Design Tradeoffs In Joint Powerline and Wireless Transmission For Smart Grid Communications 1 Ghadi Sebaali and Brian L. Evans Department of Electrical

Design Tradeoffs In Joint Powerline and Wireless Transmission For

Smart Grid Communications

1

Ghadi Sebaali and Brian L. Evans

Department of Electrical and Computer EngineeringWireless Networking and Communications Group

The University of Texas at Austin

Collaboration with Prof. Naofal Al-Dhahir and Mr. Mostafa Sayed at UT Dallas Support from National Instruments, and Semiconductor Research Corporation with

liaisons Freescale Semiconductor and Texas Instruments

ImpairmentsChannel distortion and time-varying gainImpulsive and thermal noise, and external interference

GoalIncrease reliability

ApproachJointly transmit over PLC and wireless channels

Contributions Review channel modeling Review of noise modelingExplore design tradeoffsExplore noise mitigation techniques

Smart Grid Communications

2Introduction |PLC/Wireless Links| PLC/Wireless Combining| Wireless Receiver| Summary

[MaRS Market Insights, 2012]

PLC Link Wireless LinkFrequency band

3-500kHz (unlicensed)

902-928MHz(unlicensed)

3

Joint Transmission

Transmitter side: send same info over PLC and wireless links

Receiver side:combine received signals into one

Introduction |PLC/Wireless Links| PLC/Wireless Combining| Wireless Receiver| Summary

Com

bine

r

DM

Dominant noiseCyclostationary impulsive noisein time and frequency with T = half AC power cycle

hτ

(1)

hτ

(2)

hτ

(3)

AWGN

60%

30%

10%

Cyclo-stationary

noiseN (0,1)

Caused bySwitching mode power suppliesNon-linear electronic devices Broadcast stations

Modeled by Linear periodically time-varying system

[Nassar et al., 2012]

4

Narrowband PLC Noise


11 12 13

Narrowband PLC Channel

Multi-path model

Transmission-line modelParameters: ABCD parametersDrawback: assumes topology is known

Extends transmission-line modelAccounts for multipath effects due to branches, impedance mismatch

Parameters: delay, attenuation, total number of paths, etc.Drawback: doesn’t capture topology of channel

5Introduction |PLC/Wireless Links| PLC/Wireless Combining| Wireless Receiver| Summary

Statistical model

[Ferreira, 2010]

Dominant noiseUncoordinated impulsive noise

Noise sourcesUncoordinated transmissionsNon interoperable devicesNeighboring devices

Noise modelGaussian Mixture Model (GMM)

Channel Model Rayleigh Fading

6

Wireless Link

[Interference Mitigation Toolbox, UT Austin]


7

Combining Reception

Combining Schemes

SelectionCombining

Largest SNR

Saturated Metric Combining

Saturated log likelihood

Maximum Ratio Combining

Log likelihood ratio


[Lai, 2012]

8

Combining Reception

FFT (N)

Cyclic Prefix Length Modulation Number of Paths Combining Scheme

128 26 BPSK 5,20 Saturated MetricSelection Maximal Ratio

Combining Schemes for a 5-path channel model Combining Schemes for a 20-path channel model


9

Wireless Receiver Design

Zero Forcing: detects signal by inverting channel matrix

Minimum Mean Square Error: ranks received signals based on their SNR

Maximum Likelihood: chooses symbol with least Euclidean Distance for decoding and cancellation

[Miridakis, 2013]


10

Wireless Receiver Design

Parameter Value

Channel Multipath

Channel Model

Rayleigh

Channel Taps 6

Noise Model AWGN, GMM

GMM Parameters

99% σw= 0.001 and 1% σw= 100

Successive Interference Cancellation Techniques

Zero ForcingMin. Mean Squared ErrorMaximum Likelihood


11

Increased reliability via joint PLC/wireless transmissionRecommendations

Maximal ratio combining for PLC/wireless linksZero-forcing to mitigate wireless interference

Future workCoexistence in 900 MHz band between IEEE 802.11ah & 802.15.4gInterferer separation (find critical distance for victim receiver)Link quality indicator for the IEEE 802.15.4g standard

Summary


[1] M. Sayed and N. Al-Dhahir, “Narrowband-PLC/wireless diversity for smart grid communications,” Proc. IEEE Global Comm. Conf., Dec. 2014.

[2] H. Ferreira, Power Line Communications: Theory and Applications for Narrowband and Broadband Communications Over Power Lines, 2010.

[3] K. F. Nieman, J. Lin, M. Nassar, K. Waheed, and B. L. Evans, “Cyclic spectral analysis of power line noise in the 3-200 kHz band,” Proc. IEEE Int. Symp. On Power Line Comm. and Its Applications, 2013.

[4] M. Nassar, K. Gulati, Y. Mortazavi, and B.L.Evans, “Statistical modeling of asynchronous impulsive noise in powerline communication networks,” Proc. IEEE Global Comm. Conf., Dec. 2011.

[5] M. Nassar, B. L. Evans, and P. Schniter, “A factor graph approach to joint OFDM channel estimation and decoding in impulsive noise environments,” IEEE Trans. Signal Proc., vol. 62, no. 6, Mar. 2014.

[6] M. Nassar, A. Dabak, I. H. Kim, T. Pande, and B. L. Evans, “Cyclo- stationary noise modeling in narrowband powerline communication for smart grid applications,” Proc. IEEE Int. Conf. Acoustics, Speech, and Signal Proc., Mar. 2012.

[7] K. Gulati, M. Nassar, A. Chopra, N. B. Okafor, M. DeYoung, and B. L. Evans. (2011, Apr.) UT Austin Interference Modeling and Mitigation Toolbox. [Online].

Available: http://users.ece.utexas.edu/~bevans/projects/rfi/software/

[8] N. Miridakis and D. Vergados, “A survey on the successive interference cancellation performance for single-antenna and multiple-antenna OFDM systems,” IEEE Comm. Surveys & Tutorials, vol. 15, no. 1, Feb. 2013.

[9] S. W. Lai and G. G. Messier, “Using the wireless and PLC channel for diversity,” IEEE Trans. on Comm., Dec. 2012.

References

Documents

Design Tradeoffs In Joint Powerline and Wireless Transmission For Smart Grid Communications 1 Ghadi Sebaali and Brian L. Evans Department of Electrical