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Author: Anthony Donald Demeri Publisher: ISBN: Category : Spread spectrum communications Languages : en Pages :
Book Description
This Paper surveys different techniques of acquiring Direct Sequence Spread Spectrum Systems. It classifies different systems, indicates the strongpoints and weakness of each, along with some applications. One method, The Single Dwell Serial PN Acquisition System is then focused on in detail. The detail includes analysis of standard version, derivation of the mean time to acquire, the variance, the probability of detection and the probability of a false alarm. In the last section of the paper the analytical results of the Single Dwell Serial PN Acquisition System shall be confirmed by computer simulation.
Author: Anthony Donald Demeri Publisher: ISBN: Category : Spread spectrum communications Languages : en Pages :
Book Description
This Paper surveys different techniques of acquiring Direct Sequence Spread Spectrum Systems. It classifies different systems, indicates the strongpoints and weakness of each, along with some applications. One method, The Single Dwell Serial PN Acquisition System is then focused on in detail. The detail includes analysis of standard version, derivation of the mean time to acquire, the variance, the probability of detection and the probability of a false alarm. In the last section of the paper the analytical results of the Single Dwell Serial PN Acquisition System shall be confirmed by computer simulation.
Author: Meera Srinivasan Publisher: ISBN: Category : Languages : en Pages : 214
Book Description
Parallel search schemes are presented for the acquisition of spreading sequences in chip-asynchronous direct-sequence spread-spectrum communication systems. In a parallel acquisition scheme, an estimate of the delay of a direct-sequence signal is made directly from a number of correlations of the received signal against different shifted versions of the spreading signal. Parallel schemes acquire the signal very quickly, but are more computationally intensive than serial schemes. In this thesis, we investigate several parallel strategies for the acquisition for general binary spreading sequences and develop suboptimal acquisition schemes that are easier to implement than the previously proposed optimal schemes. The techniques presented are attractive in that they approximate the optimal parallel schemes in terms of probability of successful acquisition, but are much easier to implement than the optimal schemes. The single-user phase-coherent situation is considered first. In this case, both carrier frequency and phase are known. We first discuss the optimal and maximum likelihood estimators for general binary spreading sequences and then present two new suboptimal schemes. One of these schemes is a small signal approximation of the optimal scheme, and it performs very well over a large range of signal-to-noise ratio. The other scheme is a hybrid of the optimal and maximum likelihood schemes, and is extremely simple. The hybrid scheme can be analyzed precisely in terms of its probability of unsuccessful acquisition. It is shown that this hybrid scheme has error probability decreasing exponentially with increasing SNR, and that this scheme is practically the simplest possible parallel scheme that has this property. Our result also proves an earlier conjecture that the optimal parallel estimator has error probability that decreases exponentially with increasing SNR. The same approach is used to devise simple acquisition schemes for the single-user noncoherent situation. A locally optimal estimator for low SNR is presented, along with two different noncoherent analogues of the coherent hybrid scheme. One of the noncoherent hybrid schemes is analyzed, and it is shown that this scheme also has exponentially decreasing error probability. This also proves that the error probability of the optimal noncoherent estimator decreases exponentially with increasing SNR. The problem of acquiring several direct-sequence signals in the absence of data modulation is also considered. The chip-synchronous situation is considered first and decorrelating methods are used to develop two near-far resistant strategies. One of these schemes estimates the signal delays in multiple stages, with each delay estimate depending on previous delay estimates, while the other scheme estimates the delays simultaneously and independently of each other. Schemes for the chip-asynchronous case are then developed by combining the coherent hybrid scheme for the single-user situation with the multistage decorrelating method. Monte Carlo simulation is used to obtain the error probabilities for the various schemes.
Author: Richard August Korkosz Publisher: ISBN: Category : Languages : en Pages : 262
Book Description
We consider serial search schemes for the acquisition of a pseudo-noise (PN) sequence in a direct-sequence spread-spectrum (DS/SS) communication system. Serial search acquisition schemes are by far the most commonly used class of acquisition schemes, due to the ease with which they are implemented. The main assumptions invoked in this thesis are that no data modulation is present during the acquisition process, and that the RF carrier has already been perfectly acquired, both in frequency and phase. Within this context, two basic models are considered, the chip synchronous model and the chip asynchronous model. In the chip synchronous model it is assumed that the chip boundaries of the received PN sequence are known to the receiver. Under this model, the unknown timing offset between the received PN sequence and the local PN sequence is an integer multiple of the chip duration. We extend the results of previous work for the chip synchronous model, in which the PN sequence arising under the out-of-phase hypothesis is modeled either as a random sequence or a zero sequence. In particular, we show that the stopping times for the sequential probability ratio tests (SPRTs) used in the testing stage are exponentially bounded random variables when actual periodic spreading sequences are employed. Moreover, we study the mean acquisition time of the overall serial search scheme, and show that the scheme based on the random sequence model offers considerable savings in mean acquisition time for moderate to large values of signal to noise ratio (SNR). A more general model is the chip asynchronous model, in which the chip boundaries of the received PN sequence are not known to the receiver. Thus, measured in units of the chip duration, the unknown timing offset between the received PN sequence and the local PN sequence is modeled as a real number. We propose and study a novel serial search acquisition scheme for this model, in which the integer part and the fractional part of the offset are estimated separately. This is accomplished by splitting the available observations into two sets. One of these sets of observations is used to estimate the integer offset via serial search, and we show that the other set may be used to estimate the fractional offset simultaneously. We consider the design and performance of sequential probability ratio tests (SPRTs) for use in the testing stage which are based on both the random sequence and zero sequence models. In particular, we have obtained an SPRT based on the random sequence model which yields near optimal performance regardless of the (unknown) fractional offset. We prove that the stopping times of the SPRTs are exponentially bounded for any value of the fractional offset, provided the spreading sequence is periodic. A modified verification stage is presented such that the verification error probability satisfies any given specification. Moreover, as in the chip synchronous case, we show that the acquisition scheme based on the random sequence model offers considerable savings in mean acquisition time for moderate to large SNR. (Abstract shortened by UMI.)
Author: Don Torrieri Publisher: Springer Nature ISBN: 3030753433 Category : Technology & Engineering Languages : en Pages : 715
Book Description
This textbook, now in its 5th edition, provides updated state-of-the-art coverage of spread-spectrum communication systems with new applications throughout the book. In this edition, the author extends sections with more comprehensive details about many topics. Some of the more complex sections have been rewritten to make them easier to understand. New subsections, sections, figures, and problems have been added throughout the book. New or expanded topics include frequency-hopping systems with multisymbol CPFSK detection, derivations of spread-spectrum systems with differential data modulations, chaotic systems, channel-state information, and MIMO. As with previous edition, the author presents mathematical analyses of spread-spectrum systems that provide insights into their operations and limitations and are of theoretical and practical interest to both researchers and system designers. He includes updated problems at the end of each chapter, which are intended to assist readers in consolidating their knowledge and to give practice in analytical techniques. Eight appendices provide the mathematical tools that are useful in understanding the main text.
Author: Don Torrieri Publisher: Springer Science & Business Media ISBN: 1441995951 Category : Technology & Engineering Languages : en Pages : 589
Book Description
This book provides a concise but lucid explanation of the fundamentals of spread-spectrum systems with an emphasis on theoretical principles. Throughout the book, learning is facilitated by many new or streamlined derivations of the classical theory. Problems at the end of each chapter are intended to assist readers in consolidating their knowledge and to provide practice in analytical techniques. The choice of specific topics is tempered by the author’s judgment of their practical significance and interest to both researchers and system designers. The evolution of spread spectrum communication systems and the prominence of new mathematical methods in their design provided the motivation to undertake this new edition of the book. This edition is intended to enable readers to understand the current state-of-the-art in this field. More than 20 percent of the material in this edition is new, including a chapter on systems with iterative channel estimation, and the remainder of the material has been thoroughly revised.
Author: Anthony Donald Demeri
Author: Anthony Donald Demeri
Author: Zhiyuan Yan
Author: Meera Srinivasan
Author: Eric Mathew Ollila
Author: Richard August Korkosz
Author: Marvin K. Simon
Author: Don Torrieri
Author: Elahe Sharifnejad
Author: Don Torrieri
Author: Michael R. Schuster