Fakultät E&I, Institut für Nachrichtentechnik, Professur Kommunikationsnetze
Cross-Layer Optimization of Power Line Communications for Smart Grid Stanislav Mudriievskyi
Klagenfurt, 22.09.2015
Agenda Smart grid traffic Protocols performance Switching mechanism CSMA/CA -> TDMA TDMA -> CSMA/CA Conclusions
TU Dresden, 22.09.2015
Cross-Layer Optimization of Power Line Communications for Smart Grid
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Traffic of Smart Grid Examples: 1. “Control” traffic: • •
Small packet size (64 – 128 bytes) High delay requirements (in ms)
•
Warranted delivery from the first transmission
Offered load may be small
2. “Software update”, tariffs update traffic: • •
Big packet size (>1000 bytes) High throughput requirements (in Mbit/s)
•
Retransmission time not critical
Overload may happen
3. Meter reading: • •
High availability of nodes (99,9%) No other specific critical requirements
TU Dresden, 22.09.2015
Cross-Layer Optimization of Power Line Communications for Smart Grid
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Cross-Layer Optimization Possible optimization goals: • Access delay • Throughput • Reliability (warranted delivery)
TU Dresden, 22.09.2015
Cross-Layer Optimization of Power Line Communications for Smart Grid
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Access Protocols Performance
[Hammond Joseph L, and Peter J. P. O'Reilly. Performance Analysis of Local Computer Networks. Reading, Mass: Addison-Wesley Pub. Co, 1988. Print.] TU Dresden, 22.09.2015
Cross-Layer Optimization of Power Line Communications for Smart Grid
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Cross-Layer Optimization Application PDU in
Application PDU out
…
MAC Layer (TDMA, CSMA/CA)
PHY Layer (FEC block, bit loading, repetitions)
1. Adaptation of PHY-MAC layer parameters 2. Switching of MAC layer mechanisms 3. Swithching of MAC layer mechanisms and adaption of PHY-MAC layer parameters
Medium
TU Dresden, 22.09.2015
Cross-Layer Optimization of Power Line Communications for Smart Grid
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Basic Principles for Switching Mechanism • Observe traffic load • Observe channel conditions • Adopt MAC-PHY to the current channel and traffic • Switch to more efficient protocol • “Hysteresis” at the switch point for stability • Switch for all the slaves (including relayed) Prerequisites: • Delay vs. throughput dependencies under variation of other parameters (packet size, channel conditions, settings of the protocol, etc.) • Master – slave architecture TU Dresden, 22.09.2015
Cross-Layer Optimization of Power Line Communications for Smart Grid
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Switching Mechanism Start switch = false
Operate in CSMA/CA
!switch && load > threshold+w
yes
Find out system load
switch = true
Switch to TDMA
switch = false
Switch to CSMA/CA
no switch && load < threshold-w
yes
no TU Dresden, 22.09.2015
w – hysteresis width Cross-Layer Optimization of Power Line Communications for Smart Grid
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Switching from CSMA/CA to TDMA Nodes may transmit
Switch to TDMA CSMA/CA TDMA
40 ms
40 ms
Scheduling information
TU Dresden, 22.09.2015
Cross-Layer Optimization of Power Line Communications for Smart Grid
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Load Assessment in CSMA/CA • Calculate for the last k packets • Time used for data transmission / whole observation time • If upper bound of threshold reached -> switch to TDMA • This switching is possible for the next packet transmission • For G.hn data transmission in one MAC cycle (40 ms)
TU Dresden, 22.09.2015
Cross-Layer Optimization of Power Line Communications for Smart Grid
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Switching from TDMA to CSMA/CA Switch to CSMA/CA Nodes may transmit 40 ms
40 ms
TDMA
CSMA/CA
Scheduling information
TU Dresden, 22.09.2015
Cross-Layer Optimization of Power Line Communications for Smart Grid
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Load Assessment in TDMA • Calculate for the last MAC cycle (40 ms) • Time used for data transmission / MAC cycle time (40 ms) • If lower bound of threshold reached -> switch to CSMA/CA • This switching is possible only after the end of next MAC cycle
TU Dresden, 22.09.2015
Cross-Layer Optimization of Power Line Communications for Smart Grid
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Access Protocols Performance
[Hammond Joseph L, and Peter J. P. O'Reilly. Performance Analysis of Local Computer Networks. Reading, Mass: Addison-Wesley Pub. Co, 1988. Print.] TU Dresden, 22.09.2015
Cross-Layer Optimization of Power Line Communications for Smart Grid
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Initial Start of Operation Problem: • Big network (100s of nodes) • Long delay (seconds or even 10s of minutes) Solution proposal: • Cancel nodes registration • Use short delay access protocol (CSMA/CA) • Use the most robust mode • Switch to more efficient access protocol
TU Dresden, 22.09.2015
Cross-Layer Optimization of Power Line Communications for Smart Grid
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Conclusions • Switching mechanism to reach performance boundaries • 2 simple access mechanisms instead of 1 complicated • Initial start without registration • Channel model from Vancouver (Prof. Lampe) [1]
[1] F. Aalamifar, A. Schloegl, D. Harris, L. Lampe, „Modelling Power Line Communication Using Network Simulator-3“, IEEE Global Communications Conference (Globecom 2013), Atlanta, GA, USA, December 2013. TU Dresden, 22.09.2015
[
Cross-Layer Optimization of Power Line Communications for Smart Grid
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Thank you for attention!
TU Dresden, 22.09.2015
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