Homeplug AV and IEEE 1901 E-Book

Haniph A. Latchman

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 559

Veröffentlichungsjahr: 2013

Beschreibung

The only authorized book explaining the HomePlug networking standards HomePlug is a growing technology for creating high-speed Power Line Communication (PLC) networks by transmitting data over in-home or in-office power lines. Users only need to plug adapters into wall outlets to create an instant network of computers, printers, routers, home entertainment devices, and appliance control systems. HomePlug AV and IEEE 1901: A Handbook for PLC Designers and Users provides for the first time an opportunity for non-members of the HomePlug Alliance to gain in-depth insight into the design and operation of the HomePlug standards. Offering a clear and simple description of the standards, this groundbreaking resource presents HomePlug AV and the associated IEEE 1901 standards in terms more readily understood by a much wider audience, including nontechnical managers, engineers, students, and HomePlug designers. The book details the many benefits of HomePlug AV, including: * An affordable, secure alternative or complement to WiFi--especially in buildings where WiFi reception is poor or running new network wires is impractical * Higher potential data transmission rates up to 200 Mbps * Support for multimedia applications such as HDTV and VoIP The book also provides an overview of the HomePlug Green PHY standard that is targeted for use in smart energy applications, and the HomePlug AV 2.0 standard that operates at up to 1.5 Gbps. An essential tool for designers of HomePlug devices, network administrators, and individual users of HomePlug networks who need to understand the features and capabilities of HomePlug, HomePlug AV and IEEE 1901: A Handbook for PLC Designers and Users will also prove useful for researchers in academia and the power line communications industry.

Leseprobe

Contents

Cover

IEEE Press

Title Page

Copyright

Dedication

List of Figures

List of Tables

Preface

Acknowledgments

Biographical Sketches of the Authors

Chapter 1: Introduction

1.1 HomePlug AV and ITS Relationship to IEEE 1901

1.2 Focus of the Book

1.3 The HomePlug Powerline Alliance

1.4 The Role of PLC in Multimedia Home Networking and Smart Energy Applications

1.5 Book Outline

Chapter 2: The Homeplug AV Network Architecture

2.1 Introduction

2.2 Protocol Layers

2.3 Network Architecture

2.4 Summary

Chapter 3: Design Approach for Powerline Channels

3.1 Introduction

3.2 Channel Characteristics

3.3 Frequency Band

3.4 Windowed OFDM

3.5 Turbo Convolutional Code

3.6 Channel Adaptation

3.7 Beacon Period Synchronized to AC Line Cycle

3.8 TDMA with Persistent and Nonpersistent Schedules

3.9 Data Plane: Two-Level Framing, Segmentation, and Reassembly

3.10 PHY Clock Synchronization

3.11 Summary

Chapter 4: Physical Layer

4.1 Introduction

4.2 PPDU

4.3 Preamble

4.4 Frame Control

4.5 Payload

4.6 Priority Resolution Symbol

4.7 Transmit Power, Tone Mask, and Amplitude Map

4.8 Summary

Chapter 5: MAC Protocol Data Unit (MPDU) Format

5.1 Introduction

5.2 Beacon

5.3 Start-of-Frame (SOF)

5.4 Selective Acknowledgment (SACK)

5.5 Request to Send (RTS)/Clear to Send (CTS)

5.6 Sound

5.7 Reverse Start-of-Frame (RSOF)

5.8 Summary

Chapter 6: MAC Data Plane

6.1 Introduction

6.2 MAC Frame Generation

6.3 MAC Frame Streams

6.4 Segmentation

6.5 Long MPDU Generation

6.6 Reassembly

6.7 Buffer Management and Flow Control

6.8 Communication Between Associated But Unauthenticated STAs

6.9 Communication Between STAs not Associated with the Same AVLN

6.10 Data Encryption

6.11 MPDU Bursting

6.12 Bidirectional Bursting

6.13 Automatic Repeat Request (ARQ)

6.14 Summary

Chapter 7: Central Coordinator

7.1 Introduction

7.2 CCo Selection

7.3 Backup CCo and CCo Failure Recovery

7.4 Transfer/Handover of CCo Functions

7.5 CCo Network Management Functions

7.6 Summary

Chapter 8: Channel Access

8.1 Introduction

8.2 Beacon Period and AC Line Cycle Synchronization

8.3 Beacon Period Structure

8.4 CSMA Channel Access

8.5 TDMA Channel Access

8.6 Summary

Chapter 9: Connections and Links

9.1 Introduction

9.2 Packet Classification

9.3 Connection Specification (CSPEC)

9.4 Connections and Links

9.5 Connection Services

9.6 Bandwidth Management by CCo

9.7 Summary

Chapter 10: Security and Network Formation

10.1 Introduction

10.2 Power-on Network Discovery Procedure

10.3 Forming or Joining an AVLN

10.4 Security Overview

10.5 Summary

Chapter 11: Additional MAC Features

11.1 Introduction

11.2 Channel Estimation

11.3 Bridging

11.4 Homeplug 1.0.1 Coexistence

11.5 Proxy Networking

11.6 Summary

Chapter 12: Neighbor Networks

12.1 Introduction

12.2 Transition Between Neighbor Network Operating Modes

12.3 Coordinated Mode

12.4 Passive Coordination in CSMA-Only Mode

12.5 Neighbor Network Bandwidth Sharing Policy

12.6 Summary

Chapter 13: Management Messages

13.1 Introduction

13.2 Management Message Format

13.3 Station–Central Coordination (CCo)

13.4 Proxy Coordinator (PCo) Messages

13.5 Central Coordinator–Central Coordinator

13.6 Station–Station

13.7 Manufacturer-Specific Messages

13.8 Vendor-Specific Messages

13.9 Summary

Chapter 14: IEEE 1901

14.1 Introduction

14.2 FFT

14.3 Wavelet

14.4 Coexistence

14.5 Summary

Chapter 15: HomePlug GREEN PHY

15.1 Introduction

15.2 Physical Layer

15.3 MAC Layer

15.4 Summary

Chapter 16: HomePlug AV2

16.1 Introduction

16.2 MIMO

16.3 Extended Frequency Band

16.4 Efficient Notching

16.5 Short Delimiter and Delayed Acknowledgment

16.6 Immediate Repeating

16.7 Power Save

16.8 Summary

Appendix A: Acronyms

Appendix B: HomePlug AV Parameter Specification

References

Index

IEEE Press

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IEEE Press Editorial Board 2013

John Anderson, Editor in Chief

Kenneth Moore, Director of IEEE Book and Information Services (BIS)

Copyright © 2013 by The Institute of Electrical and Electronics Engineers, Inc.

Portions Copyright © 2007 – 2012 by the HomePlug Powerline Alliance, Inc.

Published by John Wiley & Sons, Inc., Hoboken, New Jersey. All rights reserved.

Published simultaneously in Canada.

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Library of Congress Cataloging-in-Publication Data

Latchman, Haniph A.

Homeplug AV and IEEE 1901: a handbook for PLC designers and users / Haniph

Latchman, Srinivas Katar, Lawrence W. Yonge III, Sherman Gavette.

p. cm

ISBN 978-0-470-41073-8 (cloth)

1. Electric lines–Carrier transmission–Design and construction. 2. Home computer networks–Design and construction. I. Title.

TK3226.L27 2012

621.39′81–dc23

2012033916

To our families, our mentors, and our colleagues.

List of Figures

Figure 2.1 System block diagram

Figure 2.2 Protocol layer architecture

Figure 2.3 HomePlug AV network architecture

Figure 3.1 Sample powerline channel impulse response

Figure 3.2 Sample channel frequency response

Figure 3.3 Examples of powerline impulse noise

Figure 3.4 OFDM symbol timing

Figure 3.5 Windowed OFDM PSD

Figure 3.6 Turbo Convolutional Code performance

Figure 3.7 Turbo Convolution Code compared with capacity

Figure 3.8 Beacon Period and Tone Map Regions

Figure 3.9 Beacon Period and TDMA allocations

Figure 4.1 HomePlug AV transceiver block diagram

Figure 4.2 AV PPDU structure

Figure 4.3 MPDU to PPDU encoding

Figure 4.4 Hybrid Mode PPDU structure

Figure 4.5 AV Mode PPDU structure

Figure 4.6 OFDM symbol timing

Figure 4.7 AV Preamble waveform

Figure 4.8 AV Frame Control FEC Data Path

Figure 4.9 Data scrambler

Figure 4.10 AV Turbo Convolutional Encoder

Figure 4.11 8-State Constituent Encoder

Figure 4.12 PN Generator

Figure 4.13 Spectral occupancy for semi-infinite number of carriers

Figure 4.14 AV PRS waveform

Figure 4.15 Spectral occupancy of set of HomePlug carriers

Figure 5.1 General MPDU formats

Figure 5.2 Beacon MPDU format

Figure 5.3 Network identifier

Figure 5.4 Example of Beacon Relocation

Figure 5.5 Start-of-Frame MPDU format

Figure 5.6 Measurement of FL_AV

Figure 5.7 PHY Block formats

Figure 5.8 SACK MPDU format

Figure 5.9 RTS/CTS MPDU format

Figure 5.10 Duration field in RTS/CTS when IGF is set to 0b0

Figure 5.11 Long Sound MPDU format

Figure 5.12 Reverse SOF MPDU format

Figure 6.1 MSDU Format

Figure 6.2 MAC Data Plane Overview

Figure 6.3 MAC Frame Format

Figure 6.4 MAC Segmentation and MPDU Generation

Figure 6.5 Transmitter MAC Frame Stream FSM

Figure 6.6 Receiver MAC Frame Stream FSM

Figure 6.7 Illustration of Multinetwork Broadcast Transmission

Figure 6.8 Example of MPDU Bursting

Figure 6.9 Bidirectional Burst Mechanism

Figure 6.10 Interframe Spacing during Bidirectional Burst

Figure 6.11 Bidirectional Bursts during CSMA

Figure 7.1 User-Appointed CCo

Figure 7.2 Transfer of CCo function

Figure 8.1 HomePlug AV network architecture

Figure 8.2 Basic Beacon Period structure

Figure 8.3 Example of Beacon Period structure in Uncoordinated Mode

Figure 8.4 Example of Beacon schedule persistence

Figure 8.5 Beacon Period structure in CSMA-only mode

Figure 8.6 Example of Beacon Period structure in Uncoordinated Mode

Figure 8.7 Example of Beacon Period structure in Coordinated Mode

Figure 8.8 Medium States when a MPDU is transmitted or detected in Contention State

Figure 8.9 Medium States when a station gets pre-empted in the Priority Resolution Period and detects no MPDU transmission in Contention State

Figure 8.10 Medium States when MPDU frame control errors or collision lead to a busy state and no delimiter is detected for an EIFS_X period

Figure 9.1 Connection setup

Figure 9.2 Global Link setup

Figure 9.3 Connection teardown for Connections with only Local Links

Figure 9.4 Connection teardown for Connections with Global Links

Figure 9.5 Connection reconfiguration

Figure 9.6 Connection Squeeze/De-Squeeze

Figure 9.7 Global Link life cycle

Figure 10.1 Power-on Network Discovery Procedure

Figure 10.2 Unassociated STA behavior

Figure 10.3 Unassociated CCo behavior

Figure 10.4 Behavior as an STA in an AVLN

Figure 10.5 Behavior as a CCo in an AVLN

Figure 10.6 Getting Full AVLN information

Figure 10.7 STA Association

Figure 10.8 Provision NEK for a new STA (Authentication)

Figure 10.9 AVLN formation by two unassociated STAs with matching NIDs

Figure 10.10 AVLN formation using a DAK-Encrypted NMK

Figure 10.11 AVLN formation using UKE by one STA in SC-Add and one STA in SC-Join

Figure 10.12 AVLN formation using UKE by two STAs in SC-Join

Figure 10.13 New STA joins existing AVLN with matching NID

Figure 10.14 New STA ioins AVLN by DAK-Encrypted NMK

Figure 10.15 New STA joins existing AVLN using UKE

Figure 10.16 Disassociation—STA leaves AVLN

Figure 10.17 Provision NEK for part or all of the AVLN

Figure 10.18 Encrypted payload message when PID is between 0x00 and 0x03

Figure 10.19 Encrypted payload message when PID = 0x04

Figure 11.1 Initial channel estimation

Figure 11.2 Dynamic channel adaptation

Figure 11.3 HomePlug AV bridging to Ethernet Networks

Figure 11.4 LBDAT and RBAT of HomePlug AV Stations

Figure 11.5 Proxy Network created by Network 1

Figure 11.6 HSTA association

Figure 12.1 Neighbor Network Mode transitions

Figure 12.2 Flowchart for computing INL allocation

Figure 12.3 MSC to set up a new network in Coordinated Mode

Figure 12.4 New CCo detects two groups of networks

Figure 12.5 MSC to request additional bandwidth in Coordinated Mode

Figure 12.6 MSC to shut down an AVLN in Coordinated Mode

Figure 13.1 Management Message format

Figure 13.2 Illustration of fragmentation of a MMENTRY

Figure 14.1 Wavelet transmitter and receiver

Figure 14.2 PPDU frame format

Figure 14.3 Generator

Figure 14.4 Scrambler

Figure 14.5 CRC encoder

Figure 14.6 Convolutional encoder

Figure 14.7 Example of frame control transmitted data

Figure 14.8 Example of TMI transmitted data

Figure 14.9 Example of FL transmitted data

Figure 14.10 Example of frame body diversity transmitted data

Figure 14.11 Image of the relation between ramp process and output wave of IDWT

Figure 14.12 Short preamble signal

Figure 14.13 Preamble signal

Figure 14.14 PPDU frame format with postamble

Figure 14.15 Frame bodies using pilot signals

Figure 14.16 Example transmission spectrum of Wavelet OFDM with notches (up to 30 MHz)

Figure 14.17 Notch frequency characteristics

Figure 14.18 Sync points

Figure 14.19 ISP time Window and ISP fields concept

Figure 14.20 Periodicity of ISP windows

Figure 14.21 ISP fields

Figure 14.22 ISP general TDMA structure

Figure 14.23 Structure of TDMA

Figure 15.1 Examples of Power Save Schedules

Figure 15.2 Illustration of PEV–EVSE association

Figure 15.3 Charging harness

Figure 16.1 HomePlug AV2 MIMO transceiver block diagram

Figure 16.2 Short delimiter

Figure 16.3 PPDU format with Short Delimiter

Figure 16.4 Short Delimiter efficiency improvement

Figure 16.5 Delayed acknowledgment

Figure 16.6 Throughput improvement for CSMA

Figure 16.7 Throughput improvement for TDMA

Figure 16.8 Immediate repeating channel access for CSMA

Figure 16.9 AV2.0 SISO PHY rate with repeating

List of Tables

Table 1.1 HomePlug Specifications Timeline

Table 4.1 PPDU Formats

Table 4.2 OFDM Symbol Characteristics

Table 4.3 Rate ½ Puncture Pattern

Table 4.4 Rate 16/21 Puncture Pattern

Table 4.5 Interleaver Parameters

Table 4.6 Interleaver Seed Table for FEC Block Size of 16 Octets

Table 4.7 Interleaver Seed Table for FEC Block Size of 136 Octets

Table 4.8 Interleaver Seed Table for FEC Block Size of 520 Octets

Table 4.9 Channel Interleaver Parameters

Table 4.10 Sub-Bank Switching

Table 4.11 ROBO Mode Parameters

Table 4.12 Modulation Characteristics

Table 4.13 Tone Mask Amplitude Map and Tone Map

Table 4.14 Bit Mapping

Table 4.15 Symbol Mapping (Except 8 QAM)

Table 4.16 Symbol Mapping for 8 QAM

Table 4.17 Modulation Normalization Scales

Table 4.18 Relative Power Levels

Table 4.19 North American Carrier and Spectral Masks

Table 4.20 Amplitude Map

Table 5.1 HomePlug AVMPDU Types and their Functionality

Table 5.2 General AV Frame Control Fields

Table 5.3 Delimiter Type Field Interpretation

Table 5.4 HomePlug AV Beacon Payload Fixed Fields Grouped based on Functionality

Table 5.5 Beacon Management Information Format

Table 5.6 Beacon Entry Header Interpretation

Table 5.7 Nonpersistent Schedule BENTRY

Table 5.8 Session Allocation Information Format without Start Time

Table 5.9 Session Allocation Information Format with Start Time

Table 5.10 Persistent Schedule BENTRY

Table 5.11 Regions BENTRY

Table 5.12 Discovered Info BENTRY

Table 5.13 Start-of-Frame Frame Control Fields Grouped based on Functionality

Table 5.14 PHY Block Header Fields

Table 5.15 SACK Frame Control Fields Grouped based on Functionality

Table 5.16 RTS/CTS Frame Control Fields Grouped based on Functionality

Table 5.17 Sound Frame Control Fields Grouped based on Functionality

Table 5.18 Sound Payload Fields

Table 5.19 Reverse SOF Frame Control Fields Grouped based on Functionality

Table 6.1 MAC Frame Stream Command Interpretation

Table 6.2 MAC Frame Stream Response Interpretation

Table 8.1 Setting the VCS Timer

Table 8.2 CW and DC as a Function of BPC and Priority

Table 8.3 Channel Access Priority versus Priority Resolution

Table 9.1 Recommended VLAN User Priority-to-CSMA Priority Mapping

Table 9.2 Recommended Application Class-to-User Priority Mappings

Table 9.3 QoS and MAC Parameter Exchanged between HLE and CM and Between CMs

Table 9.4 Additional QoS and MAC Parameter Fields Exchanged Between Two CMs

Table 9.5 QoS and MAC Parameter Fields Between CM and CCo

Table 9.6 Summary of Link and Connection Identifiers

Table 10.1 TEI Values

Table 10.2 Security-Level Interpretation

Table 10.3 Security Level and NMK Provisioning

Table 12.1 Rules for Computing INL Allocation

Table 13.1 Station–Central Coordinator Messages

Table 13.2 Proxy Coordinator Messages

Table 13.3 Central Coordinator-Central Coordinator Messages

Table 13.4 Station–Station Coordinator Messages

Table 14.1 Rate 16/18 Puncture Pattern

Table 14.2 Puncture Patterns

Table 14.3 Number of Transmission Bits for Tail-Bit Coding

Table 14.4 FEC Type Parameter

Table 14.5 Modulation Methods for Each Informational Type

Table 14.6 Applications of Tone Maps/Tone Masks

Table 14.7 Wavelet OFDM Major Specifications

Table 14.8 ISP Signal Phases and their Use

Table 14.9 Meaning of ISP Window Fields

Table 14.10 ISP Parameter Specification

Table 14.11 ISP Parameter Specification

Table 15.1 ROBO Mode Parameters

Table 15.2 Allowed PPDU Combinations

Table B.1 HomePlug AV Parameter Specifications

Preface

Broadband powerline communication systems are continuing to gain significant market adoption worldwide for applications ranging from IPTV delivery to the Smart Grid. The suite of standards developed by the HomePlug Powerline Alliance plays an important role in the widespread deployment of broadband PLC. To date, more than 100 million HomePlug modems are deployed and these numbers continue to rise.

HomePlug AV is one of the most successful HomePlug Standards and it also forms the basis of the IEEE 1901 Standard. It was the result of several years of research by multiple companies to define a communication system that optimizes performance for the harsh powerline environment. This book is intended to provide insight into the unique design choices made in the HomePlug AV Specification. This book also contains a history of the HomePlug Powerline Alliance as well as general details on the PHY and MAC and other features of the HomePlug AV Specification. The objective is to produce a handbook that would serve as a supplement and guide to HomePlug AV while also providing background on the evolution and development of the specification. Thus, the authors sought to prepare a handbook that would be useful for designers and users of HomePlug AV compliant devices, providing a clear and simple description of the key features and capabilities of the specification.

Since HomePlug AV technologies feature prominently in the finalized IEEE 1901 Standard, the authors decided to include a discussion of the IEEE 1901 Standard as part of the HomePlug AV Handbook and hence the title of the present volume is HomePlug AV and IEEE 1901: A Handbook for PLC Designers and Users. The book also introduces the recently released HomePlug Green PHY and HomePlug AV 2.0 Standards.

It is the hope of the authors that this book will indeed prove useful as a PLC reference and in providing an accessible exposition of the core HomePlug and IEEE 1901 technologies that have significantly impacted high speed Powerline Communications and will continue to do so for years to come.

Haniph A. LatchmanSrinivas KatarLawrence W. Yonge IIILarry YongeSherman Gavette

Acknowledgments

It is impossible to undertake a project of the scope and magnitude encompassed in the finished volume HomePlug AV and IEEE 1901: A Handbook for PLC Designers and Users, without incurring a great deal of indebtedness.

The authors, having all participated in various roles in the development of the powerline specifications and standards described in this book, are intimately and acutely aware of the enormous amount of work and time that went into the development of both the HomePlug AV Specification and the IEEE 1901 Standard. Thus, it is our pleasure and duty to acknowledge the indefatigable and resolute efforts of our many colleagues in the HomePlug AV Alliance (including past members who contributed to the HomePlug specifications) as well as the work of those colleagues in the IEEE1901 working groups, who contributed to the IEEE 1901 Standard. We hope that our feeble attempts to describe their work in a format accessible to PLC designers and users, does some semblance of justice to their combined intellectual capital embodied in those standards and specifications.

The authors would also like to acknowledge the very useful feedback provided by the reviewers, Jim Allen and Scott Willy, at various stages of the project. Their insightful comments, observations, and suggestions helped us to focus the book on explaining the reasoning behind the technical decisions that were made in the development of the HomePlug AV Specification and the IEEE 1901 Standard.

We also gratefully acknowledge the support and help of the Wiley-IEEE staff in moving this project along, despite the delays occasioned by the evolution of HomePlug AV and the emergence of IEEE 1901 as the project was proceeding. The guidance, reminders, and suggestions of Mary Hatcher, the Associate Editor assigned to the project were invaluable as the project progressed.

In addition, the authors would like to thank their employers (Qualcomm Atheros and the University of Florida) for allowing them the freedom to produce this book. Thanks also to our many work and professional colleagues and students who have contributed to this work in some form and in guiding and honing our skills in this area of work. A special word of thanks goes to Anim Amarsingh and Duotong Yang, graduate students at the University of Florida, for their work in helping to proof read the final draft of the book and their assistance in refining the references and acronym definitions. We would also like to thank Peter Scarborough for designing the book cover.

Finally, the authors would like to thank their families without whose patience and tolerance, this work would not have been possible.

Haniph A. LatchmanSrinivas KatarLawrence W. Yonge IIILarry YongeSherman Gavette

Biographical Sketches of the Authors

Dr. Haniph A. Latchman received the B.Sc. (Hons) from the University of the West Indies in 1981 and the D.Phil. from the University of Oxford in 1986. He is presently Professor of Electrical and Computer Engineering and teaches and conducts research in the areas of Control Systems, Communications, and Computer Networks. He is a Rhodes Scholar (Jamaica, St. Edmund Hall, 1983), a Senior Member of the IEEE and has published over 170 technical journal articles, conference proceedings, and three books in the general areas of Communication Networks and Control Systems. He has guided 23 Ph.D. dissertations and 37 M.S. theses. He has served as an Associate Editor and Guest Editor for several international journals, and as General Chair and member of technical program committees for conferences in the areas of communications, control systems, and networks. His teaching and research have been recognized by numerous awards, including several Best Paper Awards, the University of Florida Teacher of the Year Award, the IEEE Undergraduate Teaching Award, the Boeing Summer Faculty Fellowship, and a 2001 Fullbright Fellowship. He is an active member of the IEEE Communication Society Technical Committee on Broadband Powerline Communications and was the General Chair of the 2006 IEEE International Symposium on Powerline Communications (ISPLC) and Co-chair of the General Conference of Globecom 2006 and 2013. From 1999 to 2009 he served as a consultant to Intellon Corporation, now known as Qualcomm Atheros (PLC Technologies).

Dr. Srinivas Katar received his Bachelor of Technology degree from the Indian Institute of Technology, Kanpur in 1998 and the Ph.D. degree from the University of Florida in 2006. He is currently Principal Engineer at Qualcomm Atheros and is responsible for research and development of Medium Access Control protocols for powerline communication systems. He has more than 13 years of experience in developing PLC systems. He was a prolific contributor to the MAC Layer for several PLC standards including HomePlug AV, IEEE 1901, HomePlug AV2, and HomePlug Green PHY. He is currently an active member of HomePlug AV technical working group and Green PHY technical working group. He is an inventor of several key features in HomePlug and IEEE 1901 Standards and has more than 50 issued patents and pending patent applications. He has also authored or co-authored a number of journal and conference papers. He is a senior member of the IEEE.

Lawrence Yonge III is currently Senior Director of Technology for Qualcomm Atheros and is responsible for advanced powerline communications technology development in Ocala, Florida. He manages a research team that was a key contributor to the development of the HomePlug powerline specifications including HomePlug 1.0, HomePlug AV1.1, HomePlug Green PHY, HomePlug AV2.0, and the IEEE 1901 Standard. He is the chairman of the HomePlug AV Technical Working Group which developed the HomePlug AV1.1 and AV2.0 specifications. He joined Intellon Corporation in 1997 where he was Vice President of Research and Development. Intellon Corporation was acquired by Atheros Communication in 2009, which was acquired by Qualcomm in 2011. From 1987 to 1997 he worked as an independent engineering consultant to communication companies. He was a co-founder and President of Raydx Satellite Systems, Inc. from 1983 to 1987 and a design engineer for Microdyne Corporation from 1980 to 1983. He holds a B.S. in engineering from LeTourneau University. He is an inventor of approximately 80 US issued patents and pending applications.

Sherman Gavette received his B.S. in Mathematics from Arizona State University, Tempe and his M.S. in Information Science from the University of Chicago. He has over 47 years of experience in computers and communications, including telephony (ESS and PCS) and networking (Tymnet, UWB, and PLC). His work experience includes stints at Bell Telephone Laboratories, Tymshare (Tymnet), and Omnipoint, where he was the “guardian of the protocols” for IS661, an FCC Pioneer's Preference winner in PCS. While working at Sharp Laboratories of America (SLA), he actively participated in the development of both HomePlug 1.0 and HomePlug AV. His work on HomePlug 1.0 earned him a HomePlug Fellow Award. For HomePlug AV, he served as Chair of the Pre-Spec Working Group (PSWG), which created the AV Baseline specification, as Vice Chair of the Specification Working Group (SWG) which finalized the HomePlug AV specification, and as a member of the HomePlug Board of Directors. He holds several patents in PLC and Mobile Communications. He retired from SLA as a Principle Scientist in 2007. Since then he has served as Technical Editor on several HomePlug projects and on several IEEE Standards, including IEEE Std 1901™-2010.

1

Introduction

The explosive growth of the Internet has led to the need for ubiquitous data and multimedia communications in the twenty-first century. In-home distribution of multimedia content is still a challenge, particularly for homes not equipped with specialized wiring to support high-speed data and multimedia communications. Retrofitting buildings with new wiring is prohibitively expensive and wireless solutions do not reliably provide “whole house” coverage for multimedia applications. Hence, the need arises for a new LAN technology that enables affordable and ubiquitous connectivity within the home. The existing electrical wiring is unique in that it provides a large number of connection points throughout the home, eliminating a significant limitation of other existing wires, specifically coax cables or traditional telephone lines. However, unlike the relatively clean communication coax and phone line channel, there are many challenges in communication over the harsh powerline channel that must be overcome to make powerline communication (PLC) a viable “no new wires” home networking solution for high speed multimedia applications.

This book provides a clear and simple overview of key features of the HomePlug AV specification and the associated IEEE 1901 standard. It provides details on how the challenges associated with communicating over the electrical wiring were overcome and also the justifications and explanations of the reasoning behind the technical decisions that were made in the specification. The reader is referred to the HomePlug AV specification and the IEEE 1901 standard for the technical details needed for implementation. The book primarily focuses on HomePlug AV and discusses the IEEE 1901 standard, highlighting the features of HomePlug AV that have been incorporated into the standard, as well as providing a description of key provisions of IEEE 1901 standard. The book also gives an overview of the HomePlug Green PHY specification that targets Smart Energy applications (10 Mbps) and the HomePlug AV 2.0 specification that adds MIMO, repeating, and other enhancements to HomePlug AV, thus providing operation up to 1.5 Gbps.

1.1 HomePlug AV and ITS Relationship to IEEE 1901

The HomePlug AV 1.1 specification [1] (referred to throughout this book as HomePlug AV) was released in May 2007 by the HomePlug Powerline Alliance. At that time HomePlug AV was the flagship specification in an emerging PLC suite by the HomePlug Powerline Alliance, including the HomePlug 1.0.1 specification (2001). The HomePlug AV specification describes a PLC system operating at 200 Mbps and built upon an Orthogonal Frequency-Division Multiplexing (OFDM) FFT-based physical layer (PHY) protocol and a hybrid TDMA/CSMA Medium Access Control (MAC) protocol. The CSMA component is identical to that used in the HomePlug 1.0.1 CSMA technology. The OFDM FFT PHY uses the frequency band of 1.8 –30 MHz with modulation up to 1024 QAM and a turbo convolutional code FEC.

The emergence of the HomePlug Powerline Alliance specifications together with a number of other incompatible industry-driven PLC specifications led to the need for a globally coordinated PLC standard. Industry organizations such as the HomePlug Powerline Alliance with membership open to competing PLC companies made some attempts at generating consensus on design choices in specification development. However, competing corporate interests often made this a very difficult and often impossible process.

In 2005, the IEEE Communications Society (COMSOC) sponsored the IEEE P1901 project to define a global IEEE standard for high-speed PLC systems. Several competing proposals were considered from research and development groups and manufacturers of PLC equipment in Europe, Asia, and the Americas. In 2007, about the same time as the release of the HomePlug AV 1.1 specification, the IEEE 1901 working group selected a consolidated proposal by the HomePlug Powerline Alliance and the HD-PLC Alliance. The final proposal featured three technology areas or “clusters,”, namely, the In-home cluster, the Access cluster, and the Coexistence cluster, and the approved IEEE 1901 standard [2] was published in December 2010. IEEE 1901 represented a standard of compromise between the FFT-based OFDM PHY in HomePlug AV and the Wavelet-based OFDM PHY used in Panasonic's HD-PLC devices. The standard specifies both PHYs as optional, with an Intersystem protocol (ISP) providing coexistence but not interoperability between the in-home FFT and Wavelet PHY realizations of IEEE 1901. This compromise with two noninteroperable PHY specifications is, in reflection, analogous to the case of the original IEEE 802.11 standard that was released with two noninteroperable PHY specifications, namely, the direct-sequence and frequency-hopping spread spectrum. In addition to enabling coexistence between these noninteroperable PHYs, the ISP is also designed to ensure coexistence between in-home IEEE 1901 system and IEEE 1901 Access or G.hn systems.

While both the HomePlug AV and the newer IEEE 1901 specifications contemplated and provided for coexistence with PLC Access systems, at present efforts to build or deploy HomePlug AV- or IEEE 1901-based PLC Access systems are at best in the very early stages. Though the technology for Access systems is available and technically viable, past experience with PLC-based systems for Internet access has been commercially unsuccessful in the United States and Europe. However, the emergence of Smart Grid and Smart Energy market drivers may portend new developments in this area in the near future.

In the present-day in-home PLC market, in the absence of interoperability, the major emphasis is on manufacturing HomePlug AV devices with IEEE 1901 certification to ensure coexistence guarantees as outlined above. At the same time, IEEE 1901 PLC devices with non-HomePlug options may still be deployed with guaranteed coexistence. The legacy HomePlug AV devices and newer IEEE 1901-certified devices with the HomePlug FFT currently have the largest market penetration and momentum globally.

1.2 Focus of the Book

Numerous scholarly papers, white papers, and reports have been published that present individual aspects of the HomePlug AV specification and the IEEE 1901 standard, and of course there is full technical specification of each. The IEEE 1901 standard can be purchased from the IEEE and the full HomePlug AV specification is available to members of the HomePlug Powerline Alliance. In contrast, the goal of this handbook is to provide a comprehensive yet clear and simple description of HomePlug AV and the IEEE 1901 standard that will be useful to designers of HomePlug compliant devices and also accessible and beneficial to network administrators and individual users of compliant PLC networks. From this perspective, the main focus of the book will be on HomePlug AV with relevant details from IEEE 1901 presented to clarify how IEEE 1901 is built upon and expands on HomePlug AV technologies.

In the fact, if we consider an IEEE 1901 compliant device with the FFT HomePlug AV-based FFT option for the PHY, what we have is essentially an augmented HomePlug AV system with certain extensions to the HomePlug AV 1.1 PHY and MAC, as well as the mechanisms to enable coexistence with IEEE 1901 devices with the Wavelet PHY option and with G.hn and IEEE 1901 Access systems. In summary, the extensions of the of the HomePlug AV PHY include (i) the extension of the frequency band from 1.8–30 to 1.8–50 MHz, (ii) a larger set of guard intervals—some shorter and some larger than that in HomePlug AV, (iii) a higher code rate—8/9 to complement the 1/2 and 16/21 code rates, and (iv) a higher order modulation—4096 QAM (the HomePlug AV maximum was 1024 QAM). MAC augmentations include (i) the addition of repeating, which was not present in HomePlug AV 1.1, (ii) adjustments to the Short Network IDentifiers (SNID), and (iii) the addition of the ISP for coexistence [2].

The book will not only provide a general understanding of the features and capabilities of HomePlug AV but will also give sufficient details of the PHY and MAC and other features to be helpful to PLC product designers. The book will be a supplement and guide to the HomePlug AV specification and the IEEE 1901 standard and will provide background on the evolution and development of the related specifications and standards.

1.3 The HomePlug Powerline Alliance

The HomePlug Powerline Alliance is a powerline networking industrial association that was formed in 2000 to promote the rapid development and adoption of powerline communications solutions. The charter of the alliance is to develop specifications and certification programs for using the powerlines for reliable home networking and Smart Grid applications. HomePlug is the largest and most established industry group for PLC, with about 65 member companies. The HomePlug specifications were designed specifically to serve a number of in-home digital entertainment and networking applications. These include easy access to services such as online video and music programming from anywhere with a power outlet, high-speed PLC broadband connections to HDTV's, Blu-ray players, DVRs, PCs, and game consoles, as well as general purpose in home computing. As of early 2012, there are a number of different HomePlug chipsets available from at least 6 vendors and close to 280 different HomePlug PLC products, with HomePlug products controlling over 90% of the broadband PLC market and over 100 million HomePlug products shipped worldwide.

1.3.1 HomePlug Specifications

Toward achieving the goals of its charter, in the last decade the HomePlug Powerline Alliance has released or has been a major contributor to a range of PLC specifications and standards operating between 14 Mbps and 1.5 Gbps. Table 1.1 shows the timeline and data rate supported by six such specifications and standards.

Table 1.1 HomePlug Specifications Timeline.

Specification/StandardRatification/Publication DateData Rate SupportedHomePlug 1.0.1December 200114 MbpsTIA-1113 (HomePlug 1.0.1)May 200814 MbpsHomePlug AV v1.1May 2007200 MbpsIEEE 1901December 2010400 MbpsHomePlug Green PHY v1.0August 201010 MbpsHomePlug AV v2.0March 20121.5 Gbps

With this suite of specifications and associated products, the HomePlug Powerline Alliance is well poised to make a significant contribution to the converged digital and Smart Grid networking requirements, with products that are both compatible and interoperable. In fact, HomePlug AV is one of the four technologies (the others being Wi-Fi [3] (IEEE 802.11x [4]), Ethernet (IEEE 802.3 [5]), and MoCA [6]) that will form the new IEEE 1905.1 standard that provides a common interface for the most compelling converged home networking technologies, in support of interoperable voice, video, and data services inside the smart home.

1.3.2 How the HomePlug AV Specification Was Developed

The HomePlug Industrial Alliance uses a well-streamlined process in the development of all its specifications, somewhat paralleling the operation of other standards organizations such as the IEEE.

For the HomePlug AV specification, the process started with the HomePlug Board of Directors (BoD) appointing a committee to develop a Marketing Requirements Document (MRD) that specifies what features and characteristics HomePlug AV should have in order to address the perceived needs.

The MRD included several typical cases of multiple multimedia video sessions, IP telephony sessions, gaming sessions, and data networking applications occurring simultaneously and specified the target range of aggregate data rate that HomePlug AV should support. A Technology Evaluation Group (TEG) was also appointed by the BoD and the TEG issued a request for proposals for technologies that could meet the MRD. The TEG reviewed submissions and made the baseline selection of core technologies from multiple submissions that would form the basis of the HomePlug AV specification. Since no member company had all the requisite technologies in their portfolio, HomePlug AV was developed from a merger of ideas from several HomePlug member companies.

Finally, the HomePlug AV specification was developed through much laborious and intensive work by the HomePlug AV Technical Working Group (TWG), which produced the HomePlug AV 1.1 specification published in May 2007. Note that although HomePlug AV version 1.0 specification was published in December 2005, version 1.1 became the definitive HomePlug AV base specification since it was published about the time the first AV products were introduced to the market.

Various members of the HomePlug Powerline Alliance participated in the IEEE 1901 standardization efforts, contributing technologies and solutions to the various challenges faced in the development of this important global PLC standard.

One may now regard the present relationship between IEEE 1901 and HomePlug as being similar to the relationship between IEEE 802.11 and Wi-Fi (the Wi-Fi Alliance). Today the Wi-Fi Alliance certifies that wireless networking products conform to the 802.11x standard in much the same way as the HomePlug provides certification to PLC products as IEEE 1901 compliant. HomePlug will also provide certification for IEEE 1905.1 products that will feature HomePlug AV technology.

The Compliance and Interoperability Working Group(C&IWG) of the HomePlug Powerline Alliance is responsible for the processes and protocols for testing and certifying chips, devices, and products to be compliant with HomePlug specifications or IEEE standards. The C&IWG coordinates HomePlug Plugfests for multivendor interoperability and compliance testing for the HomePlug AV specification and the IEEE 1901 powerline networking standard.

1.3.3 The Regulatory Working Group

The Regulatory Working Group (RWG) of the HomePlug Powerline Alliance is responsible for the development of strategy and processes to ensure that HomePlug products conform to global regulatory requirements. The design of PLC systems such as HomePlug AV and IEEE 1901 must also deal with these regulatory constraints. For example, in the United States, PLC systems operate under FCC Part 15 [7] rules in the frequency band between 1.8 and 30 MHz. Several subbands within this range are notched out in HomePlug products to prevent interference in licensed services. Moreover, the regulatory environment in Europe is in flux: aeronautical bands may be added and power levels are under debate. Japan made amendments to their regulations in 2006 that enabled in-building PLC and is currently considering further amendments that would allow outdoor PLC. This relatively unstable international regulatory environment requires that PLC systems be flexible to adapt to changing regulations.

In sections 1.3.3.1–1.3.3.3, we consider the present PLC regulatory domains in the United States, Europe, and the rest of the world.

1.3.3.1 The United States and the FCC

Regulations for powerline communications in the United States are established by the Federal Communications Commission (FCC) and are specified in Title 47 of the Code of Federal Regulations, Part 15 [7]. The FCC rules define “Access Broadband over Power Line” (Access BPL) and “In-House Broadband over Power Line” (In-House BPL).

In-House BPL is defined as “A carrier current system, operating as an unintentional radiator, that sends radio frequency energy by conduction over electric powerlines that are not owned, operated or controlled by an electric service provider. The electric powerlines may be aerial (overhead), underground, or inside the walls, floors or ceilings of user premises. In-House BPL devices may establish closed networks within a user's premises or provide connections to Access BPL networks, or both.”—47 CFR Ch. I (10–1–10 Edition), § 15.3 [7].

1.3.3.1.1 FCC Compliance Testing

Part 15.31 (d) [7] specifies that carrier current devices be tested for compliance with the FCC regulations in three typical installations. The ANSI C63.4-1992 [8] document gives details concerning how to install the test equipment and how to make the measurements. The equipment is installed in a typical operating scenario, usually with a transmit duty factor very close to 100%. Measurements are then made at 16 equally spaced radials around the periphery of the house in which the equipment is operating. Measurements are made with a loop antenna in the H-field, with the antenna centered 1 m above the ground and oriented to maximize the readings.

The equipment built to the HomePlug specification and providing nominally the highest signal level permitted by the HomePlug specification is tested for compliance with Part 15 requirements in three typical home installations. The powerline modem under test is plugged into an electrical outlet that is on an exterior wall. Tests are usually conducted by independent FCC-certified test labs such as Compatible Electronics of Brea, CA, for west coast locations and Product Safety Engineering of Dade City, FL, for the east coast.

The FCC Part 15 requirement for unlicensed devices, including PLC, is that the device may not cause “harmful interference.” Regulatory compliance testing ensures that products bearing the HomePlug or IEEE 1901 stamp do not cause such harmful interference. If the FCC receives a report of harmful interference from a HomePlug or IEEE 1901 PLC device, the manufacturers may refer to the testing protocol and results, but will be also be required to respond to the complaint to remove the harmful interference.

Notching amateur band is not required by FCC Part 15. However, HomePlug PLC devices notch the amateur frequency bands to avoid interference in these bands. HomePlug Compliance testing evaluates both the quality and effectiveness of the notching implemented in the target devices to ensure compliance with the HomePlug specification and the adherence to FCC rules across the spectrum.

1.3.3.2 Europe, CISPR, and CENELEC

Although the European Union does not have an equivalent body as the U.S. FCC, PLC products sold in Europe are required to comply with the essential requirements of “Directive 2004/108/EC of the European Parliament and of the Council” [9].

This Directive regulates the electromagnetic compatibility of equipment. The following is the essential requirement:

“Equipment shall be so designed and manufactured, having regard to the state of the art, as to ensure that:

a.the electromagnetic disturbance generated does not exceed the level above which radio and telecommunications equipment or other equipment cannot operate as intended;

b.it has a level of immunity to the electromagnetic disturbance to be expected in its intended use which allows it to operate without unacceptable degradation of its intended use.”

The broad principles set forth in the Directive are given more explicit technical expression by harmonized European standards, yet to be adopted by the various European standardization bodies such as the European Committee for Standardization (CEN), the European Committee for Electrotechnical Standardization (CENELEC), and the European Telecommunications Standards Institute (ETSI).

Thus, the standards set by these organizations become, in essence, the PLC regulations for Europe and PLC devices can be put on the market or into service in the European Union only if the manufacturers concerned have established that such devices have been designed and manufactured in conformity with the requirements of this EU Directive. Approved devices should bear the “CE” marking attesting their compliance (Conformité Européene) with the EU Electromagnetic Compatibility Directive.

To date, no formal harmonized standards for PLC have been adopted in Europe. Previous efforts in the Comité International Spécial des Perturbations Radioélectriques (CISPR) to amend CISPR-22 [10] specifying compliance testing procedures for powerline communications generated various draft standards, but these were never approved by CISPR member states. More recently, a draft standard has been created in CENELEC prEN50561-1 [11], which is largely based on the most recent draft from CISPR, and it is hoped that this draft will be ratified and approved.

CE mark certification can be obtained by having the devices tested by a “Notified Body” that is recognized and registered by the European Union. The testing organization will then apply state-of-the-art assessment, which in practice is based on the existing CISPR and CENELEC draft documents or related standards from other international organization such as the International Telecommunication Union—Radiocommunication (ITU-R). The “no harmful interference” approach allows static notching in spectral mask or even dynamic notching based on sensing the presence of interfering signals. The essential expectation is that there should be again “no harmful interference” and the manufacturers are held liable to respond to and rectify any legitimate complaints.

It should also be noted that in the European Union, individual countries are not bound by the above formative PLC regulations and can set their own independent standards for PLC.

1.3.3.3 Rest of the World

Other countries apart from the European Union and the United States have a variety of stances on PLC regulations. Each country usually has the equivalent of a Public Utility Regulator that manages access to and use of radio frequency spectrum. Some countries are very open to the use of PLC technology, often adopting or adapting to the EU or U.S. standards, while others generate local standards. Each manufacturer of HomePlug or IEEE 1901 devices destined for such countries needs to ensure compliance with relevant regulations and the HomePlug Regulations Working Group ensures this for the HomePlug Powerline Alliance.

1.4 The Role of PLC in Multimedia Home Networking and Smart Energy Applications

Powerline communication has a unique role to play in the broad areas of in-home networking and Smart Energy applications.

HomePlug AV and IEEE 1901 have as a main target multimedia high speed in home networking in support of video, voice, gaming, and data services. PLC has the advantage of near whole house coverage with a large number of convenient outlets at data rates that are usable for high-speed applications. PLC products based on IEEE 1901 and HomePlug AV offer application data rates to support one or more HDTV channels. Most of the PLC products are individual adapters that include an Ethernet interface. Several manufacturers are now embedding HomePlug AV and IEEE 1901 devices directly into multimedia set-top boxes to allow media delivery over the PLC network. Some network routers are also now being made with both wireless and PLC interfaces.

Many competing technologies have also targeted the multimedia in-home market, the most well known being the wireless networking technologies based on the IEEE 802.11 (Wi-Fi) suite of protocols. Although Wi-Fi does provide a convenient mobile solution, it faces the challenge of whole house coverage with sustained and reliable throughput when subject to typical interferences. This situation is especially challenging when Wi-Fi is used in large residences and those made of solid concrete walls through which wireless signal do not propagate well. In this regard, PLC provides an ideal complement to the Wi-Fi mobile solution by offering PLC Wi-Fi extender products that use the PLC infrastructure as the backbone connecting multiple wireless routers and thus allowing seamless mobility without the need for spectrum sharing Wi-Fi repeaters.

Of course, one could also use dedicated Ethernet and also digital communications over Coaxial cable (Multimedia over Coaxial (MoCA) [6]) or even over the telephone lines (HomePNA [12]). The emerging IEEE 1905.1 standard provides an integrated solution with seamless routing and load balancing over Ethernet, PLC (HomePlug AV), MoCA, and Wi-Fi and promises to provide a well-suited solution for the converged digital home.

PLC is also well suited for Smart Energy applications. Since the energy is electrical in nature, attached PLC devices to the electrical wires delivering the energy are ideal candidates for Smart Grid monitoring, control, and computational optimization applications. Indeed, the “simplified HomePlug AV” (aka HomePlug Green PHY) specification directly provides a low-cost Smart Energy solution, ensuring full interoperability with broadband HomePlug AV and IEEE 1901 PLC systems. We can now envision a world where appliances, meters, and other electrical devices have embedded Smart Energy PLC devices that enable a truly intelligent home.

1.5 Book Outline

Following this introductory chapter, the rest of this book is organized as follows.

Chapter 2 gives an overall description of the HomePlug AV network architecture, delineating the protocol layers in HomePlug AV and how these relate to the standard OSI protocol layers. Special attention is given to the function and role of the HomePlug AV Convergence layer. This chapter also introduces the HomePlug AV network topology, identifying the various station roles and defining the HomePlug AV Local Network (AVLN). With this infrastructure in place, the chapter then proceeds to outline the essentials of peer-to-peer communication, bridging, network membership, and channel access in HomePlug AV networks.

In Chapter 3, the authors take a step back and examine the overall philosophy and reasoning that guided the technology selection in overcoming the challenges of high-speed multimedia communications in one of the harshest communication channels known to man. The frequency and time characteristics of the typical PLC channel are reviewed with snapshots of real measurements taken to illustrate the enormity of the challenge. The chapter then gives the details of the frequency band selection, the selection of windowed FFT-based OFDM with some commentary on comparisons with other possible technologies, the use of Turbo Convolution Codes (TCC) again with observations about the performance of rival approaches and providing the guiding principles in the selections made. An entire section is dedicated to a discussion of the intelligent channel adaptation schemes used in HomePlug AV, giving details of the bit-loading adaptive modulation scheme adopted and the exploitation of the cyclostationary noise behavior in the AC line cycle-based adaptation and Beacon synchronization especially with a focus on enabling TDMA allocations in HomePlug AV. The chapter also discusses how the two-level segmentation and reassembly scheme used in HomePlug AV yields higher overall efficiency and how this is implemented in the Data Plane. The chapter concludes with an explanation on persistent and nonpersistent schedules for TDMA operation.

Chapter 4 presents the details of the HomePlug AV physical layer protocol, including the preamble used for synchronization as well as the structure of the PHY Protocol Data Unit (PPDU), Frame Control, and Payload. The adaptive Tone Maps used to achieve high-throughput in the PLC channel as well as the associated parameters used for robust (ROBO) communication for critical control-related messages are described. The chapter concludes with a discussion of the Tone Mask used to mitigate interference, the Amplitude Map used to maintain acceptable power levels in each subband, and the overall functional transceiver block diagram.

Chapter 5 is devoted to the MAC Protocol Data Unit (MPDU) and discusses the various types of delimiters and associated variant fields used in HomePlug AV. The structure of the payloads for the Beacon, Data, and Sound frames are presented in detail.

Chapter 6 discusses the HomePlug AV Data Plane, giving specific attention to the segmentation and reassembly strategies used to convert between the MAC Service Data Unit (MSDU) and the MPDU via a PHY Block (PB) used as a basic unit of encryption. The chapter also explains the HomePlug AV queuing strategy for management, broadcast, connectionless and connection-oriented queues, as well as the operation of HomePlug AV Data Plane structures in a multinetwork infrastructure.

Chapter 7 takes up the important topic of the operation of the Central Coordinator (CCo) in HomePlug AV, including the CCo selection, backup, and failure recovery, as well as the CCo discovery process. Since the CCo is central to the operation of HomePlug AV, CCo functions are also discussed as needed in other chapters of the book.

Chapter 8 explains the hybrid HomePlug AV CSMA/TDMA channel access mechanisms. It shows how the operation of the Beacon and the Beacon period structure enable the coordination of CSMA access and TDMA access with admission control and persistent and nonpersistent scheduling.

Chapter 9 begins with an overview of the packet classification mechanism that enables HomePlug AV to distinguish the QoS needs of various MSDUs. This is followed by details on connection specification (CSPEC) and the associated connection setup, modification, and teardown procedures that enable the provisioning of parameterized QoS. The role of the CCo in bandwidth management is also explained.

Chapter 10 examines the question of security and network formation in HomePlug AV, from power-on to association, authentication, and authorization. The chapter discusses the various security keys used in HomePlug AV, including the various key entry modes (direct, remote, and push button).

The next three chapters present useful details on the practical functioning of HomePlug AV. Chapter 11 discusses the key HomePlug AV operations of channel adaptation, bridging, coexistence with HomePlug 1.0.1, and Proxy Networking. Chapter 12 covers bandwidth sharing in neighbor networks in HomePlug AV, including the specific cases of CSMA-Only, Uncoordinated, and Coordinated modes. Chapter 13 presents a summary of key management messages used in HomePlug AV.

Chapter 14 provides an overview of the IEEE 1901 standard, with separate sections devoted to the PHY and MAC of the FFT-based realization and the Wavelet-based option. The chapter also discusses the functional elements of the Inter System Protocol (ISP) used to ensure coexistence between FFT and Wavelet IEEE 1901 devices as well as between any IEEE 1901 in-home device and an IEEE 1901 Access device or a G.hn device.

The concluding chapters give an overview of the HomePlug Green PHY specification (Chapter 15) as a simplified HomePlug AV incarnation and the HomePlug AV2 specification (Chapter 16) as an enhancement of HomePlug AV, with MIMO, power save, repeating, delayed acknowledgments, and larger bandwidth, all of which combine to yield a PHY rate of 1.5 Gbps.

2

The Homeplug AV Network Architecture

2.1 Introduction

This chapter presents an overall description of the HomePlug AV network and its associated architecture. Special attention is given to the function and role of the HomePlug AV PHY, Medium Access Control (MAC), and Convergence layers as well as the grouping of protocol entities into the Data Plane and the Control Plane. The chapter also defines the HomePlug AV network topology, station roles, and the HomePlug AV Local Network (AVLN) and its associated Central Coordinator (CCo). The chapter then uses these definitions to outline the essentials of peer-to-peer communication, bridging, network membership, and channel access in HomePlug AV networks.

2.2 Protocol Layers

At the highest level of abstraction, the HomePlug AV system consists of the protocol layers shown in Figure 2.1. The functions at the transmitter are also implemented in reverse order at the receiver. The PHY layer performs forward error correction (FEC), mapping data onto OFDM symbols, and the generation of requisite time-domain waveforms. The MAC layer determines the correct position of transmission, formats the data frames into fixed-length entities for transmission on the channel, and ensures timely and error-free delivery through Automatic Repeat Request (ARQ). The MAC and PHY layers are separated by a logical PHY interface. The Convergence layer performs bridging, classification of traffic into Connections, and data delivery smoothing functions. The Convergence and MAC layers are separated by a logical M1 (MAC) interface. The logical H1 (Host) interface exposes the services provided by HomePlug AV to higher layer entities (HLE).

Figure 2.1 System block diagram.

In relation to the International Standards Organization's (ISO) Open System Interconnect (OSI) model, the HomePlug AV specification covers the lower two layers, namely, the PHY layer and the data link layer.

Figure 2.2 shows the protocol entities defined in the HomePlug specification. Protocol entities that are directly involved in the transfer of user Payload make up the Data Plane of the protocol stack, while protocol entities that are involved in creating, managing, and terminating the flow of data are defined in the Control Plane. The HomePlug AV specification further divides the Control Plane into a Central Coordinator component and a Connection Manager (CM) component. In each AV Logical Network (AVLN), defined in greater detail shortly, one station (STA) is designated as the CCo. The CCo is responsible for setting up and maintaining the logical network, managing the communication resource on the wire and coordinating with neighbor networks (NNs). The control functions associated with the CCo are treated as part of the CCo component of the Control Plane, while functions associated with each local station fall within the CM component of the Control Plane.

Figure 2.2 Protocol layer architecture.

2.3 Network Architecture

A HomePlug AV Powerline Network consists of a set of HomePlug stations connected to the AC powerline. From the physical layer perspective, stations in one dwelling might be able to communicate with stations in another dwelling. However, HomePlug AV enables stations to be logically separated by a privacy mechanism based on a 128-bit AES encryption scheme associated with a unique Network Encryption Key (NEK). An AV Logical Network is the set of STAs, typically used in a home environment, that possess the same Network Identifier (NID) and Network Membership Key (NMK). In certain situations, the CCo may deploy multiple NEKs (possibly using multiple NMKs), thus forming several logical subnetworks of the AVLN. These are called sub-AVLNs. Coordination, clock reference, and scheduling are performed on the basis of an AVLN. Cryptographic isolation is provided at the level of the sub-AVLN.

Each AVLN is managed by a single controlling station, the CCo, introduced earlier (Figure 2.3). The CCo performs network management functions such as authentication and association of new stations joining the AVLN, AC line cycle synchronization of transmission intervals, and admission control and scheduling for Time Division Multiple Access (TDMA), and Carrier Sense Multiple Access (CSMA) sessions and allocations.

Figure 2.3 HomePlug AV network architecture.

The authentication of new stations is based on the knowledge of a shared secret, namely, the NMK. A user can provide the new station with the NMK or use a push-button approach for enabling it to join the AVLN. Successful authentication will enable the station to associate with the AVLN. During the association process, the CCo provides the new station with a Terminal Equipment Identifier (TEI). The TEI is used to identify a station uniquely within the AVLN. All transmissions in HomePlug AV carry the source and destination TEIs for addressing. It should be noted that although the CCo is used to manage the AVLN as describer earlier, HomePlug AV stations normally communicate directly with one another without having to go through the CCo. Communication with the CCo is needed only to manage TDMA allocations and certain other infrequent control functions. This is in contrast with popular technologies like Wi-Fi in which all transmissions go through the Access point in Infrastructure mode.

Figure 2.3 shows the organization of HomePlug AV devices into different classes of networks. The CCo and the devices in the logical network that can directly communicate with it form the Central Network (CN). The attenuation and noise characteristics on the powerline channel may give rise to situations where certain devices that belong to the same home network may not be able to communicate with the CCo. A Proxy Network (PN) is instantiated in such scenarios to allow control of the “hidden devices” through a relay of communications between a Proxy Coordinator (PCo) and a CCo. Direct peer-to-peer communications are still enabled between devices in a PN and devices in the CN with which the PN is associated. The PN concept improves coverage by enabling communications for hidden devices. Due to the robust physical layer used by HomePlug AV, proxy networks are very rare.

While PNs always depend on and are associated with a CN, a Neighbor Network (NN) is an entirely autonomous association of HPAV devices. Neighbor networks are independent networks that can exist in neighboring homes. The HPAV system provides for coordination among the neighboring networks so that access to the medium is shared fairly by the various networks and Quality of Service (QoS) is preserved for communications within a network.

2.3.1 Station Roles

Each HomePlug AV station is capable of operating as a CCo of the AVLN. The selection of the station in the AVLN to assume the role of a CCo is typically done in an automated manner based on the station capabilities and network topology. The user may also appoint a specific station to act as the CCo. For example, it may be prudent to assign the Home Gateway/Router with HPAV capabilities as the default CCo. HomePlug AV defines three different levels of CCo capability:

Level-0 CCo: A basic CCo that can only support CSMA-based channel access (i.e., supports CSMA-Only mode).Level-1 CCo: A CCo that can support TDMA-based channel access when there are no neighbor networks (i.e., supports Uncoordinated mode).Level-2 CCo: A CCo that can support TDMA-based channel access even in the presence of neighbor networks (i.e., supports Coordinated mode).

All HomePlug AV stations are required to, at a minimum, support Level-0 CCo functionality. Furthermore, all HomePlug AV stations are required to be capable of operating under Level-0, Level-1, and Level-2 CCos.

HomePlug AV stations may also assume the role of a Proxy Coordinator to enable hidden stations to join the AVLN. Proxy Coordinators are selected by the CCo of the AVLN.

All other HomePlug AV stations in the AVLN operate as normal stations and rely on stations that assumed the role of CCo and PCo for managing the AVLN.

2.3.2 Bridging

One or more stations in the AVLN may also act as bridges to other networks. The bridge is responsible for routing traffic between the AVLN and other networks based on the list of MAC addresses of devices it is bridging for. The bridge also provides this list to other stations in the AVLN so that other stations can efficiently deliver traffic within the AVLN using unicast transmissions.

2.3.3 Channel Access