OPTICS AND OPTOELECTRONICS VOLUME: 15 |NUMBER: 3 |2017 |SEPTEMBER
Ac i e P e-Equalize o B oadband
o e Visible Ligh
Tomas STRATIL1, Pe KOUDELKA1, Radek MARTINEK2, Tomas NOVAK3
1Depa men o Telecommunica ions, Facul y o Elec ical Enginee ing and Compu e Science,
VSB–Technical Uni e si y o Os a a, 17. lis opadu 15, 708 33 Os a a, Czech Republic
2Depa men o Cybe ne ics and Biomedical Enginee ing, Facul y o Elec ical Enginee ing and Compu e
Science, VSB–Technical Uni e si y o Os a a, 17. lis opadu 15, 708 33 Os a a, Czech Republic
3Depa men o Gene al Elec ical Enginee ing, Facul y o Elec ical Enginee ing and Compu e Science,
VSB–Technical Uni e si y o Os a a, 17. lis opadu 15, 708 33 Os a a, Czech Republic
[email p o ec ed], pe .koudelk[email p o ec ed], [email p o ec ed], omas.no [email p o ec ed]
DOI: 10.15598/aeee. 15i3.2210
Abs ac . This pape in oduces a new echnology
called B oadband o e Visible Ligh (BVL) which com-
bines wo echnology solu ions like Visible Ligh Com-
munica ion(VLC) and B oadband o e Powe Line
(BPL). This new echnology is sui able o con e ing
mode n LED ligh ing sys ems in o communica ion sys-
ems. Howe e , he e a e some de iciencies in BVL
echnology such as he low bandwid h o LED op ical
ansmi e s. P e-equaliza ion may be solu ion o his
p oblem. This pape p oposes highe bandwid h using
he p e-equaliza ion ci cui . Also, i shows eal expe i-
men al esul s demons a ing an imp o emen o band-
wid h and ansmission a e.
Keywo ds
Equaliza ion, Lab iew, p e-equaliza on,
So wa e-de ined adio, Visible Ligh Com-
munica ion, VLC.
1. In oduc ion
The ecen de elopmen in he a ea o whi e LEDs
caused hei common use as a highly e icien al e na-
i e o he con en ional sou ces o op ical adia ion in
he isible ange. This de elopmen b ough p og es-
si e changes in he ligh ing echnology. The physical
p inciple o whi e LEDs allows hei use o commu-
nica ion pu poses. The physical p inciples, including
changes in ends o he ligh ing echnology, caused he
eme gence o a new esea ch di ec ion gene ally called
Visible Ligh Communica ion (VLC), which is a de i a-
i e o o iginal esea ch di ec ion gene ally known as in-
doo Op ical Wi eless Communica ion (indoo OWC),
ope a ing exclusi ely in he in a- ed spec um o op i-
cal adia ion. The objec i e o his esea ch di ec ion
is me ging ligh ing and communica ions [1], [2] and [?].
The B oadband o e Visible Ligh (BVL) is a new
esea ch di ec ion based essen ially on VLC echnology.
Again, i is in ended o u ilize he isible spec um o
op ical adia ion as a communica ion di ec ion o he
end use (downlink) and o u ilize he in a- ed spec-
um o op ical adia ion (940 nm) in he e e se com-
munica ion di ec ion (uplink). Mo eo e , compa ed o
he VLC concep , in he case o BVL, i is in ended
o use he chipse o he B oadband o e Powe Line
(BPL) echnology, which, in e alia, allows he use o
he OFDM MQAM modula ion o ma a he num-
be o 1155 sub-ca ie s in he equency ange om
2 MHz o 32 MHz ( o example HomePlug AV). The
BVL echnology should, by i s na u e, enable ans-
mission speed o 100 Mb·s−1. Addi ionally, he BVL
echnology p o ides connec i i y o e powe conduc-
o s in an e icien way. I gi es us he oppo uni y o
ansmi he modula ed signal o he op ical ansmi -
e by i s powe lines, and use isible ligh as a wi eless
da a ansmi e .
Whi e ligh LEDs as ansmi e s o communica ion
link ha e he big disad an age as low bandwid h. Low
bandwid h is caused by op oelec onic esponse o he
LED and due o physical p inciples o luo escence in
a hin laye o phospho which is esponsible o c e-
a ing whi e ligh om blue ligh . Fluo escence inse s
some delay o he op ical signal and hus in luences
he maximum bi a e. Whi e powe LEDs achie e se-
e al MHz o bandwid h [8]. Some esea che s achie e
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10 MHz o bandwid h due o op ical band pass il e on
de ec ion side, whe e only blue pa o wa eleng h p o-
cesses pass on pho ode ec o wi hou delayed yellow
pa om luo escence. Equaliza ion echniques a e
used o elimina ion o LEDs op oelec onic esponse
o achie e highe bandwid h [6] and [7]. This a icle
deals wi h his ac ual issue and b ings new unpublished
esul s, which can help o de elop BVL echnology.
2. Bandwid h o LEDs
B oadband Powe Line echnology ope a es in he e-
quency ange om 2 MHz o 32 MHz a HomePlug AV
speci ica ion and p o ides a 200 Mb·s−1PHY channel
a e and 150 Mb·s−1in o ma ion a e. Sui able band-
wid h o op ical ansmi e has o be eached o coop-
e a ing HomePlug AV speci ica ion wi h VLC. The e-
quency esponse o high powe ligh LED Philips Fo -
imo LED DLM 3000 44 W/830 was measu ed. Ne -
wo k analyze Rhode-Schwa z ZVB 4 (3 kHz o 4 GHz)
[9] was used wi h ou own designed ci cui Bias-T [12].
PIN pho ode ec o Tho labs PDA10A-EC was applied
on de ec ion side. Philips Fo imo LED DLM 3000
44 W/830 has sys em e iciency 62 lm/W. This LED
ligh sou ce o e s an ad an age o VLC measu ing and
es ing, because o i s concep o cons uc ion. The e
we e used blue LED chips, which a e di ec ly placed
on he aluminum block o e ec i e cooling. Ex e -
nal di use in on o blue LED chips con e s pa
o blue (lowe ) wa eleng hs ange in o highe wa e-
leng hs due o phospho laye as seen in Fig. 1. This
whi e ligh LED has pa en ed emo e phospho ech-
nology. This LED ligh sou ce mee s equi emen s o
u u e duplex communica ion. Pho ode ec o ope a -
ing in he in a ed wa eleng h ange could be used be-
hind di use wi h he phospho laye . Measu ed alues
o equency esponse we e i ed by cubic unc ion o
Blue
ligh
Whi e
ligh
Di use
wi h
phospho
Blue LEDsHea sick
Fig. 1: Concep o Philips FORTIMO LED DLM 3000.
elimina e oughness caused by noise and o he signal
dis o ion. The smoo he cu e o equency esponse
p o ides ideal condi ions o design he p e-equaliza ion
ci cui . −3dBm bandwid h was achie ed a 2 MHz
wi h a high powe whi e ligh LED as shown in Fig. 6,
and a 7 MHz wi h blue pa o adia ion wi hou phos-
pho e ec .
2.1. Design o P e-Equalize
The pu pose o equaliza ion is o compensa e signal
dis o ion in a communica ion channel. The main dis-
o ion o he signal was p oduced by he op ical ans-
mi e a VLC channel due o an op oelec onic e-
sponse o LED and delay o he phospho [6]. We used
well-known equaliza ion echniques and echniques o
designing il e s o each sui able bandwid h. App o-
p ia e bandwid h was eached wi h a eally simple elec-
onic ci cui , because he simplici y o designed ci cui
was he impo an equi emen .
P e-equaliza ion ci cui was designed acco ding o
he e e sal o measu ed equency esponse, which can
be seen in Fig. 6. The ci cui is composed o an ac i e
and mainly passi e pa , which de e mines shape o
equency esponse. The passi e pa o he ci cui is
high pass il e , which causes 35 dBm a enua ion, as
i can be seen in Fig. 3. The ac i e pa o he ci cui
con ains ope a ional ampli ie OPA847 elimina ing a -
enua ion o he passi e pa . The comple e ci cui
p o ides equency esponse closed o he e e sal o
measu ed equency esponse. Ci cui diag am o p e-
equalize can be seen in Fig. 2. The ans e unc ion
o he p e-equaliza ion ci cui was exp essed as:
H(jω) = 1 + R5
R4·R3
R2
jωR2C+ 1 +R3
,(1)
whe e ωis de ined as 2π .
−
+
R1
C
R2
R3
R4
R5
OPA847
R6
IN
OUT
Passi e Ac i e
Fig. 2: Ci cui diag am o ac i e p e-equalize wi h OPA847.
2.2. Simula ions
Passi e pa o he ci cui shapes he cu e o equency
esponse and con ains pa allel connec ion o esis o R2
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F equency (MHz)
1 10 50
Response (dB)
-40
-35
-30
-25
-20
-15
-10
-5
R2 = 2 k ; C = 22 pF; R3 = 200
R2 = 2 k ; C = 50 pF; R3 = 200
R2 = 3 k ; C = 22 pF; R3 = 200
R2 = 2 k ; C = 22 pF; R3 = 500
Fig. 3: Simula ion esul s o pasi e pa o p e-equalize and
e ec componen s alues on equency esponse.
and capaci o Cand esis o R3, pa allelly connec ed
o hem. Figu e 3 shows he cu es om simula ions,
whe e he e ec o componen s alues on he shape o
equency esponse can be no iced. The bes esul o
e e sal equency esponse was eached by he compo-
nen s R2= 2 kΩ,C= 22 pF and R3= 200 Ω.
Ope a ional ampli ie OPA847 was used in ac i e
pa o he p e-equaliza ion ci cui . The OPA847 p o-
ides a unique combina ion o a e y low inpu ol age
noise, along wi h a e y low dis o ion ou pu s age
o gi e one o he highes dynamic ange o op amps
a ailable. Vol age- eedback o op amps, unlike cu en -
eedback designs, can use a wide ange o esis o ’s al-
ues o se up hei gain. R4was se o 39.2 Ωand R5
was op imized acco ding o desi ed gain. Using his
guideline ensu es ha he noise added a he ou pu
due o he Johnson noise o he esis o s does no sig-
ni ican ly inc ease he o al noise o e he 0.85 V/√Hz
inpu ol age noise o he op amp i sel . This R4 alue
is sugges ed as a good s a ing poin o he design o
he ci cui .
Cu es gained by simula ions o di e en adjus ed
alues o eedback esis o R5a e shown in Fig. 4,
F equency (MHz)
1 10 50
Response (dB)
-20
-10
0
10
20
30
R5 = 200
R5 = 750
R5 = 1.5 k
Fig. 4: Simula ion esul s o ac i e pa o p e-equalise and
di e en eedback esis o alues e ec on equency e-
sponse.
whe e open-sou ce simula ion so wa e Qucs was used.
R4 alue was 39.2 Ω whe eas we we e ying o achie e
ideal ampli ica ion o he p e-equaliza ion ci cui by
adjus ing alue R5.R5= 750 Ω p o ided he bes e-
sul o e e sal equency esponse and achie ed gain
+20 V/V o ope a ion ampli ie . Values o R4and R5
a ec ed comple e ampli ica ion o ac i e pa o he ci -
cui . On he o he hand, hey also a ec ed shape o he
equency esponse o o e all p e-equaliza ion ci cui as
shown in Fig. 4.
2.3. Measu emen
The equency esponse o cons uc ed p e-equalize
was measu ed and he esul s we e compa ed wi h
simula ions. Ne wo k analyze Rhode-Schwa z ZVB 4
(3 kHz o 4 GHz) was used. Resul s om simula ions,
measu emen s and e e se a e shown in he Fig. 5. F e-
quency esponse om simula ions and measu emen s
o he p e-equaliza ion ci cui a e almos same o he
e e se equency esponse, which is desi able. Ope -
a ional ampli ie OPA847 ope a es up o 40 MHz as
seen in Fig. 5. This is due o high ampli ica ion o
OPA847, howe e 40 MHz is su icien o BVL echnol-
ogy solu ion. The designed p e-equalize ci cui a en-
ua es he inpu signal by abou 1 dBm in he equency
ange 0.2 o 2 MHz. Designed and cons uc ed ci cui
achie es powe le el 15 dBm a 40 MHz. Bandwid h
om 2 MHz o 40 MHz o designed ci cui is compli-
an acco ding o HomePlug AV echnology solu ion o
B oadband Powe Line communica ion.
F equency (MHz)
1 10 50
Response (dB)
-5
0
5
10
15
20
Calcula ed esponse
Simula ed esponse
Measu ed esponse
Fig. 5: F equency esponse o designed ci cui gi en by e e se,
simula ion and measu emen .
3. Tes ing E ec o
P e-Equalize on Bandwi h
and Modula ion
To e i y designed and cons uc ed p e-equalize e ec ,
a new measu emen was done on Philips Fo imo LED
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DLM 3000 44 W/830 by a o emen ioned ec o ne -
wo k analyze . The equency esponse o LED ligh
sou ce wi hou designed ci cui was measu ed a i s ,
hen wi h p e-equalize . To allow de e mining in lu-
ence o luo escence in he phospho , measu emen was
epea ed wi hou di use wi h he phospho laye on
he men ioned whi e ligh LED sou ce. Uni o m dis-
ance 40 cm be ween he op ical ansmi e and pho-
ode ec o was se .
The p e-equalize measu emen esul s a e shown
in Fig. 6. I is e iden how designed ci cui o p e-
equalize in luences equency esponse o phospho
based whi e ligh and also blue pa o adia ion wi h-
ou in luencing he delay due o luo escence a phos-
pho laye . A bandwid h o −3dBm was achie ed a
2 MHz wi h whi e ligh LED wi hou p e-equaliza ion,
whils , a bandwid h o −10 dBm was achie ed a
6 MHz. In he case o whi e ligh LED wi hou
p e-equaliza ion, −3dBm bandwid h was achie ed a
2 MHz and −10 dBm bandwid h a 6 MHz. When wi h
he p e-equaliza ion ci cui connec ed be ween he ne -
wo k analyze and Bias-T, −3dBm bandwid h was ob-
ained a 3 MHz and −10 dBm bandwid h a 40 MHz.
I p o es how p e-equaliza ion mi iga es na u al incli-
na ions o low bandwid h o semiconduc o phospho
based LED ligh ansmi e s. The bandwid h o blue
pa o adia ion wi hou he e ec o luminescence
achie ed ampli ica ion by 5 dBm a 20 MHz equency
due o p e-equaliza ion.
F equency (MHz)
2 32
Powe le el (dBm)
-80
-60
-40
-20
0
20
P e-eq esponse
Whi e pa wi hou p e-eq
Whi e pa wi h p e-eq
Blue pa wi hou p e-eq
Blue pa wi h p e-eq
-39.07 dBm
-35.64 dBm
Fig. 6: E ec p e-equalize on equency esponse o whi e ligh
LED and blue ligh LED.
The powe le el o he signal has highe inclina-
ion o d op owa d inc easing equency, due o in lu-
ence o phospho laye . Di use wi h phospho laye
dec ease powe le el. BVL echnology wi h espec
o HomePlug AV echnology solu ion ope a es om
2 MHz o 32 MHz, hence BVL solu ion needs o achie e
his bandwid h. An a enua ion o 3.43 dBm was
achie ed wi h men ioned bandwid h due o designed
p e-equaliza ion ci cui .
3.1. Expe imen al Se up
The block diag am o he expe imen al se up is shown
in Fig. 7. RF VSG NI PXI-5670 (Vec o signal gene a-
o ) [11] was used o gene a e he digi ally modula ed
signal. MQAM digi al modula ion was es ed [10] and
[14], 4QAM was used speci ically.
Vec o signal analyze RF VSA NI PXI-5661 [11]
was used on he ecei e side. The signal modula ed
by a digi al modula ion scheme was moni o ed by con-
s ella ion diag am and simul aneously an E o Vec o
Magni ude (EVM) was measu ed. The EVM p o ides
a comp ehensi e measu e o he quali y o he digi ally
modula ed signal. We used i o e i y p e-equaliza ion
ci cui e ec on he ansmi ed digi al signal, depend-
ing on he symbol a e ( used bandwid h ).
SI PIN pho ode ec o Tho Labs PDA10A-EC is
ope a ing in he wa eleng h ange om 200 nm o
1100 nm. Pho ode ec o PDA10A-EC has an e ec i e
a ea Ae = 0.8mm2only, he e o e N-BK7 Plano-
Con ex Lens wi h a ocal leng h o 25.4 mm was used.
Thanks o he lens, an adequa e signal ou pu was ob-
ained o e i y he unc ionali y a a ealis ic dis ance
o 3 m be ween ansmi e and ecei e . Cen e e-
quencies 5 MHz, 10 MHz, 15 MHz and 20 MHz we e
used in digi al modula ion scheme.
The de ec ed signal can be ep esen ed by:
y(n) = g(n)x(n) + η(n),(2)
whe e g(n)and η(n) ep esen he mul iplica i e and
addi i e impai men s o he de ec ed signal. The mul-
iplica i e impai men s can be a esul o channel es i-
ma ion e o s o IQ imbalances, o example. The ad-
di i e impai men s a e usually caused by he mal noise
and a e modeled as an i.i.d. (Independen and Iden i-
cally Dis ibu ed andom a iables) complex AWGN
samples wi h Powe Spec al Densi y (PSD) o N0/2.
EVM can be designed as he oo -squa e (RMS)
alue o he di e ence be ween an a ay o measu ed
symbols and ideal symbols. The EVM can be ep e-
sen ed as:
EV MRMS =
u
u
u
1
N
N
P
n=1|S (n)−S (n)|2
P0
,(3)
whe e Nis he numbe o symbols o e which he alue
o EVM is measu ed. S (n)is he no malized ecei ed
n h symbol which is dis up ed by Gaussian noise. S (n)
is he ideal ansmi ed alue o he n h symbol x(n),
and P0is ei he he maximum no malized ideal sym-
bol powe o he a e age powe o all symbols o he
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RF+DC
Fig. 7: Block diag am o expe imen al measu emen .
chosen modula ion. P0can be ep esen ed by:
P0=1
M
M
X
m=1|Sm|2.(4)
The EVM alue is no malized wi h a e age symbol
ene gy o emo e he dependency o EVM on he mod-
ula ion o de . Conside he de ec ed signal in Eq. (2),
whe e g(n)≈1. Fo non-da a-aided ecei e s, he
EVM is:
EV MRMS =
u
u
u
1
N
N
P
n=1|y(n)−˜x(n)|2
P0
,(5)
whe e ˜x(n)a e ansmi ed symbols, which a e es i-
ma ed and used o measu e he EVM alue.
Acco ding o [13], he EVM o QAM signals is:
EV MQAM =
="1
SNR −8 3
2π(M−1)SNR
√M−1
P
i=1
γie
3β2
iSNR
2(M−1)
+12
M−1
√M−1
P
i=1
γiβie c s3β2
iSNR
2(M−1)!#1/2
,
(6)
whe e
γi= 1 −i
√M, and βi= 2i−1.(7)
The EVM o a QAM signal in Eq. (6) can be di ided
in o wo pa s. The i s pa is 1/SNR, which ep e-
sen s he ideal EVM when no e o s a e in oduced o
he symbol de ec ion. The second pa is QAM signal,
which is he sum o he exponen ial and e o unc ion,
ep esen ing he educ ion in measu ed EVM due o
he e o de ec ion.
3.2. Resul s and Discussions
The esul s we e measu ed by he block diag am shown
in Fig. 7. 4QAM digi al modula ion scheme was ans-
mi ed ia whi e pa o adia ion wi h e ec o he
luminescence and esul s a e shown in Fig. 8. Small
di e ences we e measu ed be ween EVM alues o VLC
sys em wi hou he p e-equalizaion ci cui and wi h
p e-equaliza ion o cen e equency 5 MHz. The p e-
equaliza ion ci cui had signi ican in luence a highe
equencies.
Signi ican imp o emen o EVM alues was e i ied
wi h VLC sys em wi h p e-equaliza ion. Mos sig-
ni ican di e ence o EVM alues was o cen e e-
quency o 20 MHz due o equency esponse o p e-
equaliza ion ci cui seen in Fig. 6. EVM alue in-
c eased when symbol a e was inc eased, due o non-
linea i y o equency spec um.
EVM alues we e inc eased due o low signal powe
le el and na u al inclina ions o he equency e-
sponse as shown in Fig. 6. Highe bandwid h was
used wi h highe symbol a e and i inc eased EVM
and dec eased communica ion possibili y because o
inadequa e equency esponse. The VLC sys em
was no sui able o use in highe cen al equen-
cies and highe bandwid h o digi al modula ions
wi hou p e-equaliza ion. The VLC sys em wi h he
p e-equaliza ion ci cui p o ided complian condi ions,
hus highe cen al equencies and bandwid h could
be used.
4. Conclusion
In his pape p e-equaliza ion o VLC ansmi e has
been p esen ed. In o de o ge sui able equency e-
sponse o VLC ansmi e based on phospho whi e
LED ligh sou ce, we ha e been p oposed equaliza ion
ci cui used in ou VLC sys em. The a o emen ioned
HomePlug AV echnology bandwid h om 2 MHz o
32 MHz was achie ed wi h 3.43 dBm a enua ion by
comme cial phospho escen whi e ligh LED and p o-
posed equalize ci cui . The objec i es o his pape
we e o achie e sui able equency esponse o he
men ioned BVL echnology solu ion. The p oposed
sys em demons ably imp o es ope a ional bandwid h
in VLC sys em and could be conside ed as sui able
sys em imp o emen o u u e B oadband o e Visi-
ble Ligh (BVL) echnology deploy.
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Symbol a e (MHz)
1 2 3 4 5
EVM (%)
0
50
100 Wi hou p e-eq
Wi h p e-eq
Symbol a e (MHz)
1 2 3 4 5
EVM (%)
0
50
100
Wi hou p e-eq
Wi h p e-eq
Symbol a e (MHz)
1 2 3 4 5
EVM (%)
0
50
100
Wi hou p e-eq
Wi h p e-eq
Symbol a e (MHz)
1 2 3 4 5
EVM (%)
0
50
100
Wi hou p e-eq
Wi h p e-eq
(a) 5 MHz.
Symbol a e (MHz)
1 2 3 4 5
EVM (%)
0
50
100 Wi hou p e-eq
Wi h p e-eq
Symbol a e (MHz)
1 2 3 4 5
EVM (%)
0
50
100
Wi hou p e-eq
Wi h p e-eq
Symbol a e (MHz)
1 2 3 4 5
EVM (%)
0
50
100
Wi hou p e-eq
Wi h p e-eq
Symbol a e (MHz)
1 2 3 4 5
EVM (%)
0
50
100
Wi hou p e-eq
Wi h p e-eq
(b) 10 MHz.
Symbol a e (MHz)
1 2 3 4 5
EVM (%)
0
50
100 Wi hou p e-eq
Wi h p e-eq
Symbol a e (MHz)
1 2 3 4 5
EVM (%)
0
50
100
Wi hou p e-eq
Wi h p e-eq
Symbol a e (MHz)
1 2 3 4 5
EVM (%)
0
50
100
Wi hou p e-eq
Wi h p e-eq
Symbol a e (MHz)
1 2 3 4 5
EVM (%)
0
50
100
Wi hou p e-eq
Wi h p e-eq
(c) 15 MHz.
Symbol a e (MHz)
1 2 3 4 5
EVM (%)
0
50
100 Wi hou p e-eq
Wi h p e-eq
Symbol a e (MHz)
1 2 3 4 5
EVM (%)
0
50
100
Wi hou p e-eq
Wi h p e-eq
Symbol a e (MHz)
1 2 3 4 5
EVM (%)
0
50
100
Wi hou p e-eq
Wi h p e-eq
Symbol a e (MHz)
1 2 3 4 5
EVM (%)
0
50
100
Wi hou p e-eq
Wi h p e-eq
(d) 20 MHz.
Fig. 8: Resuls o measu emen EVM depending on symbol a e and ca y equency ansmi 4QAM modula ion ia whi e ligh
LED.
Acknowledgmen
The esea ch desc ibed in his a icle could be ca -
ied ou hanks o he ac i e suppo o he Min-
is y o Educa ion o he Czech Republic wi hin he
p ojec s no. SP2017/97: Remo e Con ol o Public
Ligh ing Luminai es ia he Sma Technology Suppo
and SP2017/128: Vi ual ins umen a ion o he mea-
su emen and es ing IV. This a icle was suppo ed
by p ojec s Technology Agency o he Czech Repub-
lic TG01010137: B oadbandLIGHT. The esea ch has
been pa ially suppo ed by he Minis y o In e io o
he Czech Republic h ough g an p ojec MVCR No.
VI20172019071: Analysis o isibili y o anspo in-
as uc u e o sa e y inc easing du ing nigh , sun ise
and sunse .
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Abou Au ho s
Tomas STRATIL was bo n in 1990 in Olomouc,
Czech epublic. In 2015 He ecei ed Mas e ’s deg ee in
op ical communica ion om VSB–Technical Uni e -
si y o Os a a. His esea ch in e es s include Visible
ligh communica ion and Sma echnologies.
Pe KOUDELKA was bo n in 1984 in P os ejo ,
Czech Republic. In 2006 ecei ed Bachelo ’s deg ee
on VSB–Technical Uni e si y o Os a a, Facul y
o Elec ical Enginee ing and Compu e Science,
Depa men o elecommunica ions. Two yea s la e
he ecei ed on he same wo kplace his Mas e ’s deg ee
in he ield o Op oelec onics. In 2015 he success ully
de ended his disse a ion hesis i led "S udy o he
In oo Op ical Wi eless Ne wo k in he Visible Op ical
Radia ion". He wo ks as an Asis an P o esso a
VSB–Technical Uni e si y o Os a a since 2016. His
cu en esea ch in e es s include Wi eless Op ical
Communica ions, Op ical Access Ne wo ks and Sma
Ci y echnologies.
Radek MARTINEK was bo n in 1984 in Czech
Republic. In 2009 he ecei ed Mas e ’s deg ee in
In o ma ion and Communica ion Technology om
VSB–Technical Uni e si y o Os a a. Since 2012 he
wo ked he e as a Resea ch Fellow. In 2014 he success-
ully de ended his disse a ion hesis i led „The Use
o Complex Adap i e Me hods o Signal P ocessing
o Re ining he Diagnos ic Quali y o he Abdominal
Fe al Elec oca diog am". He became an Associa e
P o esso in Technical Cybe ne ics in 2017 a e
de ending he habili a ion hesis i led "Design and
Op imiza ion o Adap i e Sys ems o Applica ions
o Technical Cybe ne ics and Biomedical Enginee ing
Based on Vi ual Ins umen a ion". He wo ks as an
Associa e P o esso a VSB–Technical Uni e si y o
Os a a since 2017. His cu en esea ch in e es s in-
clude: Digi al Signal P ocessing (Linea and Adap i e
Fil e ing, So Compu ing - A i icial In elligence and
Adap i e Fuzzy Sys ems, Non-Adap i e Me hods, Bio-
logical Signal P ocessing, Digi al P ocessing o Speech
Signals); Wi eless Communica ions (So wa e-De ined
Radio); Powe Quali y Imp o emen . He has mo e
han 70 jou nal and con e ence a icles in his esea ch
a eas.
Tomas NOVAK was bo n in 1972 in P ib am,
Czech Republic. In 1996 ecei ed Mas e ’s deg ee
on VSB–Technical Uni e si y o Os a a, Facul y
c
2017 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 559
OPTICS AND OPTOELECTRONICS VOLUME: 15 |NUMBER: 3 |2017 |SEPTEMBER
o Elec ical Enginee ing and Compu e Science,
Depa men o Elec ical Enginee ing. Se en yea s
la e he ecei ed on he same wo kplace his Ph.D.
deg ee in he ield o Elec ic Ligh and Diagnos ic.
Now he wo ks as an Associa e P o esso a he same
uni e si y. His cu en esea ch in e es s include
Public Ligh ing, Ligh ing Pollu ions, In e io Ligh
Con olling and Sma Ci y echnologies.
c
2017 ADVANCES IN ELECTRICAL AND ELECTRONIC ENGINEERING 560