Academic literature on the topic 'Baseband signal generator'

This chapter presents mathematical models of baseband and bandpass digital communication systems based on binary and quaternary phase-shift keying, frequency-shift keying, and quadrature amplitude modulation. The systems are deduced as special cases from the general generic system structure and the related theory of orthonormal basis functions. The systems are uniquely presented using mathematical operators and detailed derivatives for signals in time and frequency domains at the system’s vital points, that is, the transmitter, the receiver, and the noise generator, using the concepts of both stochastic (continuous and discrete) and deterministic (continuous and discrete) signal processing. The vital characteristics of the system and its blocks are expressed in terms of amplitude spectral density, autocorrelation functions, power and energy spectral densities, and bit error probability.

This chapter focuses on noise processes in discrete communication systems. The problem with white Gaussian noise process discretization is that a strict definition implies that the noise has theoretically infinite power. Thus, it would be impossible to generate discrete noise, because the sampling theorem requires that the sampled signal must be physically realizable, that is, the sampled noise needs to have a finite power. To overcome this problem, noise entropy is defined as an additional measure of noise properties, and a truncated Gaussian probability density function is used. Adding entropy and truncated density to the definition of the noise autocorrelation and power spectral density functions allows mathematical modelling of the discrete noise source for both baseband and bandpass noise generators and regenerators. Noise theory and noise generators are essential for a theoretical explanation of the operation of digital and discrete communications systems and their design, simulation, emulation, and testing.

Achieving widespread access by all European citizens to new services and advanced applications of the information society is one of the crucial goals of the European Union’s (EU) strategic framework for the future. Towards realizing this primary target, multiple access platforms are expected to become available, using different access methods for delivery of services (and of related digital content) to a wide variety of end-user terminals, thus creating an “always-on” and properly “converged” technological and business environment, all able to support and to promote innovation and growth (Commission of the European Communities, 2005). The result will be a “complementarity” of services and markets in an increasingly sophisticated way. Economic and technology choices imply certain networks for certain service options. As these networks become more powerful, the temptation is to adapt certain characteristics of the network technology to make it suitable for modern services. The challenge is to build “bridges” or “links” between the different convergent technologies without undermining the business models on which they are built. In such a context, converging technology means that innovative systems and services are under development with inputs, contributions, and traditions from multiple industries, including telecommunications, broadcasting, Internet service provision, computer and software industries, and media and publishing industries, where the significance of standardization and interoperability can be fundamental. In any case, digital technology can offer the potential for realizing the future electronic information highways or integrated broadband communications. However, for the multiplatform environment to proliferate in liberalized markets and for the platforms themselves to complement each other, the related prerequisites and the governing regulatory environment must favor technologically neutral conditions for competition, without giving preference to one platform over others (Chochliouros & Spiliopoulou, 2005a). Among the latest European priorities for further development of the information society sector as described above were several efforts for extending the role of digital television based on a multiplatform approach (European Commission, 2002a). If widely implemented, digital (interactive) television may complement existing PC- and Internet-based access, thus offering a potential alternative for market evolution (Chochliouros, Spiliopoulou, Chochliouros, & Kaloxylos, 2006). In particular, following current market trends, digital television and third generation (3G) mobile systems driven by commonly adopted standards can open up significant possibilities for a variety of platform access to services, offering great features of substitution and complementarity. The same option holds for the supporting networks as well (European Commission, 2003a). Within the above fast developing and fully evolutionary context, the thematic objective of digital video broadcasting (DVB) applications (including both the underlying network infrastructures and corresponding services offered) can influence a great variety of areas (http://www.dvb.org). In particular, DVB stands as a suite of internationally accepted open standards, mainly related to digital television- and data-oriented applications. These standards (in most cases already tested and adopted in the global marketplace) are maintained by the so-called DVB Project, an industry-driven consortium with more than 300 distinct members, and they are officially published by a joint technical committee (JTC) of the European Telecommunications Standards Institute (ETSI), the European Committee for Electrotechnical Standardization (CENELEC), and the European Broadcasting Union (EBU). The existing DVB standards cover all aspects of digital television, that is, from transmission through interfacing, conditional access, and interactivity for digital video, audio, and data. In particular, DVB not only includes the transmission and distribution of television program material in digital format over various media, but also a choice of associated features (considered for exploiting capabilities of all underlying technologies). However, market benefits can be best achieved if a “harmonized” approach, based on a longterm perspective, is adopted since the beginning of all corresponding efforts, intending to facilitate a progressive development towards new (and more advanced) services in a smooth and compatible manner (Oxera, 2003). An essential precondition for this progress is the adoption, in the market sector, of common standards which, while providing necessary clarity for both producers and consumers in the short term for early introduction of digital television facilities, also supply the potential for subsequent smooth upgrading to new and higher grades of service. Thus, in the framework of competitive and liberalized environments DVB can support major efforts for the penetration (and the effective adoption) of enhanced multimedia-based services (Fenger & Elwood-Smith, 2000) independently of the type and/or format of the content offered while simultaneously promoting broadband opportunities. Furthermore, being fully conformant to the requirements imposed by convergence’s aspect, DVB can advance optimized solutions for different technical communications platforms. The European market has been widely developed in the area of (interactive) digital television (Chochliouros et al., 2006; European Commission, 2003b) and the EU is now leading further deployment through DVB procedures. The focus provided by a common set of technical standards and specifications has given a market advantage and spurred the appearance of innovation perspectives. Baseband: 1) In radio communications systems, the range of frequencies, starting at 0 Hz (DC) and extending up to an upper frequency as required to carry information in electronic form, such as a bitstream, before it is modulated onto a carrier in transmission or after it is demodulated from a carrier in reception. 2) In cable communications, such as those of a local area network (LAN), a method whereby signals are transmitted without prior frequency conversion.

In recent past years, PAPR (Peak-to-Average Power Ratio) of OFDM (Orthogonal FrequencyDivision Multiplexing) system has been intensively investigated. Published works mainly focus on how to reduce PAPR. Since high PAPR will lead to clipping of the signal when passed through a nonlinear amplifier. This paper proposes to extend the work related to "Gaussian Tone Reservation Clipping and Filtering for PAPR Mitigation" which has been previously published. So, in this paper, we deeply investigate the statistical correlation between PAPR reduction, and the distortion generated by three (3) adding si