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About this book

This book systematically discusses the signal design theory and technologies for next-generation satellite navigation systems. It provides comprehensive information on the basic concept, theory, and key technologies employed in satellite navigation system signal design. Starting from the basic elements of the navigation signal, it combines traditional and advanced technologies into an organic whole, offering readers a complete system for signal design. Thanks to its rich content and clear structure, it is well suited as a reference guide for researchers and engineers in the fields of satellite navigation, positioning, etc. The book can also be used as teaching material or supplemental reading material by professors and graduate students alike.

Table of Contents

Frontmatter

Chapter 1. Introduction

Abstract
This chapter reviews the development of satellite navigation technology, and then explains the development and current status of the United States’ Global Position System (GPS), Russia’s GLObalNavigation Satellite System (GLONASS), the European Union’s Galileo Navigation Satellite System, and China’s BeiDou Navigation Satellite System (BDS). After a detailed discussion of the importance of navigation signals in Global Navigation Satellite System (GNSS) construction, a review is given of the development of the signal structure for the above-mentioned major GNSSs, thus providing a background for the next-generation GNSS signal design discussion.
Zheng Yao, Mingquan Lu

Chapter 2. Structure of Satellite Navigation Signals

Abstract
This chapter begins with explaining the basic principles of satellite navigation so as to clarify the missions and functions to be carried out by a navigation signal. Then, using the structural elements of satellite navigation signals as the main thread, this chapter systematically expound on the important basic concepts in the design of the signals. We also discuss the effects of various factors on system performance, such as center frequency, transmission power, polarization characteristics, spreading modulation, spreading code, message structure, and the multiplexing of signals. This chapter serves as the basis for subsequent chapters. Since the elements that make up the satellite navigation signal are closely related, the design of many elements of the signal is carried out in the form of trade-offs and compromises. Therefore, it is necessary to have a systematic understanding of the structure of the entire signal before conducting in-depth research on each aspect.
Zheng Yao, Mingquan Lu

Chapter 3. Basic Properties of Direct Sequence Spread Spectrum Signals

Abstract
In order to utilize the frequent sign altering in the spreading codes to measure the distance accurately, and to achieve better performance of multiple access, multipath resistance, and anti-interference, direct sequence spread spectrum (DSSS) technology is used in satellite navigation signals. With different spreading chips, the time domain waveform and power spectrum shape of the signal will exhibit significant differences, which will affect many key performances. Therefore, the spreading chip waveform becomes the key factor in determining the intrinsic performance of the satellite navigation signal, and the spreading modulation design has become the core technology of the GNSS signal design. From this chapter, we will start our journey on the spreading modulation design of satellite navigation systems. In this chapter, we will discuss some basic concepts and properties of direct sequence spread-spectrum technology, illustrating the mathematical models of spreading modulated signals and their important characteristics in time and frequency domains. These characteristics will be used frequently in the following chapters.
Zheng Yao, Mingquan Lu

Chapter 4. Spreading Modulation Techniques in Satellite Navigation

Abstract
The optimized design of the spreading modulation technique is considered to be the major way to achieve both spectrum compatibility and performance improvement. To allow a variety of signals to share the limited frequency band of GNSS and further improve the signals’ ranging accuracy and anti-interference performance, several new spreading modulation techniques have been proposed in recent years. In this chapter, we will introduce a variety of typical spreading modulation techniques such as BPSK with rectangular chips (BPSK-R), binary offset carrier (BOC), binary coded symbol (BCS), composite BCS (CBCS), time-multiplexed BOC (TMBOC), composite BOC (CBOC), quadrature multiplexed BOC (QMBOC), as well as alternative BOC (AltBOC). The processing ambiguity threat of BOC and MBOC signals and possible solutions are also discussed. Considering that in the next-generation GNSS implementations, new requirements and new constraints will constantly emerge and new modulation methods will be needed, this chapter is not meant to be regarded as a review of the development of navigation signal modulation technology, or an interpretation of the signal formats being used by several major satellite navigation systems. Instead, we regard the spreading modulations used in satellite navigation signals as general techniques and focus our discussion on the principles of these modulation techniques and the design ideas behind their generation processes.
Zheng Yao, Mingquan Lu

Chapter 5. Performance Evaluation Theory for Satellite Navigation Signals

Abstract
Theoretical evaluation is an objective and convenient method to acknowledge the performance of a signal. In this context, since the obtained performance is largely associated with the processing techniques implemented by receivers, the theoretical evaluation of a signal should also comprehensively consider the receiving strategies. In order to provide better performance for a wide range of users, the performance under traditional matched receiving, as well as under the various other receiving strategies, should be considered and optimized, where the theoretical evaluation criteria are treated as the guidance and objective for the signal design process. With respect to signal receiving, theoretical evaluation is a convenient method to compare the performance under various receiving strategies, thus providing useful information for choosing appropriate implementations for receiver manufacturers. Accordingly, the theoretical evaluation of signal performance becomes an essential topic for both the signal design and receiving in GNSS. In this chapter, we will discuss the theory and methods of navigation signal performance analysis based on time and frequency-domain characteristics of the spreading modulation waveform. A set of evaluation methods that both supports the various local receiving strategies and decouples from unrelated factors is provided. Specifically, the mismatch of the code chip waveform of the local despreading signal is considered. These methods have provided direct guidance for the spreading modulation optimization and selection of the next-generation satellite navigation signals.
Zheng Yao, Mingquan Lu

Chapter 6. Fundamental Theory of Constant Envelope Multiplexing for Spread-Spectrum Signals

Abstract
This chapter offers an in-depth discussion of the basic theory of constant envelope multiplexing (CEM) for satellite navigation signals. It mathematically models the constant envelope multiplexing process of general satellite navigation signals and gives mathematical and geometric descriptions of the constant envelope on the basis of the baseband complex envelope concept. Further, the concepts of the phase mapping table, constellation diagrams, and multiplexing efficiency are given. Then, starting from the intermodulation component structure and the phase mapping table, this chapter explores the design equations and analysis methods of general constant envelope multiplexing technology of these two seemingly disparate constant envelope multiplexing design concepts. Finally, by using the concept of the baseband signal to unify the conclusions of the two viewpoints, three equivalent representations of a constant envelope multiplexing scheme are discussed. We believe that with this elaborate text structure, this chapter will give the reader a global overview of CEM highlighting connections and differences between the assorted techniques.
Zheng Yao, Mingquan Lu

Chapter 7. Constant Envelope Multiplexing Techniques for Spread-Spectrum Signals

Abstract
This chapter offers a detailed discussion of the typical constant envelope multiplexing (CEM) techniques for satellite navigation spread-spectrum signals, such as QPSK multiplexing, time division multiplexing, quadrature product subcarrier modulation (QPSM), Interplex, phase-optimized constant-envelope transmission (POCET), constant envelope multiplexing via intermodulation construction (CEMIC), majority voting (MV) multiplexing, and asymmetric constant envelope BOC (ACE-BOC) multiplexing. Some of these techniques have been used in satellite navigation systems currently in operation, while others have good application prospects in future system construction. The content of this chapter is not a simple list of the various technical implementations. We will focus on the principles of these constant envelope multiplexing methods and the design concepts behind the development process,in order to understand the implementation details of each technique, and to display the essential connections between them. This allows us to offer a more systematic understanding of the research field to readers. Remaining challenges in this field are also discussed in the end of this chapter.
Zheng Yao, Mingquan Lu

Chapter 8. Multicarrier Constant Envelope Composite Signal

Abstract
This chapter takes a close look at how we can enable future development by implementing excellent signal designs with higher adaptability and flexibility. This chapter can also be regarded as a comprehensive example of how to apply the theory and techniques provided in this book to future signal design. In this chapter, we will see that under the conventional idea of separately optimizing carrier frequency, spreading modulation, and multiplexing, a Gordian knot is emerging in future GNSS signal design. In order to get out of the cycle of contradictions among measurement accuracy, services variety, RF compatibility, as well as multiplexing efficiency, the concept of using multicarrier modulation and multiplexing joint design is proposed. Performance analysis with some typical case studies demonstrates that the proposed multicarrier constant-envelope composite (MCC) signal provides a promising solution for the next generation GNSS signal design.
Zheng Yao, Mingquan Lu

Chapter 9. Conclusion

Abstract
This book has provided a systematic discussion of satellite navigation signal structure and a series of key design elements, as well as a detailed description of the theory and technology of signal design. The text has also briefly summarized the evolution of signal design in the development of satellite navigation systems over the course of several decades. In this conclusion, we will attempt to discuss two issues that what type of signal can be regarded as a good satellite navigation signal, and how future satellite navigation signals will develop.
Zheng Yao, Mingquan Lu
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