Adaptive arrays for weak interfering signals an experimental system an experimental adaptive antenna system was implemented to study the performance of adaptive arrays in the presence of weak interfering signals. Applications of array signal processing signal processing for. It is still widely used in adaptive digital signal processing and adaptive antenna arrays, primarily because of its simplicity, ease of implementation and good convergence properties. A simple adaptive algorithm for realtime processing in. The topic of multielement steered beam and adaptive antenna arrays has received attention within the gps. Implementation of an adaptive antenna array algorithm for. This is the final report of a study into adaptive processing techniques for rf antenna. The main research directions of array processing, in general, are adaptive. The input to the signalprocessing segment is now a complexbaseband data stream.
Both theory and experiments are covered in the lectures. Adaptive interference suppression in multiuser wireless ofdm. Antennas and propagation slide 2 chapter 4 5 antenna arrays advantage combine multiple antennas more flexibility in transmitting receiving signals spatial filtering beamforming excite elements coherently phaseamp shifts steer main lobes and nulls superresolution methods nonlinear techniques allow very high resolution for direction finding. Practical applications of multichannel signal processing are found in many digital signal processing and communication systems for wireless. If youre looking for a free download links of adaptive antenna arrays. This paper presents a discussion of the applications of adaptive array processing methods in mobile communication systems.
This type of antenna works by using a diversity effect at the wireless systems transceiver. It is shown that the interference rejection capabilities of the antenna array depend upon its geometry. Adaptive antenna arrays in mobile communications springerlink. Array processing techniques for direction of arrival.
It involves adaptive array processing algorithms to aid in target detection. The outputs from these sensors can be processed in an adaptive manner to respond to an unknown interference environment in an attempt to optimise the performance of the system in some defined manner. Speedsensitive weighting algorithm for digital beamforming. Adaptive antenna arrays are expected to play a key role in meeting the demands of the. Weight optimization for adaptive antenna arrays using lms and. This article proposes a speedsensitive adaptive algorithm for estimating the weights of smart antenna systems based on least mean squares lms or constant modulus cm algorithms.
Adaptive interference suppression in multiuser wireless. An array is defined as a set of sensors, for example antennas or acoustic transducers. Since array signal processing has widespread applications, the study is carried out. Spacetime adaptive processing stap combines a spatial adaptive array with a temporal adaptive array to improve clutter cancellation and null placement.
Ppt adaptive array antenna powerpoint presentation. The book begins with a presentation of the basic theory, equations, and data models of narrowband arrays. Spacetime adaptive processing stap is a signal processing technique most commonly used in radar systems. An antenna array is a group of identical antenna elements arranged usually in a regular fashion. However, adding time taps to allow spacetime adaptive processing stap yields a finite impulse response filter that may distort the spreadspectrum gps ranging signal. Neural methods for antenna array signal processing. The basic theory of stap for the traditional singleinput multipleoutput simo radar has been well developed 32, 33.
The interference mitigation capabilities of antenna arrays and. Adaptive antennas and phased arrays mit opencourseware. This digitization can be performed at either if or baseband frequencies. Providing gain and interference mitigation leading to improved signal quality and spectral efficiency. The 16 lectures in this course cover the topics of adaptive antennas and phased arrays. Chapter 3 introduces the fundamentals of adaptive antenna arrays, the basics of adaptive beamforming with arrays, and an introduction to the music algorithm for direction of arrival estimation. Compared to traditional onedimensional signal processing with a singlesensorsystem, array processing can provide more flexible beam control, larger signal gain, stronger inference suppression and better spatial discrimination. An adaptive antenna system uses spatially separated antennas called array antenna and processes received signals with a digital signal processor after analog to digital conversion and the name is derived from an adaptive filter or adaptive filter signal processing. Recent advances in design and signal processing for antenna arrays. So far there does not exist any theory of adaptive spatial signal processing assp for signals with uncertain parameters. Pdf designing antenna arrays using signal processing. A study of implementation of digital signal processing for. An adaptive array with the goal of suppressing interference is investigated. Implementation of an adaptive antenna array using the.
A new onlineoffline adaptive antenna array beamformer for. Marchok, and yihfang huang,fellow, ieee abstract this paper considers the problem of mitigating. Distinguish between desired signals, multipath and interfering signals. The input to the signal processing segment is now a complexbaseband data stream. Weight optimization for adaptive antenna arrays using lms.
Iterative adaptive computation procedures are then presented, from which it is obvious that a. As shown in fixedbeam methods, statistically optimum weight vectors for beamforming can be calculated by the wiener solution. In practice, manual sorting of aps in large volumes of experimental data is prohibitively. Adaptive algorithm based on antenna arrays for radio. Iterativeadaptive computation procedures are then presented, from which it is obvious that a. Chapter 3 introduces the fundamentals of adaptive antenna arrays, the basics of adaptive beamforming with arrays, and an introduction to the music algorithm for direction of. An adaptive antenna system uses spatially separated antennas called array antenna and processes received signals with a digital signal processor after analog to digital conversion and the name is derived from an adaptive filter or. Adaptive beamforming is a versatile approach to detect and estimate the signalofinterest soi at the output of sensor array using data adaptive spatial or spatiotemporal filtering and interference cancellation. The adaptive techniques for processing the data from airborne antenna arrays are called spacetime adaptive processing stap techniques. Configurations of adaptive arrays before discussing methods of adaptive filtering and signal processing to be used in the adaptive array, various spatial and electrical configurations of antenna arrays will be considered. Implementation of an adaptive antenna array using the tms320c541.
One of the main objectives of adaptive antenna array processing is reducing the computational complexity and convergence time in a joint state. Methods of signal processing for adaptive antenna arrays. Pdf designing antenna arrays using signal processing, image. Smart antenna systems employ more than one antenna element and exploit the spatial dimension in signal processing to improve some system operating parameters. Thus, these classical methods cannot be applied under conditions of apriory uncertainty about the spatial structure of the signal. Adaptive algorithm based on antenna arrays for radio communication systems 305 the simplest is the rayleigh and rice channel models. These models allow to imagine an appropriate picture of the signal propagation in a fading channel 11. Since an antenna patternor beam is formed by digital signal processing, it is often referred to as digitalbeam forming. Reflection from objects leads to the appearance of delayed versions. Fiddle with the amplitude and phase of a complex nature weights. This algortihm was developed by bernard widrow in the 1960s, and is the first widely used adaptive algorithm. Analog signal processor for adaptive antenna arrays.
All known methods and algorithms of classical theory of adaptive spatial signal processing assp are oriented on usage of precise data about spatial structure of the signal. Smart antennas also known as adaptive array antennas, digital antenna arrays, multiple antennas and, recently, mimo are antenna arrays with smart signal processing algorithms used to identify spatial signal signatures such as the direction of arrival doa of the signal, and use them to calculate beamforming vectors which are used to track and locate the antenna beam on the mobiletarget. Phase shifting can also be done in digital signal processing at baseband. To my colleagues in the sensor signal processing group, in particular rowan fry, joy li, cloudia newland, alvin goh and dr. Multichannel signal processing has been the focus of tremendous theoretical advances and applications over the last nearly four decades, and continues to attract much attention by the signal processing community in both research and applications.
Testing of adaptive beamsteering for interference rejection. The concept of an interference environment is introduced, which enables. They are arranged on a grid of points on a plane for a planar array. Another relatively recent development is multiple input, multiple output mimo antenna array systems where an adaptive array is used for both transmit and receive to increase channel capacity. Reflection from objects leads to the appearance of. Request pdf neural methods for antenna array signal processing. Adaptive beamforming an overview sciencedirect topics.
By combining adaptive digital signal processing with spatial processing techniques, adaptive array systems can achieve greater performance improvements than attainable using switched beam systems. Narrowband direction of arrival estimation for antenna arrays. A smart antenna commonly known as multiple antenna or adaptive array antenna can be defined as a digital wireless communications system with increased efficiency. Antenna arrays using adaptive beamforming techniques can reject interfering. This book provides an introduction to narrowband array signal processing, classical and subspacebased direction of arrival doa estimation with an extensive discussion on adaptive direction of arrival algorithms. Antenna arrays, which use spacetime adaptive processing stap, signi.
A brief history of the development of adaptive arrays is presented together with a summary of current methodologies used for implementation. Adaptive array processing for gps interference rejection. The design of a matrix completion signal recovery method. An adaptive array codguration for processing narrowband signals is shown in fig.
Array processing is a wide area of research in the field of signal processing that extends from the simplest form of 1 dimensional line arrays to 2 and 3 dimensional array geometries. Ppt adaptive array antenna powerpoint presentation free. Adaptive antennas can only suppress interference that was measured in the training data. Adaptive arrays for veak interfering signals a thesis by. Trends and applications signals and communication technology pdf, epub, docx and torrent then this site is not for you. This requires the array outputs to be digitized through the use of an ad converter. It is a sidelobe canceler with two auxiliary elements. Mar 21, 2017 these are the antenna arrays having smart signal processing algorithms that are used for identification of the spatial signal signature. In a linear array, the elements are arranged along a straight line. Wireless communication using adaptive smart antenna system a. The major applications of the smart antennas can be found notably in radio astronomy, radio telescopes, cellular systems, acoustic signal processing, scan radar and much more.
Array signal processing methods are proposed to solve the problem. These are antennas built using a multitude of smaller antennas and are called adaptive antenna arrays. Controllable sparse antenna array for adaptive beamforming. Signal processing robust multichannel signal processing. Radar signal processing benefits from stap in areas where interference is a problem i. The performance of steered beam adaptive arrays in the presence of weak interfering signals was studied in our earlier work 6,7. In general, adaptive beam forming is an effective technique because it makes use of a digital algorithm which dynamically optimizes the array pattern according to the changing electromagnetic environment 6.
Thus, after proper signal conditioning, the if signal is downconverted, downsampled, and filtered for baseband processing with the adaptive array algorithm in the tms320c541 evm evaluation board. The intended audience for this course is primarily practicing engineers and. The sensors used for a specific problem may vary widely, for example microphones. Parts one and two can be studied independently in either order. As a result, there are many efforts on the design of smart antenna arrays. However, knowledge of the asymptotic secondorder statistics of the signal and the interferenceplusnoise should be assumed. Array structure can be defined as a set of sensors that are spatially separated, e. Pdf trends in adaptive array processing researchgate. Unlike mechanical positioning of the antenna, changing the antenna pattern is an electrical process which does not involve any type of mechanical inertia, resulting in. When the generated output signal array is complex, a digital signal processing unit handles the signal radiated by the weight at the base station by a composite adaptive algorithm. The effects of various types of errors on the performance of an array system are illustrated. Background material on null steering antenna arrays. Unlike mechanical positioning of the antenna, changing the antenna pattern is an electrical process which does not involve any type of mechanical inertia, resulting in an almost instantaneous response.
Danny gibbins, who made the cssip an excellent place to. To be protected against surprise interference or insufficiently measured interference a compromise solution using a moderate low sidelobe antenna with simultaneous adaptive beamforming is often sought. Wireless communication using adaptive smart antenna system. Data acquisition from the digital downconversion ddc boards is. Through careful application of stap, it is possible to achieve orderofmagnitude. Calibrating adaptive antenna arrays for highintegrity gps. According to the next estimated location as well as the source. Methods of signal processing for adaptive antenna arrays targets professionals, students and phd students in the area of telecommunications and should be useful for everybody connected with the new information technologies. The proposed algorithm shows great potential for satellite communication 39, tactical military communication systems 40, and many other applications that use sparse antenna. An adaptive method for selecting the cluster size of cmimo transmis. User one user two multiple rf module conventional communication module advanced signal processing algorithms 21. The paper is intended as an introduction to, and to some extent a survey of, some of the methods used in.
937 186 214 465 85 1500 152 688 586 275 1371 429 641 1313 1280 503 1117 1175 1187 1513 92 823 524 1220 927 999 1444 131 642 1480 79 554 863 134 113 444 945