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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
IEEE 802.11ba Discover the latest developments in IEEE 802.11ba and Wake-up Radios In IEEE 802.11ba: Ultra-Low Power Wake-up Radio Standard, expert engineers Drs. Steve Shellhammer, Alfred Asterjadhi, and Yanjun Sun deliver a detailed discussion of the IEEE 802.11ba standard. The book begins by explaining the concept of a wake-up radio (WUR) and how it fits into the overall 802.11 standard, as well as how a WUR saves power and extends battery life. The authors go on to describe the medium access control (MAC) layer in detail and then talk about the various protocols used to negotiate WUR operation, its uses for different functionalities (like wake up of the main radio, discovery, synchronization, and security). The book offers a detailed description of the physical (PHY) layer packet construction and the rationale for the design, as well as the various design aspects of the medium access control layer. It also includes: * A thorough introduction to the motivations driving the development of the WUR in 802.11 * Practical overviews of IEEE 802.11, including the basic concepts of 802.11 (the PHY and MAC) and background material on current low power modes * Comprehensive discussions of the physical layer and PHY layer performance, including the generic receiver, the PPDU, Transmit Diversity, and the FDMA mode * In-depth examinations of the medium access layer and its frame designs Perfect for professional wireless engineers, IEEE 802.11ba: Ultra-Low Power Wake-up Radio Standard will also earn a place in the libraries of academics and students researching and studying in fields involving wireless communications.
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Table of Contents
Cover
Series Page
Title Page
Copyright Page
Author Biography
1 Introduction
1.1 Background
1.2 Overview
1.3 Book Outline
2 Overview of IEEE 802.11
2.1 Introduction
2.2 Overview of the IEEE 802.11 PHY Layer
2.3 Overview of IEEE 802.11 MAC Layer
2.4 Conclusions
References
3 Wake‐up Radio Concept
3.1 Introduction
3.2 Primary Sources of Power Consumption in an IEEE 802.11 Station
3.3 Wake‐up Radio Concept
3.4 Example of Power Consumption Using a Wake‐up Radio
3.5 Selection of Duty Cycle Values
3.6 Conclusions
4 Physical Layer Description
4.1 Introduction
4.2 Requirements
4.3 Regulations
4.4 Link Budget Considerations
4.5 Modulation
4.6 Physical Layer Protocol Data Unit (PPDU) Structure
4.7 Symbol Randomization
4.8 FDMA Operation
4.9 Additional Topics
4.10 Conclusions
References
5 Physical Layer Performance
5.1 Introduction
5.2 Generic Non‐coherent Receiver
5.3 Simulation Description
5.4 PHY Performance: Simulation Results
5.5 Link Budget Comparison
5.6 Conclusions
References
6 Wake‐up Radio Medium Access Control
6.1 Introduction
6.2 Network Discovery
6.3 Connectivity and Synchronization
6.4 Power Management
6.5 Frequency Division Multiple Access
6.6 Protected Wake‐up Frames
6.7 Conclusion
7 Medium Access Control Frame Design
7.1 Introduction
7.2 Information Elements
7.3 Main Radio MAC Frames
7.4 WUR MAC Frames
7.5 Conclusion
Index
End User License Agreement
List of Tables
Chapter 3
Table 3.1 Example power consumption values.
Chapter 4
Table 4.1 Summary of regulatory transmit power limits for 20 MHz and 4 Hz s...
Table 4.2 Link budget difference between the 802.11ba PHY and the OFDM PHY....
Chapter 6
Table 6.1 Summary of MR delivery contexts.
Chapter 7
Table 7.1 Contents of Supported Bands field and WUR Capabilities Informatio...
Table 7.2 Contents of the WUR Operation Parameters field.
Table 7.3 Combined settings for Action Type and WUR Mode Response Status fi...
Table 7.4 Contents of the WUR Parameters field for a WUR non‐AP STA.
Table 7.5 Contents of the WUR Parameters field for a WUR AP.
Table 7.6 Summary of WUR frame types.
Table 7.7 Identifiers in ID field of WUR frames.
Table 7.8 List of sample OUIs.
List of Illustrations
Chapter 2
Figure 2.1 OFDM symbol with cyclic prefix.
Figure 2.2 IEEE 802.11a PPDU structure.
Figure 2.3 IEEE 802.11n PPDU structure.
Figure 2.4 IEEE 802.11ac PPDU structure.
Figure 2.5 IEEE 802.11ax SU PPDU structure.
Figure 2.6 Network discovery with passive scanning or active scanning.
Figure 2.7 Connection setup.
Figure 2.8 L‐PHY for better coexistence with legacy STAs.
Figure 2.9 Power management.
Figure 2.10 Illustration of OFDMA introduced in 802.11ax.
Chapter 3
Figure 3.1 Generic transmitter block diagram.
Figure 3.2 Generic receiver block diagram.
Figure 3.3 Basic timeline for wake‐up radio (WUR) operation.
Figure 3.4 Duty cycled timeline for wake‐up radio with duty cycle operation....
Figure 3.5 Average power consumption for example.
Figure 3.6 Modes of the IEEE 802.11ba receiver duty cycle.
Chapter 4
Figure 4.1 Theoretical BER for coherent BPSK demodulation and noncoherent OO...
Figure 4.2 IEEE 802.11ba PHY protocol data unit (PPDU).
Figure 4.3 Autocorrelation of the bit sequence
W
.
Figure 4.4 Power spectral density of HDR Data field without symbol randomiza...
Figure 4.5 Power spectral density of LDR Data field without symbol randomiza...
Figure 4.6 Symbol randomizer.
Figure 4.7 Power spectral density of HDR Data field with symbol randomizatio...
Figure 4.8 Power spectral density of LDR Data field with symbol randomizatio...
Chapter 5
Figure 5.1 Non‐coherent receiver model.
Figure 5.2 Sync field detector used in simulation.
Figure 5.3 Sync field detection error rate in AWGN channel.
Figure 5.4 Sync field detection error rate in Channel Model D.
Figure 5.5 Sync field classification error rate in AWGN channel.
Figure 5.6 Sync field classification error rate in Channel Model D.
Figure 5.7 Probability mass function of the HDR Sync field timing error in A...
Figure 5.8 Probability mass function of the HDR Sync field timing error in C...
Figure 5.9 Probability mass function of the LDR Sync field timing error in A...
Figure 5.10 Probability mass function of the LDR Sync field timing error in ...
Figure 5.11 HDR and LDR packet error rate in AWGN.
Figure 5.12 HDR and LDR packet error rate in Channel Model D.
Figure 5.13 HDR packet error rate with transmit diversity in AWGN channel.
Figure 5.14 HDR packet error rate with transmit diversity in Channel Model D...
Figure 5.15 LDR packet error rate with transmit diversity in AWGN channel.
Figure 5.16 LDR packet error rate with transmit diversity in Channel Model D...
Chapter 6
Figure 6.1 Transition from WUR scanning to MR scanning.
Figure 6.2 Maintaining WUR connectivity and synchronization with WUR Beacon ...
Figure 6.3 IEEE 802.11ba power management.
Figure 6.4 Flowchart diagram of WUR modes.
Figure 6.5 Example with different WUR mode functionalities.
Figure 6.6 WUR duty cycle operation.
Figure 6.7 An example for the group addressed delivery context.
Figure 6.8 An example for the critical BSS update delivery context.
Figure 6.9 Operation with WUR FDMA PPDUs.
Chapter 7
Figure 7.1 Element format.
Figure 7.2 DSSS Parameter Set element format.
Figure 7.3 EDCA Parameter Set element format.
Figure 7.4 AC_X Parameter Record field format.
Figure 7.5 Channel Switch Announcement element format.
Figure 7.6 Extended Channel Switch Announcement element format.
Figure 7.7 HT Operation element format.
Figure 7.8 VHT Operation element format.
Figure 7.9 Wide Bandwidth Channel Switch element format.
Figure 7.10 Channel Switch Wrapper element format.
Figure 7.11 HE Operation element format.
Figure 7.12 WUR Capabilities element.
Figure 7.13 WUR Operation element format.
Figure 7.14 WUR Mode element.
Figure 7.15 WUR Discovery element format.
Figure 7.16 WUR PN Update element format.
Figure 7.17 MAC frame format.
Figure 7.18 Wake‐up Radio (WUR) frame format.
Figure 7.19 Schematic for 16‐bit CRC computation.
Figure 7.20 CRC‐16 implementation.
Figure 7.21 WUR Beacon frame format.
Figure 7.22 FL WUR Wake‐up frame format.
Figure 7.23 VL WUR Wake‐up frame format.
Figure 7.24 Format of the Frame Body field in a WUR VL Wake‐up frame.
Figure 7.25 WUR Discovery frame format.
Figure 7.26 WUR Vendor‐Specific frame format.
Figure 7.27 WUR Short Wake‐up frame format.
Guide
Cover Page
Series Page
Title Page
Copyright Page
Author Biography
Table of Contents
Begin Reading
Index
Wiley End User License Agreement
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IEEE Press445 Hoes LanePiscataway, NJ 08854
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Peter (Yong) Lian
Thomas Robertaazi
IEEE 802.11ba
Ultra‐Low Power Wake‐up Radio Standard
Steve ShellhammerAlfred AsterjadhiYanjun Sun
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Library of Congress Cataloging‐in‐Publication DataNames: Shellhammer, Stephen J., author. | Asterjadhi, Alfred, author. | Sun, Yanjun (Engineer), author.Title: IEEE 802.11ba : ultra‐low power wake‐up radio standard / Stephen Jay Shellhammer, Alfred Asterjadhi, Yanjun Sun.Description: Hoboken, New Jersey : Wiley, [2023] | Includes bibliographical references and index.Identifiers: LCCN 2022049546 (print) | LCCN 2022049547 (ebook) | ISBN 9781119670957 (paperback) | ISBN 9781119670995 (adobe pdf) | ISBN 9781119670902 (epub)Subjects: LCSH: IEEE 802.11 (Standard) | Radio–Receivers and reception.Classification: LCC TK5105.5668 .S54 2023 (print) | LCC TK5105.5668 (ebook) | DDC 004.67–dc23/eng/20221107LC record available at https://lccn.loc.gov/2022049546LC ebook record available at https://lccn.loc.gov/2022049547
Cover Design: WileyCover Image: © Jackie Niam/Shutterstock
Author Biography
Steve Shellhammer is a Principal Engineer and Manager in the Qualcomm’s Wireless Research and Development division, working on new IEEE 802.11 standards. These standards include IEEE 802.11be (Extreme High Throughput), IEEE 802.11az (Enhanced Positioning), and IEEE 802.11bf (RF Sensing). He was the PHY ad hoc chair for the IEEE 802.11ba Wake‐up Radio Task Group. He initiated and led a project to develop a prototype ultra‐low power wireless wake‐up receiver. He recently has been leading a project on RF Sensing at Qualcomm, focusing on RF Sensing applications. In the past at Qualcomm he led a cognitive research project for wireless networks.
He is currently the chair of the IEEE 802.19 working group on wireless coexistence and a member of the IEEE 802 Executive Committee, overseeing development of new IEEE 802 standards. He was previously a member of the IEEE‐SA Standards Board and the IEEE‐SA Review Committee. He was also the chair of the IEEE 802.15.2 Task Group on wireless coexistence addressing coexistence between Wi‐Fi and Bluetooth. He was also the Spectral Sensing lead for the 802.22 wireless regional area networking working group.
Before joining Qualcomm, he worked as a Wireless Architect at Intel’s wireless local area network division. Prior to that, he was the director of the Advanced Development department at Symbol Technologies. He was also an adjunct professor at SUNY Stony Brook, where he taught graduate courses in electrical engineering. These courses focused on probability, linear systems, digital signal processing, communication theory, and detection theory.
He has a PhD in electrical engineering from University of California Santa Barbara, an MSEE from San Jose State University, and a BS in physics from University of California San Diego. He is a senior member of the IEEE.
Alfred Asterjadhi is a Systems Engineer in the Qualcomm’s Wireless Research and Development division. His focus is on the design, standardization, and performance evaluation of MAC protocols in wireless systems. Special emphasis has been given to increasing efficiency, scalability, and reducing power consumption in wireless networks. He is the chair of IEEE 802.11be, and has served as the vice chair of IEEE 802.11ax and the vice chair and technical editor of IEEE 802.11ah. He has made significant technical contributions to these amendments in both standardization and certification of Wi‐Fi interoperability. He has authored and coauthored multiple conference and journal papers in wireless communications, a book in underwater acoustic networking, and is the holder of several patents in wireless communications. Alfred Asterjadhi received his PhD degree in information engineering and BSc and MSc degrees in telecommunications engineering from the University of Padova, Italy.
Yanjun Sun is a Senior Staff Engineer in the Qualcomm’s Wireless Research and Development division, working on new IEEE 802.11 standards.
He received his PhD degree in computer science from Rice University and was a research engineer in the DSP systems R&D center at Texas Instruments before joining Qualcomm.
His research interests include systems design and standards development related to Wi‐Fi, Bluetooth, Zigbee, protocol stacks, operating systems, and embedded systems. He has published papers at top IEEE and ACM conferences with best paper awards and driven R&D ideas into best‐selling products in the market.
1Introduction
1.1 Background
The Institute of Electrical and Electronic Engineers (IEEE) is a major professional organization which, among other things, develops standards. One of the most famous IEEE standard is IEEE 802.11, which is a standard for wireless local area networks. Implementations of IEEE 802.11 number in the billions. IEEE 802.11 implementations are certified by the Wi‐Fi Alliance and referred to as Wi‐Fi products in the marketplace. These Wi‐Fi products have become ubiquitous and are used for wireless connectivity for smartphones, laptop computers, tablet computers, and numerous other devices. Wi‐Fi networks are used in homes, business enterprises, and many other locations.
Since the first version of the IEEE 802.11 standard published in 1997, there have been many amendments to the standard which provide additional capabilities. An amendment to the standard adds content to the standard specifying new features and capabilities. Some of these are well‐known major amendments like 802.11n, 802.11ac, and 802.11ax, which bring significant increases in data rate and network throughput. There are also smaller amendments to the IEEE 802.11 standard, which are more focused on a few new key features.
Many of these new amendments to the 802.11 standard, which increase the data rate and throughput of the network, often also increase the power consumption of the 802.11 devices. This is because either additional electronic circuits are needed to implement these new higher‐rate features or the electronic circuits need to operate at a higher clock rate, both of which can lead to an increase in power consumption. This is the trade‐off that comes with these increases in network speed and throughput.
There are a number of methods to reduce power consumption in 802.11 devices. Most of them focus on allowing the device to enter a power save (PS) mode where some of the electronic circuits are not needed at the moment and hence lead to the power saving. However, often the 802.11 device needs to exit PS mode periodically to allow it to transmit and/or receive data packets. Therefore, there are limits to how much power savings can be obtained using these power savings techniques. So it became apparent that there was a need for a new amendment to the 802.11 standard to focus specifically on power savings and to use a more aggressive power savings technique to enable more significant power savings in 802.11 devices. This led to the development of the IEEE 802.11ba amendment of the 802.11 standard.
The IEEE 802.11ba, which was published in 2021, is a standard for a wake‐up radio (WUR). A WUR is a low‐power wireless technology that enables the development of ultra‐low‐power devices. The term “radio” is used here as a synonym for “wireless.” A WUR is a wireless technology that supports implementation of an ultra‐low‐power wake‐up receiver, which has limited wireless functionality but can be operated at very low‐power consumption levels. An 802.11 device that includes this wake‐up receiver can allow its main transmitter and receiver to be placed into a deep sleep mode, while the wake‐up receiver can be used to receive messages from an 802.11 access point (AP) when information is to be sent to or received from this 802.11 device. When the WUR receives a wake‐up message, then the main wireless technology, or main radio (MR), in the devices can be brought out of its deep sleep mode and exchange messages with the AP. This MR can be any of the standard 802.11 PHY layers, including 802.11n, 802.11ac, 802.11ax, and so forth.
One can think of this as a hierarchy of wireless systems where the MR is used to transfer data, often at a high data rate (HDR), and the WUR is used to maintain a connection between nodes in the wireless network and wake up the MR when it is time to transfer data. This hierarchy of wireless systems provides both low‐power consumption and the ability to transfer data, often at HDRs, when needed.
The WUR is particularly good at addressing one of the most challenging power consumption problems, which is when the device needs to support low‐latency data traffic while still maintaining low‐power consumption. We can illustrate this problem with an example. Say the 802.11 device needs to control an actuator in a home automation use case. Let us say the response time for the actuator needs to be short since the user wants to visually see or hear the response. The user could be turning on a set of lights around the house, locking a set of doors, or maybe even remotely turning on some music. The user does not want to have to wait multiple seconds to see or hear the response to the action taken, say on a smartphone application, where the smartphone is connected to the 802.11 home network. The user wants to push a button on the smartphone and see or hear the response within a fraction of a second. To do this the smartphone needs to send a message over the 802.11 network to the AP, which then needs to send a message to the actuator over the same 802.11 network. The 802.11 device connected to the actuator needs to be ready to take action at any time, so it needs to be listening to the 802.11 network frequently, say every 100 ms, or possibly even more frequently. However, without a WUR, this means that the main receiver needs to listen to the AP very frequently and cannot spend much of its time in sleep mode. However, with a WUR the MR attached to the actuator can be in a deep sleep mode almost all the time, and the WUR can signal it to “wake‐up” out of deep sleep mode, when an action is required. So we see how the ultra‐low‐power WUR can help solve this most difficult problem of supporting both low latency and lower power consumption.
1.2 Overview
This book provides a description of the IEEE 802.11ba standard, which as mentioned above is an amendment to the overall IEEE 802.11 standard. The IEEE 802.11 standard has grown over the years as more and more amendments have been added to the standard. IEEE 802.11ba is one of the more recent amendments. Many of the 802.11 amendments are focused on increases in wireless data rates and an increase in the overall network throughput. Many technologies are used to increase the data rate and the network throughput, like increased bandwidth, multiple input multiple output (MIMO) technology, and improvements in protocol design to optimize efficiency. IEEE 802.11ba is unique in that it focuses on power savings in order to increase the battery life in battery‐operated devices.
The amendments that provide higher data rates typically also result in increased power consumption. Increases in bandwidth lead to increases in radio frequency (RF) and analog circuit power consumption. Use of MIMO technology requires duplication of RF/analog and digital processing circuits since circuits are needed for each spatial stream. With the use of more powerful forward error correction (FEC) codes, like low‐density parity check (LDPC) codes, improved network performance comes at the cost of increased power consumption. Some of this is offset by improved integrated circuit technology, particularly for digital circuits. However, for RF and analog circuits, the improvements in integrated circuit technology do not typically result in significant offsets in power consumption.
The IEEE 802.11ba standard addresses these issues by providing a specification that enables implementations that require very low‐power consumption. The standard does not mandate a specific implementation but makes it possible for an implementer to design an implementation with low‐power consumption.
Details of the standard will be left for subsequent chapters, but here we can highlight some of the key aspects of the standard which enable a very low‐power implementation.
First, let us explain that the standard was developed to enable an ultra‐low‐power wake‐up receiver. The power consumption of the transmitter is not a major factor in the design. The reason for this is that in typical use cases the 802.11ba transmitter is implemented in the 802.11 AP, which is typically connected to AC power and is not battery‐operated. On the other hand, the 802.11 station (STA) is often battery‐operated and the 802.11ba wake‐up receiver is implemented in this battery‐operated device. So, the majority of design aspects of the 802.11ba standard are focused on saving power at the battery‐operated STA.
The first design aspect of the standard that is different than other amendments is that the bandwidth is for 4 MHz operation, which is quite different than the amendments which focus on higher data rates, which have increased the bandwidth from 20 to 40, 80, and 160 MHz. There is also an amendment under development (IEEE 802.11be) which will support 320 MHz operation.
The second design aspect is the use of a simple on‐off keying (OOK) modulation, which allows for the use of a non‐coherent wake‐up receiver. Most standards use modulations that require coherent receivers, leading to higher performance at the cost of higher power consumption at the receiver. The OOK modulation used in 802.11ba is a little different than traditional OOK, in that the underlying waveform is a multicarrier waveform. However, it is still possible to use a non‐coherent receiver with this modulation. More details of the modulation will be provided in subsequent chapters.
Another design aspect to reduce power consumption is to use a low data rate (LDR). This enables an RF implementation with a higher receiver noise figure. The receiver noise figure is a measure of how much noise the receiver introduces to the received signal. A lower receiver noise figure means lower noise and better performance. But to obtain a lower noise figure usually requires higher power consumption. An RF low‐noise amplifier (LNA) with a low noise figure requires a high operating current, which leads to increases in LNA power consumption. The power budget of the wake‐up receiver implementation cannot support a high‐power LNA, so the system design needs to address the higher receiver noise figure in some way.
By using a low data rate, the receiver can be built with a higher noise figure while still operating at a reasonable receive power level. By using a lower data rate, even with a higher receiver noise figure, the 802.11ba system can have a similar range as the main 802.11 radio. This is important so that when the main 802.11 radio is placed in a deep sleep mode, and the wireless link relies on 802.11ba, the supported range between the AP and the STA is not reduced.
All of these aspects of 802.11ba allow for ultra‐low‐power receiver implementations by saving power in the RF, analog, and digital circuits.
The impact of having an LDR puts strong requirements on the medium access control (MAC) layer design to fit the necessary information for the MAC messages into a small number of octets (bytes). In that way the overall time duration of the 802.11ba packets is not excessive. If the duration of these packets were too long, they would lead to an overall drop in network throughput, by using too much airtime. IEEE 802.11 refers to the airwaves as the wireless medium, so we say the medium utilization of the WUR packets cannot be too high, since that would prevent the other higher data rate 802.11 devices from using the wireless medium, which would result in an overall reduction in the wireless network throughput.
To avoid this problem, it is very important to design the MAC frames to be very short. The design of these MAC frames is described in detail in the subsequent chapters.
Another MAC layer design that is critical to power saving is to support duty cycling of the 802.11ba wake‐up receiver. If the receiver can operate at a low‐duty cycle, then the power consumption can be reduced even further. To support duty cycling of the 802.11ba receiver, a WUR beacon is used so that the 802.11ba receiver can maintain synchronization with the 802.11ba transmitter. The local clock within the 802.11ba receiver will drift between these WUR beacons, but the receiver can utilize the beacon to resynchronize its local clock with the clock in the 802.11ba transmitter. There is also a MAC layer procedure for establishing how frequently the beacon is transmitted and how often the 802.11ba wake‐up receiver should be listening for messages, like a WUR beacon or a wake‐up message. It is quite possible to duty cycle the 802.11ba receiver at 1% or less, leading to significant additional power savings.
So, in summary the following design aspects of the 802.11 standard enable ultra‐low‐power receiver implementations:
Narrow bandwidth: Reduced RF and analog circuit power consumption.
Non‐coherent modulation: Enabling the use of a low‐power non‐coherent wake‐up receiver.
LDR: Enable a high receiver noise figure to save RF power consumption.
Duty cycling of the 802.11ba wake‐up receiver: Allowing the 802.11ba receiver to be in the powered‐off mode for a high percentage of the time.
1.3 Book Outline
Chapter 2 provides a brief overview of the IEEE 802.11 standard, to provide the necessary background for the reader to understand the subsequent chapters on the WUR physical (PHY) and MAC layers. The focus is on the aspects of the standard that are relevant to the 802.11ba amendment. The chapter gives an overview of the orthogonal frequency division multiplexing (OFDM) PHY layer with a focus on the preamble design. There is also an overview of the IEEE 802.11 MAC layer, so the reader has a background on 802.11 MAC frames, procedures, and protocols.
Chapter 3 describes the concept of the WUR and how it is used to save power in the battery‐operated STA. It includes a description of the primary circuits in the receiver, which consume significant amounts of power. It shows how a WUR can be used to save power, particularly in cases where the data transfer between the AP and the STA is infrequent. A description of the impact of latency between the AP and the STA is provided and how that impacts power consumption. The reader can then understand how, with the use of a WUR, it is possible to maintain a low latency link between the AP and the STA, along with low‐power consumption at STA. This is one of the key benefits of using a WUR, which makes it possible to support both low‐latency operation and ultra‐low‐power consumption. Without a WUR, that is very difficult to accomplish.
A description of the 802.11ba PHY layer is provided in Chapter 4. The PHY protocol data unit (PPDU) is described. There is an explanation of how the first portion of the 802.11ba PPDU is intended to be decoded by 802.11 devices that do support 802.11ba. These devices are often referred to as legacy devices since they do not understand the new 802.11ba PPDU. This is important so that those devices do not transmit at the same time as the 802.11ba PPDU, so as to avoid a packet collision. The chapter describes how the second part of the PPDU is intended to be decoded by the 802.11ba receiver. That portion consists of a synchronization (Sync) field which is used by the receiver for packet detection, timing recovery, and data rate determination. There are two data rates supported in the 802.11ba PHY layer: LDR and HDR. After the Sync field is the Data field, which carries the information provided by the MAC layer.
Chapter 5 focuses on the performance of the 802.11ba PHY layer. Simulation results are provided for different channel conditions and different signal‐to‐noise ratios (SNRs). The performance of packet detection by using the Sync field is provided for both the LDR and the HDR. Other simulations of Sync field processing included simulations of timing recovery accuracy and data rate determination. Finally, overall packet error rate (PER) is shown for additive white Gaussian noise (AWGN) channels and multipath channel models commonly used in 802.11 simulations. Finally, PER simulations are provided for the case when multiple transmit antennas are available at the AP, showing how the reliability of the link can be improved using multiple transmit antennas at the AP, which are typically available in most APs.
Chapter 6 gives an overview of the 802.11ba MAC protocol including the procedures for setting up a WUR link, setting up duty cycle operation, and how the WUR beacon works. This chapter describes how the WUR fits into the overall 802.11 power management system.
Chapter 7 gives a detailed description of the 802.11ba MAC frames, including the WUR Beacon frame, the Wake‐up frame, the Discovery frame, and the Vendor Specific frame. The WUR Beacon frame is sent by the AP periodically so that the 802.11ba devices can maintain synchronization with the AP. This synchronization is important to support duty cycling of the 802.11ba client device. Without this synchronization the clocks in the AP and the client device would diverge and duty cycle operation would fail. The Wake‐up frame can be used to wake up a single 802.11 client device or a group of 802.11 devices. The Discovery frame can be used to “discover” other 802.11ba devices which are within range, and that can be used to facilitate a variety of applications. One such application is when a mobile device wants to find an AP within its range. Using the 802.11ba Discovery frame, this discovery operation can be accomplished using an ultra‐low‐power wake‐up receiver, resulting in lower power consumption. Finally, the Vendor Specific frame is an 802.11ba MAC frame that can be customized by a vendor which implements the 802.11ba standard for a custom use case. This provides great flexibility for use cases not foreseen during the development of the 802.11ba standard. Last but not least, Chapter 7 describes how existing management frames in 802.11 are expanded so that the 802.11ba WUR works seamlessly with the main 802.11 radio.
