1 session 2, presentation: modelling of physical layer behaviour in a hs-dsch network simulator...
DESCRIPTION
3 Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator Overview Network simulator Link adaptation Physical layer model requirements Hybrid ARQ Modeling for network simulator Narrow band modeling Wide band modeling Physical layer behaviour ConclusionsTRANSCRIPT
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11Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator
Modelling of physical layer behaviour in a HS-DSCH
network simulator
Frank BrouwerTwente Institute for Wireless and Mobile
Communications
![Page 2: 1 Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator Modelling of physical layer behaviour in a HS-DSCH network](https://reader036.vdocuments.us/reader036/viewer/2022082412/5a4d1af77f8b9ab0599820c9/html5/thumbnails/2.jpg)
22Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator
Overview
Network simulator• Link adaptation• Physical layer model requirements• Hybrid ARQ
Modeling for network simulator• Narrow band modeling• Wide band modeling
Physical layer behaviour Conclusions
![Page 3: 1 Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator Modelling of physical layer behaviour in a HS-DSCH network](https://reader036.vdocuments.us/reader036/viewer/2022082412/5a4d1af77f8b9ab0599820c9/html5/thumbnails/3.jpg)
33Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator
Overview
Network simulator• Link adaptation• Physical layer model requirements• Hybrid ARQ
Modeling for network simulator• Narrow band modeling• Wide band modeling
Physical layer behaviour Conclusions
![Page 4: 1 Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator Modelling of physical layer behaviour in a HS-DSCH network](https://reader036.vdocuments.us/reader036/viewer/2022082412/5a4d1af77f8b9ab0599820c9/html5/thumbnails/4.jpg)
44Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator
Network simulator
End-to-end performance analysis HSDPA Streaming video, web browsing, file transfer Mutual influence PHY, MAC, RLC <> IP, TCP/UDP
• Detailed implementation of MAC, RLC, IP, TCP/UDP• Abstract and realistic model PHY
Abstract PHY model• Channel conditions
Distance lossShadowing (correlation distance)Channel model (Vehicular A, Pedestrian A, Indoor A, …)
• Physical layer characteristicsBLER per TTILink adaptation, Hybrid ARQ
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55Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator
Link adaptation
Keep BLER constant by changing Transport Block Size
More data under good channel conditions
0
5000
10000
15000
20000
25000
30000
TBS
12345678910111213
CQI generation
-16
-14
-12
-10
-8
-6
-4
-2
0 20 40 60 80 100 120 140 160 180 200
TTI
SN
R (d
B)
0
2
4
6
8
10
12
14
CQ
I
SNR
CQI
UE transmits CQI:max TBS with BLER = 0.1
Node-B decides TBS:CQI + own algorithm
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66Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator
Physical layer model requirements
Condition in network simulator includes:• 30 Transport Block Sizes• Any SNR value (-20 to 15 dB continuous)
Required output• Monotonous relation SNR – BLER for given TBS• More focus on relative than on absolute accuracy• One BLER value per TTI
Calculation should not require more that some (tens of) floating point operations
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77Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator
PDUPDUPDU
Hybrid ARQ Reception in error => combine received signal with a
second reception Possible H-ARQ schemes
• Incremental redundancy (Send additional information)• Chase combining (Repeat the same information)
Chase combining assumed
Maximum Ratio Combining (= add powers)• Power of first reception aids second reception• Higher probability of successful reception
PDU+ = PDU
ErroneousSuccess
Node B UE
NACKACK
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88Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator
Overview
Network simulator• Link adaptation• Physical layer model requirements• Hybrid ARQ
Modeling for network simulator• Narrow band modeling• Wide band modeling
Physical layer behaviour Conclusions
![Page 9: 1 Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator Modelling of physical layer behaviour in a HS-DSCH network](https://reader036.vdocuments.us/reader036/viewer/2022082412/5a4d1af77f8b9ab0599820c9/html5/thumbnails/9.jpg)
99Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator
Narrow band modeling
Generate a varying SNR in network simulator• All received power of wanted signal is captured• PHY layer behavior equal to AWGN
WP2 PHY AWGN simulations as input Modeled through analytical approximation
• Shape of curve equal for all CQI• Steepness function of CQI• Offset function of CQI
• Can generate for each CQI,SNR and BLER
CQI = Channel Quality Indicator
BLER vs SNR simulation and model
0.01
0.1
1
-20 -15 -10 -5 0 5 10 15
SNR (dB)
BLE
RCQI1 sim CQI22 sim CQI1 anal CQI22 anal
CQI8 sim CQI30 sim CQI8 anal CQI30 anal
CQI15 sim CQI15 anal
3.1703.1
)...1(log2
)(log3 7.01010
CQI
BLERCQISNR 1010
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1010Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator
Wide band modeling (1)
Channel produces delayed copies
RAKE receiver:• Estimate tap delay line• One finger per tap• Maximum Ratio Combine
ISI model: All power over symbol border turns into noise
Transmitted signal
Channel
Received signal
RAKE fingers
Signal Interference
N
iit
N
i
niit
nt
p
pisi
1,
1,
,
))1(
(log10
1,,
1,,10
nisip
isipSNR N
iitit
N
iitit
t
10
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1111Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator
Wide band modeling (2)
Symbol time options:Raw symbols (240
ksymbols/s for all CQI)Bitrate including overheadBitrate excluding overhead
Corrections needed for ISI performance of receiver
Example:• Vehicular A is 0.3 times bitrate
excluding overhead
0.01
0.1
1
-20.0 -15.0 -10.0 -5.0 0.0 5.0 10.0 15.0
SNR (dB)
BLER
CQI1 sim CQI15 sim CQI1 anal CQI15 anal
CQI8 sim CQI8 anal CQI22 anal
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1212Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator
Overview
Network simulator• Link adaptation• Physical layer model requirements• Hybrid ARQ
Modeling for network simulator• Narrow band modeling• Wide band modeling
Physical layer behaviour Conclusions
![Page 13: 1 Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator Modelling of physical layer behaviour in a HS-DSCH network](https://reader036.vdocuments.us/reader036/viewer/2022082412/5a4d1af77f8b9ab0599820c9/html5/thumbnails/13.jpg)
1313Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator
Physical layer behaviour
SNR generated from channel model
BLER generated from PHY model
Observations:• CQI lags to SNR (delay in
reporting• Actual BLER strongly
varyingRounding of CQILagging of CQI (“wrong”
selection of TBS)
CQI generation
-16
-14
-12
-10
-8
-6
-4
-2
0
0 50 100 150 200TTI
SNR
(dB
)
0
2
4
6
8
10
12
14
16
CQ
I
SNRCQI
Resulting BLER
1E-7
1E-6
1E-5
1E-4
1E-3
1E-2
1E-1
1E+0
0 50 100 150 200TTI
BLER
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1414Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator
Overview
Network simulator• Link adaptation• Physical layer model requirements• Hybrid ARQ
Modeling for network simulator• Narrow band modeling• Wide band modeling
Physical layer behaviour Conclusions
![Page 15: 1 Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator Modelling of physical layer behaviour in a HS-DSCH network](https://reader036.vdocuments.us/reader036/viewer/2022082412/5a4d1af77f8b9ab0599820c9/html5/thumbnails/15.jpg)
1515Session 2, Presentation: Modelling of physical layer behaviour in a HS-DSCH network simulator
Conclusions
Network level simulations need “simple” model covering all CQIs and all SNRs• No physical layer simulations• No difficult look-up structures
Physical layer model provides subset Analytical model matches perfectly in narrow
band channel conditions Model adaptation for wide band channel
conditions has sufficient match