C cf radio propagation theory and propagation models

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The radio propagation theory is an important lesson in the radio communication curriculum. This lesson answers the following questions:
How are radio waves transmitted from one antenna to the other antenna?
What features does the radio wave have during the propagation? Which factors affect the propagation distance?
What fruits are achieved by predecessors in the radio wave propagation theory? How to apply the theory to practice?
Chapter 1 Radio Propagation Theory
Chapter 2 Radio Propagation Environment
Chapter 3 Radio Propagation Models

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C cf radio propagation theory and propagation models

  1. 1. Radio Propagation TheoryISSUE 2.1
  2. 2. Page 2The radio propagation theory is an importantlesson in the radio communicationcurriculum. This lesson answers the followingquestions:How are radio waves transmitted from oneantenna to the other antenna?What features does the radio wave haveduring the propagation? Which factors affectthe propagation distance?What fruits are achieved by predecessors inthe radio wave propagation theory? How toapply the theory to practice?
  3. 3. Page 3TargetBy learning this lesson, you would understand: Propagation modes of radio waves Classification of radio propagation environment Radio propagation models
  4. 4. Page 4Chapter 1 Radio Propagation TheoryChapter 1 Radio Propagation TheoryChapter 2 Radio Propagation EnvironmentChapter 3 Radio Propagation Models
  5. 5. Page 5300-3000GHzEHFExtremely HighFrequency30-300GHzSHFSuper High Frequency3-30GHzUHFUltra High Frequency300-3000MHzVHFVery High Frequency30-300MHzHFHigh Frequency3-30MHzMFMedium Frequency300-3000KHzLFLow Frequency30-300KHzVLFVery-low Frequency3-30KHzVFVoice Frequency300-3000HzELFExtremely LowFrequency30-300Hz3-30HzDesignationClassificationFrequencyFrequencies in different bands havedifferent propagation features.Spectrum AllocationSpectrum AllocationRadio Propagation Theory
  6. 6. Page 6Irradiated wave and ground reflected wave(most common propagation mode)Tropospheric reflected wave(The propagation is random to a great extent)Diffracted wave (signal source for shadedarea)Ionospheric reflected wave(trans-horizon communication mode)Propagation ModesPropagation ModesRadio Propagation Theory
  7. 7. Page 7① Building reflected wave② Diffracted wave③ Direct wave④ Ground reflected waveRadio Propagation Theory
  8. 8. Page 8 Slow fading Slow fading occurs as the user moves and due toshadowing by local obstructions. Power control willovercome slow fading. Rapid fading Rapid fading occurs as signals received frommany paths drift into and out of phase.− The fades are roughly− 2 apart in space: 7 inches apart at 800 MHz, 3inches apart at 1900 MHz− Fades also appear in the frequency domainand time domain− Fades are typically 10-15 db deep,occasionally deeper− Rayleigh distribution is a good model for thesefadesFading TypeFading TypeRadio Propagation Theory
  9. 9. Page 9 Space diversity The main and diversity antennas are usedfor reception. The fading of signals in the two ways isirrelevant and is counted independently. The diversity distance D ranges fromwavelength 10 to 20− 800M system, greater than 4 m− 1900M system, greater than 2 m− 450M system, greater than 7 mKey Technologies for CDMAKey Technologies for CDMA SystemSystem toto RelieveRelieve Fast FadingFast FadingRadio Propagation Theory
  10. 10. Page 10 Polarization diversity The dipole antenna which integrates twodirections of polarization is used. The multi-path A and B in two ways withirrelevant fading feature are integrated into oneway signals. Two multi-path fingers A and B arefinally integrated into one path signals. Compared with the space diversity, thepolarization diversity saves the installationspace. Frequency diversity The bandwidth of the CDMA system is 1.23M.It has the function of frequency diversity.Key Technologies for CDMA System to Relieve Fast FadingKey Technologies for CDMA System to Relieve Fast FadingRadio Propagation Theory
  11. 11. Page 11 Rake receiverKey Technologies for CDMA SystemKey Technologies for CDMA System to Relieve Fast Fadingto Relieve Fast FadingRadio Propagation Theory
  12. 12. Page 12ReceiverFinger 1Finger 2Finger 3Searcher DelaycalculationCombiner The combinedsignaltts(t) s(t) Rake receiver The RAKE receiver can relieve the multi-path fading and improvethe reception performanceKey Technologies for CDMA to Relieve Fast FadingKey Technologies for CDMA to Relieve Fast FadingRadio Propagation Theory
  13. 13. Page 13 Time diversity Interleave, detect and rectify codes. The continuous bit errors caused byfading become incontinuous after interleaving, which makes it easy torectify errors.Key Technologies for CDMA to Relieve Fast FadingKey Technologies for CDMA to Relieve Fast FadingRadio Propagation Theory
  14. 14. Page 14Problems Which are the key technologies for relieving multi-path?
  15. 15. Page 15Chapter 1 Radio Propagation TheoryChapter 2 Radio Propagation EnvironmentChapter 2 Radio Propagation EnvironmentChapter 3 Radio Propagation Models
  16. 16. Page 16Actual Coverage PlanningActual Coverage PlanningRadio Propagation EnvironmentWhat is different?Please comparewith the followingknowledge points
  17. 17. Page 17The radio wave propagation is influenced by terrain andartificial factors. The radio propagation environmentdetermines the propagation model directly.Radio Propagation Environment Main factors that influence the radio propagation environment: Terrain (Mountain, foothill, plain and water area) Number, distribution, material of artificial buildings (Artificialenvironment) Vegetation of an area Weather Natural and artificial electromagnetic noises Artificial environment Urban areas, suburbs and rural areas
  18. 18. Page 18Radio Propagation EnvironmentPropagation loss in free spacePloss =32.4+20lgf(MHz)+20lgd(km)If the frequency is specified, the formula canbe:Ploss=L0+10lgd,  =2 path loss slope. In theactual situation,  ranges from 3 to 5.Propagation loss in even areaPloss = L0+10lgd -20lghb - 20lghm =4 path loss slopehb: height of base station antennahm: height of mobile station antennaPropagation LossPropagation Loss
  19. 19. Page 19Propagation loss for quasi-flat terrain and anomalistic terrainQuasi-flat terrainsThe terrains ripple mildly and the ripple height isless than 20 m.Anomalistic terrainsThe terrains exclude the quasi-flat terrains andcan be divided into the following:Foothill, isolated mountain, versant andterraqueous terrainRTTRPropagation LossPropagation LossRadio Propagation Environment
  20. 20. Page 20TRTR• Diffraction loss• Penetration lossPropagation LossPropagation LossRadio Propagation Environment
  21. 21. Page 21¦ Ȧ Ȧ Å0¦ Ì 0 ¦ Ŧ Ì ¦ Å0¦ Ì 0dDw1 w2E1E2XdBmWdBmPenetration LossX-W=B dBPenetration LossX-W=B dB Reflection and refraction of radio wavesafter penetrating wallsPenetration LossPenetration LossRadio Propagation Environment Indoor signal propagation depends on the penetration loss of buildings. The building materials have a great influence on the penetration loss. The angle of incidence of radio waves has a great influence on thepenetration loss. The higher the frequency is, the higher the penetration is.
  22. 22. Page 22penetrationpenetration LossLossRadio Propagation Environment Object barrier/penetration loss: Wall partition barrier: 5–20dB Floor barrier: >20dB The indoor loss is the function of building height. The lossdecreases by 1.9dB for each ascending floor. Barrier of furniture and other obstacles: : 2–15dB Thick glass: 6–10dB Penetration loss of the carriage: 15–30dB Penetration loss of the elevator: about 30dB Loss of flourishing leaves: 10dB
  23. 23. Page 23Chapter 1 Radio Propagation TheoryChapter 2 Radio Propagation EnvironmentChapter 3 Radio Propagation ModelsChapter 3 Radio Propagation Models
  24. 24. Page 24 The propagation models are used to forecast theinfluences of terrains and artificial environments onpath loss The propagation models are the basis ofcoverage planning. Good models ensure theprecision of planning. The radio propagation modules are affected bythe system working frequency. Different modelshave different working frequency ranges, and theranges differ for indoor propagation models andoutdoor propagation models. When using the propagation models, payattention to the value set for each parameter.Radio Propagation ModelsSignificance of radio Propagation ModelsSignificance of radio Propagation Models
  25. 25. Page 25Model Applicable RangeOkumura-Hata Macro cell forecast, 150-1500 MHz,distance, 1-20kmCost231-Hata 1500-2000 MHz, macro cell forecastWalfish-lkegami 800-2000MHz (urban area), micro cellforecast for urban areas with a densepopulationKeenan-Motley 800-2000MHz, indoor environmentforecastOne used in theplanning software400-2000MHz, macro cell forecastRadio Propagation ModelsCommon Propagation ModelCommon Propagation ModelTypical models are gradually studied out by scientists through the CW test dataTypical models are gradually studied out by scientists through the CW test data
  26. 26. Page 26Lp=69.55 + 26.16logf - 13.82loghb+(44.9 -6.55loghb)logd – A(hm)For small and medium cities: A(hm)=(1.1logf - 0.7)hm - (1.56logf - 0.8)For metropolises: A(hm)=3.2(log11.75hm) 2- 4.97Okumura/Hata modelLp fbhmhdmhAPath loss (dB)BS antenna height (m)MS antenna height (m)Carrier frequency (MHz)Distance between BS and MS(Km)Correction factor of MSantenna (dB)The frequency ranges from 150MHZ to 1500MHZRadio Propagation ModelsCommon Propagation ModelCommon Propagation Model
  27. 27. Page 27Cost231-Hata Modelmhbbp CAdhhfL m+−−+−+= log)log55.69.44(log82.13log9.333.46Cm = 0dB Medium cities and central areas in suburbsCm = 3dB MetropolisesThe frequency ranges from 1500MHZ to 2000MHZRadio Propagation ModelsCommon Propagation ModelCommon Propagation Model
  28. 28. Page 28Ordinary Planning Software Model :Lp=K1+K2lgd+K3(hm)+K4lg(hm)+K5lg(Heff) +K6lg(Heff)lgd +K7diffn+KclutterK1—Constant related to frequency (MHz) K2—Constant related to distance (km)K3,K4—Correction factor of MS antenna height (m)K5,K6—Correction factor of BS antenna height (m)K7—Diffraction correction factorKclutter—Correction factor of clutter attenuationd—Distance between BS and MS (km)hm,Heff—Valid height of BS antenna and MS antenna (m)The initial K factor is resulted from typical modulesThe initial K factor is resulted from typical modulesRadio Propagation ModelsCommon Propagation ModelCommon Propagation Model
  29. 29. Page 29Problems What is the applicable range of the Okumura-Hata model? What are the differences between Okumura-Hata and Cost231-Hata? What is the significance of propagation models?
  30. 30. Page 30Conclusion Basic theory of radio propagation Classification of radio environments Traditional radio propagation modelsSummarySummary

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