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Application Note: Simulating Multipath

Simulating Multipath

Multipath effects, caused by direct and refracted versions of the same satellite signals reaching a GNSS receiver, can seriously compromise receiver accuracy in a range of applications.

Download the Application Note to discover how you can use Spirent RF simulators to model and mitigate multipath effects in GNSS receivers. Topics include:

  • The impact of multipath effects on GNSS receiver accuracy
  • The benefits of using RF simulation to model and mitigate multipath issues
  • How to simulate different multipath effects using Spirent simulators

Simply enter a few details opposite to receive the Application Note—and happy reading!

About Spirent

Spirent has been the global leader in GNSS testing for near 30 years. Spirent delivers navigation and positioning test equipment and services to governmental agencies, major manufacturers, integrators, test facilities and space agencies worldwide.

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    Simulating Multipath APPLICATION NOTE Spirent Communications PLC Paignton, Devon, TQ4 7QR, England Web: nulltp:nullnullnullnullpirentnullomnullositioning Tel: null4 nullnull nullnullnull nullanull null4 nullnull nullnullnull Copnullignull nullnullnull Spirentnull nulll Rignulls Reservednull nulll onulltnull compannullnames andnullr brand names andnullr product names renullrred to in tnulls document, in particular, tnull name nullpirentnulland its logo device, are eitnullr registered trademarnull or trademarnull onull Spirent plc and its subsidiaries, pending registration in accordance nulltnullrelevant national lanullnullnulll otnullr registered trademarnull or trademarnull are tnull propertnull onulltnullir respective onullersnull Tnull innullrmation contained in tnulls document is subnullct to cnullnge nulltnullut notice and does not represent a commitment on tnull part onullSpirentnull Tnull innullrmation in tnulls document is believed to be accurate and reliablenull null ever, Spirent assumes no responsibilitnull or liabilitnullnullr annullerrors or inaccuracies tnullt manullappear in tnull documentnull Page 2SPIRENT Application Note Contents nulludience null nullntroduction null RnullSimulation null Tnullical nullS Simulators 4 Tnull nullSS environment 4 Wnullt is nullultipatnull null Simulating nullultipatnull 7 nullnullultipatnullimplementation in tnull simulator 7 nullnulletnullds onullapplnullng a multipatnull 7 nullnullinulled nullnullnullet nullultipatnull null nullnullround Renullction nullultipatnull null nullDoppler nullnullnullet nullultipatnull null nullRenullction Pattern nullultipatnull null nullLegendre nullultipatnull null nullPolnullomial nullultipatnull null nullSinusoidal nullultipatnull null nullLand nullobile nullultipatnullnullnullnull null nullnullader nullultipatnull null Conclusions null Renullrenced Documents null Denullition onullTerms null nullurtnullr nullnnullrmation null Page 3SPIRENT Application Note Audience Tnulls nullpplication nullote is nullr users onull Spirent simulators nullo are designing, developing, integrating and testing nullSS receivers or snulltems, and need to ensure tnullir products nullll pernullrm in tnull intended applicationnull Spirent recommends nullou nullve a basic understanding onullsatellite navigation principles and Rnull simulation as a test metnulldnull Introduction Tnullre is a steadnullgronullnullin tnull use onullnullSS in nenulland enullsting marnulltsnull Consenullentlnull, tnullre is an increasing reliance on nullSS tecnullolognullnull Witnulltnulls in mind, it is important nullr designers, manunullcturers and consumers onulltnullse products to understand nullat to enullect nullom sucnull snulltemsnullTnulls includes nullrmulating an understanding onulltnull limitations and problems onullnullSS tecnullologiesnull Tnulls application note discusses tnull problem onullnullultipatnull nullicnullis a pnullnomenon tnullt can cause serious reductions in a nullSS receivernulls pernullrmance in a range onullapplicationsnull Complementarnullto tnulls, it demonstrates nullnullnullou can use Spirentnulls range onullnullSS Test Solutions to create and run controlled and repeatable simulations tnullt include multipatnullmodellingnullnullt also includes test metnulldolognullspecinullallnullnullr users onullSpirentnulls simulation snulltemsnull Page 4SPIRENT Application Note nulligure null RnullSimulation nulllonull RnullSimulation null RnullConstellation Simulator reproduces tnull environment onulla nullSS receiver on a dnullamic platnullrm bnullmodelling tnull venullcle and satellite motion, signal cnullracteristics, atmospnullric and otnullr enullnullcts, sucnulltnullt tnull receiver nullll actuallnull navigate according to tnull parameters onulltnull test scenarionull nullnullits vernullnature, simulation is a representation onulltnull real nullrldnull Simulation cannot reproduce tnull nullll ricnulless onullreal nullrld conditionsnull null common misconception is tnull need to enullctlnullreplicate real nullrld conditions nullr a nullSS test to be validnullnullonullever, application onullrepresentative enullnullcts via simulation is proven nullver some null nullears onulltestingnullto enullercise receivers and adenullatelnullidentinull tnullir limitations allonullng nullr design centring and optimisationnullnullore importantlnull, it gives complete repeatabilitnull, control and enullct nullonulledge nulldonull to bit level nullonulltnull signal stimulating tnull receivernull Tnulls is not possible in tnull real nullrldnull We snulluld loonullupon simulator testing as representing tnull real nullrld, ratnullr tnulln replicating itnull Continued, successnulll deplonullent onullreceiver designs in mannull applications, prove tnullt tnull simulators being used nullr tnullir development and verinullation are accurate in tnullir implementation onulltnull nullSS environmentnull nulligure nullsnullnull tnull concept onullsimulation nullsing a nullSnullnull simulatornull Tnullical nullS Simulators nulll tnull tests discussed in tnulls nullpplication nullote can be pernullrmed using annullonull Spirentnulls multinullnullnnel simulatorsnull nullor nullrtnullr innullrmation on Spirentnulls range onullSimulators, please contact nullour local Spirent representative, or visit nullnullnullpirentnullomnullositioning null The nullSS Ennullronment null nullSS receiver nullrnull nullell nullen it nulls a clear, unnullnterrupted vienullonulltnull orbiting satellites transmitting tnull ranging and navigation signalsnullnulln mannullsituations, tnulls is not tnull case, and ranging measurements to tnull satellites are anullnullctednull Tnull degree tnullt pernullrmance is anullnullcted depends on tnull application and tnull environment onulltnull receivernull null varietnullonull nullctors can anullnullct a receivernulls pernullrmance, some specinull to or empnullsised bnull certain applicationsnullnullultipatnullis a potential problem, nullicnullis nullrse in some application environments tnulln otnullrsnull Tnull discussions in tnulls document are nulltnull regard to nullS, unless otnullrnullse statednull Page nullSPIRENT Application Note nullat is Multipathnull nullultipatnullis described to some enullent bnullits namenullnull radio signal convenullng innullrmation or on nullicnullradio ranging measurements are pernullrmed, snulluld travel in a direct, single and unnullltered patnullnullom tnull transmitter to tnull receivernull nullnullen tnulls is not tnull casenullRadio signals can be dinullnullacted and renullcted bnullpnullsical structures in tnull vicinitnullonulltnull receiver, creating unnullnted replicas onulltnull original, desired, Lnull signalnullTnull composite signal is said to tanull nullmultiplenullatnullnullto tnull receivernull nullor nullSS, tnull problem onullreplica signals is signinullant, as measurement onulltransit time nullr tnull signal nulln order to determine pseudorangenull is nullndamental nullr calculating tnull navigation solutionnull Several renullctions manulltanull place, and tnullir relative pnullse delanull nullo eacnullotnullr and tnull Lnullnull combine in eitnullr a constructivelnull nullnnullncing tnull multipatnull or a destructivelnull nullancellingnullut tnull multipatnull Tnull perceived nullcoming and goingnull onulltnull composite multipatnullis called nulldingnull nullccording to Renullrence null a multipatnull completelnullinnullnullse nulltnulltnull Lnull signal generates tnull largest error, and one nullicnull is nullnulldegrees outnullnullpnullse generates tnull smallest errornullnull simple representation onulla singlenullanullmultipatnullrenullction is snullnull in nulligure null nulln tnulls enullmple, a renullction onulltnull nullnted signal tanulls place on tnull surnullce onulltnull buildingnullTnull receiver sees tnulls delanulled and attenuated signal as nullell as tnull direct nullnted signalnullnullt also snullnull tnull tnull opposing states tnullt create nullll constructive internullrence and nullll destructive internullrencenull nulligure null Enullmple onulla simple multipatnull Page nullSPIRENT Application Note nullou manullalso logicallnullassume tnullt tnull longer tnull delanullnullegardless onullpnullse addition or subtractionnulltnull greater tnull pseudorange error, but tnull operation onull tnull receivernulls spreadnullpectrum correlation process means tnullt renullctions nulltnulllong delanull are attenuated and onullen completelnull eliminatednullnullnulltnull delanullonulltnull multipatnull signal is long compared to a cnullp nulldtnull nullppronullnullnull, or nullicrosecond nullr Cnull codenull tnull autonullorrelation properties onull tnull code suppress tnull enullnullctnull Snullrtnullelanullrenullctions nullnullever, are mucnull more onulla problem, nullicnullis unnullrtunate as most realnullinull multipatnulltends to be tnull closenulln, snullrt delanulltnullenull Tnullre are several multipatnullmitigation tecnullinulles emplonulled bnullreceiversnull nullarronullcorrelators, nullst introduced in tnull nullnullnulls, are probablnullone onulltnull best nullonull tecnullinullesnullnulltnullr more upnullonull date tecnullinulles include Strobe nullEdge Correlators, nullignullResolution Correlators nullRCnulland nullated CorrelatorsnullTnull latest developments include nullPosteriori nullultipatnull Estimation nullPnullnull nullicnullrelies on an anullosteriori estimate onulltnull multipatnullerror tnullougnulluse onulla nullurtnullreplica onulltnull PRnull code nullee Renullrence nullnullnulltnullr mitigation tecnullinulles include Carrier Smootnullng and nullultipatnullLimiting nulltennas nullucnullas cnullnullnullingsnull nullnulltnull relative pnullse betnulleen tnull Lnull and renullcted signals cnullnges rapidlnull, tnull receiver can average nullarrier smootnull tnull pseudorange measurements, attenuating tnull erroneous measurementsnull null nullultipatnullLimiting nulltenna can reduce ground renullctions nullom satellites tnullt are vernulllonullon tnull nullrinullon bnullattenuating or blocnullng signals belonulla certain elevationnull nullSS signals can also be renullcted nullom belonullgroundnullTnullnulltravel tnullougnulldrnull ground and tnulln renullct onullnullmore moist lanullers nullrtnullr belonulland can be particularlnull troublesome at nullgnullnullalitnullDnullS renullrence stations, nullere specialised antennas are essential nullee Renullrences nulland nullnull nulln marine environments, strong multipatnull nullom lonullelevation satellites is created bnulltnull surnullce onulltnull sea, nullicnullis a vernullenullcient surnullce nullr renullcting Lnulland signalsnull Tnullre are mannulltecnullinulles nullr mitigating multipatnull too numerous nullr discussion nullrenullnullonullever, tnullre are also mannull boonull on tnull subnullctnullRenullrences nulland nullprovide good introductions to multipatnull in relation to nullSSnull nulligure null Correlation Peanullnulltnullnullnnullnullse and nulltinullnullse nullnternullrence Page null SPIRENT Application Note Simulating Multipath Proper multipatnullmitigation in receiver designs nullr all applications is essentialnull Complementarnullto tnulls is tnull need nullr proper testingnull Real nullrld testing presents vernullcomplenulland unnulluantinullble multipatnull environments tnullt are unnullepeatable and can be time consuming and costlnull to trialnull null nullSS simulator provides nullou nulltnullponullernulll metnullds nullr generating multipatnullsignals in a varietnullonulldinullnullrent nullnull, but unlinull tnull real nullrld, tnullse are nullllnullnullantinulld and controlled bnulltnull simulator usernull Tnulls section provides a set onulltest metnulldologies giving stepnullnullstep instructions on nullnullnullou can create simulator scenarios tnullt include multipatnull enullnullctsnull Spirentnulls Simnullnull sonullnullre contains several multipatnullnullatures and a demonstration onulleacnullone is givennull Multipath implementation in the simulator Witnulltnull enullception onullnullder multipatnull all multipatnullsignals tnullt are simulated in addition to a given Lnull are considered as discrete signalsnullTnulls means tnullt tnull simulator uses a separate nullrdnullre cnullnnel to generate eacnullsignalnull nullor enullmple, a Lnull nulltnulltnullee multipatnullecnulles nullll renullire nullur simulator cnullnnelsnull nullt is important to remember tnulls, as tnullre is a limit to tnull number onullcnullnnels in tnull simulatornull nullnullnullr tnull Spirent nullSnullnull nullr enullmplenull nulln general, tnulls is not a problem as tnullre are usuallnullnullnuller visible satellites in environments nullere tnullre are more multipatnull nullrban cannullons nullr enullmplenull and less multipatnull nullere tnullre are more visible satellites, so tnull overall number onull renullired nullrdnullre cnullnnels balances outnull nullader multipatnulltecnullinulles, available on some Spirent snulltems, uses digital replica signals, giving up to nullur multipatnull per Lnull, nullile using nullst one simulator nullrdnullre cnullnnelnull Page nullSPIRENT Application Note Methods onullapplnullng a multipath null Cnullnnel nullsignment nullallonull manual application during scenario runnullime null nullser nullctions nullallonull nullou to set up multipatnullvia prenullcripted commands nullicnullare enullecuted in a timenullrdered manner null Remote Control Commands null nullou can pernullrm complenullsignal modinullation at nullgnulliteration rates using specinull commands Clicnullon tnull nullstatenull dropnullonull arronull to reveal tnull various state optionsnull Select tnull nullultipatnullnull state to bring up tnull nullanual nullultipatnullSettings nullndonull, as snullnull in nulligure null Select tnull multipatnulltnulle and add tnull renullired number onullecnulles, setting tnull parameters nullr eacnullas renullirednull Channel Assignment To access tnull Cnullnnel nullsignment nullndonull, clicnullon tnull Cnullnnel nullsignment button on tnull toolbarnullTnulls brings up tnull Cnullnnel nullsignment nullndonullas snullnull in nulligure 4null nulligure 4 Cnullnnel nullsignment Windonull nulligure null nullanual nullultipatnullSettings Windonull Page nullSPIRENT Application Note nullser Actions To applnulla multipatnullsignal using tnull nullser nullction nullile, nullst edit tnull nulle nullom tnull scenario tree nulloptions brancnull tnulln select tnull nullnulltcnullSimulated Satellitenull nullom tnull Command Tnulle dropnullonull listnull Specinull tnull time into tnull scenario nullen nullou nullnt tnull multipatnullto begin, and set tnull venullclenullntenna and nullicnullSnullPRnull nullou nullnt tnull multipatnullto applnulltonull Set tnull nulltatenull parameter to nullultipatnullnull and clicnulltnull Settings button to open tnull settings nullndonullnull Select tnull multipatnulltnulle and add tnull renullired number onullecnulles, setting tnull parameters nullr eacnullas renullirednull nulligure nullillustrates tnull metnulld Remote Commands Simnullnullnulls SimREnullTE nullature allonull nullou to setnullp multipatnullusing tnull nullWnullCnullSnullTnull and nullPnullWnullCnull commandsnull Remote commands can be sent in real time over a selection onullinternullces, or nullom a nulle nullicnullis eitnullr locallnullor remotelnullstorednull Renullrence 4 gives nullll details nullr setting up multipatnullvia SimREnullTEnull nulligure null Setting nullp nullultipatnullnullsing tnull nullser nullctions nullile Page nullSPIRENT Application Note nullinulled Onullnullet Multipath Tnull most basic multipatnullmodel used in Simnullnull is tnull nullinulled nullnullnulletnullnullor tnulls tnulle onullmultipatnull tnull simulator produces an nullecnullnull signal, nulltnullconstant usernullenulled range and ponuller onullnullets nullom tnull normal nullnullnullsignalnullnullnce denulled, tnull settings remain nullnullednull in relation to tnull Lnull during tnull scenario runnull Tnull variable nulllds are as nullllonull:null Tnull Attenuation nullld specinulls tnull dinullnullrence in level betnulleen tnull main signal and tnull renullcted ecnullnull Tnull Range nullnullnullet nullld specinulls tnull delanull in meters onulltnull multipatnullsignal compared to tnull Lnull nulllnullnull a positive number null tnull delanulled multipatnullsignal cannot arrive benullre tnull Lnullnull Tnull cnullnge in relative pnullse betnulleen tnull renullcted and Lnull signals nullue to tnull venullcle and satellite motionnullis not modelled in tnulls simple case, so tnull net internullrence betnulleen tnullse signals remains nullednull nulldditional ecnull signals nulltnulldinullnullrent attenuation and delanullvalues can be addednull Tnull limitation is tnull number onullcnullnnels available in tnull simulator nullrdnullre nullnull simulator allocates a single separate nullrdnullre cnullnnel nullr eacnullmultipatnullecnull addednull nullt is possible to remove tnull Lnull signal nullom tnull simulation bnullticnullng tnull nullemove Lnullnull bonull Tnulls simulates tnull situation nullere tnull Lnull is completelnullobscurednull nulligure 7 snullnull a multipatnullsignal denulled nullr satellite PRnull tnullt is nullnull lonuller tnulln tnull Lnull and delanulled bnull nullmnullnullt is not sensible to denulle more tnulln one multipatnullsignal nullr a given satellite using tnulls metnulldnull nulligure 7 nullinulled nullnullnullet nullultipatnull Page nullSPIRENT Application Note nullround Renullction Multipath nullround Renullction nullultipatnullsimulates tnull ecnull signal tnullt manullbe caused bnull tnull Lnull signal renullcting nullom tnull ground nullr sea surnullcenull in terms onulltnull relative geometrnullonulltnull transmitting satellite and tnull receivernullTnull signal generated is based on tnull arrival angle at tnull Wnullnull4 ellipsoid nullignullnull null nullt, plane surnullce is assumed nullr tnull renullctionnullTnull receiver antenna position must nullve some nullignull nullelative to tnull ellipsoid nullignullnullassociated nulltnull nullr tnull groundnullenullcted signal to enullstnull Tnull amount onulldelanullis automaticallnull modelled as a nullnction onulltnull receiver antenna nullignull and arrival angle onulltnull satellite signalnull nulligure nullsnullnull tnulls conceptnull null nulltnullnullinulled nullnullnullet nullultipatnull nullou can adnullst tnull ponuller level attenuation in dnullonulltnull nullround Renullction nullultipatnull signal relative to tnull LnullnullTnulls allonull tnull renullction loss onulltnull groundnullea to be accounted nullrnullTnull relative delanullin tnull renullcted signal nullll varnullnulltnullsatellite position, and as a result, tnull internullrence nulltnulltnull direct signal nullll also varnullnull nullou can remove tnull Lnull signal nullom tnull simulation bnullticnullng tnull nullemove Lnullnull bonull nullt is not sensible to denulle more tnulln one multipatnullsignal nullr a given satellite using tnulls metnulldnull nulligure null Concept onulla nullround Renullction nullultipatnull Page nullSPIRENT Application Note nulloppler Onullnullet Multipath Tnulls multipatnulltnulle nulls originallnull developed to support a specinull test in tnull nullPP nullobile Pnullne test standard nullPP TSnullnull7null nullonullever, it is also usenulll nullr otnullr testingnullnullt is an ennullncement onulltnull nullinulled nullnullnullet nullultipatnulltnullenull nulln addition to tnull level and initial delanull, nullou can set a Doppler nullenullencnullonullnullet betnulleen tnull multipatnulland tnull Lnull, nullicnullcauses tnull delanullbetnulleen tnull multipatnulland Lnull to cnullnge nullependent on tnull amount onullDoppler appliednull nullou can set tnull dinullnullrence in initial carrier pnullse betnulleen tnull Lnull and tnull multipatnull ecnull to a nulled value or randomisednull nullnulltnull bonullis ticnulld, tnull initial carrier pnullse dinullnullrence nullll varnullrun to runnull nullnullunnullicnulld, it nullll remain nullednullnullou can set up Doppler nullnullnullet nullultipatnullin tnull same nullnullas tnull previous enullmplesnull nulligure nullsnullnull tnull settings nullndonullnullnullote nullou can set tnull nullnitial Delanullin eitnullr Cnull cnullps nullode transitions are nullillisecondnull or in metres nullne cnullp is appronull nullnullnull nullnullnullou specinull several multipatnull, nullr tnull same satellite, nulltnulldinullnullrent Doppler values, a greater disturbance onulltnull Lnull signal nullll resultnull nulligure null Settings Windonullnullr Doppler nullnullnullet nullultipatnull Page nullSPIRENT Application Note Renullction Pattern Multipath nulln order to enulllain tnull nullnction onull Renullction Pattern nullultipatnull nulle must nullst loonullat tnull nulltenna Pattern nullature onull Simnullnull, as botnulluse tnull same editor and principlesnull Tnull nulltenna Pattern null nullnction allonull nullou to model tnull electrical properties onulla nullsimulatednull antenna in nullour testnull Wnulln nullou are connecting tnull Rnulloutput nullom tnull simulator to tnull input onulltnull receiver nulltnulla suitable Rnullcoanullal cable, tnull receivernulls antenna is omittednull nullSS signals arrive at tnull receivernulls antenna nullom dinullnullrent directions, because tnull satellites are spatiallnull separated in tnullir constellationnull nullnullvariation onullpernullrmance over tnull antennanulls aperture nullts nulleld onullvienullnull snulluld be accounted nullr, as signals arriving at tnull antenna nullom some directions manull be anullnullcted dinullnullrentlnullto tnullse arriving nullom otnullr directionsnull Tnull nulltenna Pattern Editor in its denullult state denulles an omninullirectional isotropic spnullrical antenna nullnulloretical antenna nulltnull uninullrm gain in all directionsnull nullt tanulls tnull surnullce area onulltnulls spnullre and divides it into enullalnullinulled portions nullinimum resolution null bnullnullnull Tnull nulltenna Pattern Editor represents tnull spnullrical antenna as a nullD arranull, in tnull same nullnulltnullt a globe map onulltnull nullrld can be represented as a nullD mapnullnulligure null snullnulltnull nulltenna Pattern Editornull nulligure null Settings Windonullnullr Doppler nullnullnullet nullultipatnull nullonullload tnull Spirent nullpplication nullote null nulleeping nullour enulle on tnull snullnullTnull importance onullantenna modelling in nullSS testing null Page nullSPIRENT Application Note nullou can enter attenuation nullnd pnullsenull values nullr eacnullnullld, so tnullt inulltnull satellite signal nulllls on tnullt part onulltnull antenna, it is modinulld according to tnull settings nullr tnullt nullldnull null tnull satellites and antenna move, tnull signals nullll nullll upon dinullnullrent parts onulltnull antenna, and nullll be adnullsted accordinglnullnull Similarlnull, in tnull contenull onullRenullction Pattern nullultipatnull tnull settings are attenuation and delanullnull nullnullnullou specinull a Renullction Pattern nullultipatnullon Snullnull nullr enullmple, tnulln an ecnull signal is generated according to tnull arrival vector onulltnull signal nullr tnulls satellite relative to tnull venullclenulls renullction pattern, and tnull appropriate delanulland attenuation values are appliednullTnulls does not implnulltnullt tnull multipatnullsignal comes nullom tnull same direction as tnull Lnull, but tnullt tnulls Lnull gives a renullction nulltnulltnullse cnullracteristicsnull Tnull Lnull nullll be unanullnullctednull null tnull antenna and satellites move, multipatnullsignals nullll be varied as tnull Lnull moves nulltnullrespect to tnull renullction patternnull Tnulls metnulld can be usenulll nullere tnull source onulltnull multipatnullsignals is predominantlnullnullom tnull nullst venullclenull Tnull receiver antenna pattern can be used to attenuate signals nullicnullare blocnulld bnullparts onulltnull venullcle structure, and tnull renullction pattern used to give consistent cnullnges in multipatnullsignals as tnull venullcle cnullnges its orientationnullnullotnullr benenull is tnullt enullctlnulltnull same multipatnullsignals nullll be generated at enullctlnulltnull same times nullen tnull scenario is renullund and renullunnull Tnulls repeatabilitnullis not possible nulltnull nullivenullnullnull testingnullnullt is sensible to denulle onlnullone multipatnullsignal nullr eacnullLnull using tnulls modelnull Page nullSPIRENT Application Note Legendre Multipath Tnulls model enables nullou to specinull multipatnullsignals using a nulltnullorder Legendre Polnullomial, nullr tnull relative amplitude and delanullonulltnull multipatnull signalnullTnulls is tnullicallnullused to model multipatnullsignals in a nullirlnullstatic environment, nulltnullgraduallnullcnullnging multipatnullcnullracteristicsnullTnull advantage onulltnulls model is tnullt tnull same polnullomial coenullcients can be used over annullperiod onulltime, so tnull cnullracteristics onulltnull multipatnullsignal are alnullnull nullpt nulltnulln tnull same boundsnullnulln tnulls model, tnull renullcted signals are not particularlnullrepresentative onulltnull relative geometrnullonulltnull satellites and tnull receiver, but give a tnullical enullnullctnull Tnull more multipatnull denulled, tnull more complenulltnull internullrencenull Tnull polnullomials used are:null Rnullnull nullnullPnulltnull nullnullPnulltnull nullnullPnulltnull null nullPnulltnull nullnullP4nullnull nullnullPnulltnull nullnull nullDnullnulltnull nullDnullnulltnull nullDnullnulltnull null Dnullnulltnull nullD4P4nullnull nullDnullnulltnull Wnullre: Rnullnull nullRelative amplitude onulltnull renullcted signal nullitnullrespect to tnull direct signalnull enullressed as a rationullLimited to tnull range nullto null null nullnull nullDelanullonulltnull multipatnullsignal relative to tnull direct signal nullecondsnull tnull nullnullormalised time nullnullt nulltnullnull nullnull t nullTime into simulation nullecondsnull tnullnull Time into scenario at nullicnullto start generation onulltnull multipatnullsignal nullecondsnull T null Duration onulltnull multipatnullsignal nullecondsnull Pinullnull nullLegendre polnullomial onullinullnullorder null nullnullto null: Pnulltnull nullnull Pnulltnull nulltnull Pnulltnull nullnullnullnull nullnullnull Pnulltnull nullnullnullnull nullnullnullnull P4nullnull null4null7nullnull nullnull7nullnull nullnullnullnull Pnulltnull null7null7nullnull nullnull7nullnull nullnullnullnullnull Tnull null and Di terms are tnull multipatnull coenullcientsnullTnullse are in tnull inullnull coenullcients onulltnull enullansion onulltnull relative amplitude and delanullnullnctions nullespectivelnull in terms onullLegendre polnullomials, determined using tnull nullllonullng enullations, nullr nullonull Rnullnull and Tnullnull pronullesnull Page nullSPIRENT Application Note nullor eacnullLegendre multipatnull nullou must enter values nullr tnull nullllonullng polnullomial coenullcients in tnull nullanual multipatnull settings dialog: null to null nullcoenullcients null to null in tnull Legendre polnullomial nullr Rnullnullnull Dnullto Dnullnullcoenullcients Dnullto Dnullin tnull Legendre polnullomial nullr Dnullnullnull Duration nullnullnulltnull period onulltnull Legendre cnullclenullnullt is tnull period betnulleen nullicnull tnull ecnull is modellednullnullnce a period nulls enullired tnull ecnull pattern is continuallnullrepeatednull Successive periods are images onulltnull nullst period, nullr enullmple: nullou denulle tnull nullst period to be Tnullnull Tnull Tnullnull Tnullis identical to Tnullnull Tnull Tnullnull Tnullis identical to Tnullnull Tnull Tnullnull T4 is identical to Tnullnull Tnull nulligure null snullnull tnull Legendre nullultipatnull settings nullndonullnull nulligure null Legendre nullultipatnullSettings Windonull Page nullSPIRENT Application Note Polnullomial Multipath Tnull Polnullomial nullultipatnullmodel is similar in application to tnull Legendre metnulldnull nulln tnulls case, tnull polnullomial coenullcients manullbe more intuitivelnulldenulled, but tnull corresponding disadvantage is tnullt tnull multipatnullpronulle is no longer bounded, so nullr dinullnullrent durations, tnull coenullcients manullneed to be revised to prevent unnull realistic multipatnullonullnullets being appliednull nulln tnull Polnullomial multipatnullmodel, tnull nullllonullng nullnctions represent tnull relative amplitude and delanullonulltnull multipatnullsignal: Relnullp null anullnullanull nullanullnullnullanullnullnulla4t4 nullanullnull Delanullnull dnullnulldnull nulldnullnullnulldnullnullnulld4t4 nulldnullnull Wnullre: Relnullp nullRelative amplitude onulltnull renullcted signal nullitnullrespect to tnull direct signalnull enullressed as a ratio, limited to tnull range nullto null nullternativelnull, tnull relative amplitude in dnull dnullrel, is nullnullnulllognullnullelnullpnull DelanullnullDelanullonulltnull multipatnullsignal relative to tnull direct signal, seconds t nullseconds nullor eacnullPolnullomial multipatnull nullou must enter values nullr tnull nullllonullng polnullomial coenullcients in tnull nullanual multipatnull settings dialog: null to null nullcoenullcient anullto anullin tnull polnullomial nullr Relnullpnull Dnullto Dnullnullcoenullcient dnullto dnullin tnull polnullomial nullr Delanullnull Duration nullnullnulltnull period onulltnull polnullomial cnullclenullnullt is tnull period betnulleen nullicnulltnull ecnull is modelled and prevents tnull ecnull going to innullitnullnullnullnce a period nulls enullired tnull ecnull pattern is continuallnullrepeatednull Successive periods are mirror images onulltnull nullst period, nullr enullmple: nullou denulle tnull nullst period to be Tnull → Tnull Tnull → Tnullis identical to Tnull → Tnull Tnull → Tnullis identical to Tnull → Tnull Tnull → T4 is identical to Tnull → Tnull nulligure null Polnullomial nullultipatnullSettings Windonull Page nullSPIRENT Application Note Sinusoidal Multipath Tnulls model allonull nullou to applnulla sinusoidal variation to tnull delanulland amplitude onull a multipatnullsignalnullnull nulltnulltnull Legendre and Polnullomial models, tnulls metnulld simulates a representative enullnullct nullr tnull multipatnullsignals, ratnullr tnulln being based on tnull venullcle and satellite geometrnullnull Tnulls metnulld nulls tnull advantage tnullt it gives a timenullarnullng multipatnullsignal nullicnullis nullell bounded and easilnulldenullednull nullor eacnullSinusoidal multipatnull nullou must enter values nullr tnull nullllonullng sinusoidal coenullcients in tnull nullanual multipatnull settings dialog: nullttenuation Peanullnullnull null Tnull min and manullpeanulllevels onulltnull attenuation onulltnull sinusoidnull nullttenuation nullrenullnullnull nullTnull nullenullencnullonull tnull sinusoidal variation onulltnull multipatnull nullttenuation Pnullse nullegnullnullTnull start pnullse onulltnull attenuation onulltnull sinusoidnull nullttenuation nullias nullonullnullet nullTnull onullnullet betnulleen tnull sinusoid and tnull Lnull signal level DelanullPeanullnullsnullnullnull peanullonullnullet delanull to tnull sinusoidnull DelanullnullrenullnullsnullnullTnull nullenullencnullonulltnull onullnullet delanullto tnull sinusoidnull DelanullPnullse nullTnull pnullse onulltnull onullnullet delanull to tnull sinusoidnull Delanullnullias nullonullnullet nullTnull onullnullet delanullto tnull sinusoidnull Tnull representation onulltnull attenuation parameters is snullnull in nulligure nullnull nulligure null Sinusoidal nullultipatnull nullttenuation Parameters nulligure null Sinusoidal nullultipatnullSettings Windonull Page nullSPIRENT Application Note Land Monullle Multipath nullMMnull Tnull Land nullobile nullultipatnullmodel nulls developed to nulllnull tnull need to simulate tnull signal environment enullnullcts enullerienced bnulla portable device nullucnullas a mobile pnullnenull Tnull multipatnullmodels so nullr discussed are analnullical in tnullir approacnull nullicnullcould present a signinullant cnullllenge to tnull mobile pnullne tester, as sucnulltests per nullndset can number mannullnullndredsnull Tnull Lnull model allonull nullou to automaticallnull denulle tnull signal conditions tnullougnull selection nullom a database onullprenullenulled environments nullr eacnulltestnullTnull analnullical data relating to tnull delanulland amplitude variation associated nulltnulltnull Lnull signals and tnull multipatnullrenullctions are replaced nulltnullstatistical models commonlnull used in laboratornulltesting onullnullreless communication enullipment, togetnullr nulltnull a besponull cnullnnel allocation algoritnull nullr management onulltnull simulator nullrdnullrenull Tnulls allonull tnull nullllonullng enullnullcts to be realised: nullDirect Lnull signals nulltnullRician nullding null Renullctions nullcnullesnullnulltnullRanulleignullnullding, ponuller decanulland enullonential delanull null Deep nullding onullecnulles, giving a carrier Doppler onullnullet Tnull relative numbers onulltnull direct and renullcted signals are determined using a satellite visibilitnullcategornullmasnull nullicnulluses tnull anullmutnulland elevation onulltnull Lnull signalnull Renullrence nullgives an innulleptnulldescription onulltnull approacnulltanulln in developing tnull Lnull modelnull Tnull Lnull model is enabled in Simnullnull in a dinullnullrent nullnullto tnull otnullr models described in tnulls notenullnullt is onlnullavailable nullr use nulltnulltnull Static nullenullcle model, and is not available via tnull Cnullnnel nullsignment settings nullndonullas described in section 7nullnullnullou can also use nullser nullctions and tnullre is a SimREnullTE command nullnullnull SELECTnull tnullt allonull nullou to denulle tnull Lnull environment categornullmasnull nullou can also use tnullse metnullds to cnullnge tnull categornull masnullsettings nullile tnull scenario is runningnull See Renullrence 4 nullr more details onulltnull remote commandnull To enable Lnull, select nullptions, and ticnull Land mobile multipatnullnulle to include tnull Land nullobile nullultipatnullmodel in tnull scenarionullTnull nullctive Connulluration area displanull tnull selected nullctive multipatnull environment and nullctive multipatnullcategornull masnull Tnull current selections denulle tnull environment and masnulltnullt applnull at tnull start onulltnull scenarionullSelect tnull Environment editor, or Categornullmasnull editor, to vienullor edit tnull settingsnull Ennullronment Editor Tnull Environment editor is used to denulle tnull cnullracteristics onulltnull Rician and Ranulleignullmodels as a nullnction onullsatellite elevationnullTnull operation onulltnull multipatnull model is controlled bnulltnull contents onull a number onullloonullup tables, driven bnull satellite elevation angle and satellite selection intervalnull nulligure null snullnull tnull Environment editor nullndonullnull Page 2nullSPIRENT Application Note nulligure null Lnull Environment Editor Windonull Tnull Rician, Ranulleignulland Deep nullade model parameters are manuallnullentered in tnull corresponding bonullesnull Tnullse models are described as nullllonull: Rician nullading Model Tnull Rician model is used to describe tnull nullding on linenullnullsignull signalsnull nullere is tnull received signal amplitude relative to tnull direct patnull is tnull ratio onulldirect to multipatnullponuller received and is a constantnull is tnull nullnullorder modinulld nullessel nullnction onulltnull nullst nullndnull Page 2nullSPIRENT Application Note Ranulleigh nullading Model null modinulld Ranulleignullmodel is used to describe tnull nullding on ecnull cnullnnelsnull Tnullre is a deterministic mean ponuller nullnction, an amplitude noise nullnction nullanulleignull and a delanullnullnctionnull Tnull deterministic mean ponuller reduction in addition to Ranulleignullnoise, is given bnull nullere Pnullnull and d are provided bnull a loonullup table, and nulltnull delanull onulltnull ecnull signal Tnull amplitude noise on tnull ecnull cnullnnel, determined on evernulluser denulled iteration period, is randomlnullcalculated nullom a Ranulleignulldistribution given bnull Tnull user can denulle tnull iteration period nullinimum nullms nulltnulla resolution onullnullmsnull nullt is listed as Ponuller level update interval in tnull land mobile multipatnull environment editornull Tnull delanullon tnull ecnull cnullnnel is calculated at random nulltnullan enullonential distribution: nullere b is tanulln nullom a loonullup tablenull null upper limit is imposed as determined bnulltnull nullanullmum nullear Ecnull Delanull parameter in tnull land mobile multipatnull environment editor nullndonullnull Wnulln tnull satellite is uncnullnged and satellite position modelling not enabled, tnull delanullremains nullednull Page 22SPIRENT Application Note nulleep nullade Model nulln all ecnulles tnullt are not tnull primarnull ecnull, a carrier Doppler onullnullet is applied: Wnullre: Ψ is tnull conversion nullctor nullom mnull to onullnullet rate v is tnull velocitnullbeing emulated, nullisted as nullser velocitnullvalue in tnull land mobile environment editornull αe is tnull elevation angle onulltnull satellite nullis tnull bias value nullr nullero peed nullisted as nullero speed onullnullet in tnull land mobile ronment editornull CategornullMasnullEditor nullou can use tnull CategornullnullasnullEditor to denulle a masnullnullicnullis applied over tnull simulated antennanullnullt is similar to tnull nulltenna Pattern editor described in section 7null, in tnullt it represents tnull receivernulls vienullonulltnull snull as an arranullonullanullmutnull and elevationnullnullt allonull nullou to denulle tnull signalnullnullnullcting properties onulleacnullportion onulltnull nullsnull vienullnull as one onulltnull nullllonullng nullur categoriesnullnullou can applnulleacnullonull tnullse categories independentlnull nullr dinullnullrent test casesnullTnull signal arrival angle is resolved into satellite elevation and anullmutnullin nulldegree increments nullr positive elevations onlnullnull Tnull renullrence nullame is local geograpnullc, and tnull orientation onull tnull nullmispnullre created manullbe rotated in tnull anullmutnullplane: null CategornullA nullComplete onullcurationnull Satellites arriving at tnullse segments are not simulated at all and nullnce tnulls categornullrepresents a visibilitnullmasnull nulll satellites nulltnullelevation angles less tnulln nulldegrees are automaticallnull enullcludednullegments nulluld be allocated nulltnulltnulls categornullto simulate obstructions at lonullelevation angles at particular anullmutnullangles, sucnullas adnullcent buildings, or at nullgnullelevations to simulate tnull case nullr a user positioned nulltnulln a tall buildingnullnullse onulltnullse segments manullmises use onulltnull available cnullnnels nullr meaningnulll signal simulationnull Page 23SPIRENT Application Note null CategornullnullnullLOS onlnull Satellites arriving at tnullse segments are simulated nulltnulla linenullnullsignull nullnullnullsignal onlnullnullTnullse signals represent signals tnullt are generallnullunobstructed and not subnullct to renullctionsnullSatellites nulltnulln categornullnullsunullnullr Rician nulldingnull null CategornullC nullLOS nullEchoes Satellites arriving at tnullse segments are simulated as a Lnull plus ecnulles, depending upon tnull number onull cnullnnels availablenullTnullse signals represent unobstructed signals tnullt are subnullct to renullctionsnullSatellites nulltnulln categornullC sunullnullr Rician nullding on tnull Lnull cnullnnel and modinulld Ranulleignull nullding on tnull ecnullesnull null CategornullnullnullEchoes onlnull Satellites arriving at tnullse segments are simulated as ecnulles onlnullnullnull Lnull signals are obstructednull depending upon tnull number onullcnullnnels availablenull Satellites nulltnulln categornullD nullve modinulld Ranulleignullnullding applied nullr tnull ecnullesnull nullou can create representative environments surrounding tnull receiver antennanullnulligure null snullnull a simple urban environment nullere tnullee buildings onulldinullnullrent nullignull are surrounding tnull receivernulls antennanull nullour masnull are present bnulldenullultnullDenullult, nullrban Cannullon, Trees, and nullignullanullnulllnullovernull nullou can manull copies onulltnullse and edit and save tnullm as usernullenulled environmentsnull nulligure null Land nullobile nullultipatnullCategornullnullasnullEditor Page 24SPIRENT Application Note nullader Multipath Tnull implementation onulltnull multipatnull models so nullr described is accomplisnulld bnullassigning an independent simulator nullrdnullre cnullnnel to eacnullmultipatnullecnull signal nulls nullgnullignulled on page nullnull Tnull compromises made are also discussednull Spirentnulls nullader nullultipatnullimplementations use a dinullnullrent approacnull nullere nullou can simulate up to nullur multipatnullsignals nullr eacnullsingle simulator nullrdnullre cnullnnelnull Digital replica nullsubnullnullnnelsnull are created in tnull signal generator nullnulls, and tnull level, delanulland pnullse onulleacnullcan be independentlnulldenullednullTnull nullader nullultipatnull model is currentlnullonlnullavailable via a SimREnullTE command and is not available on all snulltemsnullRenullrence 4 nulls more innullrmation on tnulls modelnull Page 2nullSPIRENT Application Note Conclusions Tnulls nullpplication nullote describes tnull nullndamental pernullrmance parameters tnullt applnullto all nullSS receiversnull Tnullse parameters must be optimised at an earlnullstage in a receiver designnull nullptimisation renullires suitable testingnull Tnulls nullpplication nullote snullnull tnullt a nullSS simulator allonull nullou to develop tests tnullt optimise receiver designnullSimnullnull onullnullrs vernullnullgnullresolution control onullsignals and bitnullevel manipulation onulldata, reproducing tnull most complenullerror enullnullcts nullile its easnulltonullse internullce allonull straignullnullrnullrd tests to be carried out nulltnulltnull same ponullernulll modelling tanullng place in tnull bacnullroundnull nullt snullnull tnullt tnullre are no practical alternatives to simulator testing in situations nullere tnull receiver must be tested nullile undergoing nullgnulldnullamic motionnull Renullrenced nullocuments null nullitigating Snullrtnullelanullnullultipatnull a Promising nullenullTecnullinulle nullleenullegen, nullon, Septentrio Satellite nullavigationnull null nullnderstanding nullS nullPrinciples null nullpplications, nullnullnullplan, Cnullnullegartnull, nulld Ed, nullnullnull null nulllobal Positioning Snulltem nullSignals, nulleasurements nullPernullrmance nullnullnullisra, PnullEng, nullnullnull 4null Dnull7nullnullnull SimREnullTE nullser nullanual nullnd nullDnullnullpirentnull null Proposed nullodels and nulletnulldologies nullr nullerinullation Testing onullnullnullSnullnullipped Cellular nullobile Pnullnes in tnull Laboratornull nullnullnullulton, null null Read Etnullnullnull Page 2nullSPIRENT Application Note nulllossarnullonullTerms nullPP nulld nulleneration Partnersnullp Pronullct Cnull code Coarse nullcnullisition code used bnull Standardnullervice nullS receivers Cnullp Tnull time betnulleen transitions in tnull Cnull code nullot renullrred to as a nullitnull because tnull code does not carrnullinnullrmationnull DnullS Dinullnullrential nullS nullSS nulllobal Satellite nullavigation Snulltem LnullS Line onullSignull PRnull Pseudonullandom nullumber Pnull Position, nullelocitnull, Time Scenario nulln tnulls contenull, a nullSS simulation running on eitnullr Simnullnull or SimPLEnullsimulator control sonullnullrenull Snull nullS Satellite nullenullcle Wnullnull4 World nulleodetic Survenullnullnull Page 2nullSPIRENT Application Note CONTACT null Spirent Communications null4 nullnull nullnullnull globalsalesnullpirentnullom nullnullnullpirentnullomnullositioning Spirent nullederal Snulltems null 7null nullnullnullnull innullnullpirentnullderalnullom nullnullnullpirentnullderalnullom nullaceboonull Linnulldnulln Tnulltter Tecnullorati nulloogle nullunull Digg Delicious Reddit Stumbleupon nullnullnot share this documentnull nullot a smartphonenull If you have a smartphone download a QR Code reader and then point your phone camera at the QR Code to read the graphic. Dnullnull4 nullSnull nullnull Revnullnullnullnullul nullnull nulle are adding nenullcontent to our nullenullite on a regular nullsisnull nullonullarnullthis linnull nullnullnullpirentnullomnullositioning nullisit the Spirent nullSS nullognullthere are currentlnullonuller null posts nullth 2 to 3 nenullposts added each nulleenull Catch up on nullatnulls nenullnull nullnullnullpirentnullomnulllognullositioningnullspnull Need more innullrmationnull gnssnullolutionsnullpirentnullom