Papers by Sabrina Queiroz
The digital communication industry is an enormous and rapidly growing industry, roughly com parab... more The digital communication industry is an enormous and rapidly growing industry, roughly com parable in size to the computer industry. The objective of this text is to study those aspects of digital communication systems that are unique to those systems. That is, rather than focus ing on hardware and software for these systems, which is much like hardware and software for many other kinds of systems, we focus on the fundamental system aspects of modern digital communication.
1 As explained more fully later, there is no fundamental difference between a code and a signal s... more 1 As explained more fully later, there is no fundamental difference between a code and a signal set. 2 The principles here apply essentially without change for a countably infinite set of hypotheses; for an uncount ably infinite set of hypotheses, the process of choosing an hypothesis from an observation is called estimation. Typically, the probability of choosing correctly in this case is 0 and the emphasis is on making an estimate that is close in some sense to the correct hypothesis.
Chapter 6 discussed modulation and demodulation, but replaced any detailed discussion of the nois... more Chapter 6 discussed modulation and demodulation, but replaced any detailed discussion of the noise by the assumption that a minimal separation is required between each pair of signal points. This chapter develops the underlying principles needed to understand noise, and the next chapter shows how to use these principles in detecting signals in the presence of noise.
1 As explained later, the actual transmitted waveforms are real. However, they are usually bandpa... more 1 As explained later, the actual transmitted waveforms are real. However, they are usually bandpass real waveforms that are conveniently represented as complex baseband waveforms.
In the previous chapter, we showed that any L 2 function u(t) can be expanded in various orthog o... more In the previous chapter, we showed that any L 2 function u(t) can be expanded in various orthog onal expansions, using such sets of orthogonal functions as the T -spaced truncated sinusoids or the sinc-weighted sinusoids. Thus u(t) may be specified (up to L 2 equivalence) by a countably infinite sequence such as {u k,m ; −∞ < k, m < ∞} of coefficients in such an expansion.
This chapter has a dual objective. The first is to understand analog data compression, i.e., the ... more This chapter has a dual objective. The first is to understand analog data compression, i.e., the compression of sources such as voice for which the output is an arbitrarily varying real or complex valued function of time; we denote such functions as waveforms. The second is to begin studying the waveforms that are typically transmitted at the input and received at the output of communication channels. The same set of mathematical tools are needed for the understanding and representation of both source and channel waveforms; the development of these results is the central topic in this chapter.
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Papers by Sabrina Queiroz