Wireless Coexistence

Standards, Challenges, and Intelligent Solutions
 
 
Standards Information Network (Verlag)
  • 1. Auflage
  • |
  • erschienen am 2. September 2021
  • |
  • 336 Seiten
 
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978-1-119-58412-4 (ISBN)
 
Wireless Coexistence

Explore a comprehensive review of the motivation for wireless coexistence and the standards and technology used to achieve it

Wireless Coexistence: Standards, Challenges, and Intelligent Solutions delivers a thorough exploration of wireless ecosystems sharing the spectrum, including the multiple standards and key requirements driving the current state of wireless technology. The book surveys several standards, including IEEE 802.22, 802.15.2, and 802.19.1 and expands upon recent advances in machine learning and artificial intelligence to demonstrate how these technologies might be used to meet or exceed the challenges of wireless coexistence.

The text discusses cognitive radio in the context of spectrum coexistence and provides a comparison and assessment of using artificial intelligence in place of, or in addition to, current techniques. It also considers applications to communication theory, learning algorithms for passive wireless coexistence strategies, spectrum situational awareness, and active wireless coexistence strategies.

With the necessity of spectrum sharing and the scarcity of unused spectrum on the rise, the standardization of wireless coexistence becomes more important with each passing day. Readers will learn about the challenges posed by shrinking wireless real estate and from the inclusion of topics like:

  • A thorough introduction to the concept of, and motivation for, wireless coexistence, including congestion and interference, policies, and regulations
  • An exploration of different wireless coexistence standards, including the need for standardization and various protocols, including 802.22, 802.15.2, 802.19.1, P1900, and 3GPP Release 13/14 LAA
  • A discussion of the applications of communication theory, including primary user strategies, primary multi-user protocols, and successive interference cancellation
  • A treatment of concepts in learning algorithms

Perfect for scientists, researchers, engineers, developers, educators, and administrators working in the area of wireless networks, Wireless Coexistence: Standards, Challenges, and Intelligent Solutions will also earn a place in the libraries of graduate students studying wireless networks and seeking a one-stop reference for subjects related to wireless coexistence standards.

Daniel Chew is a member of the Senior Professional Staff at The Johns Hopkins University Applied Physics Laboratory. He teaches in the Engineering for Professionals program at Johns Hopkins University. His current research focuses on improving spectrum utilization and security.

Andrew L. Adams is a member of the Senior Professional Staff at The Johns Hopkins University Applied Physics Laboratory. He teaches in the Engineering for Professionals program at Johns Hopkins University. His current research interests include wireless technology and artificial intelligence.

Jason Uher, PhD, is a member of the research staff at The Johns Hopkins University Applied Physics Laboratory. His research focuses on PHY/MAC layer security and anonymity, SDR processing techniques, and analysis of complex distributed systems.

1. Auflage
  • Englisch
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John Wiley & Sons Inc
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978-1-119-58412-4 (9781119584124)
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Daniel Chew is a member of the Senior Professional Staff at The Johns Hopkins University Applied Physics Laboratory. He teaches in the Engineering for Professionals program at Johns Hopkins University. His current research focuses on improving spectrum utilization and security.

Andrew L. Adams is a member of the Senior Professional Staff at The Johns Hopkins University Applied Physics Laboratory. He teaches in the Engineering for Professionals program at Johns Hopkins University. His current research interests include wireless technology and artificial intelligence.

Jason Uher, PhD, is a member of the research staff at The Johns Hopkins University Applied Physics Laboratory. His research focuses on PHY/MAC layer security and anonymity, SDR processing techniques, and analysis of complex distributed systems.
Author biographies - to follow

Preface - to follow

1 Introduction

A Primer on Wireless Coexistence: The Electromagnetic Spectrum as a Shared Resource

The Role of Standardization in Wireless Coexistence

An Overview of Wireless Coexistence Strategies

Standards Covered in this Book

1900.1 as a baseline taxonomy

Organization of this Work

2 Regulation for Wireless Coexistence

Traditional frequency assignment

Policies and Regulations

Bands for unlicensed Use

3. Concepts in Communication Theory

Types of Channels and Related Terminology

Types of Interference and Related Terminology

Types of Networks and Related Terminology

Primer on Noise

Primer on Propagation

Primer on Orthogonal Frequency Division Multiplexing

Direct-Conversion Transceivers

4 Mitigating Contention in Equal-Priority Access

Designating Spectrum Resources

Interference, Conflict, and Collisions

What is a Primary User?

Tiers of Users

Unlicensed Users

Contention in Spectrum Access and Mitigation Techniques

Division of Responsibility among the Protocol Layers

Duplexing

Multiple Access and Multiplexing

Frequency and Time Division Multiple Access

Spectral Masks Defined in Standards

Spread Spectrum Techniques

Carrier Sense Multiple Access

Orthogonal Frequency Division Multiple Access

Final Thoughts

5 Signal Detection

Introduction

Definitions and Taxonomy

Generic Framework for Signal Detection

Noise Floor Estimation and Threshold Setting

Matched Filter Detection

Energy Detection

Cyclic Spectral Analysis

Final Thoughts

6 Intelligent Radio Concepts

Introducton

Intelligent Radio Use-Cases

Making Radios Intelligent

Intelligent Radio Architectures

Learning Algorithms

Looking Forward

7 Coexistence Standards in IEEE 1900

DySPAN Standards Committee (IEEE P1900)



8 Coexistence Standards in IEEE 802

The Standards to be addressed in this Chapter

Types and Spatial Scope of Wireless Networks

Stacks: The Structure of Wireless Protocol Standards

IEEE 802.22

IEEE 802.11

TVWS Geolocation Databases in the United States

IEEE 802.19.1

IEEE 802.15.2

9 LTE Carrier Aggregation and Unlicensed Access

Introduction

3G to LTE

LAA Motivation

LTE Overview

Carrier Aggregation

License Assisted Access

Conclusions

10 Conclusion and Future Trends

Summary of the Preceding Chapters

Nonorthogonal Multiple Access and Underlaying

Intelligent Collaborative Radio Networks

Validation and Verification of Intelligent Radios

Spectrum Sharing Utopia

Conclusion

1
Introduction


It is common for both the general public and sophisticated engineers alike to take the concept of wireless communications for granted. Since the early research into the properties of the electromagnetic spectrum, scientists have sought understanding of the so called "Luminiferous Aether" [1]. Even with the vast amount of wireless devices in play today, the subject is often treated as a form of black magic: you put energy into a medium and it simply shows up where you want it. Though human understanding of the electromagnetic world has come a long way since the days of the Aether, there is still much that we do not understand about the propagation of electromagnetic waves in complex environments such as the natural and manmade landscapes we expect our wireless devices to operate in. As our understanding of the electromagnetic spectrum has changed over time, so have the methods by which we use that spectrum. While communicating over long distances was the original, and still most popular, use of spectrum there are now several aspects of an average person's day-to-day life that are made better by use of the spectrum. Outside of the communications role, we also use spectrum every day for things like sensing our environment, transferring energy from one place to another, heating objects, and many more. Every single one of these applications requires that the operator "use up" some amount of electromagnetic spectrum while accomplishing their goal. In order to understand why the efficient use of this spectrum is important, it is essential that we first understand what makes the electromagnetic spectrum a shared resource.

1.1 A Primer on Wireless Coexistence: The Electromagnetic Spectrum as a Shared Resource


In this section, we will seek to establish a fundamental baseline of understanding around wireless communications. This section is targeted at the wireless communications novices utilizing this book as a crash course in wireless coexistence standards. However, even seasoned RF scientists and engineers may find it useful as a number of key principles critical to the analyses in the remainder of the book are spelled out explicitly. This section, then, establishes a baseline of thinking from fundamental principles that can be used to reason about the how and why of coexistence from a consistent perspective. This common baseline allows for a like-to-like comparison when dealing with different styles of coexistence and gives the reader a consistent rubric for considering the potential tradeoffs of those styles.

1.1.1 Basic Description of Spectrum Use and Interference


When examining spectrum use, there are three orthogonal bases that are used to separate different users: time, space, and wavelength. When trying to understand these bases it is common to use sound as an analogous system to help reason about the properties of waves. Electromagnetic waves behave in many of the same ways that sound waves do, with the primary difference being which physical medium is excited with energy.

The first basis, time, is the easiest to understand. If someone is currently transmitting radio waves, they will be occupying the same portion of the spectrum at that time. The second basis, location, is similar but with a caveat. When someone transmits from a particular place, they are occupying the spectrum around that place. However, there are a number of factors that influence the degree to which they are using the spectrum there which will be discussed later in the propagation section. The third basis is the wavelength, or frequency, of waves used to transmit your radio signal. The signal sent through the air will always occupy a contiguous band of the spectrum; the width depends upon the amount of information being sent over the air. Figure 1.1 shows an example of a time-frequency map that might depict the transmitters in use at a given location. The larger a block is along the frequency axis, the more bandwidth it consumes at that time.

Figure 1.1 An example of a time frequency map.

These types of maps can be helpful to visualize the spectrum usage by different users in a particular area. Which users are able to transmit in each section of a frequency band are typically displayed using a band plan. For example, Figure 1.2 shows one of the United States amateur radio band plans for the 80?m allocations. Different users, separated into different classes by their capabilities, are allowed to use different sections of the spectrum according to this plan at any time.

Figure 1.2 An example of a band plan.

One deficiency in a band plan is that it does not specify the physical location from which a user may transmit. This is typically enforced through a combination of the licensing authority and limits on the transmit power that a user can broadcast with. For example, broadcast AM radio stations transmit from known locations (where antenna the tower is), and are assigned a maximum amount of power they can use to transmit. Because the propagation characteristics of the AM Broadcast band are well understood, limiting the power to a certain level performs the same function as ensuring the signal will only be received within a given geographic area. Similarly, mobile users usually have the same power restrictions but have the additional restriction of ensuring that they are operating within a specific boundary, typically the jurisdiction of the licensing authority. With these three potential bases, it is relatively easy to answer the question "what is interference?" IEEE 1900.1 [2] defined Interference as:

In a communication system, interference is the extraneous power entering or induced in a channel from natural or man-made sources that might interfere with reception of desired signals or the disturbance caused by the undesired power.

Interference, in the context of wireless coexistence, means impairing the transmission of another user. This is caused when multiple users operate at the same time, within the same bandwidth, and in the same geographic location as each other, with no means to de-conflict that resource. Chapter 4 will discuss in depth several multiple access strategies such as Code Division Multiple Access (CDMA), which is intended to allow concurrent use of a spectrum resource in time, frequency, and space; but suffers from interference caused by the multiple independent users on one spectrum resource. This is type of interference called Multiple User Interference (MUI). Chapter 10 will expand on that discussion and delve into Non-Orthogonal Multiple Access (NOMA), which revolves around concurrent use of spectrum resources and the interference this causes.

1.1.2 Understanding What It Means to Occupy a Band


Using the earlier definition of interference, "operating at the same time, within the same frequency band, and in the same geographic location as another user," leaves a number of practical questions about what it actually means to be in the same band or the same place. The logical representation of band usage, such as that shown in Figure 1.1, shows an idealized representation of what it means to occupy a band. In reality, wireless transmissions are a physical process that do not cleanly start and end at the exact edges of the allocated band. A more realistic interpretation of the spectrum usage is shown in Figure 1.3.

Figure 1.3 Example of realistic spectrum usage for one signal.

Due to the physical nature of modulating data onto signals, it is impossible for a transmitter to keep all of the energy only in the band of interest. This means that there will always be interference outside of the allowed band, even if it is only a very small amount.

1.1.3 Spectral Masks


It is an unfortunate fact of radio communications that an information-carrying signal cannot be made to occupy a finite bandwidth. Because transmitted signals will always produce some amount of noise outside the primary transmission band, the majority of the regulations and licensing requirements in place today focus on ensuring that the interference introduced outside the allocated bands is limited to a manageable amount. These limits are usually defined through the use of what are called Spectral Masks. A spectral mask outlines the amount of power that a licensee's devices can radiate over bandwidth. Power over bandwidth is called the Power Spectral Density (PSD). Spectral masks are determined from a variety of constraints including but not limited to international regulations, other users in the same band or adjacent bands, and the likelihood of interference with other equipment. For example, Figure 1.4 shows the spectral mask imposed on 802.11 devices when using Direct-Sequence Spread Spectrum (DSSS) [3].

Figure 1.4 Example of a transmit mask.

Source: IEEE 802 [3].

The bold line in Figure 1.4 is the spectral mask and it limits the power spectral density of the signal that may be transmitted in terms relative to the peak as a function of frequency. The limit is imposed in decibels relative to the reference level (dBr). 0?dBr is at the reference level. The reference level is the highest spectral density of the transmission. The channel, in this context defined as the intended transmission bandwidth, spans from...

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