Okumura-Hata ?· • The COST-231 Hata model is an extension of the Okumura-Hata Model to 2GHz • It…

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<p>Okumura-Hata Model The okumura and Hata Model is good but more complex </p> <p>propagation model that is based on extensive empirical measurements taken in urban environments and was further approximated by Hata</p> <p>The model includes parameters such as frequency, frequency range, heights of the transmitter and receiver and building density.The model is the most popular model for macrocell loss prediction</p> <p>10 10</p> <p>10 10</p> <p>( ) (69.55 26.16log 13.82log )(44.9 6.55log ) log</p> <p>c t</p> <p>t</p> <p>L dB f hh d C</p> <p>= + </p> <p>+ </p> <p> Where d distance between transmitter and receiver in km</p> <p> ht height of the transmitter antenna in meter Ht height of the receiver antenna in meter Fc Carrier frequency</p> <p>2102 log ( ) 5.428</p> <p>cfC = +</p> <p>210 104.78 log 18.33log 40.94c cC f f= + +</p> <p>210</p> <p>210</p> <p>10 10</p> <p>3.2 log (11.75 ) 4.97</p> <p>8.29log (1.54 ) 1.1(1.1log 0.7) (1.56log 0.8)</p> <p>r</p> <p>r</p> <p>c c</p> <p>h</p> <p>C hf f</p> <p>= </p> <p>, large cities, fc &gt;= 300MHz</p> <p>, large cities, fc &lt; 300MHz</p> <p>, Medium or small cities</p> <p>For Suburban area</p> <p>For Open area</p> <p>For Urban area</p> <p> The model was intended for macrocells and is applicable over distance of 1-100km, frequency range 150-1500MHz, Base station height 30-200m and MS height 1-10m</p> <p> The model is satisfactory in Urban and Suburban areas but not suitable for rural areas</p> <p> The model is suitable for 1G cellular systems but is not applicable to current cellular systems which have smaller cell sizes and higher frequency</p> <p> This model is also not applicable for indoor wireless communication systems</p> <p>COST-231 Hata Model</p> <p> The COST-231 Hata model is an extension of the Okumura-Hata Model to 2GHz</p> <p> It is also an empirical model and is suitable for micro cells and small macro cells.</p> <p> This model is suitable for fc within 1.5GHz 2GHz, ht is within 1-10m and d is within 1 20km range</p> <p> It is used by the ITU-R IMT-2000 standards for the outdoor case</p> <p>10 10</p> <p>10 10</p> <p>( ) (46.3 33.9 log 13.82log )(44.9 6.55log ) log ( )urban c t</p> <p>t M</p> <p>L dB f hh d C C</p> <p>= + </p> <p>+ +</p> <p> Where C Correction factor for mobile antenna heightCM - is 0dB for medium sized cities and Suburban areas, </p> <p>is 3dB for metropolitan areas Both the Okumura-Hata and COST-231Hata models </p> <p>are specified to have a BS height above 30m, they can be used when ht is less than 30m, as long as surrounding buildings are well below this height.</p> <p> They are not suitable for microcells like urban canyons</p> <p>Example</p> <p> Determine the path loss using Hata model at a frequency of 1GHz with ht=50meter, hr= 2meter and distance d = 2km</p> <p> Answer: 170.75dB</p> <p>Other empirical models In most of the models received power can be </p> <p>estimated using the following equation</p> <p>Where d0 - reference distance d distance at which power to be find out n path loss exponent</p> <p>00</p> <p>P ( )n</p> <p>r rdP dd</p> <p>= </p> <p>00</p> <p>P ( ) ( ) 10 logr rddB P d nd</p> <p> = </p> <p> Lees Model: </p> <p> Lees model is used topredict the path loss over flat terrain. It also takes into account the influence of the heights of the transmit and receive antenna ht and hr</p> <p> But it is based on measurement at 900MHz, for suburban areas it has a d3.84 power law.</p> <p>COST-231-Walfisch-Ikegami Model(WI-model)</p> <p> In most of the cases diffraction is a major propagation mechanism. </p> <p> Diffraction: Diffraction occurs when the radio path between transmitter and receiver is obstructed by sharp edges.</p> <p> A number of physical models based available for diffraction analysis like Ikegami model, the flat-edge model, and Walfisch-Bertoni model</p> <p> The COST-231-Walfisch-Ikegami model combines the Walfisch-Bertoni and Ikegami Model plus some empirical correction factors.</p> <p>d</p> <p>hroofh r</p> <p>Incident wave</p> <p>Building</p> <p>br l w</p> <p>ht</p> <p>As shown into the diagram model defines more parameters like </p> <p> height of buildings hroof , </p> <p>width of roads w , </p> <p>building separation b,</p> <p>road orientation with respect to direct radio path </p> <p> Restrictions : Frequency f between 800 MHz and 2000 </p> <p>Mhz TX height hBase between 4 and 50 m RX height hMobile between 1 and 3 m TX - RX distance d between 0.02 and 5 km</p> <p>2 cases : LOS and NLOSLOS :</p> <p>LLOS [dB] = 42.6 + 26 log10 d[km] + 20 log10 f [MHz]</p> <p>NLOS : LNLOS [dB] = LFS + Lrts (wr, f, hMobile , ) + </p> <p>LMSD (hBase, hBase, d, f, bS )where</p> <p>LFS = free space path loss = 32.4 + 20 log10 d[km] + 20 log10 f [MHz]Lrts= roof-to-street loss</p> <p>LMSD= multi-diffraction loss</p> <p>Example</p> <p> Lfs =98.42dB Lrts =37.63dB Lbsh =-23.79dB Kf =-3.94 Lmsd = 9.39 Lnos = 145.44dB</p>


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