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Flat Fading Modeling in Fixed Microwave Radio Links Based on ITU-R P.530-11

Flat Fading Modeling in Fixed Microwave Radio Links Based on ITU-R P.530-11. Iran Telecommunication Research Center (ITRC) Mehrbod Mohajer, Ramin Khosravi, Mehrnoosh Khabiri. Outlines. Introduction Outage Calculation Fading Prediction in ITU-R P.530-11 Simulations Conclusion.

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Flat Fading Modeling in Fixed Microwave Radio Links Based on ITU-R P.530-11

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  1. Flat Fading Modeling in Fixed MicrowaveRadio Links Based on ITU-R P.530-11 Iran Telecommunication Research Center (ITRC) Mehrbod Mohajer, Ramin Khosravi, Mehrnoosh Khabiri Iran Telecommunication Research Center

  2. Outlines • Introduction • Outage Calculation • Fading Prediction in ITU-R P.530-11 • Simulations • Conclusion

  3. Propagation Scenarios in LOS Point-to-Point Links Link Design

  4. What is the Problem? • In multi path situation, several rays with different delays and amplitudes are constructively or destructively added to the ray of direct or line-of-sight (LOS) path which introduce signal fluctuations. • If the signal falls below a certain point the link can be considered to be non functioning. Outage

  5. What can we do about it? • We cannot possibly know all the details of the environment through which the signal propagates. • We need to take a statistical view of the behaviour of the received field strength. • It is necessary to model the fading effects in such a way that a reasonable fade margin is obtained to achieve acceptable outage time. • Regarding to PTP links are used ashigh-availability links in the backboneof networks, the model should have thedetailed shape of low probability section of distribution.

  6. Which Model? • Traditionally, the well-known lognormal distribution is widely used in the fixed wireless system design procedure. • In order to evaluate the performance of high-availability links, a distribution fading model is required which can precisely present the deep fade depths probability distribution. • Conventional distributions can not provide the detailed shape of deep fade depths probability. • The ITU-R P.530-11 model derived from empirical measurements can perform this task excellently.

  7. Why ITU-R P.530-11? All Important Propagation Standards TIA-845: Radiowave Propagation ETSI: BRAN HIPERACCESS ITU-R P.530-11 (2005) IEEE 211-1997 IEC 60050-705

  8. Propagation Effects in ITU-R P.530 Multi-Hop Links Rain Attenuation Diffraction Fading XPD Distortion Variation in Angle of Arrival/Launch

  9. Outlines • Introduction • Outage Calculation • Fading Prediction in ITU-R P.530-11 • Simulations • Conclusion

  10. Fade Margin Concept waveguide Transmitter 1 Transmitter 2 Splitter Splitter Receiver 1 Receiver 2 Antenna Gain Propagation Losses Antenna Gain Output Power (Tx) Branching Losses Branching Losses Fade Margin Receiver threshold Value

  11. Outage Time The RSL value for a path subject to Free-space and atmospheric attenuation only. The real RSL value which varies in time due to fading processes. RSL Fade Margin Noise power threshold t

  12. Improving Outage Time • By increasing the fade margin, we can improve the outage time. Free-space and atmospheric losses. RSL Fade Margin Noise power threshold t

  13. Outlines • Introduction • Outage Calculation • Fading Prediction in ITU-R P.530-11 • Simulations • Conclusion

  14. Fading Prediction in ITU-R P.530-11 • Flat Fading Prediction • For Small Percentage of Time(Deep Fade Depths) • For All Percentage of Time(Shallow and Deep Fade Depths) • Selective Frequency Fading Prediction

  15. Flat Fading (Deep Fade Depth) Detailed Link Design Applications Quick Planning Applications These relations were derived from multiple regressions on fading data for 251 links in various geo-climatic regions of the world with

  16. Flat Fading (Shallow and Deep Fade Depths) Detailed Link Design Applications Quick Planning Applications Shallow Fade Depths Deep Fade Depths

  17. Outlines • Introduction • Outage Calculation • Fading Prediction in ITU-R P.530-11 • Simulations • Conclusion

  18. Simulations Fade probability for ITU-R P.530-11 and Lognormal models

  19. PDF of the ITU-R P.530-11 model Shallow fade depths probability Deep fade depths probability

  20. Simulations BER of QPSK modulation with various channel models

  21. Conclusion • The outage calculation and fade margin concept are reviewed. • The prediction methods of multi-path fading are introduced based on ITU-R P.530-11 standard. • The ITU-R P.530-11 model is more accurate in comparison to the conventional models like Lognormal model. • It is shown that using the theoretical lognormal model instead of empirical ITU-R model will cause to overestimation or underestimation in link design calculations. Therefore, please use ITU-R P.530 model in your link design

  22. Thanks For Being Such a Good Audience Any Question?

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