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Über dieses Buch

This book summarizes the authors’ latest research on narrowband interference and impulsive noise mitigation and cancelation, including (i) mitigating the impacts of NBI on synchronization; (ii) improving time-frequency interleaving performance under NBI and IN; (iii) accurately recovering and eliminating NBI and IN. The complicated, random and intensive narrowband interference and impulsive noise are a serious bottleneck of the next-generation wireless communications and Internet of things. This book also proposes effective and novel frameworks and algorithms, which will significantly improve the capability of mitigating and eliminating NBI and IN in the next-generation broadband communications systems.
This book not only presents thorough theoretical models and algorithm design guidelines, but also provides adequate simulation and experimental engineering methods and results. The book is a valuable reference for those engaged in theoretical study, algorithm design and engineering practice in related fields, such as wireless communications, smart lighting, IoT and smart grid communications.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Abstract
As the introductory content of this thesis, this chapter firstly introduces the development process and key technologies of broadband digital communications systems and the main noise and interference in it, and describes the characteristics and detrimental effects of NBI and IN, raising the main research topic, i.e., NBI and IN in broadband communications systems; Secondly, a comprehensive survey on the current research on the technologies of NBI and IN mitigation is given, with the major problems and challenges that the current related researches are faced with; Later the key problems to be solved and the research aims are given, based on which the research routine, the main research contents, the technological roadmap, the research outcomes and contributions of this thesis are described; Finally, a brief introduction to the structure of the thesis contents is presented.
Sicong Liu

Chapter 2. System Model and Fundamental Knowledge

Abstract
This chapter mainly introduces the background models and fundamental knowledge related with the research work of this thesis. Firstly, the main modules and the related key techniques of the broadband digital communication systems based on the technique of block transmission OFDM are briefly described. Secondly, the preamble structure in the frame header and the structure of data sub-frames commonly seen in many kinds of broadband digital communication systems and standards are introduced. Then, the theoretical models of the research objective of this thesis, i.e. narrowband interference and impulsive noise, which was proposed and widely adopted in literature, are described in detail, providing the model basis for the research contents of this thesis. Finally, the theory of sparse recovery is briefly introduced, including compressed sensing, structured compressed sensing, sparse Bayesian learning, etc, which provides theoretical basis and guidance for the research on sparse recovery in this thesis.
Sicong Liu

Chapter 3. Synchronization Frame Design for NBI Mitigation

Abstract
Synchronization has an important impact on the system performance of broadband communication systems. In particular, OFDM systems are very sensitive to the accuracy of synchronization. In the presence of narrowband interference, the performance of frame synchronization and carrier synchronization is severely influenced. The conventional synchronization frame structure and synchronization algorithms are not designed for mitigating the narrowband interference, resulting in serious performance loss of synchronization in the presence of narrowband interference. Hence, the problem of accurate and efficient synchronization in the presence of narrowband interference is the first utmost important problem to be solved to improve the system performance of broadband communication systems. In this chapter, the design of the OFDM preamble synchronization frame structure for effective narrowband interference mitigation is devised. Efficient and robust algorithms of receiver side frame synchronization and carrier recovery are studied. Besides, the method of frame header signalling transmission robust to the narrowband interference is investigated. Through these studies, the disadvantage of the conventional synchronization methods is overcome, and the synchronization performance of the OFDM system in the presence of narrowband interference is guaranteed. This research will provide basis technical support for the improvement of the overall system performance of the broadband communication systems in the presence of narrowband interference, and provide performance guarantee in the perspective of synchronization for the research of this thesis.
Sicong Liu

Chapter 4. Optimal Time Frequency Interleaving with NBI and TIN

Abstract
As described in Chap. 2, in order to get rid of the time and frequency bursting errors or deep fading in communication systems, it is necessary to design interleavers and deinterleavers. The conventional interleaving methods have many disadvantages. For example, the design is complicated. It is required to re-design a corresponding interleaving scheme for each coding and modulation parameter, so the adaptability and flexibility are quite limited. The state of the art methods cannot take time and frequency interleaving into account simultaneously, so they cannot suppress the time domain and frequency domain bursting errors simultaneously. Conventional bit or symbol interleaving patterns have no theoretical guarantee for the optimal performance, so it cannot ensure that the optimal scheme is devised and the maximum time and frequency diversity gains are achieved. In order to overcome the disadvantages of the conventional methods, this chapter is focused on the research idea of providing time and frequency diversity gains to suppress the time and frequency bursting noise and interference. The optimal time and frequency combined interleaving scheme in the presence of narrowband interference and impulsive noise is proposed, for which the theoretical analysis and guarantee are provided. Firstly, the scheme to optimize the interleaving parameters that maximize time diversity gain is proposed. Then, the symbol interleaving block cyclic shifting technique is proposed to maximize the frequency diversity gain. In this way, the time and frequency diversity gains are maximized, and the time and frequency bursting errors are effectively suppressed. Meanwhile, the interleaving performance and the decoding performance are significantly improved in the presence of both narrowband interference and impulsive noise. The research in this chapter will provide theoretical basis and feasible technical routines for the interleaving schemes in broadband communication systems in the severe channel condition with complicated narrowband interference and impulsive noise.
Sicong Liu

Chapter 5. Sparse Recovery Based NBI Cancelation

Abstract
As described in Chap. 1, the conventional methods of NBI mitigation in the state-of-the-art research cannot accurately estimate the NBI signal. The “passive” approach of suppressing the NBI makes it difficult to completely eliminate the impacts of the NBI on the system performance. Hence, it is necessary to find the theory and technology capable of accurately reconstructing the NBI. Making use of the naturally sparse property of the NBI signal in the frequency domain, and based on the newly emerged sparse recovery theory, this chapter will investigate and propose the compressed sensing based and structured compressed sensing based method of NBI differential measuring and sparse recovery, the efficient multi-dimensional compressed sensing based recovery algorithm, the sparse Bayesian learning based recovery algorithm, etc, in order to solve the scientific problem that the NBI is difficult to estimate and cannot be completely eliminated. The technical challenge of accurate sparse signal recovery in complicated and severe conditions, such as intensive background noise, insufficient measurement data, large sparsity level, low interference-to-noise ratio, etc, will be overcome. A new theoretical framework of sparse recovery for proactive NBI reconstruction is formulated in this chapter, which provides a new approach and theoretical and technical support for breaking the bottleneck of the system performance using the conventional methods and essentially improving the performance of the broadband communication system.
Sicong Liu

Chapter 6. Sparse Recovery Based IN Cancelation

Abstract
In this chapter, the second key techn ology on the third scientific problem of this book, i.e. the sparse recovery theory based impulsive noise (IN) reconstruction and cancelation, is investigated. The highly efficient new technique of accurate IN recovery and cancelation based on compressed sensing and structured compressed sensing theories is proposed to overcome the limitation of the conventional “passive” anti-IN methods and reach the research target of actively and accurately recover and completely eliminate the IN in broadband communication systems. In this chapter, first, to address the issue of the state-of-the-art methods, the IN recovery and cancelation method based on prior aided compressed sensing is proposed. Second, for the MIMO system, a structured compressed sensing based IN recovery algorithm exploiting spatial correlation is proposed. Finally, the method of combined NBI and IN recovery and cancelation based on the time-frequency combined compressed sensing framework is proposed to overcome the impacts from the NBI and IN on broadband communication systems.
Sicong Liu

Chapter 7. Conclusions

Abstract
This monograph is aimed at the urgent needs of the ever-increasing transmission performance of the next-generation broadband communications systems. It is focused on the key bottleneck that limits the current broadband transmission performance seriously, i.e. the non-conventional interference and noise, NBI and IN. The drawbacks of the conventional methods such as high implementation complexity, low applicability, low estimation accuracy and unstable performance, etc., should be overcome by breaking the fundamental limitation of the conventional “passive” anti-NBI and anti-IN approaches. In this chapter, we draw the conclusions of this book.
Sicong Liu
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