propagation channel characterization and modeling
DESCRIPTION
Propagation Channel Characterization and Modeling Outdoor Power Supply Grids as Communication Channels Prof. Dr.-Ing. habil. Klaus Dostert Institute of Industrial Information Systems UNIVERSITY OF KARLSRUHE (TH). Overview. Communication over outdoor electrical power supply lines. - PowerPoint PPT PresentationTRANSCRIPT
Propagation Channel Characterization and Modeling Outdoor Power Supply Grids
as Communication Channels
Prof. Dr.-Ing. habil.
Klaus Dostert
Institute of Industrial Information SystemsUNIVERSITY OF KARLSRUHE (TH)
2
Overview
Analysis of line and cable properties characteristic impedance branching & matching
Communication over outdoor electrical power supply lines
General aspects of channel modeling transfer function, impulse response, channel parameterization interference scenario
PLC channel simulation and emulation channel adapted system development
Network structures and their basic properties Access domain in Europe, ASIA, America
Conclusions and further work
3
History: Carrier Frequency Transmission since 1920 (on the high voltage level only)
no branching optimal „wave guiding“ by network conditioning
4
Current and Upcoming PLC Applications
High Speed Indoor Applications: 12 … 70MHz - PLC for digital entertainment systems (>100
Mbits/s)
Low Speed (10…100 kbits/s)- Office and home automation (intelligent appliances)- Energy information systems- Urban rail-based traffic systems
Broadband Services: 1…30 MHz (1…2 Mbits/s - „Last Mile“ and „Last Meter“ high-speed internet access,
voice over IP etc.
PLC in automobiles PLC for factory automation PLC for advanced safety systems in the mining industry
5
The European Power Supply Network Structure
high voltage level: 110..380 kV
medium voltage level10...30kV
low voltage distribution grid3 Phases: 230V, 400V
LV transformerstations
supply cells up to 350 households cable length 100...400m
transformerstation
400V 400V
400V
230V
230V
3-phase supplydetails
6
Typical Topology of European Power DistributionNetworks in Residential Areas
1 2
3 4 5
6
789
10 11 12 13 14
15
1617
19 20 2122
23
24
25262728
2930
3132
33
18
ServerTransformer Station
cabl
e le
ngth
: max
. 1 k
m
supply cable typeNAYY150SE
House connection cableNAYY50SE
NL1
L3L2
7
Some Details of “Last Mile” and “Last Meter” Environments
mediumvoltagenetwork
local transformerstation
cross-barsystem
ZL1 ZL2
points of mismatchhouse connection forming
a low impedance point - almost short circuit -
8
Power Supply Structures in Asia and Americahigh voltage level: 110..380 kV
1st medium voltage level10…30 kV
low voltage distribution gridsingle or split phase supply125V, 250V many LV transformers
transformerstation
2nd medium voltage distribution level 6 kV
125V 125V
250V
single andsplit-phase
small supply cells few households per transformer cable length 100m grounding of 3rd wire highly unsymmetrical
9
The Ideal Two-Wire System
X
compensation of exterior field
compensation of exterior field
10
Symmetry in Multi-Wire Structures
open wires
passive conductors
3-phase supply cable
X •X •
passive conductors
“earth” in case of a three-wire supply
11
Simplified Analysis of a Two-Wire System 650
100 150 200 250 300 350 400350
400
450
500
550
600
D in mm
ZL/ r =2mm
r =2mm
r =4mm
r =5mm
open wires: r=1
10 15 20 25 30
20
40
60
80
100
120
r =5mm
r =7mm
r =10mm
D in mm
ZL/
cable: r=3.5
0 5 10 15 20 25 30
-8
-6
-4
-2
0
f in MHz
A(f)/dB
l =5000m
l =2000m
l =1000m
l =500m
d=2r=5mm
attenuation at open wires due to Skin effect
D
r
2120
ln 12 2
L
r
Z D D
r r
2
'( )
2
'( )
L
R ff
Z
fR f
r
characteristic impedance
12
RF Properties of Typical Supply Cables
0' 2 r
rC
0 2L
r
02
fR
r
2 tanG f C
Lossy Line Parameters (low losses)
' '( ) ( ) ( )
2 2L
R GL
R G Zf f f
Z
'
'L
LZ
C
Attenuation CoefficientCharacteristic
Impedance
NL1r
L3L2ra
ri
L1
r
L2
L3
PEN
Access Cable Types
L1
N
L3
Model
10
0
1 2 5 10 20
A(f)[dB]
20
30
40
50
70
60
NAYY50SE
NAYY 150SE
40
30
50
20
10
01 2 5 10 20
ZL/
NAYY50SE
NAYY150SE
f /MHz
House Connection
Main Supply Cable
f /MHz
Characteristic Impedance Attenuation over 1km
13
ZL
ZLZL
ZL
ZL
mismatch: ZL/2
The problem of Branching and Possible Solutions
ZL
ZLZL
ZL
ZL
matched to ZL
ZL/3
ZL/3
L >> ZL
R=ZL/3
14
Some Ideas for Signal Coupling with Enhanced SymmetryImproving EMC
typical RF coupling devices Transformer Stationcross-bar system
cable: ZLC
L10µH
BALUN
MODEM
RF-shorts
impedancematching
decoupling
L > 10µH
RF-shorts
BALUN
House Connection
MODEM
powermeter
impedancematching
decoupling
cable: ZLC
Ferrite material is required for these decoupling coils, which carry high currents! Transformer: >150A House connection: >30A
15
Reflections Causing Echoes and Inter-Symbol Interference
direct echo
result
strong inter-symbol interference: Tbit
Tbit
1 1d / v
T
R2 2d / v
delay: =2-1
direct path echo path
wireless channel as example
t1 2
impulse response
simplified analysis of aline with 1 unmatched branch
T R1
2
in practice:multipleechoes
16
Approaches Toward Deterministic Network Modeling
bq
ri
a
bra
a
bS11 S12
S21 S22
a2
b2
a1
b1
source line element sink
a2
b2
a1
b1
a 3 b 3branch example
high computational effort requires detailed knowledge of network topology and device parameters not applicable in practice
17
1
N
E i ii
h t k t
impulse response
transfer function
j2
1
e i
Nf
E ii
H f k
0.5...11 2 0 1( )f c f c f a a f
skin-effect dielectric losses
Attenuation Coefficient:
The Echo-based Channel Modelconsidering only echoes : ki=const
( )( , ) e if di i ik k f d g
low-pass behavior
dependent on number, lengthand matching of branches
generally complex
s(t)
k1
r(t)
k2 k3 kN
vi
i
d
Fouri
er
transf
orm
j2
1
e ei
i
dN f f dvi
i
H f g
Result
18
T R200m 1
225m 2
FT
0 5 10 15 20 25 30-20
-15
-10
-5
0
f in MHz
dB
0 5 10 15 20 25 30
-40
-20
0
f in MHz
dB
path 2path 1
attenuation
1e ia f dig
H(f): single reflection, no losses
0 5 10 15 20 25 30
-40
-20
f in MHz
0
dB
single reflection, including losses
1 1.17 1.33 1.5 1.67 1.83 20
0.5
1
t in µs
path 1
path 2
h(t): impulse response
j2e ii
fg
19
0.52
0.347
0.26
0.208
0.173
0.149
0.46
0.627
0.71
0.76
0.793
0.817
Two-Path Channel without Losses butVarying Path Weights
Path 1
Path 2
20
path di/m gi
1 200 0.64
2 222.4 0.38
3 244.8 -0.15
4 267.5 0.05
j2
1
e ei
i
dN f f dvi
i
H f g
10 1 1
m7.8 10 f f
8 m
s1.5 10
r
cv
ZLG
30m
11m170m
0 5 10 15 20 25 30-50
-40
-30
-20
-10
0
frequency in MHz
dB |H(f)|
0 0.5 1 1.5 2 2.5 3 3.5
0
0.5
1
time in µs
h(t)
A First Realistic Example
0 5 10 15 20- 50
- 40
- 30
- 20
-10
0
f in MHz0 1 2 3 4 5
0
1
t in µs
0.5
calculationmeasurement
21
A Second Example(more complex)
path di/m gi
1 90 0.029
2 102 0.043
3 113 0.103
4 143 -0.058
5 148 -0.045
6 200 -0.040
7 260 0.038
8 322 -0.038
9 411 0.071
10 490 -0.035
11 567 0.065
12 740 -0.055
13 960 0.042
14 1130 -0.059
15 1250 0.049
10 1 1
m7.8 10 f f
8 m
s1.5 10
r
cv
0 5 10 15 20 25 30
-80
-60
-40
-20|H(f)|
dB
frequency in MHz
0 0.5 1 1.5 2 2.5 3 3.5-0.5
0
0.5
1
h(t)
time in µs
110m 15m
22
2 4 6 8 10 12 14 16 1880
70
60
50
40
30
20
10
0
Att
enua
tion
in d
B
Frequency in MHz
Transmission Characteristics According to Length Classes
150 m
200 m
300 m
380 m
23
A General Powerline Interference Model
tIAT
Am
plit
ude
time
tA
tB
A
A, tB and tA are random variables with exponential distributions
threat of burst errors
H(f) h(t)
Channel as a Linear Filter
narrowband-interference
backgroundnoise
Interference
+
periodic impulsive noiseasynchronouswith the mains
periodic impulsive noise synchronous with the mains
aperiodicasynchronous
impulsive noise
24
Idea of a Universal PLC-Channel Emulator
PLCModem
PLCModem
ConfigurationInterface
Host-PC
+
PGA
PGA DA
DA FIR
Filter
NoiseGenerator
DA
LPF
LPF LPF
FIRFilterLPF D
AD
A PGA +LPF
NoiseGenerator D
A PGALPF
25
FPGA8from
ADC
signal DACFIFO
channel emulation filtersdelay
5x7bitdelay
5x5bitcoeff.
32x8bitcoeff.
control
1420FIRNotch
FIRlowpass
32P_DATA
26
8 14
8-bit-circular memoryof length 500
periodic, synchronous, asynchronous impulsive noise & background noise
narrow band noise
control
+
P_ADDR
8x20bits load
500 x 8bitsload control
14
148
interference DAC
20bit shift register
8 m-sequences of length 220-1
control / load
Ampli-tude
Ampli-tude
14D
A
14D
A
Some Details Toward Emulator Realization
26
P LC M odem(Tran sm itte r)
P LC M odemL P
A D C
D A C
FPGA
EEPROM
D A C
S ign a l
N o ise
P G A
P G A
L P
ChannelEm ulator Hardware
PC
A First Powerline Channel Emulator Prototype
f in MHz
f in MHz
|H| in dB
|H| in dB
coeff. filter 1 coeff. filter 2reference channel modified filter structure
simulations,implementation
hardware
verificationmeasurements
27
FSK, GMSK
f1 f2 f3
ffN
not usable due to high attenuation
restricted e.g. for protection of broadcast services
OFDM sub-channel
Channel Transfer Function
Why OFDM for PLC?
28
Conclusions and Further Work
PLC or BPL offers a variety of valuable applications data rates exceeding many Mbits/s will enable numerous new servicesMature channel models are covering any channel of interest successful development of a new generation of ”channel adapted” PLC systems is possible no more pitfalls: sophisticated simulation and emulation
Further development and standardization of PLC or BPL goes on ETSI, CENELEC, CISPR EU Project OPERA (Open PLC European Research Alliance) HomePlug Alliance (USA) IEEE PHY/MAC Working Group
Building advanced and user-friendly simulation and emulationenvironments is now an important issue