Report

ATDI Propagation Models in ICS telecom Webinar aim: identify which radio propagation models are implemented in ICS telecom Including: • Propagation model limitations • Clutter settings • What calculations take place • Identifying the most appropriate model • Examining the useful / popular radio propagation models nb. Due to time constraints the lesser known radio propagation models including corrections such as rain, gas and reflections will not be covered. Webinar aim: present propagation models in a similar form to ITU-R P.1144-5 Method Application Type Output Frequency Distance % time % location Terminal height Input data ATDI implementation & comments Name of Where the Point- Field Valid Valid % time % locations Valid Data Comments on Method application tostrength, frequency distance factored factored range of required to implementation in ICS is used eg. point pathloss range of (s) into into terminal operate the in ICS Telecom Telecom Broadcast, or operation calculation calculation heights propagation areonautical point calculation etc to area A guide to radio propagation models in ICS telecom will be published shortly. Definitions • • • • Digital Terrain Model (DTM) – bare ground height – man-made modifications tend to be ignored such as cuttings and embankments, etc Clutter – What is on the bare ground including trees, buildings (suburban, urban) Absorption Power absorbed by obstacle Diffraction Diffraction loss • • T = transmitter R = receiver How clutter is used Clutter code 9 Used for “building layers” – not covered in this presentation Applies factor to clutter height ie, if forrest 15m high diffraction point = 0.6 x 15 = 9m dB/km applied every time clutter is in transit Flat attenuation Applied only at Receiver pixel Clutter height Applied at all locations Clutter settings Clutter RX RX T/R over ground spot T/R over ground relaxed Over Clutter Over Ground Clutter Ground General Concept Represents pixel of clutter urban Represents pixel of ground (DTM) Represents pixel of ground (DTM) Represents pixel of clutter suburban Represents pixel of clutter urban Diffraction loss From last diffraction point Represents pixel on ground (DTM) Represents pixel of clutter urban with clutter height x and dB/km y Absorption loss = 4 x y / DTM raster size Clutter attenuation = MIN (diffraction loss , absorption loss) Clutter attenuation = Diffraction loss + Absorption loss dB/km Diffraction loss from last diffraction point A B Flat attenuation Absorption loss = 4 x y / DTM raster size At Location A (RX height > Clutter height) Clutter attenuation = MIN(Diffraction loss , Absorption loss) Clutter attenuation = Diffraction loss + Absorption loss At Location B (RX height < Clutter height) Clutter attenuation = MIN(Diffraction loss , Absorption loss) + Flat attenuation Clutter attenuation = Diffraction loss + Absorption loss + Flat attenuation Diffraction loss from last diffraction point 10dB Flat + absorption 10dB Represents pixel of ground (DTM) Represents pixel of clutter urban with clutter height x and dB/km y Clutter attenuation = MIN (Diffraction loss , Absorption loss = summation of flat loss for each separate obstacle) Clutter attenuation = Diffraction loss + Absorption loss which is summation of flat loss for Each separate obstacle Clutter height 8m Clutter height 30m 10dB Diffraction loss Only if RX > clutter height Flat + diffraction mode If RX height < Clutter height Clutter loss = diffraction + clutter attenuations into RX pixel) Clutter might be used to identify Roof tops / street levels Clutter not used in calculation Clutter when using DSM or DEM Other Clutter modes • CCIR and UER are similar to flat + diffraction, except with standard values for mobiles (CCIR) and TV reception (UER) • TSB-88 Mode (NTIA report TSB-88-B similar to flat + diffraction except clutter attenuation need to change with frequency (clutter height should be set to zero) • USER same as flat + diffraction except where RX height > clutter height in which case it is diffraction + flat attenuation into last pixel Clutter code 9 has a specific role and is used as identification for building layer Building layers are not covered in this webinar Demonstrate best way to test clutter settings and attenuations. DEMO Radio Propagation Models • Main Models – – – – – ITU-R 525/526 Deygout ITU-R 525/526 Bullington ITU-R 1546-3 ITU-R 1812-2 ITU-R 452 • Other Useful Models – Okumura/ Hata / Davids – ITU-R 528 (optional add on) These models will be covered in detail during this webinar. • • Other models – Fresnel method + – Wojnar method – Wein method – ITU-R 370 – ITU-R 1225 – Medium Frequency – 3GPP – LTE Rural – 3GPP – LTE urban – SUI method – Hata – Cost 231 – Cost 231 Open – Skywave LF & MF Add-on models – Itm122 - Irregular Terrain Model – ITM_NTIA Longley Rice (ITM) – Ground wave – ITU-R P368-7 – RRC04 – Skywave ITU-R P.435, ITU-R P.1147 – Tropospheric Scatter These models will not be covered during the webinar . The applicability of these models will be covered in the Guide to Radio Propagation models ICS Telecom / HTZ Warfare Radio Propagation model settings • In concept Some propagation models do not split into these 3 conditions easily; in some cases they do not apply TX Location RX Location(s) ITU-R 525 / 526 Deygout • Standard model in ICS telecom since version 1 • Three worst-case intrusions into the Fresnel zone taken into account • ATDI updated method with Deygout94 diffraction where multiple intrusions are taken into account • The ITU have now updated method Method Rec ITU-R P.525 Rec ITU-R P.526-11 and earlier Application Type All services Point-topoint Point-topoint All services Output Frequency Field strength 100 MHz to 100 GHz Field strength 30 MHz to 100 GHz Distance % time Not specified Not applicable Radio Not horizon applicable (50% time only) % location Not applicable Not applicable Terminal height No Limits specified No Limits specified Input data Frequency Distance Path profile data Frequency Distance ATDI implementation & comments Implemented Implemented, This model takes into account a maximum of 3 intrusions into the Fresnel zone and is a Dygout model ITU-R 525/526-12 Bullington • 526 model uses the following parts of 526-12 – Spherical earth section 3.2 – Bullington model section 4.5 • Rounded earth, knife edge, multiple obstacles , smooth earth not implemented because it causes discontinuities as models switch Bullington model uses single effective Diffraction point Method Rec ITU-R P.525 Rec ITU-R P.526-12 and latter Application Type All services Point-topoint Point-topoint All services Output Frequency Field strength 100 MHz to 100 GHz Field strength 10 MHz to 100 GHz Distance % time Not specified Not applicable Radio Not horizon applicable (50% time only) % location Not applicable Not applicable Terminal height No Limits specified No Limits specified Input data Frequency Distance Path profile data Frequency Distance ATDI implementation & comments Implemented Implemented, This model takes into account the worst intrusions and develops and single representative intrusion and uses Bullington model ITU-R 452 • Point to Point calculation • Based on ITU-R P. 525 / 526-10 (Deygout)** • For 50 to 0.001% time • Settings must be correct in ICS telecom • 2 clutter variables in the calculation ha and dk. – - ha is set in clutter heights – dk value applied is based on clutter code Method Rec. ITU-R P.452 Application Type Services Point-toemploying point stations on the surface of the Earth; interference Output Path loss Frequency 100 MHz to 50 GHz Distance % time Not specified but up to and beyond the radio horizon 0.001 to 50 Average year and worst month % location Not applicable ** Note this will be changed to Bullington in near future Terminal height Input data No limits specified Path profile data Frequency Percentage time Tx antenna height Rx antenna height Latitude and longitude of Tx Latitude and longitude of Rx Meteorological data ATDI implementation & comments Implemented. Note do NOT tick “Flat earth profile sent to DLL” The codes 2,3,4,5,8,10 are fixed for a given clutter e.g. if you have coniferous trees it must be code 8 , then fill in height = 20m. Similarly, .dk is derived from a lookup – DON’T enter it. If clutter code=8 (Coniferous trees), dk=0.05; If clutter code=5 (Tropical rain forest), dk=0.03; If clutter code=2, 3 or 4 (Urban), dk=0.02; If clutter code=10 (Industrial zone), dk=0.05. For the remaining clutters, fill in the heights and it will use the corresponding value of dk: If clutter height=4m, dk=0.1; If clutter height=5m, dk=0.07; If clutter height=15m, dk=0.05; If clutter height=9m, dk=0.025; If clutter height=12m, dk=0.02; If clutter height=25m, dk=0.02; ha must be set in the clutter dialogue box MUST be un-ticked ITU-R P.453 (Fig 1,2) or 452-14 (Fig 13) ITU-R P.453 (Fig 4-7) or P. 452-14 (Fig 11) Recommended clutter settings based on 452-14 Table 4 ATDI recommends that ATDI standard clutter designations are used Note 1: Clutter level 6 must be sea / water Note 2: Ofcom has modified version of Infotera Clutter to use with P.452 model. ITU-R 1546 • • • • • Broadcast / International Coordination / Interference Related to ITU-R 370 Only considers terrain within 15km of transmitter Uses clutter and takes off angle to modify prediction Uses propagation curves for different frequencies / % time • Not symmetrical (loss A B Loss B A ) If not standard then ATDI clutter codes will need to be set up Method Rec. ITU-R P.1546 Application Terrestrial services Type Output Frequency Point-to-area Field strength 30 to 3 000 MHz Distance 1 to 1 000 km % time 1 to 50 % location 1 to 99 Terminal height Input data ATDI implementation & comments Tx/base: effective Terrain height and Implemented. Clutter height from less ground cover needs to be loaded than 0 m to 3 000 (optional) and clutter heights m Path classification and calculation Rx/mobile: ³1 m Distance method defined. This Tx antenna height has also been Frequency extended for GE06 Percentage time (separate DLL file) use Rx antenna height with warm/cold sea Terrain clearance definition. Note this angle model in nonPercentage locations reciprocal Refractivity gradient ITU-R 1812-2 • This is a combination of ITU-R P.452, P525, P526-12 and is for point to area calculations • This is the only propagation model that takes clutter into account at both ends of the path Method Application Rec. ITU-R P.1812 Terrestrial services Type Output Frequency Point-to-area Field strength 30 MHz to 3 000 MHz Distance % time Not 1 to 50 specified but up to and beyond the radio horizon % location 1 to 99 Terminal height No limit Input data ATDI implementation & comments Path profile data Frequency Percentage time Tx antenna height Rx antenna height Latitude and longitude of Tx Latitude and longitude of Rx Meteorological data Implemented. Clutter heights need to be defined for mid path clutter height, Clutter values used with terminal heights from table 2 as standard for terminal clutter losses ITU-R P.1812-2 Terminal clutter height is related to Clutter code (ITU-R P.1812-2 Table 2) ATDI Clutter code 6 0 1 2,3,4,5,8 7 Okumura Hata • Mobile operators tend to use this model and fine tune it with drive tests • Model is based on clutter not terrain, so is designed for small ranges The extended Hata model has not been implemented yet. If required please let ATDI know. NB. this model is for SRD with ranges in meters and for indoor and outdoor. To use this model effectively on a DTM a high resolution map would be required (1 -5 m / pixel) Propagation Regions • Line of sight (LOS) Loss Distance • Diffraction • Tropospheric Note: This propagation model is an add on to ICS Telecom and needs to be Purchased separately Other Corrections to Propagation Models • Rain - World based on ITU-R P.538 and UK rain on Ofcom data • Snow – Isotherm level (level at which water freezes) if path passes though this level this correction is applied • Fog – ITU-R 840 • Gas – ITU-R 676 (Note ITU-R F.1820 is Gas attenuation from HAP at 47GHz) • Wave height - (applies an effective clutter height depending on wind strength) • Reflections Comparison of Radio Propagation models in ICS telecom DEMO Thank you for attending today Any questions? ATDI Limited The Beehive – City Place – Gatwick West Sussex – RH6 0PA – UK Tel +44 (0)1293 522052 - Fax +44 (0)1293 522521 Email: [email protected]