#15 1 Victor S. Frost Dan F. Servey Distinguished Professor Electrical Engineering and Computer...

#15 1

Victor S. FrostDan F. Servey Distinguished Professor Electrical Engineering and Computer

ScienceUniversity of Kansas2335 Irving Hill Dr.

Lawrence, Kansas 66045Phone: (785) 864-4833 FAX:(785) 864-

7789 e-mail: [email protected]

http://www.ittc.ku.edu/

Specific Systems:

Broadband Powerline Communications Networks

(PLCs)#15

All material copyright 2006Victor S. Frost, All Rights Reserved

http://www.ittc.ku.edu/

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Outline

• What is a PLC?• Topology• Channel characteristics• Noise characteristics• A MAC protocol for PLC networks

– Assumptions– Operation

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What is a Broadband PLC Network

• Powerlines have been used for: – Low speed data transport for many

years• Control• Telemetry

– In home power wiring have been used for networking

– Broadband PLC is an alternative for internet access-last mile

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Broadband PLC topology

From: Distributed MAC protocols and priority oriented schedulingfor a PLC access network Sundaresan, S. Anand, S. Srikanthn,y and C. N. Krishnan, International Journal Of Communication Systems Int. J. Commun. Syst. 2003; 16:475–495

Modified from: Design and performance evaluation of an hybrid reservation Polling MAC protocol for power-line communicationsG. Bianchi, Tinnirello, and G. Conigliaro, International Journal Of Communication Systems Int. J. Commun. Syst. 2003; 16:427–445

Base station

Access Units

Internet

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Broadband PLC System Architecture

From: Broadband PLC Access Systems and Field Deployment inEuropean Power Line Networks Weilin Liu, Hanspeter Widmer, and Philippe Raffin, IEEE Communications Magazine, May 2003.

• OM = outdoor master

• OR = outdoor repeater

• OAP = outdoor access point

• IA = Indoor adaptor

• IC = Indoor Controller

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PLC Channel

• Time varying• Frequency dependent• EMC issues with amateur radio operators• CENELEC

– Europe– 3-148.5 kHz– 5 mW– 144 kb/s

• Broadband PLC:1-30 Mhz

*Niovi Pavlidou, Aristotle University of ThessalonikiA. J. Han Vinck, Javad Yazdani and Bahram Honary, Power Line Communications: State of the Art and Future Trends, IEEE Communications Magazine, April 2003

*

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Channel Transfer Function Characteristics

*

*Klaus Dostert, “Powerline Communications,”Prentice Hall, 2001

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PLC noise environment

• Colored background noise– Source: Sum of low power noise sources– Timescale: minutes to hours

• Narrowband noise– Source: broadcast stations– Timescale: varies with time of day

• Periodic impulsive noise asynchronous to the main frequency– Source: Switching power supplies– Timescale: ms (repetition rate 50-200Hz)

• Periodic impulsive noise synchronous to the main frequency– Source: appliances– Timescale: ms (repetition rate 50-100Hz or 60Hz and 120Hz),

duration 10-100us• Asynchronous impulsive noise

– Source: Switching transients in the power grid– Timescale: duration us-ms and level 50dB above background noise

level major source of errors

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Estimation of Channel Capacity for Broadband PLC Networks

Link Length 100-300m

Best Case Worst Case

Theoretical 250 Mb/s 14 Mb/s

Realizable 100 Mb/s 5 Mb/s

• Based on last mile capacity analysis in: “Powerline Communications”, Klaus Dostert, Prentice Hall 2001– Channel characteristics– Noise characteristics

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A MAC protocol for Broadband PLC Networks

• Focus on protocol discussed in: “Design and performance evaluation of an hybrid reservation Polling MAC protocol for power-line communications G. Bianchi, Tinnirello, and G. Conigliaro, International Journal of Communication Systems Int. J. Commun. Syst. 2003; 16:427–445

• Assumptions– Fast ARQ is better that FEC in impulsive noise

environments like broadband PLC• FEC has a constant bandwidth penitity• Fast ARQ is only invoked when errors, here induced via

impulsive noise.– Half duplex channel: same resources used for up and down

stream communications– Time division

• Frames• Slots• Minislots

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From: “Design and performance evaluation of an hybrid reservation Polling MAC protocol for power-line communications,” G. Bianchi, Tinnirello, and G. Conigliaro, International Journal Of Communication Systems Int. J. Commun. Syst. 2003; 16:427–445

F=FramingCi=Command

-AU ID-Acks

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• DLW– Link layer at AU send ACK on a slot by slot basis fast

retransmission• UPL

– Supports one fixed length packet – AU’s request slots– BS grants slots– Acks for UPL from AUi are piggybacked in the control in next

DLW even if slot not destine for AUi • RSV

– AU has packet to send contending state– Reservation slots are subdivided into minislots– A random access protocol like ALOHA is used for contention– When BS receives a minislot for AUi a grant for AUi is placed

in a polling list– The command in the next DLW contains a reservation ack

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• A connection set-up is used to identify all AU’s that can access the channel– AU’s are given a connection ID– AU’s provide traffic/QoS parameters

• Maximum tolerable delay (MD)• Data Rate expressed as interarrival time (IT), maybe

dynamically updated for VBR traffic– For each AU the BS also tracks

• the remaining lifetime head-of-line packet = MD – W; W is waiting time for HOL packet

• Number of retransmission attempts

• AU is – Idle– Active – Contending

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• Active AU is granted slots according to scheduling rules

• Transition from Active Idle: AU notifies BS to stop sending grants

• Transition from Idle Active: AU enters contending state

• Controlling the frequency of RSV slots– Too frequent uses capacity– Not frequent enough high delay– Proposed process

• Issue RSV slot every T sec• If one collision of a minislot in RSV then send

consecutive RSV slots subject to QoS constraint

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• The BS is designed to be an earliest deadline first scheduler

• Let MDmax = Max MD of all AU’s• Set up a polling register that

controls the order of polling the AU’s

• AU placed at position k in the polling register implies that the relevant packet must be transmitted on the channel in at most k slots, otherwise it expires

• Upon reservation the AU ID is placed a position MD-W or below.

MDmax - 1

k ID for target AU transmission time

0

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• If no retransmissions then the scheduler issues grants for the AU in the lowest position in the polling register

• The AU in the bottom position of the polling register is always transmitted, it is that packets last opportunity.

• If retransmissions then the scheduler issues grants for the AU in the lowest position in the polling register and a retransmission counter

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• At the end of a transmission the BS learns– Transmission successful

• If the AU is active the next grant is scheduled IT slots later

– Transmission successful• If the AU transitions from active to idle the AU is

removed from polling register

– Transmission unsuccessful• Leave in same position in polling an increment

the retransmission counter• Note that MAC/scheduled deals with

retransmissions

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• The polling register is shifted down each time slot.

• Note if packet in bottom of the polling register is corrupted then it is lost, that is a retransmission will exceed MD for that AU.

• Use of retransmission counter– the transmission grant is assigned to the

station in the lowest register position, among the ones with lowest retransmission counter value

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• Example:– 3 AU’s– Assume

WA = Wb = WC = 0

– Minislot for A arrives first MD = 5 so place in 5th position in polling register

– Minislot for B arrives second MD = 4 so place in 4th position in polling register

– Minislot for C arrives last MD = 4, 4th position in polling register is full, so place in 3rd position in polling register

A B C

RSV Slot

Bold = New reservation

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• AUC is lowest in polling register so it is transmitted

• Assume this packet is corrupted

• Left in same position before shift down

• Increment retransmission counter shown by X

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• B granted next– Lowest in polling

register with lowest retransmission count

• Assume B successful

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• Using ITB = 3 MD = 4: a new reservation for B in placed in the 4th

• Note A is next to be granted and assume it is corrupted

• Increment its retransmission counter

• So stays in polling register and after shift down is in the 2nd location

• New reservation for A is not placed in the polling register until the previous one is cleared out

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• C is given a grant next because it is in the bottom position of the polling register

• Assume this is successful

• So a new reservation for C is place in the polling register because it has an

MD = 4

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• In time slot 5 a grant is given to AU B

• Assume this is transmission is successful

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• AU A is given a grant for slot 6

• Assume this is successful

• Now new reservation for AU A can be placed on the polling register; should go in position 2, but after shift C is there so it goes in position 1

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• Multiple classes of service– Allow more than one AU per position in the

polling register• Low priority AU granted after all high priority AU• View as multiple polling registers; when the high

priority polling register is empty the low priority polling register is used to make grants

– Rearrange the polling register• high priority AU’s are substituted for low priority

AU’s in the polling register


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• Performance Evaluation*– Focus on Packet voice with on/off model

• Ave on time = 1 sec• Ave off time = 1.3 sec• Durations ~ exponentially• Slot time 576 bits

– payload– Command– Packet header– Guard time

• Packet interarrival time = 16 ms– Rates 720 Kb/s, 1.44 Mb/s and 2.88 Mb/s– Noise

• Glibert model– Good/Bad states– Bad state models impulse noise– IMT mean time between noise bursts


* From: “Design and performance evaluation of an hybrid reservation Polling MAC protocol for power-line communications,” G. Bianchi, Tinnirello, and G. Conigliaro, International Journal Of Communication Systems Int. J. Commun. Syst. 2003; 16:427–445

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*From: “Design and performance evaluation of an hybrid reservation Polling MAC protocol for power-line communications,” G. Bianchi, Tinnirello, and G. Conigliaro, International Journal Of Communication Systems Int. J. Commun. Syst. 2003; 16:427–445

**Also see: Hrasnica H, Haidine A, Lehnert R. Reservation MAC protocols for powerline communications. Proceedings of ISPLC 2001–5th International Symposium on Powerline Communications and its Applications, April 3–6, 2001, Sweden, 2001.

*, **

*

F=R/(576bits/16ms)

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Conclusions

• PLC access networks operating in a harsh environment

• Available capacity is not very high• Requires MAC protocols to

overcome impulsive noise• Standards still evolving

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References

• Begain, K., et al., Modeling of a PLC access network, in First Polish-German Teletraffic Symposium. 2000: Dresden, Germany.

• Bianchi, G., I. Tinnirello, and G. Conigliaro, Design and performance evaluation of an hybrid reservation-polling MAC protocol for power-line communications. International Journal of Communication Systems, 2003. 16(5): p. 427-445.

• Klaus Dostert, “Powerline Communications,” Prentice Hall, 2001• Hrasnica H, Haidine A, Lehnert R. Reservation MAC protocols for powerline

communications. Proceedings of ISPLC 2001–5th International Symposium on Powerline Communications and its Applications, April 3–6, 2001, Sweden, 2001.

• Hrasnica, H. and A. Haidine. Modeling MAC Layer for Powerline Communications Networks,. in Internet, Performance and Control of Network Systems, part of SPIE's symposium on Information Technologies. 2000. Boston, MA, USA.

• Hrasnica, H., A. Haidine, and R. Lehnert. Performance comparison of reservation MAC protocols for broadband powerline communications networks. in Proceedings of ISPLC 2001-5th International Symposium on Powerline Communications and its Applications. 2001. Malm.o, Sweden.

• Hrasnica, H., A. Haidine, and R. Lehnert, Broadband powerline communications networks : network design. 2004, Chichester, England ; Hoboken, NJ: Wiley. xiii, 275 p.

• Hrasnica, H. and R. Lehnert. Investigation of MAC protocols for broadband PLC networks under realistic traffic conditions. in 7th ISPLC 2003. 2003. Kyoto, Japan.

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References

• Lin, Y.-J., et al. Periodic contention-free multiple access for power line communication networks. in 19th Internation Conference on Advanced Information Networking and Applications, 2005. 2005.

• Weilin Liu, Hanspeter Widmer, and Philippe Raffin, “Broadband PLC Access Systems and Field Deployment in European Power Line Networks, IEEE Communications Magazine, May 2003.

• Majumder, A. and J. Caffery, Jr., Power line communications. Potentials, IEEE, 2004. 23(4): p. 4-8.

• Mollenkopf, J., Presentation to Cincinnati IEEE Meeting. 2004. p. 1-25.• Pavlidou, N., et al., Power line communications: state of the art and

future trends. Communications Magazine, IEEE, 2003. 41(4): p. 34-40.• Sundaresan, S., et al., Distributed MAC protocols and priority oriented

scheduling for a PLC access network. International Journal of Communication Systems, 2003. 16(5): p. 475-495.

• Sutterlin, P. and W. Downey. A power line communication tutorial - challenges and technologies. in 1998 International Symposium on Power-line Communications and its Applications. 1998. Tokyo, Japan.

• Weilin, L., H. Widmer, and P. Raffin, Broadband PLC access systems and field deployment in European power line networks. Communications Magazine, IEEE, 2003. 41(5): p. 114-118.

#15 1 Victor S. Frost Dan F. Servey Distinguished Professor Electrical Engineering and Computer...

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