Blumens ein e al. EURASIP Jou nal on Wi eless Communica ions and
Ne wo king (2015) 2015:104
DOI 10.1186/s13638-015-0332-3
RESEARCH Open Access
Measu emen s o ul a wide band in- ehicle
channel - s a is ical desc ip ion and TOA
posi ioning easibili y s udy
Ji i Blumens ein1*, Ales P okes1, Tomas Mikulasek1, Roman Ma salek1, Thomas Zemen2
and Ch is oph Mecklenb äuke 1,3
Abs ac
This pape epo s on a eal-wo ld wi eless channel measu emen campaign o in- ehicle scena ios in he UWB
equency ange o 3 o 11 GHz. The e ec s o an enna placemen in he ehicle’s passenge compa men as well as
he e ec s due o he p esence o passenge s a e s udied. The measu emen s ha e been ca ied ou in he equency
domain, and he co esponding channel impulse esponses (CIRs) ha e been es ima ed by in e se Fou ie ans o m.
The in luence o a speci ic band g oup selec ion wi hin he whole UWB ange is also gi en. S a is ical analysis o he
measu ed channel ans e unc ions gi es a desc ip ion o he wi eless channel s a is ics in he o m o a gene alized
ex eme alue p ocess. The co esponding pa ame e se s a e es ima ed and documen ed o all pe mu a ions o
an enna placemen and occupancy pa e ns inside he ehicle’s passenge compa men . Fu he , we ha e ca ied
ou a easibili y s udy o an in- ehicle UWB-based localiza ion sys em based on he TOA. The posi ioning pe o mance
is e alua ed in e ms o a e age e o and s anda d de ia ion.
Keywo ds: UWB; In- ehicle en i onmen ; Channel model; Posi ioning; TOA
1 In oduc ion
The onboa d elec ical powe dis ibu ion, communica-
ion, and ne wo king unc ionali ies a e ealized by cable
bundles in oday’s ehicles. We obse e a end owa ds
inc easing numbe s o senso s, ac ua o s, con ol uni s,
and in o ainmen sys ems in ca s and ucks. As a di ec
esul , he weigh o he wi ing in all ypes o ehicles
inc eases. Mo eo e , hei lexible ins alla ion and eli-
abili y ep esen a challenging and cos ly ask [1]. The
weigh o he wi ing becomes e en mo e se ious when he
ehicles a e powe ed ully elec ically.
In [2,3], he au ho s conclude ha ul a wide band-
wi h (UWB) echnology wi h i s a o able adio en i on-
men cha ac e is ics o indoo a eas such as low ansmi
powe and obus ness agains mul ipa h ading could be
ex apola ed e en o he ehicula passenge compa -
men . Na u ally, a emp s o eplace cable bundle s a
*Co espondence: [email p o ec ed]
1Depa men o Radio Elec onics, B no Uni e si y o Technology, Technicka
12, 612 00, B no, Czech Republic
Full lis o au ho in o ma ion is a ailable a he end o he a icle
up wi h in- ehicle adio channel measu emen s we e pe -
o med by au ho s in [4-9] and by channel modeling in
[3,10], and a clus e ing app oach o in a-bus channel
modeling is s udied in [11,12]. A emp s o build a p o-
o ype o an UWB-based wi eless senso ne wo k wi hin
a ehicle, bo h in he passenge and he engine com-
pa men s, a e published in [13,14]. In [15], he opic o
wi eless in- ehicle communica ion links based on LTE is
discussed while eckoning wi h speci ic in- ehicle impulse
noise. In [16], he UWB channel inside a ehicle is s ud-
ied om a spa ial s a iona i y poin o iew. The necessi y
o de ailed knowledge o he channel cha ac e is ics is o
highes impo ance o he p ope physical laye design o
any wi eless communica ion sys em.
Toge he wi h his mo i a ion o subs i u e a leas pa
o he ehicle’s cable bundles by wi eless links, a wi eless
localiza ion se ice wi hin he ehicle is desi able. Fu u e
applica ions o such a localiza ion se ice include emo e
keyless en y and igni ion sys ems, ad anced child pas-
senge sa e y, and beams ee ing o in- ehicle high-speed
In e ne access.
© 2015 Blumens ein e al.; licensee Sp inge . This is an Open Access a icle dis ibu ed unde he e ms o he C ea i e Commons
A ibu ion License (h p://c ea i ecommons.o g/licenses/by/4.0), which pe mi s un es ic ed use, dis ibu ion, and ep oduc ion
in any medium, p o ided he o iginal wo k is p ope ly c edi ed.
Blumens ein e al. EURASIP Jou nal on Wi eless Communica ions and Ne wo king (2015) 2015:104 Page 2 o 10
In [14,17], a localiza ion se ice u ilizing UWB is
s udied and i is concluded ha in gene al, hanks o
he high ime esolu ion o UWB impulses, he ime
o a i al (TOA) echnique is capable o p o iding su -
icien spa ial esolu ion o a a ie y o applica ions.
Al hough he TOA wo ks eliably in en i onmen s wi h
LOS, i can be used wi h some es ic ion also in NLOS
scena ios. In he mul ipa h en i onmen , he impo an
componen o anging based on he TOA echnique
is he di ec ay, which p opaga es om he ansmi -
e owa ds he ecei e . When he beam pene a es
some obs acles whose a enua ion does no a oid he
beam de ec ion, he TOA echnique is applicable. No e
ha , o example, in he US, he equency ange o
1.99 o 10.6 GHz is de egula ed o communica ions
and wall-pene a ing ada s, enabling looking in o o
h ough non-me allic ma e ials [14,18]. Thus, he p e-
sump ion is ha e en he ha sh in- ehicle ambiance wi h
OLOS p opaga ion may p o ide su icien posi ioning
accu acy.
In [4,6,7,19], he pa h-loss, sea ma e ial, and occupancy
in luences a e p esen ed o he equency ange o 3 o
8 GHz. Since he posi ioning se ice deploymen is no
seen as he aim o [4,6,7,19], he placemen o ans-
mi an ennas is inapp op ia e om ha poin o iew.
Thus, esul ing pa ame e s could di e om pa ame-
e s ob ained by measu emen campaigns which ake he
posi ioning in o accoun in he i s place.
1.1 Con ibu ion o he pape
While aking in o accoun he in luence o he occupancy,
an enna placemen , and he in luence o a speci ic e-
quency band g oup selec ion, in his pape , we add ess he
ollowing:
•In a- ehicle channel measu emen and s a is ical
e alua ion ia GEV. This allows a ep oducibili y o
he measu ed esul s o 90 selec ed wi eless links
wi hin a passenge ca compa men .
•S a is ical analysis and he in- ehicle posi ioning in
he UWB ange o 3 o 11 GHz. The aim o he a icle
is o gi e a gene al o e iew o he achie able
accu acy o anging ega dless o LOS and NLOS
scena ios.
The pape is o ganized as ollows. In Sec ion 2, we p o-
ide an o e iew o ou measu emen si e including a
ha dwa e desc ip ion. In Sec ion 3, we p esen ou chan-
nel measu emen ools including ou conical monopole
an enna design [20] and we de ine he sough channel
pa ame e s. In Sec ion 4, he easibili y o he posi ion-
ing se ice deploymen wi hin a ehicle compa men is
assessed, while he conclusion in Sec ion 5 sums up he
pape .
2 Measu emen se up
2.1 Measu emen bandwid h and dynamic ange
Theschemeo hemeasu emen se upisshownin
Figu e 1. The complex CIRs (below in oduced by (1))
co esponds o he s41,s42,ands43 sca e ing pa ame e s
which a e measu ed in he equency domain o wo di -
e en equency bands, 3 o 11 GHz (en i e UWB band
wi h a bandwid h o B= 8 GHz ) and 3.3168 o 4.752 GHz
( i s band g oup wi h a bandwid h o B=1.58GHz),u i-
lizing a ou -po ec o ne wo k analyze Agilen Tech-
nologies E5071C (VNA; Agilen Technologies Inc., San a
Cla a, CA, USA) (Figu e 2). The spa ial placemen o he
ecei ing (RX) and ansmi ing (TX) an ennas inside he
ehicle is depic ed in Figu e 3.
The dynamic ange o he measu emen se up is highe
han 90 dB (Pou VNA = 5 dBm, IF bandwid h = 100 Hz).
The chosen equency s ep o 10 MHz esul s in 801 e-
quency poin s in he case o he en i e UWB band and 159
equency poin s in he case o he i s band g oup.
In o de o a oid a deg ada ion o he measu ed phase
accu acy due o mo emen s o he RX an enna, phase-
s able coaxial cables we e used and included in he cal-
ib a ion p ocess. The measu emen is ca ied ou in he
Skoda Oc a ia 1.8 TSI ca .
2.2 An enna placemen
As depic ed in Figu e 3, he RX an enna is placed a a i-
ous loca ions inside he ca compa men (on all sea s and
in he boo ) and he TX an ennas a e placed on he le and
igh sides o he dashboa d, op co ne s o he windshield,
and a he ea pa o he ceiling.
The channel measu emen s a e ca ied ou o bo h
LOS and NLOS scena ios. NLOS is caused by he back es
o he sea s, he dashboa d, and/o pe sons si ing inside
he ehicle.
Figu e 1 Measu emen se up con aining he ec o ne wo k analyze
Agilen Technologies E5071C and he ca Skoda Oc a ia 1.8 TSI.
Blumens ein e al. EURASIP Jou nal on Wi eless Communica ions and Ne wo king (2015) 2015:104 Page 3 o 10
Figu e 2 Images o he conical monopole an enna, measu emen posi ion, and ou -po VNA. [le ] De ail o he conical monopole an enna
moun ed on he on windshield. [middle] One measu emen posi ion inside he ehicle. [ igh ] Fou -po VNA connec ed wi h an ennas inside he
measu ed ehicle.
Since he adia ion pa e n o he conical monopole
an enna [20] is e y close o he omnidi ec ional adia-
ion pa e n, we we e able o cap u e a maximal numbe
o mul ipa h componen s ( e lec ed wa es).
In Figu e 4, he conical monopole has an omnidi ec-
ional H-plane adia ion pa e n which is in a ian in
he equency band o in e es . Due o a a iable gain
in he lowe hal E-plane adia ion pa e n (ele a ion
angle om 90° o −90°), he an ennas we e placed in he
ca compa men so ha he uppe hal E-plane adia-
ion pa e n (almos cons an ) was used. I means ha
when he an enna was placed a he cabin ceiling, i was
si ua ed bo om up. Thus, he LOS and NLOS a e min-
imally a ec ed by he adia ion pa e n; howe e , wi h
he e lec ed wa es a i ing om he TX an enna o
inciden on he RX an enna, he lowe ele a ion angle
migh be a ec ed by he non-ideal adia ion pa e n o he
an ennas.
3 Channel pa ame e s
The CIR desc ibes he wi eless channel. We u ilize an
in e se disc e e Fou ie ans o m o he windowed sca -
e ing pa ame e se ies, exp essed as:
hα(n)=
N−1

k=0
w(k)sα
ζ(k)ejkn2π/N,(1)
whe e sα
ζ(k)co esponds o he k h measu ed sca e ing
pa ame e (as desc ibed in Sec ion 2) and w(k) ep e-
sen s he Blackman window. Pa ame e αdeno es he
spa ial posi ions o he ansmi and he ecei e an enna
in he measu ed ehicle and ζ∈{41, 42, 43}. Fo p ac i-
cali y in he ollowing s a is ical p ocessing, we a bi a ily
me ge indices αand ζin o one measu emen numbe
α∈{1, ...,90}.Hence,in he ollowing,i isno possible
o assign he speci ic measu ed da a o he ac ual spa ial
posi ions.
Figu e 3 The posi ions o ansmi ing ( ed) and ecei ing (blue) an ennas. We employ wo possible ecei e an enna placemen pa e ns. As seen
on he le pa , he an ennas 1a and 2a occupy he le and igh op co ne s o he windshield, while on he igh pa , he an ennas 1b and 2b a e
posi ioned in he lowe co ne s. Please no e ha all measu emen s ha e been measu ed o a ious passenge layou s. We ha e conside ed (1)
emp y ehicle and (2) d i e and wo o h ee passenge s.
Blumens ein e al. EURASIP Jou nal on Wi eless Communica ions and Ne wo king (2015) 2015:104 Page 4 o 10
Figu e 4 Measu ed gain pa e n o he conical monopole an enna [20].
The numbe o measu ed equency poin s N=801 o
heen i eUWBo N=159 o he i s band g oup. Since
he in- ehicle channel is assumed o be ime in a ian ,
we pe o med one epe i ion o he sca e ing pa ame e
measu emen .
The ela ionship be ween disc e e ime delay nand
con inuous ime delay τis gi en by:
τn=n1
B,(2)
whe e 1/Bs ands o he ime esolu ion (see Equa ion 7).
Fo a s a is ical cha ac e iza ion o he UWB channel,
we use he MDP which is de ined as he magni ude o
complex CIR:
A(τ) =|h(τ)|.(3)
3.1 S a is ical desc ip ion o he ecei ed signal
3.1.1 Independen iden ically dis ibu ed (IID) phase
In his chap e , he phase s a is ics o he measu ed CIRs
a e p esen ed. As isible in Figu e 5 [ igh ], acco ding
o he ecd e alua ed o each measu ed CIR, he phase
α(τ) is uni o mly dis ibu ed.
Mo eo e , u ilizing he Pea son co ela ion coe icien
ρα,β, we e alua e he mu ual dependence be ween phases
o all measu ed posi ions deno ed as αand β.ThePea -
son co ela ion coe icien is gi en as:
ρα,β=E(α(τ) −ξα)β(τ) −ξβ
℘α℘β,(4)
whe e ℘αdeno es he s anda d de ia ion and ξα he mean
o α(τ). The e alua ion o he Pea son co ela ion coe -
icien is isible in Figu e 5 [le ] showing unco ela ed
beha io o α(τ). The ope a o E[·] deno es he expec ed
alue.
Figu e 5 Pea son co ela ion coe icien and ecd cu es. [le ] The Pea son co ela ion coe icien ρα,βe alua ion o he measu ed α(τ).[ igh ]
The ecd cu es o α
n. The close he blue ecd cu e o he ed line, he close he p obabili y dis ibu ion o α(τ) o he uni o m dis ibu ion.
Blumens ein e al. EURASIP Jou nal on Wi eless Communica ions and Ne wo king (2015) 2015:104 Page 5 o 10
Acco ding o he esul s p esen ed in Figu e 5, we con-
clude ha α(τ) is iid uni o mly dis ibu ed wi h espec
o he measu emen numbe α.
3.1.2 S a is ics o he ecei ed signal magni udes and GEV
U ilizing MLEs [21], we ha e ound a s a is ical model o
ecei ed signal magni udes. As seen in Figu es 6 and 7, he
ecei ed signal magni udes can be app oxima ed using he
GEV dis ibu ion [22] wi h he PDF gi en by:
(x|0, μ,σ) =1
σexp{−z−exp(−z)},whe ez=x−μ
σ,
(5)
wi h μbeing he loca ion pa ame e and σ he dis ibu-
ion scale pa ame e . Equa ion 5 ep esen s he GEV ype
I dis ibu ion, also known as log-Weibull dis ibu ion,
whe e he shape pa ame e de ined in he egula GEV is
se o ze o. This app oach is jus i ied in Sec ion 3.1.3.
In o de o cap u e he s a is ical na u e o he en i on-
men , we ha e pe o med 90 measu emen s pe mu ing
bo h he TX and RX an enna placemen s as well as he in-
ca sea occupancy. In Figu e 6, we can see he CDF cu es
o all pe mu a ions o he an enna placemen and occu-
pancy,whileeachcu eis i edbyaGEV ypeI andom
p ocess ob ained by he MLE i ing.
3.1.3 GEV pa ame e s as a andom p ocess
Acco ding o he obse a ions o esul ing GEV pa am-
e e s, we app oxima e he co esponding μ,k,andσ
pa ame e s wi h he s a is ical model ob ained by MLE.
Figu es 8, 9, and 10 compa e he CDFs o he measu ed
μ,k,andσpa ame e s wi h andom p ocesses o co e-
sponding dis ibu ions.
Figu e 7 PDF o he ecei ed signal magni udes in dBm o one
measu emen se up. The measu ed PDF is i ed wi h he GEV ype I
p ocedu e.
The loca ion pa ame e μ ollows he logno mal dis i-
bu ion gi en as:
(x|η,ν) =1
xη√2πexp −(lnx−ν)2
2η2,(6)
whe e νis he mean and η ep esen s he s anda d de i-
a ion. The ex ac ed shape pa ame e kis o signi ican ly
low alues; he e o e, ou choice o he GEV ype I (also
known as log-Weibull) cha ac e ized by k=0 is app o-
p ia e (see Equa ion 5). The scale pa ame e σis no mally
dis ibu ed.
Figu e 6 The CDF o ecei ed signal magni ude in dBm o all pe mu a ions o an enna placemen and occupancy. Measu ed cu es a e i ed wi h
he GEV ype I p ocedu e.

Blumens ein e al. EURASIP Jou nal on Wi eless Communica ions and Ne wo king (2015) 2015:104 Page 6 o 10
Figu e 8 The CDF plo o loca ion pa ame e μ i ed wi h logno mal
dis ibu ion (wi h 95% con idence in e al).
A summa ized o e iew, including he speci ic alues o
μand η, is gi en in Table 1. Thanks o a high numbe o
pe o med measu emen s, he abula ed alues ep esen
ypical da a o an in- ehicle channel which also applies o
ehicles o simila size, sea con igu a ions, and ma e ials
u ilized o i s manu ac u e.
A co ela ion be ween he de i ed pa ame e s μand η
(k=0) exhibi s a e y weak posi i e co ela ion alue o
0.35 wi h a p alue below 6 ×10−4. Thus, o ec ea e he
ecei ed signal magni udes, one can a bi a ily choose he
pa ame e s μand ηacco ding o Table 1.
−0.2 −0.15 −0.1 −0.05 0 0.05 0.10.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
k
Cumula i e p obabili y
k: shape pa ame e
o GEV, measu ed
Logis ic dis ibu ion i
Figu e 9 The CDF plo o shape pa ame e k i ed wi h a logis ic
dis ibu ion (wi h 95% con idence in e al). Since he alues o he k
pa ame e a e e y small, in he ollowing we se k=0; hus, he GEV
becomes a GEV ype I (o log-Weibull) dis ibu ion.
Figu e 10 The CDF plo o scale pa ame e σ i ed wi h a no mal
dis ibu ion (wi h 95% con idence in e al).
Due o a high lexibili y o he GEV i , which is gi en by
h ee inpu pa ame e s as opposed o usual wo pa ame-
e s, he MLE me ic ecommends he GEV dis ibu ion.
On o he hand, au ho s in [23] claim ha he e is no heo-
e ical explana ion o encoun e ing his dis ibu ion ype.
We may, howe e , add ha he GEV con ains he accep ed
log-Weibull dis ibu ion as a special case o k=0.
4 Localiza ion
One o he o en discussed UWB applica ions is p ecise
anging and localiza ion especially when he TOA ech-
nique is used. As men ioned abo e, his is because he
la ge UWB bandwid h allows excellen ime esolu ion
(see Equa ion 7) and MPC sepa a ion. Because we had
measu ed he channel ans e unc ion o many di e -
en an enna posi ions, we wan ed o ge some insigh in o
a ainable anging accu acy. Ou es ima ion o he dis-
ance esul s om he CIR calcula ed om he complex
ans e unc ion. This app oach gi es some limi a ions
compa ed o a di ec channel sounding in he ime domain
whe e some ad anced echniques such as he ma ched il-
e ing o he known Gaussian pulses o a well-co ela ed
bina y sequences can be used [24].
We calcula ed he an enna dis ance using he TOA ech-
nique based on he de ec ion o he i s ay ansmi ed
Table 1 Summa iza ion o GEV ype I pa ame e s
cha ac e izing in- ehicle en i onmen o 90 pe mu a ions
o an enna placemen and ca sea occupancy
μσk
Dis ibu ion ype Logno mal No mal Logis ic
Mean ν48.37 5.48 −0.08
Va iance η31.05 0.26 0.002
Blumens ein e al. EURASIP Jou nal on Wi eless Communica ions and Ne wo king (2015) 2015:104 Page 7 o 10
om a pa icula an enna. The p oposed h eshold-based
sea ch algo i hm compa es indi idual signal samples o
he CIR wi h a ce ain h eshold in o de o iden i y he
ampli ude peak co esponding o he i s MPC. This
app oach allows o calcula e dis ance also in he NLOS
scena io because he i s ay may no be he s onges
ay. Howe e , pene a ion o he obs acles can cause some
measu emen accu acy deg ada ion (see below). The aim
o his chap e is o gi e a basic idea abou accessible
a e age e o and s anda d de ia ion o he measu ed dis-
ances o he en i e UWB band and o he i s band
g oup and also o he emp y and occupied ca . Fo mo e
in o ma ion abou he measu emen s and he dis ance
calcula ion, see [25]. Because all he pa icula measu e-
men s we e done o h ee TX an ennas and one RX
an enna, we also calcula ed RX an enna posi ion using
he 2D localiza ion echnique in o de o assess whe he
i co esponds a leas oughly o eali y, i.e., whe he i
is possible o example o eliably de ec a de ice on a
pa icula sea . No e ha mos o he abo e men ioned
applica ion does no need an accu a e localiza ion bu
only ough es ima ion o he de ice posi ion.
4.1 Basic sys em pa ame e calcula ion
The equency band Bde e mines he ime esolu ion o
measu emen by [24]:
T =1
B=1
FU−FL
,(7)
whe e FUis he uppe equency and FLis he lowe e-
quency o he band. The p opaga ion dis ance esolu ion
is hen
D =T c,(8)
whe e c=2.998 ×108m/s is he speed o he ligh . The
maximum measu able p opaga ion dis ance depends on
he numbe o measu ed equency alues NMinside he
equency band, i.e., on he equency s ep sacco ding o
Dmax =c
BNM=c
s
.(9)
I is ob ious om he equa ions abo e ha na owing
he bandwid h dec eases he dis ance esolu ion and he
educ ion in he measu ed equency poin s sho ens he
measu able p opaga ion dis ance.
4.2 Ranging and localiza ion o he ecei ing an enna
As men ioned abo e, he main aim o his sec ion is
calcula ion o he a e age e o and s anda d de ia ion o
he anging and e i ica ion o he RX an enna posi ion
(Table 2). The p ocessing o he measu ed da a consis s in
he ollowing s eps:
•Calcula ion o he CIR
•De ec ion o he i s inciden ay
•Calcula ion o he RX - TX1 o TX3 dis ances and
anging e o s
•RX an enna localiza ion
The CIR was calcula ed using he IFFT in combina-
ion wi h a Blackman window (see Figu e 11) applied o
all 801 equency esponse poin s. Be o e e o s a is-
ics calcula ion, we es ed a ew windows ( ec angula ,
Hann, Hamming, la op, Blackman, and Kaise -Bessel).
Al hough some windows (e.g., ec angula ) a e gene ally
ecommended o he applica ions whe e good compo-
nen sepa a ion is equi ed, hese windows could be inap-
plicable in ou case as hey may p oduce la ge side lobes
ha c oss he h eshold and cause inco ec i s ay de ec-
ion. Expe imen ally, we ound ha he bes esul s gi ing
hedis ancescloses o eali ya egi enby heBlackman
window. The second bes esul s can be hen ob ained
using he Hann window.
The h eshold o he i s ay de ec ion is gene ally
de e mined by he noise loo . I s alue is equal o he le el
o he peaks o noise, i.e., o he maximum ampli ude o
he CIR whe e he mul ipa h componen ampli udes a e
below noise le el. I is ob ious ha he p oposed algo-
i hm wo ks eliably in bo h LOS and NLOS scena ios, bu
i ails in some NLOS cases when he i s (di ec ) ay is
s ongly a enua ed and d owned in noise.
The dis ance o RX and TX an ennas is gi en by he o -
mula DA=cTD,whe eTDis he i s de ec ed ay a i al
ime. The e o s a is ics we e calcula ed sepa a ely o he
emp y and occupied ca . I was expe imen ally disco e ed
ha he wo o h ee passenge s si ing in he ca compa -
men cause e y simila esul s, and he e o e, hese cases
we e joined in o one se o esul s. Fo he RX an enna
localiza ion, he ila e a ion echnique [24] was applied.
Using he h ee calcula ed dis ances, his echnique allows
2D localiza ion.
Calcula ion o he a e age e o and s anda d de ia ion
o he measu ed dis ances is summa ized in Table 3 ( o
Table 2 The pa ame e s used o he anging
Bandwid h F eq. s ep Time esolu ion Dis ance Max. p opag. Max. measu emen
[GHz] [MHz] [ns] esolu ion [cm] dis ance [m] ime [ns]
UWB 8 10 0.125 3.750 30 100
Fi s band g oup 1.58 0.633 18.987
Blumens ein e al. EURASIP Jou nal on Wi eless Communica ions and Ne wo king (2015) 2015:104 Page 8 o 10
Figu e 11 Magni udes o channel ans e unc ions and channel impulse esponses (RX an enna was placed on igh ea sea ).
he en i e UWB) and Table 4 ( o he i s band g oup).
The imein e alsused o henoisepeakde ec ionwe e
0 o 1.25 ns (be o e ecei ing o he i s MPC) and 80
o 100 ns (whe e he MPC can be neglec ed). These ime
in e als co espond o he ollowing dis ances: 0 o 37.5
cm (minimum dis ance o RX-TX an ennas in all scena ios
is 50 cm) and 24 o 30 m. The e e ence an enna dis-
ances we e measu ed by a ule . We compa ed 15 ×3
dis ances wi hou passenge s and 15 ×3dis anceswi h
wo o h ee passenge si ing on he sea s su ounding he
RX an enna. An example o peak de ec ion o he emp y
ca is shown in Figu e 12 (uppe pa o he en i e UWB
and lowe pa o he i s band g oup), while Figu e 13
depic s he 2D localiza ion esul also o he UWB and
i s band g oup.
4.3 Posi ioning esul s and sou ces o e o
I is ob ious ha he ough dis ance esolu ion in he
case o he i s band g oup measu emen causes ma kedly
highe a e age e o and s anda d de ia ion compa ed o
he measu emen o he en i e UWB band. The calcula ed
Table 3 A e age e o and s anda d de ia ion o he
measu ed dis ances o he i s band g oup
TX1 TX2 TX3 To al
A e age e o wi hou passenge s
[cm]
6.76 6.30 5.75 6.27
A e age e o wi h wo o h ee
passenge s [cm]
11.83 10.37 7.62 9.94
S anda d de ia ion wi hou
passenge s [cm]
7.49 6.86 2.10 5.87
S anda d de ia ion wi h wo o
h ee passenge s [cm]
11.13 9.28 8.95 9.80
dis ances exhibi no iceable posi i e bias caused by a ew
phenomena:
•
Exis ence o di e ence be ween he calib a ion plane
and phase cen e o he an enna.
The coaxial
in e aces o he an ennas (line be ween he
connec o and phase cen e o he an enna) we e no
included when he VNA was calib a ed. They we e
applied only du ing channel measu emen and
inc eased he o al an enna dis ance.
•
Inaccu a e e e ence measu emen .
Dis ance
measu ed be ween he an ennas by he ule was
pe o med be ween he cen e s o he op o cones
which a e no iden ical o he phase cen e s o
an ennas. In many cases, he measu ed dis ance we e
sligh ly sho e (when he TX an enna was upside
down wi h ega d o RX an enna) .
•
Time lag in he i s ay de ec ion.
The i s ay (peak)
de ec ion abo e he h eshold exhibi s andom delay
in he in e al 0 o D due o he disc e e na u e o
he CIR ime axis. Recei ed ay canno be gene ally
de ec ed in ad ance.
Table 4 A e age e o and s anda d de ia ion o he
measu ed dis ances o he i s band g oup
TX1 TX2 TX3 To al
A e age e o wi hou passenge s
[cm]
25.85 21.04 14.3 20.39
A e age e o wi h wo o h ee
passenge s [cm]
34.73 23.50 10.82 23.02
S anda d de ia ion wi hou
passenge s [cm]
20.76 13.88 8.74 15.67
S anda d de ia ion wi h wo o
h ee passenge s [cm]
20.13 12.63 7.88 17.26
Blumens ein e al. EURASIP Jou nal on Wi eless Communica ions and Ne wo king (2015) 2015:104 Page 9 o 10
Figu e 12 Fi s peak de ec ion o CIRs ( o en i e UWB) [uppe ] o emp y and [lowe ] occupied ehicle.
•
Inco ec MPC componen de ec ion.
La ge
a enua ion o some obs acles in he ca may a oid
co ec de ec ion o he di ec ay. In his case, he
o he e lec ed MPC which a els on a longe pa h is
ega ded as he i s ay.
•
Lowe wa e p opaga ion eloci y in media.
The
eloci y o an elec omagne ic wa e pene a ing an
obs acle is less han ha in ee space, and i depends
on he obs acle ma e ial cons an s.
The i s phenomenon is sys ema ic and can be sub-
ac ed (i is abou 2 cm oge he o wo an ennas). The
wo las phenomena occu only in he NLOS scena io. In
he las case, he eloci y in some ma e ial can be calcu-
la ed acco ding he o mula p=c/√ε μ ,whe e pis
he eloci y o p opaga ion in m/s, μ is he ma e ial el-
a i e pe meabili y, and ε is he ela i e pe mi i i y. I is
easy o ind ha when, o example, he wa e passes he
10-cm- hick plas ic obs acle (ε =2 o3,μ = 1 [26]),
he p opaga ion ime delays a e in he in e al 0.138 o
0.244 ns which esul s in he dis ance bias om 4.1 o
7.3 cm.
5Conclusions
We pe o med an ex ensi e UWB measu emen campaign
o he ehicula passenge compa men . The measu ed
-300 -200 -100 0 100 200 300
-200
-100
0
100
200
300
400
X coo dina es [cm]
Y coo dina es [cm]
x=36.3685cm
y=131.665cm
x=31.0792cm
y=135.2535cm
8 GHz bandwid h
1.58 GHz bandwid h
Co ec posi ion
Figu e 13 Localiza ion o he RX an enna using TOA (RX an enna was placed on on passenge sea ).