C cf radio propagation theory and propagation models
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The document covers radio propagation theory, which is essential in radio communication, discussing transmission, environmental factors, and practical applications. It includes details on various propagation modes, fading types, and the impact of terrain and artificial structures on radio wave transmission. Additionally, it outlines propagation loss formulas and models used for effective coverage planning in different environments.
C cf radio propagation theory and propagation models
- 2. Page 2 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?
- 3. Page 3 Target By learning this lesson, you would understand: Propagation modes of radio waves Classification of radio propagation environment Radio propagation models
- 4. Page 4 Chapter 1 Radio Propagation TheoryChapter 1 Radio Propagation Theory Chapter 2 Radio Propagation Environment Chapter 3 Radio Propagation Models
- 5. Page 5 300-3000GHz EHFExtremely High Frequency 30-300GHz SHFSuper High Frequency3-30GHz UHFUltra High Frequency300-3000MHz VHFVery High Frequency30-300MHz HFHigh Frequency3-30MHz MFMedium Frequency300-3000KHz LFLow Frequency30-300KHz VLFVery-low Frequency3-30KHz VFVoice Frequency300-3000Hz ELFExtremely Low Frequency 30-300Hz 3-30Hz DesignationClassificationFrequency Frequencies in different bands have different propagation features. Spectrum AllocationSpectrum Allocation Radio Propagation Theory
- 6. Page 6 Irradiated 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 shaded area) Ionospheric reflected wave (trans-horizon communication mode) Propagation ModesPropagation Modes Radio Propagation Theory
- 7. Page 7 ① Building reflected wave ② Diffracted wave ③ Direct wave ④ Ground reflected wave Radio Propagation Theory
- 8. Page 8 Slow fading Slow fading occurs as the user moves and due to shadowing by local obstructions. Power control will overcome slow fading. Rapid fading Rapid fading occurs as signals received from many paths drift into and out of phase. − The fades are roughly − 2 apart in space: 7 inches apart at 800 MHz, 3 inches apart at 1900 MHz − Fades also appear in the frequency domain and time domain − Fades are typically 10-15 db deep, occasionally deeper − Rayleigh distribution is a good model for these fades Fading TypeFading Type Radio Propagation Theory
- 9. Page 9 Space diversity The main and diversity antennas are used for reception. The fading of signals in the two ways is irrelevant and is counted independently. The diversity distance D ranges from wavelength 10 to 20 − 800M system, greater than 4 m − 1900M system, greater than 2 m − 450M system, greater than 7 m Key Technologies for CDMAKey Technologies for CDMA SystemSystem toto RelieveRelieve Fast FadingFast Fading Radio Propagation Theory
- 10. Page 10 Polarization diversity The dipole antenna which integrates two directions of polarization is used. The multi-path A and B in two ways with irrelevant fading feature are integrated into one way signals. Two multi-path fingers A and B are finally integrated into one path signals. Compared with the space diversity, the polarization diversity saves the installation space. 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 Fading Radio Propagation Theory
- 11. Page 11 Rake receiver Key Technologies for CDMA SystemKey Technologies for CDMA System to Relieve Fast Fadingto Relieve Fast Fading Radio Propagation Theory
- 12. Page 12 Receiver Finger 1 Finger 2 Finger 3 Searcher Delay calculation Combiner The combined signal tt s(t) s(t) Rake receiver The RAKE receiver can relieve the multi-path fading and improve the reception performance Key Technologies for CDMA to Relieve Fast FadingKey Technologies for CDMA to Relieve Fast Fading Radio Propagation Theory
- 13. Page 13 Time diversity Interleave, detect and rectify codes. The continuous bit errors caused by fading become incontinuous after interleaving, which makes it easy to rectify errors. Key Technologies for CDMA to Relieve Fast FadingKey Technologies for CDMA to Relieve Fast Fading Radio Propagation Theory
- 14. Page 14 Problems Which are the key technologies for relieving multi-path?
- 15. Page 15 Chapter 1 Radio Propagation Theory Chapter 2 Radio Propagation EnvironmentChapter 2 Radio Propagation Environment Chapter 3 Radio Propagation Models
- 16. Page 16 Actual Coverage PlanningActual Coverage Planning Radio Propagation Environment What is different? Please compare with the following knowledge points
- 17. Page 17 The radio wave propagation is influenced by terrain and artificial factors. The radio propagation environment determines 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 (Artificial environment) Vegetation of an area Weather Natural and artificial electromagnetic noises Artificial environment Urban areas, suburbs and rural areas
- 18. Page 18 Radio Propagation Environment Propagation loss in free space Ploss =32.4+20lgf(MHz)+20lgd(km) If the frequency is specified, the formula can be: Ploss=L0+10lgd, =2 path loss slope. In the actual situation, ranges from 3 to 5. Propagation loss in even area Ploss = L0+10lgd -20lghb - 20lghm =4 path loss slope hb: height of base station antenna hm: height of mobile station antenna Propagation LossPropagation Loss
- 19. Page 19 Propagation loss for quasi-flat terrain and anomalistic terrain Quasi-flat terrains The terrains ripple mildly and the ripple height is less than 20 m. Anomalistic terrains The terrains exclude the quasi-flat terrains and can be divided into the following: Foothill, isolated mountain, versant and terraqueous terrain R T T R Propagation LossPropagation Loss Radio Propagation Environment
- 20. Page 20 T R T R • Diffraction loss • Penetration loss Propagation LossPropagation Loss Radio Propagation Environment
- 21. Page 21 ¦ È ¦ È ¦ Å0¦ Ì 0 ¦ Ŧ Ì ¦ Å0¦ Ì 0 d Dw1 w2 E1 E2 XdBmWdBm Penetration LossX-W=B dBPenetration LossX-W=B dB Reflection and refraction of radio waves after penetrating walls Penetration LossPenetration Loss Radio 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 the penetration loss. The higher the frequency is, the higher the penetration is.
- 22. Page 22 penetrationpenetration LossLoss Radio Propagation Environment Object barrier/penetration loss: Wall partition barrier: 5–20dB Floor barrier: >20dB The indoor loss is the function of building height. The loss decreases 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. Page 23 Chapter 1 Radio Propagation Theory Chapter 2 Radio Propagation Environment Chapter 3 Radio Propagation ModelsChapter 3 Radio Propagation Models
- 24. Page 24 The propagation models are used to forecast the influences of terrains and artificial environments on path loss The propagation models are the basis of coverage planning. Good models ensure the precision of planning. The radio propagation modules are affected by the system working frequency. Different models have different working frequency ranges, and the ranges differ for indoor propagation models and outdoor propagation models. When using the propagation models, pay attention to the value set for each parameter. Radio Propagation Models Significance of radio Propagation ModelsSignificance of radio Propagation Models
- 25. Page 25 Model Applicable Range Okumura-Hata Macro cell forecast, 150-1500 MHz, distance, 1-20km Cost231-Hata 1500-2000 MHz, macro cell forecast Walfish-lkegami 800-2000MHz (urban area), micro cell forecast for urban areas with a dense population Keenan-Motley 800-2000MHz, indoor environment forecast One used in the planning software 400-2000MHz, macro cell forecast Radio Propagation Models Common Propagation ModelCommon Propagation Model Typical 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. Page 26 Lp=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 － 4.97 Okumura/Hata model Lp f bh mh d mhA Path loss (dB) BS antenna height (m) MS antenna height (m) Carrier frequency (MHz) Distance between BS and MS (Km) Correction factor of MS antenna (dB) The frequency ranges from 150MHZ to 1500MHZ Radio Propagation Models Common Propagation ModelCommon Propagation Model
- 27. Page 27 Cost231-Hata Model mhbbp CAdhhfL m +−−+−+= log)log55.69.44(log82.13log9.333.46 Cm ＝ 0dB Medium cities and central areas in suburbs Cm ＝ 3dB Metropolises The frequency ranges from 1500MHZ to 2000MHZ Radio Propagation Models Common Propagation ModelCommon Propagation Model
- 28. Page 28 Ordinary Planning Software Model ： Lp=K1+K2lgd+K3(hm)+K4lg(hm) +K5lg(Heff) +K6lg(Heff)lgd ＋ K7diffn+Kclutter K1—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 factor Kclutter—Correction factor of clutter attenuation d—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 modules Radio Propagation Models Common Propagation ModelCommon Propagation Model
- 29. Page 29 Problems 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. Page 30 Conclusion Basic theory of radio propagation Classification of radio environments Traditional radio propagation models SummarySummary