Manuel Augusto Vieira
Manuela Vieira Paula Louro Pedro Vieira
• FCT – ref. UID/EEA/00066/2013 • IPL/2017/EmGraph/ISEL
• IPL/2017/SMART_VeDa/ISEL.
ACKNOWLEDGEMENTS
”Visible light communications in smart road infrastructures”
Lisbon
SENSORCOMM 2018 September 16, 2018 to
September 20, 2018 - Venice, Italy
TUTORIAL I
http://www.cts.uninova.pt/index_dev
III Work Area: “Indoor positioning using a-SiCH technology”
• Positioning, also known as localization, is the process of determining
the spatial position of an object or person. • The leading technologies (GPS and mobile networks) are not
suitable for use within buildings.
• The omnipresence of indoor lighting makes it an ideal vehicle for pervasive communication with mobile devices.
• The SiC optical processor for indoor positioning is realized by using a SiC pin/pin photodetector.
• Additional parity logic operations are performed and checked for errors together.
• System Configuration Transmitter
Receiver
Driving range distance
Outline
• An optical full-adder. Additional parity logic operations
How do error correcting codes work?
• Topologies
• Conclusions and future trends.
. .. . ... ..A B C
Transmitters
Receivers
RG
V B
12
4
5
67
8
9
3
MUX signal, output levels and truth table SiC full adder
4
Data shows that when one or all of the
inputs are present it corresponds to four
different levels (d1, d2, d4, d7), the system
behaves as a XOR gate i.e. Sum =1
SiC tuneable background nonlinearity-based RGB logic gates
If two or three input channels are on, the
system acts as AND gate. This corresponds
to four separate levels (d3, d5, d6, d7) and
indicates the presence of CARRY bit
Co
der/
deco
der
devic
e
Three-bit additions of violet signal with two additional bits of RGB Generated parity bits are SUM bits Strongly enhanced back signal levels
.
HOW DO SYNDROME NAVIGATOR WORK?
The next closest grid positions
Co
der/
deco
der
devic
e
S Syndrome helps the receiver diagnose the “illness” (errors) in the received data.
HOW DO ERROR CORRECTING CODES WORK?
Matrix notation G Generator matrix H Parity check matrix
Co
der/
deco
der
devic
e
Matrix notation Generator matrix G Parity check matrix H Syndome helps the receiver diagnose the “illness” (errors) in the received data. The hardware syndrome generator implementation
HOW DO ERROR CORRECTING CODES WORK?
Device configuration and operation
Code and parity MUX/DEMUX signals
Transmitted data[RGBV PRPGPB ]
p
Glass
i’
200 nm
a-SiC:H
p
i
1000 nm
a-Si:H
n nTCO
TCO
lV
Op
ticalBias
lB
lG
lR
Inputchannels
Front diodes Back diodes
V=-8VTCO
p n p n
TCO
lG
lR
i’
lB
i
V=-8V
Op
ticalBias
MU
X C
OD
E M
UX
PAR
ITY
(Intuitive representation)
Design of SiC syndrome generators
ADDING PARITY BITS
S= [1 1 1]
VIOLET BIT CORRUPTED
Parity bits recalculated
Message without error
Syndrome for violet bit
Design of SiC syndrome generators
ADDING PARITY BITS S= [1 1 1]
(Intuitive representation) (Parity bits recalculated)
Syndrome linked to violet bit
The next closest grid positions
Design of SiC syndrome generators
ADDING PARITY BITS S= [1 1 0]
Parity bits recalculated
Syndrome linked to red bit
The next closest grid positions
Design of SiC syndrome generators
ADDING PARITY BITS S= [1 1 1]
Parity bits recalculated
Syndrome linked to violet bit
The next closest grid positions
SY
ST
EM
DE
SIG
N
The system is a self-positioning system in which the measuring unit is mobile.
This unit receives the signals from several transmitters in known locations, and has the capability to compute its location based on the
measured signals.
• p-i'(a-SiC:H)-n/p-i(a-Si:H)-n heterostructure produced by PECVD.
Receiver
p
Glass
i’
200 nm
a-SiC:H
p
i
1000 nm
a-Si:H
n nTCO
TCO
lV OpticalB
iasOp
tica
lBia
s
lB
lG
lR
Inputchannels
Front diode Back diode
V=-8V
• Red, Green and Blue white LED
Transmitter
0.0 0.5 1.0 1.5 2.0
[0101 0011]
V
B
G
R
Code w
ord
(R
GB
V)
Time (ms)
400 500 600 700 8000.0
0.2
0.4
0.6
0.8
1.0
B
G
R
Inte
nsity (
a.u
.)
Wavelength (nm)
Representation communication The structure of the frame
synchronization bits.ID´s,…
0.0 0.5 1.0 1.5 2.0 2.5
0.5
1.0
#7
#9
#1d
15d14
d13d
12
d11d
10
d9d
8
d7d
6
d5
d4d
3d2d1d
0
V
B
G
R
0 0 0 00 0 0 10 0 1 00 0 1 10 1 0 00 1 0 1
0 1 1 00 1 1 1
1 0 0 01 0 0 1
1 0 1 01 0 1 1
1 1 0 01 1 0 1
1 1 1 01 1 1 1
R G B V
Norm
alized M
UX
sig
nal
Time (ms)
0.0 0.5 1.0 1.5 2.0 2.50.0
0.5
1.0
0101 (#7)
1100 (#9)
1111 (#1)
RGBV
IDSync Payload data
V2,3
B2,4
G3,3
R3,4
Norm
alized M
UX
sig
nal
Time (ms)
MUX/DEMUX techniques
•The output presents 24 ordered levels each one related with RGBV bit sequences
RG
V B
12
4
5
67
8
9
3
TO
PO
LO
GY
Region 1 2 3 4 5 6 7 8 9 10 11 12 13
Overlap RGBV RGB GB GBV BV RBV RV RGV RG G B V R
Region 1 2 3 4 5 6 7 8 9 10
Overlap RGBV RGV GBV RBV RV GV RB R G B
R G
B V
1
2
3
4
5
6
7
8
9 10
11 12
13
Square
R
G B
V
Triangular
1 2
3
4
5
6 7
8
9 10
• Four modulated LEDs (RGBV), three of them (RGB-LED) are located
at the vertices of an equilateral triangle and
a fourth one (V) is located at its centroid.
• Four modulated LEDs (RGBV) located at the
corners of a square grid.
1,1 1,3
2,1
1,2
2,32,2
3,23,1 3,3
cluster
0.0 0.5 1.0 1.5 2.00.0
0.1
0.2
0.3
0.4
0.5
0.6
d11
(1011)
d0 (0000)
d4 (0100)
d8 (1000)
d15
(1111)
d (RGBV)
Back
Front
V
B
G
R
MU
X s
ignal (a
.u.)
Time (ms)
0.0 0.5 1.0 1.5 2.00.0
0.1
0.2
0.3
d0 (0000)
d4 (0100)
d8 (1000)
d12
(1100)
d15
(1111)
d (RGBV)
V
B
G
R
Back
Front
MU
X s
ign
al (a
.u.)
Time (ms)
Square topology Triangular topology.
• The background acts as selector that chooses one or more of the 2n sublevels, with n the number of
transmitted channels, and their n-bit binary code .
• 2n ordered levels pondered by their optical gains are detected and correspond to all the possible
combinations of the on/off states.
• By assigning each output level to a n digit binary code the signal can be decoded. A maximum transmission
rate capability of 30 Kbps was achieved.
Decodin
g a
lgorith
m
PO
SIT
ION
ING
M
UX
/DE
MU
X S
IGN
AL
S
0.0 0.5 1.0 1.50.0
0.5
1.0
1.5
0000
0111
1111RGBV
Position 1
d15
d0
Back
Front
V
R
B
G
MU
X s
ignal (
A)
Time (ms)
• Looking to the different levels, we have ascribed a binary code of 4 bits (RGBV) to each position, where 1 means that
the channel is received and 0 that is absent .
0.0 0.5 1.0 1.50.0
0.4
0.8
1.2Position 2
d7
d0
Back
Front
R
B
G
MU
X s
ignal (
A)
Time (ms)
0.0 0.5 1.0 1.50.0
0.5
1.0
1.5
Position 3
d4
d0
Back
Front
B
G
MU
X s
ignal (
A)
Time (ms)
[1110]
[1111]
[0110]
PO
SIT
ION
ING
0.0 0.5 1.0 1.5 2.00.0
0.5
1.0
1.5
2.0
2.5
0000
0010
01000110
1000
1010
11001110RGBV
Position 3
Position 2
B
G
R
MU
X s
ignal (a
.u.)
Time (ms)
0.0 0.5 1.0 1.5 2.00.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
00000001
0100010110001001
11001101RGBV
Position 6
Position 2
V
G
R
MU
X s
ign
al (a
.u.)
Time (ms)
Nearest regions 1 2 3 4 5 6 7 8 9 10 11 12 13
Code position
(Square topology)
1111 1110 0110 0111 0011 1011 1001 1101 1100 0100 0010 0001 1000
Code position
(Triangular topology)
1111 1101 0111 1011 1001 0101 1010 1000 0100 0010 - - -
Square topology
Triangular topology
[1110]
[0110]
[1101]
[0101]
NA
VIG
AT
ION
DA
TA
BIT
S
0.0 0.5 1.0 1.50.0
0.5
1.0
1.5
d7
1 RGBV
3 GB
4 GBV
5 BV
d15
d0
Front
V
R
B
G
MU
X s
ignal (
A)
Time (ms)
• For each transition between an initial location and a final one, two code words are generated, the initial (i) and the final (f). If the receiver stays under the same region they should be the
same, if it moves away they are different.
North
South
EastWest
NE
SE
NW
SW
1
2
3
4
CompassNeedle
5
6
North
South
EastWest
NE
SE
NW
SW
1
2
3
4
CompassNeedle
5
7
8
9
0.0 0.5 1.0 1.50.0
0.5
1.0
1.5
2.0
Position ID
t1 RGBV
t3 GB
t4 GBV
t5 BV
R
G
B
V
RGBV
GB
GBV
BV
d15
d0
Front
V
R
B
G
Photo
curr
ent (
A)
Time (ms)
0.0 0.5 1.0 1.5 2.00.0
0.5
1.0
1.5
2.0 V
R
B
G
Position ID
Front lighting t1 RGBV
t3 GB
t4 GBV
t5 BV
Photo
curr
ent (
A)
Time (ms)
G
G
G
G
B
C
D
E
• The device’s position (ID position) during the receiving process will be given by the highest detected level (vertical dot line in the figures), i. e, the level where all the n (n=1, 2, 3, 4) channels are simultaneously on.
• At each regions the MUX signals present different pattern that after
decoding give information about the mobile navigation and received
information along the time.
North
South
EastWest
NE
SE
NW
SW
1
2
3
4
CompassNeedle
5
6
North
South
EastWest
NE
SE
NW
SW
1
2
3
4
CompassNeedle
5
7
8
9N
AV
IGA
TIO
N D
ATA
BIT
S
0.0 0.5 1.0 1.5 2.00.0
0.3
0.5
0.8
1.0
1.3
1.5
Position ID
t3
t4
t2
t1
d3
d7
d9
d11
0111
0011
1001
R
G
B
V
VR
BVR
BV
GBV
1011
RGBV
V
B
G
R
MU
X s
ign
al (a
.u.)
Time (ms)
0.0 0.5 1.0 1.5 2.00.0
0.1
0.3
0.4
0.5
0.7
0.8
0.9
1.1
1.2 Position IDV B
G
R
5- t1
RV
4- t2
RBV
7- t3
BV
3- t4
GBVd
11 1011
d7 0111
d9 1001
d3 0011
RGBV
MU
X s
ignal (a
.u.)
Time (ms)
B
C
D
E
VR
BVR
BV
GBV
[1001]
[1011]
[0111]
[0011]
NA
VIG
AT
ION
DA
TA
BIT
S
•For each transition between an initial location and a final one, two code words are generated,
the initial (i) and the final (f). If the receiver stays under the same region they should be the
same, if it moves away they are different.
0.0 0.5 1.0 1.5 2.00.0
0.2
0.4
0.6
0.8
1.0
[0101 0101]
00000001
01000101
10001001
11001101RGBV
Position 6
Position 2
V
G
R
MU
X s
igna
l (a
.u.)
Time (ms)
In case of the cell being part of a cluster composed by nxm triangular cells, the ID from the cell located at row 5: column 5:,
will be [0101 0101], Triangular cell’s IDs can be encoded as
sub-region using a binary representation for decimal number.
• II. Fine-grained localization • The 4-bit code that corresponds to
the ID position inside the unit cell is: Position 2 [1101] and Position 6 [0101]..
Ce
ll lo
catio
n in the c
luste
r
and fo
r e
ach c
ell
I. Macro-grained information The Violet LED sends triangular cell ID.
Channel state localization
0.0 0.5 1.0 1.5 2.00.0
0.2
0.4
0.6
0.8
1.0 R G
V
VRG
GV
[0010 0110]
00000001
0100
0101
11001101
RGBV
Position 6
Position 2
V
G
R
MU
X s
ignal (a
.u.)
Time (ms)
In case of the cell being part of a cluster composed by nxm triangular cells, the ID from the cell located at row 2: column 6:,
will be [0010 0110], Triangular cell’s IDs can be encoded as sub-region using a binary representation
for decimal number.
• II. Fine-grained localization • The unit cell is different, but the 4-
bit code that corresponds to the ID position inside the unit cell is the same: Position 2 [1101] and Position 6 [0101] but the unit cell is different.
Ce
ll lo
catio
n in the c
luste
r
and fo
r e
ach c
ell
• The eight first bits of the violet packet give the 8-bit address of the unit cell I. I. Macro-grained information II. The Violet LED sends triangular
cell ID
CE
LL
UL
AR
TO
PO
LO
GY
Cluster of cells in no-orthogonal topology
(diamond).
Clusters of cell in an orthogonal topology
(square).
R1,2 G1,3 R1,4 G1,1
V2,1
V4,3 B4,2 V4,1 B4,4
B2,2 V2,3 B2,4
G3,3 R3,4 R3,2 G3,1
C1,1 C1,2 C1,3
C2,1 C2,2 C2,3
C3,1 C3,2 C3,3
R1,2 G1,3 R1,4 G1,1
V2,1
V4,3 B4,2 V4,1 B4,4
B2,2 V2,3 B2,4
G3,3 R3,4 R3,2 G3,1
C11 C1,2 C1,3
C2,1 C2,2 C2,3
C3,1 C3,2 C3,3
R G
V B
R G
V B
• Each node, X i,j, carries its own color, X, (RGBV) as well as its ID position in the network.
Ci,j
Ci,j
Diamond
R1,2 G1,3
B2,2
1
2 3
4
5
6
7
B2,4 V2,3 8
R3,4 G3,3
• Four modulated LEDs (RGBV) located at the corners of a
diamond grid.
Footprint regions
Four-code assignment for the LEDs
Hexagon topology
Cosmetics
Hall
RedGreenBlueViolet
Transmitters
IND
OO
R L
OC
AL
IZA
TIO
N
Hexagon
Square
0.0 0.5 1.0 1.5 2.0 2.5
payload dataIDSync.
[data transmission][10101] [r r r: c c c]
V2,3
B2,4
G3,3
R3,4
Codew
ord
(R
GB
V)
Time (ms)
The street lamp (transmitter) sends a message to the SiC receiver, located at the rooftop. The information is resent to a leader vehicle, using the headlights as transmitters, .
Receiver SiC pinpin
Transmitter RGB-LED
400 500 600 700 8000.0
0.2
0.4
0.6
0.8
1.0
B
G
R
Inte
nsity (
a.u
.)
Wavelength (nm)
Driving distance and relative speed
Representation of the I2V2V communication (working principle for the prototype)
Relative speed???
I
V
V
The structure of the frame is a classical one
1.Three sensors (L, M, W) receive the same or 2.different message
Safety, Warning or Braking Distance
Conclusions
• A a-SiC 1x5 WDM device, with channel separation in the visible range, was presented and its operation as wavelength selector explained. • Encoding and decoding data was analyzed and the codewords generated using the MUX signals due to the data transmitted together with the check parity bits tested.
• An algorithm to decode the transmitted information was presented. A transmitter capability of 60 kbps using the generated codeword was achieved.
A square, triangular, diamond, hexagonal topologies were considered for the unit cell. Calibration cell was tested to determine the position
Macro-grained information and Fine-grained indoor
localization was tested to determine the position.
Results showed that is possible not only to determine the position of a mobile target inside the unit cell but also in the cluster, celular or layout environment and to infer the travel direction along the time.
.
Code and parity MUX/DEMUX signals and syndrome generators were designed and analyzed.
Syndrome navigator helps the receiver to determine the position of a mobile target but also to infer the travel direction
