Understanding Weightless

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Oscar Benson
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1 Understanding Weightless Essential for getting to grips with the Weightless standard for M2M communications, this definitive guide describes and explains the new standard in an accessible manner. It helps you to understand the Weightless standard by revealing its background and rationale. Designed to make clear the context and the fundamental design decisions for Weightless, and to provide a readable overview of the standard, it details principal features and issues of the technology, the business case for deployment, network performance and some important applications. This informative book guides you through the key decisions and requirements involved in designing and deploying a Weightless network. Includes a chapter on applications, explaining the relevance of the standard and its potential. Written by one of the lead designers of Weightless, this is an ideal guide for everyone involved with the standard, from those designing equipment to those making use of the technology. WILLIAM WEBB is one of the founding directors of Neul, one of the core design team involved in Weightless and the CEO of the Weightless SIG. Prior to this William was a Director at Ofcom. He is a Fellow of the Royal Academy of Engineering, the IEEE and the IET, where he is a Vice President, and the author of multiple books, papers and patents.

3 Understanding Weightless Neul, Cambridge, UK

4 CAMBRIDGE UNIVERSITY PRESS Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo, Delhi, Mexico City Cambridge University Press The Edinburgh Building, Cambridge CB2 8RU, UK Published in the United States of America by Cambridge University Press, New York Information on this title: / C Cambridge University Press 2012 This publication is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. First published 2012 Printed in the United Kingdom at the University Press, Cambridge A catalogue record for this publication is available from the British Library ISBN Hardback Cambridge University Press has no responsibility for the persistence or accuracy of URLs for external or third-party internet websites referred to in this publication, and does not guarantee that any content on such websites is, or will remain, accurate or appropriate.

5 Contents Preface Acknowledgements About the author page xi xii xiii 1 The world of machine communications What defines a machine? Range: short or long? Possible applications Key requirements Market size How machine communications could change our world 8 2 The need for a new standard Machine communications does not yet have the necessary standard Barriers to delivering a machine communications network White space as a key enabler Design rules for a machine communication solution The Weightless Special Interest Group Summary 19 3 Working in white space spectrum Defining white space Determining where the white space is The greyness of white space Design rules for white space 27

6 vi CONTENTS 3.5 The US regulation The UK regulation Other countries Determining how much white space there is Regulation in other countries Other spectrum Conclusions 46 4 Weightless in overview The key requirements Immediate design implications Subsequent design thinking System overview 54 5 The network Introduction Functional elements Billing system Authentication and encryption Location register Broadcast register Base station controller Frequency assignment Code assignment Scheduling Traffic prioritisation Normalising power levels Avoiding antenna nulls Minimising interference Overall Calibration mode Load balancing Load imbalance New cell The network to base station interface Summary 73

7 CONTENTS vii 6 The MAC layer Overview Scheduled and contended access The frame concept Introduction The FCH The RS_MAP The DL_ALLOC and UL_ALLOC Acknowledgement Mapping data to resource allocations Terminal and group identities The contended access process Introduction Contended access: initial message flow Contended access for attach Contended access for resource Control messages Broadcast messages 99 7 The physical layer Introduction Overview of the PHY layer Forward error correction (FEC) encoding Whitening Modulation Spreading Cyclic prefix insertion Synchronisation (sync) insertion Root raised cosine (RRC) pulse shaping Frequency hopping Downlink, uplink and TDD High data rate downlink Low data rate downlink Narrowband uplink Wideband uplink 114

8 viii CONTENTS 7.12 RF performance Antenna issues The attach process as an example Introduction Channel discovery Decode the FCH Send a contended access message to attach Undertake authentication Agree a schedule for the next transmitted message Further functionality Encryption and authentication Security in general Security for machine communications Weightless security Moving base stations Location measurement Roaming Network design and capacity Understanding the capacity of a cell Factors that impact network capacity Capacity of a sample UK-wide network Increasing capacity Network cost and business case Comparison with mesh systems Application support Introduction Matching applications to Weightless Building an end-to-end service using Weightless The profile concept The connected car: applications and challenges 155

9 CONTENTS ix 10.3 Healthcare The healthcare productivity challenge The market today System architectures Healthcare examples Should Europe s Smart Grid gain some weight by using Weightless? Information flow and partitioning of smart grid communications solutions Smart metering standardisation and regulation landscape Smart metering communications landscape in Europe Requirements for a Weightless profile for smart metering Outlook and future applications Consumer applications Security Home energy and home automation Smart appliances Summary In closing 198 Glossary 199 Index 202

11 Preface This book is a guide to the Weightless technology. The definitive documentation for Weightless is the Weightless standard as published by the Weightless SIG and this book in no way is intended as an alternative. However, standards documents are not designed for readability and it is often helpful to start with a more descriptive text. This book is designed to explain the context for Weightless, the key design decisions and to provide a readable overview to the standard. That may be sufficient for some, and for those that will go on to read the standard they will better understand the details that they find there. This book was written to accompany version 0.6 of the standard. This is referred to throughout the book simply as the standard. Of course, this standard will evolve and it is envisaged that this book will be updated to accompany major revisions to the standard. Why the name Weightless? Like many standards such as Zigbee and Bluetooth, the name chosen is often more whimsy than descriptive. In this case, it came indirectly from making the point that this was not a new generation of cellular standard, measured in generations (2G, 3G...). Indeed, it was outside of this generation pattern and so perhaps zero-g. Zero-G is often associated with no gravity leading to weightlessness... At the time it was conceived most thought that a different name would emerge during the early standardisation process, but as is often the case names acquire a momentum all of their own, even those that have no weight.

12 Acknowledgements Any standard is the work of many individuals and companies Weightless is no exception. As always there are too many to mention them all here, but my thanks go especially to the core design team who conceived the Weightless standard and laid down its key operational parameters early in These include Robert Young, Tim Newton, Alan Coombs, Carl Orsborn and Neil MacMullen. Especial recognition is due to James Collier for having the vision to see the potential and the leadership to make it happen and to Vanessa Price for making sure we had plenty of coffee and biscuits.

About the author William is one of the founding directors of Neul, a company developing machine-to-machine technologies and networks, and the CEO of the Weightless SIG, the body developing the

13 About the author William is one of the founding directors of Neul, a company developing machine-to-machine technologies and networks, and the CEO of the Weightless SIG, the body developing the Weightless standard. He was one of the core design team involved in Weightless and instrumental in establishing the SIG. Prior to this William was a Director at Ofcom where he managed a team providing technical advice and performing research across all areas of Ofcom s regulatory remit. He also led some of the major reviews conducted by Ofcom including the Spectrum Framework Review, the development of Spectrum Usage Rights and most recently cognitive or white space policy. Previously, William worked for a range of communications consultancies in the UK in the fields of hardware design, computer simulation, propagation modelling, spectrum management and strategy development. William also spent three years providing strategic

14 xiv ABOUT THE AUTHOR management across Motorola s entire communications portfolio, based in Chicago. William has published 11 books, 80 papers and 18 patents. He is a Visiting Professor at Surrey University and DeMontfort University, a member of Ofcom s Spectrum Advisory Board (OSAB) and a Fellow of the Royal Academy of Engineering, the IEEE and the IET where he is a Vice President. William has a first class honours degree in electronics, a PhD and an MBA. In his spare time he is a keen cyclist having ridden Land s End to John O Groats, the route of the Tour de France and completed the gruelling Cent Cols Challenge, riding over 100 Alpine mountain passes in 10 days.

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