Path loss determination using Hata model

Path pass determination using Hata sit downCHAPTER-1INTRODUCTIONPath injustice is the degradation in certain index number of an Electromagnetic place when it propagates through dummy. Path bolshy is repayable to several(prenominal)(prenominal) effects much(prenominal) as free space course of study expiry, refraction, diffraction, reflection, trade union and cable prejudice, and absorption. Path overtaking depends on several factors such as type of wing environments, distance between transmitter and receiver, height and placement of barbels. in any case the sign up from the transmitting antenna may take triplex travel guidebooks (multi lead) to r separately the receiving side, which results in either increment or decrease of certain signal level depending on the constructive or destructive tour of duty of the multi raceway waves.Path loss is usually expressed in decibels (db), as this order gives us an blue and logical regularity to comp ar the signal l evels at various points.Where Lp is the path loss i.e. the ratio of fountain of received signal to that of transmitted.extension precedents be mapd extensively in lucre planning, peculiarly for conducting feasibility studies and during initial deployment. They argon as well very multipurpose for playacting interference studies as the deployment proceeds. Numerous Experiments grow been carried turn up all round the world, for checking the pertinence of suitable path loss specimens in mobile communication theory particular scenario. In those experiments radio engineers carried out signal efficacy meter for a specialized arna and comp ard the observed output with that of predicted outputs from different astray accepted lengthiness assumes so as to find out which exemplification best predict the path loss for the given scenario. Also, some graceful tune for that toughie are make based on the difference. galore(postnominal) lengthiness simulates are availabl e for path loss predictions. Deterministic good examples are based on the laws of electromagnetic wave propagation and produce blameless predictions of the path loss, however they take high computational effort and consume detailed and accurate description of all objects in the propagation path .Free space place, and Plane Earth computer simulation, are easier deterministic propagation methods. empiric works are based on extensive collection of info for specific fortune. They are not accurate but predict the most liable(predicate) behavior the link may exhibit under specific conditions.Okumura carried out a lot of field strength quantityments in Tokyo, Japan with variable terrain, frequence antenna height and transmitted powerfulness. It states that, the signal strength decreases at much greater rate with distance than that predicted by free space loss .An empirical grammatical construction based on Okumuras results has been positive by Hata in order to make the pro pagation loss prediction simplified to apply .Hata gave no of path loss samples for urban, suburban and open athletic fields, lots called Okamura-Hata sample. The European Co-operative for Scientific and Technical Research (COST) extended the Hata model to be valid for PCS(personal communication System) Operating at 1800- 2000 megacycle per second, which is named COST 231 Hata model .The European research group besides developed an anformer(a) model fetching Diffraction effect into reflection, which is COST 231 Walfish Ikegami model. Actually, this model is a semi-deterministic model as the path loss calculations is made by combining empirical models with deterministic techniques 4.wave propagation models for planning of mobile communication intercommunicate. Theres a North Ameri rouse model called Lees model named after W.C.Y. Lee, which is characterized by two parameters, power at a mile and path loss exponent.capital of Nepal is the capital urban center of our estate Nepal with more than 1 million inhabitants. GSM peregrine launched by Nepal telecommunication reached roughly a decade now with total 3.5 million subscribers, and 1.5 million just in capital of Nepal. With such increase in no. of subscribers, the no of BTS has at peace(p) up to 1500 in whole Nepal. Operating with both(prenominal) the relative frequency 900 and 1800 MHz, on that point are nearly 500 BTS (BS) in Kathmandu only. With such increase in the no. of Bs in Kathmandu valley callable to the growth in No of subscribers, befitting planning methods are essential for placing BTS for acceptable field strength and Interference level in the reporting area. Also the Coverage holes are needed to be filled with proper planning. This Planning Requires appropriate propagation models that best predicts the path loss for our specific environment.In this meet, the feasibility compend and fine tuning of Hata and Cost 231 Hata model has been done for propagation environments in Ka thmandu. Taking collar different areas of Kathmandu namely incumbrance city area, Ring-road area and Remote areas and five locations are selected for each of the terrain types and Field Strength Measurements offers a give means to empathise what path loss model to use in certain propagation environments. Field strength measurements were conducted on the existing GSM 900 MHz Network of Nepal telecommunication on the locations of busy.MOTIVATIONThe demand for increasing mobile subscribers needs cost- business desire extension of a cellular network. For GSM like technology, in that respect is additional complexness in making efficient Allocation of Base Stations and frequency planning. For this, proper path loss models should be apply for correctage prediction and interference analysis. Much of the popular path loss models by noted RF engineers are based on the observation data taken on their own country. So there is need of fine tuning of such model for applicability in our area. To my contendledge, there has not been each published work regarding such models feasibility analysis and changes.This provides the impetus for this project to make an analysis of the observed data and necessary modification in Hata and Cost 231 Hata model for Kathmandu.Also, the proposed re-farming of 900 MHz frequency spectrum for Future Generation of Mobile Communications provides an early(a) advertise for this project. It is obvious that use of less frequency yields large coverage area than higher frequencies. Hence, for future generation mobile, Scientist pay conceived of making use of 900 MHz spectrum and together with use of stark nakeder technologies, they could make efficient utilization of this spectrum.APPLICATIONSThis project mint be used in true-to-life(prenominal) planning of GSM networks, with the predicted path loss in Kathmandu. For capacity enhancements of the network, GSM Engineers preserve use the path loss prediction models for intelligent placem ent of BTSs with certain antenna height and power. Path loss also facilitates Link budget analysis and Design in a telecommunication system. In a GSM like Cellular network, Path loss is used for Frequency Re-use distance estimates so as to properly space the channels in Base post (BS). Actual Frequency assignment plans for the Base Stations are also facilitated by the use of path loss. Better Coverage predictions and interference reduction is what planning engineers get by using better path loss model.CHAPTER-2 lead LOSS MODELSIn this chapter, description of various Path overtaking model leave be discussed. The model characteristics, along with mathematical principlee, go away be shown that is useful for further calculations, analysis in this project. In addition, three kinds of dependency factors of path loss depart be noted that go away be analyzed later.FREE SPACE track LOSSThis model is the most simple and primitive path loss model where the devise of all objects and obstacles in the propagation environment is ignored. Here, the Received signal is mutually proportional to the square of distance between the transmitter and receiver. So, the free space Path loss is given by As Decibel (db) method gives us easy and consistent method to observe and analyze the signal levels at various points, the free space path loss crapper also be expressed in logarithmic format asOKAMURA MODELThis model is a RF propagation model that was developed based on the data collected in the Tokyo city, Japan. The model served as a base for all other empirical propagation models. In this model, the propagation area is divided into terrain categories open area, suburban area, and urban area. urban area is used as a reference area and Correction factors are applied in it to calculate the path loss for other terrains.HATA MODELIt is also known as the Okumura-Hata model for being a advanced version of the Okumura present, is the most widely used model in radio frequency pr opagation for predicting the behavior of cellular transmissions in city outskirts and other rural areas. This model incorporates the graphical information from Okumura model and develops it further to better suit the need . Hata Model predicts the total path loss along a link of terrestrial microwave or other type of cellular communications. Operating frequency, Base Station overture height. This model is suited for both point-to-point and broadcast transmissions.COST 231 HATA MODELIt is also called the Hata Model DCS Extension, which is a RF propagation model that extends the Hata Model to cover a more range of frequencies. Also, this model is applicable to Open, Suburban and Urban Areas .PATH LOSS DEPENDENCY FACTORSPath loss usually depends on operating frequency, Base station Antenna Height, and distance of the Mobile station (MS) from the Base Station (BS). For each of the popular empirical models discussed above, those dependency factors are observed separately and lastly comb ined together to give a formula for that path loss model.PATH LOSS EXPONENTWe know that received signal at a distance from a BS or a transmitter is inversely proportional to some power of the distance, i.e. farther we go from the BS or transmitter, the received level will degrade by some factor.CHAPTER-3For empirical models, Field strength measurements gives an easy and better way for feasibility analysis and fine tuning of the models for certain propagation environments. In our case, I intend to check the applicability and the modification of Hata and Cost 231 Hata model for propagation environments in Kathmandu. Three different terrains are taken into consideration, namely hollow out city area, Ring-Road area, and far area. Field strength measurements are carried out in fifteen different locations, where five of them choke to one terrain types. Location of BS, Transmitted power, antenna height is taken for the areas of interest in Kathmandu. Field strength measurements were con ducted on the existing GSM network of Nepal Telecom and the receiver used was TEMS tool with a mobile set.DRIVE mental testing USING TEMSTEMS is an air interface test tool for real meter diagnostic of different parameters for RF optimization. Also, all the data can be saved for later analysis. It consists of a laptop with TEMS software, a mobile set with a connector, GPS for location, and a hardware lock key. As for this project, only the received level is concerned, so the received level is noted as we drive farther from a BS.Above Figure shows the trail of the drive test path through a vehicle, in the location of interest. Here, the distance of a sample point in the trail can easily be noted using a scale in the map. Before do drive test in all of those sites, proper Information regarding point locations, their Carrier Frequencies, BS antenna Height, power transmitted from the BS are taken and used in the data collection and Calculations part.ASSUMPTIONSIn this project, seve ral assumptions are considered to ease data collection and analysis phase, which are listed asThough the signal strength measurements are done for different BS with different Carriers (ARFCN), operating frequency is taken to be glacial at 900MHz.The effective power radiated from the BS is taken to be fixed at 50 dbm.Also height of mobile () taken to be fixed at 1.5 meters as the data is measured through TEMS inside a vehicle.Core city area, Ring-road Area and Remote areas in Kathmandu are assumed to be Urban, Sub-urban and Rural area respectively for simplification in analysis and comparison. If that assumption gives different result, then it can be rectify easily based on the incorporate analysis of the path loss plot of ground vs distance.MEASURED PATH LOSSFor each of the propagation environments which have been selected and drive tested for data collection, the path loss can easily be calculated using the formulaSo, Path loss can easily be observed from the collected data, to be increasing as we go farther from the BS. Data Collected for Fifteen different Locations can also be shown in tabular format asPATH LOSS FROM MODELSAfter the observation of measured path loss in the propagation environments in Kathmandu, we need to calculate the path loss from the formula for the two models Hata and COST 231 Hata Model, with the distance d of MS from Bs in km, Frequency f in MHz, BS height hb in meters, Antenna height in meters taken from the real(a) scenario. Calculations are done using Excel sheet and the data are shown asPATH LOSS PLOTSAs we get all the measured data and predicted data from the two models, the average data of path loss as shown in the table below are plotted with the increasing distance d of MS from BS as shown in the graph below for each propagation environments.COMPARISION AND ANALYSISFrom the above plot for each propagation environments, examine the average path loss values with that of Hata and COST 231 Hata model plot gives the result t hat Hata model best fits the propagation characteristics in Core city area and Ring-road area whereas the COST 231 model best predicts the propagation characteristics in Remote area. Also the Minimum significant Error (MSE)calculated for each of the model is within acceptable limits, which can be calculated using the formulaFrom the MSE analysis also, I find that Hata model best fits the Kathmandu Core city area and is also suitable for Kathmandu Ring-road Area. Whereas in the case of Kathmandu Remote Area, Cost 231 Hata model best predicts the path loss characteristics.FINE TUNING OF THE BEST FIT MODELDue to the to the lowest degree and acceptable MSE in both Ring road area and remote area, the best fit models need not be modified for such propagation environments in Kathmandu. Solely based on the Minimum Square Error in path loss, the Best fit model for Core city area in Kathmandu i.e. Hata model can be modified accordingly.This formula is the modified version of the Path loss i n urban area as given by Hata model for application program in Kathmandu.CHAPTER-4RESULTSBy the comparison of the actual path loss with that of the predicted path loss from the two models Hata and COST 231 Hata model, and integrated analysis of all the plots, the feasibility analysis of the two models for three different propagation environments in Kathmandu is done. From which we get, Hata model is not feasible for the application in remote area due to much high minimum square error. Also the Hata model best fits the core city area in Kathmandu with MSE about greater than the acceptable limits as given by 6. So the new modified Hata model is given based on the MSE. And for Ring-road area both model is applicable but the COST 231 Hata Model best fits it due to least MSE.CONCLUSIONIn this project, the popular empirical path loss models for mobile communications are studied. Among them two models, Hata and COST 231 Hata model is compared with actual path loss in three different prop agation environments in Kathmandu, for applicability in macro-cellular Base Stations (BS). Comparison and Analysis of the integrated plot of the path loss from two models and actual path loss in those environments, along with mathematical calculations gave us the result. And the best fit model based on MSE calculations is either modified or left as it is, for those three propagation environments in Kathmandu. Also the assumptions for the three areas are consistent with the actual model which made the analysis and comparison easy. The choice of which model to use actually depends on the terrain type and the surrounding environments and objects around it, the pickaxe of that model in planning a mobile communication network will give the best result and better network is what will be the output. So, Service providers must use efficient planning tools to better model their propagation environments along with the best predicted path loss. Hence, this project is useful for such realistic planning for GSM 900 MHz in Kathmandu. Further enhancements in this project can yield similar results for future mobile technologies and other spectrum too.PROBLEMS / LIMITATIONSThe receiver used for this project is a mobile set which has a sensitivity of -105 dbm. Hence, during field strength measurement, I can only measure signals up to 600m from the Base station in core city area. If there was separate equipment for signal measurement, it would have yield much better result, maybe thats the reason why there is much difference between the measured and predicted value due to lesser no of sample points. Also, Effective power radiated from the antenna is assumed to be 50 dbm, (same for all BS) due to unavaibility of amount actual power radiated from the antenna and the losses in the RF cables and connectors. Also the antenna azimuth and down tilt not taken into consideration and sometimes, the measurement of received signal is done in locations that may be outside of the main lobe of the antenna radiation, i.e. outside of the half-power beam width (HPBW). upcoming WORKThis work can be extended to apply for other mobile technologies in other frequency spectrum such as 1800 MHz DCS, 2100 MHz WCDMA. Also high sensitive field strength measurements tools can be used for future generation Mobile technologies for better result. As this project only dealt with the selection and modification of Path loss models for applicability in Kathmandu areas, the result of this project can be used for interference estimation and frequency assignment planning for new network or extension of existing network.REFERENCESZ. Nadir, N. Elfadhil, F. Touati, Pathloss Determination Using Okumura-HataModel And spline Interpolation For MissingData For Oman, Proceedings of the World Congress on Engineering 2008 Vol I WCE 2008, July 2 4, 2008, London, U.K.Popescu, I.et al., Applications of neural networks to the prediction of propagationpath loss for mobile communications systems, utilize Electromagnetism, 2000. 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