76 Roofing -77 -77 -78 Roofin Figure 4: Attenuation of Roofing Material Figure 5: Attenuation Loss of Some Building materials (dBm)

2 1.76 0 0 0 0 0 0 0 1.5 Roofing -5 -10 1 0.55 -15 Roofing 0.41 0.37 0.32 0.5 0.21 -20

0 -25 Att Thickness Thickness -30 -35 -40 -45 -41 -41 -41 -42 -43 -42 -50 Figure 6: Roofing Materials with their Thickness

0 -68 0.41 0.37 0.55 1.76 0.21 0.32 -20 -70 -72

-40At -74 -60 -76 -66 -65 -66 -67 -65 -66 -80 Attenuation of -78 Figure 7:Attenuation measured Loss at 10m Figure.8:Roofing Materials Thickness to measured attenuation loss

IJAR Journal Page | 36 Adeniran et al., Innovation: International Journal of Applied Research; ISSN: 2347 9272 (Volume-4, Issue-1) Table.3: Measured Attenuation through the Ceiling Materials Ceiling Materials Thickness μm 4m (dBm) 6m(dBm) 8m(dBm) 0m(dBm) PVC 2.7 -49 -68 -65 -66 Pop Ceiling Non unified -50 -71 -63 -81 Eternity 2.33 -49 -69 -65 -78 Nigerite 2.2 -51 -68 -64 -76 Ply wood 1.9 -49 -67 -66 -78 Ply wood 2 7.55 -46 -69 -65 -76

Table 4: Attenuation Loss (dBm) in Ceiling materials Ceiling Materials 4m (dBm) 6m(dBm) 8m(dBm) 10m(dBm) PVC 9 4 4 5 Pop Ceiling 10 7 6 10 Eternity 9 5 4 7 Nigerite 7 4 5 5 Ply Wood 9 3 3 7 Ply Wood 2 6 5 4 5

12 0 4m10 10 6m 8m 10m 10 9 9 9 Ceiling -20 8 7 7 7 7 6 6 6 5 5 5 5 5 5 -40 4 4 4 4 4 4 3 3 -41 -41 -42 -43 -41 -42 Attenuatio -60 2 -66 -65 -66 -65 -66 -80 -70 -67 0 -73 -71-72 -72-72 -75 -73-73 --7274 PVC Pop Eternity Nigerite Ply wood Ply wood -77 Ceiling 2 -100 Figure 9: Attenuation Loss of Some Ceiling Figure 10: Measured Attenuation loss for Ceiling Materials In dBm Material

8 7.55 0

6 -20 Ceiling 4 -40 2.7 2.33 2.2 1.9 -46 -49 -50 -49 -51 -49 2 of Thickness -60 0 -63 -64 Attenuation Attenuation -68-65-66 -65 -68 -67-66 -65 0 -80 -71 -69 -69 -78 -76 -78 -76 PVC Pop Eternity Nigerite Ply Ply -81 Ceiling wood wood 2 -100 Ceilling Figure 11.: Ceiling Materials against the Thickness Figure 12: Ceiling Materials measured attenuation Loss

IX. CONCLUSSION On the basis of the received results for the selected roofing materials used in Nigeria buildings, it is clearly seen that the attenuation values practically depend on the thickness as shown in Figure 4.5, distance of the material from the signal source as explained in figure 4 -11 as well as the type of material used. The result show that in the frequency of wireless propagation (2.45 GHz) as show in Figure 4 to figure 11 the material such

IJAR Journal Page | 37 Adeniran et al., Innovation: International Journal of Applied Research; ISSN: 2347 9272 (Volume-4, Issue-1) as the Decra roof which is stone coated show a very high attenuation of -77 at distance of 8 and 10 m which is followed by Nigeria Swamp with -74 and Cameroun steel with -73, the combination of a high attenuated materials such as Decra and pop would lead to a very high attenuation loss of wireless signal in the house but the combination of two low roofing material and ceiling material will cause the attenuation to be so minimal.Categories of ceiling materials in Table 3 and Pop with non-uniform thickness has the high value of attenuation loss with -81dBm at the distance of 6 and 4m while the PVC has a very low attenuation at 10m among the set of ceiling materials.

X. RECOMMENDATIONS At the end of the research it was observed that the following recommendations should be noted in order to increase the wireless signal in home and offices in Nigeria:  The transmitter base station should be located at a place which has high network coverage.Repeater stations should be made available as to boost the signal in every distance. Materials of Low attenuation should be used in buildings ,schools and offices Builders should take note of the combination of materials for the buildings to be constructed.

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