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Simulation of spread spectrum radar using rake at the receiver end
Abstract
Abstract—Intelligent Transport Systems (ITS) are becoming,a reality, driven by navigation safety requirements and by the investments of car manufacturers and Public Transport Authorities all around the world. ITS make,it possible to imagine a future in which cars will be able to foresee and avoid collisions, navigate the quickest route to their destination, making use of up-to-the minute traffic reports, identify the nearest available parking slot and minimize their carbon emissions. Also demand for voice, data and multimedia services, while moving in car increase the importance of broadband wireless systems [1]. Efforts are being imparted towards the convergence of mobile communications, computing and remote sensing. Spread spectrum based digital RADAR can be utilized as a remote sensing device in ITS. This motivates us in development of DSSS (Direct Sequence Spread Spectrum) based digital RADAR at our institute. It is quite capable of detecting target in the open field. The experiment was carried out for different standard target like flat plates, spheres etc. The operational digital RADAR is capable of Corresponding author: D. Kandar (kdebdatta@rediffmail.com). 36,Kandar, Sarkar, and Bera rejecting interference, but fails in a strong multipath scenario. Again RAKE processing is established in communication. Our approach is
... Diversity in Multiple-Input-Multiple-Output radar systems can be achieved through multiplexing in time [1], frequency [2] or the application of orthogonal [3] or coded waveforms [4]. The main drawback of using timedivision multiplexing is given by the fact that a sequential switching of the transmitting antennas is time-consuming for a high number of transmitters. ...
... . (4) In this equation N K denotes the number of time-domain sampling points. With a known noise signature the SNR of the signal mixture at the receiver can be determined via equation (4) as SNR=18dB. ...
This paper presents a novel and patented receiver design for spread spectrum MIMO-radar systems that enables scalability to high numbers of transmitters and receivers. The proposed technique, known from MIMO-communications, is based on the concept of successive interference cancellation where the signal component for each transmitter, characterized by amplitude and time-of-arrival, is retrieved in time-domain from a signal mixture at the receiver. Hence, it is possible to obtain a sparse representation of the original radar signal. Contrary to conventional matched filters, absolute amplitude information become available for radar signal processing. This approach benefits from recent advances in orthogonal waveform design, supports arbitrary transmitter-receiver constellations (collocated or distributed) and zero sidelobes with optimal range resolution for maximum image quality.
... The output of BPSK modulation signal is proceeding to RF transmitter system. RF transmitter consists of RF mixer, power amplifier for up conversion of signal and transmits through the antenna [4]. ...
... The same technology is copied in Radar and thus named as Spread spectrum Radar [1] [3]. One of the main advantages of Spread Spectrum is to have a secure communication. ...
Spread Spectrum Radar has gained lot of importance now a days. Like communication where the data is made to spread over the entire bandwidth, in the same way in radar also the input waveform is spreaded over a large bandwidth. This has several advantages also like the waveform cannot be detected by any unwanted user or intruder as some codes are being used to to do the trick. As per the topic of the paper, multiples waveforms are being designed and implemented as input of the radar and the performance of the same has been tested in simulation.. I. Introduction In telecommunication and radio communication, spread-spectrum technique is a method by which a signal generated with a particular bandwidth is deliberately spread in the frequency domain, resulting in a signal with a wider bandwidth. These techniques are used for a variety of reasons, including the establishment of secure communications, increasing resistance to natural interference, noise and jamming, to prevent detection, and to limit power flux density (e.g. in satellite downlinks). The same technology is copied in Radar and thus named as Spread spectrum Radar [1, 3]. One of the main advantages of Spread Spectrum is to have a secure communication. In case of Radar also we need the detection and tracking of the target [2] to be secure i.e. it should not be hacked or jammed by other frequencies that may be intentional or unintentional. As discussed above, Radar using this spreading technique has quite large bandwidth which gives it another advantage of Range resolution of the target. More is the bandwidth less is the range resolution which can be proved as an extraordinary advantage in terms of vehicular application. The performance of Radar depends upon the proper choice of waveform [2] and hence the topic is justified as Waveform Diversity in Spread Spectrum Radar. Waveform diversity involves manipulating the degrees of freedom of waveforms to enhance target detection, bit error rate and the efficacy of countermeasures. Degrees of freedom that can be varied include pulse repetition frequency, carrier frequency, coding, polarization, spatial characteristics, bandwidth, amplitude, pulse width, jitter, and frequency shaping. Traditionally, communication, sensing and countermeasures has been treated as separate technologies and the lack of interchange between this discipline is a major problem. The paucity of available spectrum and the objective of full spectrum dominance make it imperative to carry out this interchange. Waveform diversity is an enabling technology for achieving this goal. The choice of waveforms depends upon the range sidelobe reduction and Doppler extraction characteristics. Modern radars are increasingly being equipped with arbitrary waveform generators that enable simultaneous transmission of different waveforms from different polarimetric antennas, even on a pulse-to-pulse basis. The available design space encompasses spatial location,
... Although this study chooses only simple models of ships as targets of recognition, one can add different types of random components to RCS for modeling RCS of complex targets. This study can be applied to many other applications in radar target recognition78910111213141516171819. ...
In this paper, the ICA (independent component analysis) technique is applied to PCA (principal component analysis) based radar target recognition. The goal is to identify the similarity between the unknown and known targets. The RCS (radar cross section) signals are collected and then processed to serve as the features for target recognition. Initially, the RCS data from targets are collected by angular-diversity technique, i.e., are observed in directions of different elevation and azimuth angles. These RCS data are first processed by the PCA technique to reduce noise, and then further processed by the ICA technique for reliable discrimination. Finally, the identification of targets will be performed by comparing features in the ICA space. The noise effects are also taken into consideration in this study. Simulation results show that the recognition scheme with ICA processing has better ability to discriminate features and to tolerate noises than those without ICA processing. The ICA technique is inherently an approach of high-order statistics and can extract much important information about radar target recognition. This property will make the proposed recognition scheme accurate and reliable. This study will be helpful to many applications of radar target recognition.
In this paper, radar target recognition is given by KSDA (kernel scatter-difference discriminant analysis) pattern recognition on RCS (radar cross section). The kernel method converts the traditional FLDA (Fisher linear discriminant analysis) to a nonlinear high-dimensional space and such a kernel technique is called KFDA (kernel Fisher discriminant analysis). The basic concept of KFDA is to map training samples in the original space to a high-dimensional feature space via a nonlinear mapping function. Pattern recognition is then implemented in the feature space through extracted nonlinear discriminant features. However, as the kernel within-class scatter matrix is singular, the optimal discriminant features can not be achieved directly. To improve this drawback of KFDA, this study utilizes the scatter difference as the discriminant function, i.e., KSDA, to implement radar target recognition. The KSDA can modify the Fisher discrimination function and then serves as an efficient tool of radar target recognition. As a result, the computational complexity is reduced and then the computational speed is increased. Of great importance, the proposed target recognition scheme (based on KSDA) can still work well even though the kernel within-class scatter matrix is singular. Our KDSA based target recognition scheme is accurate, efficient and has good ability to tolerate random noises.
Radar as the name says it is Radio Detection And Ranging. Earlier it was used only for defence purpose but now a days its become popular in commercial applications too. In defence, it was used for detection for enemy. In commercial application also its use is detection only. One of the emerging commercial application is vehicular application. RADAR is used in vehicular application for the purpose of collision avoidance, increase security and saving of mankind. The performance of RADAR highly depends on the use of input waveform Its the input waveform which decides the efficiency and effectiveness of RADAR. In this paper the author has tried to show the performance of different waveforms.
In this paper, a frequency-diversity radar cross section (RCS) based target recognition scheme with independent component analysis (ICA) projection is proposed. The goal is to identify the similarity between the unknown and known targets through collected frequency-diversity RCS. Note that the unknown target means the test target and that known targets mean previously seen targets in a database. To enhance the recognition ability, frequency-diversity RCS data are projected into the ICA space, and the recognition is performed using features of ICA space. The ability to tolerate noise effects for proposed recognition scheme is also investigated. The frequency-diversity technique can greatly reduce the efforts of collecting RCS because only a small number of measuring locations are required to achieve accurate recognition. With the use of ICA projection, the recognition scheme will have good abilities in both discriminating targets and tolerating noise effects.
Provides an abstract of the workshop presentation and a brief professional biography of the presenter. The complete presentation was not made available for publication as part of the conference proceedings.
Information theory research has shown that the rich-scattering
wireless channel is capable of enormous theoretical capacities if the
multipath is properly exploited. In this paper, we describe a wireless
communication architecture known as vertical BLAST (Bell Laboratories
Layered Space-Time) or V-BLAST, which has been implemented in real-time
in the laboratory. Using our laboratory prototype, we have demonstrated
spectral efficiencies of 20-40 bps/Hz in an indoor propagation
environment at realistic SNRs and error rates. To the best of our
knowledge, wireless spectral efficiencies of this magnitude are
unprecedented and are furthermore unattainable using traditional
techniques
This paper addresses digital communication in a Rayleigh fading environment when the channel characteristic is unknown at the transmitter but is known (tracked) at the receiver. Inventing a codec architecture that can realize a significant portion of the great capacity promised by information theory is essential to a standout long-term position in highly competitive arenas like fixed and indoor wireless. Use (nT, nR) to express the number of antenna elements at the transmitter and receiver. An (n, n) analysis shows that despite the n received waves interfering randomly, capacity grows linearly with n and is enormous. With n = 8 at 1% outage and 21-dB average SNR at each receiving element, 42 b/s/Hz is achieved. The capacity is more than 40 times that of a (1, 1) system at the same total radiated transmitter power and bandwidth. Moreover, in some applications, n could be much larger than 8. In striving for significant fractions of such huge capacities, the question arises: Can one construct an (n, n) system whose capacity scales linearly with n, using as building blocks n separately coded one-dimensional (1-D) subsystems of equal capacity? With the aim of leveraging the already highly developed 1-D codec technology, this paper reports just such an invention. In this new architecture, signals are layered in space and time as suggested by a tight capacity bound.
Abstract—With the technological growth of broadband,wireless technology like CDMA, OFDM and MIMO, a lots of development efforts towards wireless communication,system and imaging radar system are well justified. It has been recently shown that multiple- input multiple-output (MIMO) antenna systems have the potential to dramatically improve the performance of communication systems over single antenna systems. Efforts are also being imparted towards a Convergence Technology. The convergence between a communication and radar technology which will result in ITS (Intelligent Transport System) and other applications. This motivates development of the present article. This is an effort in the direction to utilize or converge the communication,technologies towards radar and to achieve the interference and clutter free quality remote images of targets.
An abstract is not available.
From the Publisher:This state-of-the-art text is written for first year graduate level courses and provides an introduction to the basic principles of communication systems. The text also provides a comprehensive introduction to the new and rapidly growing area of spread spectrum communications. In addition,the text is a useful reference source for practicing engineers from which they can gain ready access to many of the analytical results available for the analysis of communications systems. Problems are provided at the end of each chapter and answers to a number of the problems are included at the end of the book.
From the Publisher:A major expansion and revision of the 1985 edition. Describes in detail the fundamental principles and latest techniques that resist unintentional interference, prevent jamming and detection by an opponent, and thwart unauthorized extraction of information from a transmitted waveform. Would-be intruders are becoming increasingly sophisticated; to hold their own, design engineers must know the physical and mathematical principles involved and how to perform a thorough systems-level security analysis. Annotation copyright Book News, Inc. Portland, Or.
Code Division Multiple Access (CDMA) has become one of the main candidates for the next generation of mobile land and satellite communication systems. CDMA is based on spread spectrum techniques, which have been used in military applications for over half a century. Only recently, however, has it been recognised that spread spectrum techniques, combined with some additional steps, can provide higher capacity and better flexibility for the mobile cellular radio communications.
Code Division Multiple Access Communications comprises a set of contributions from the most distinguished world scientists in the field. These papers review the basic theory and some of the most important problems related to spread spectrum and CDMA. The topics covered centre on the information theory aspects of CDMA; interference suppression and performance analysis.
The material presented in this book summarises the main problems in modern CDMA theory and practice and gives a solid starting point for studying this complex and still challenging field. As such Code Division Multiple Access Communications is essential reading for all researchers and designers working in mobile communication systems and provides an excellent text for a course on the subject.
This paper addresses digital communication in a Rayleigh fading environment when the channel characteristic is unknown at the transmitter but is known (tracked) at the receiver. Inventing a codec architecture that can realize a significant portion of the great capacity promised by information theory is essential to a standout long-term position in highly competitive arenas like fixed and indoor wireless. Use (nT, nR) to express the number of antenna elements at the transmitter and receiver. An (n, n) analysis shows that despite the n received waves interfering randomly, capacity grows linearly with n and is enormous. With n = 8 at 1% outage and 21-dB average SNR at each receiving element, 42 b/s/Hz is achieved. The capacity is more than 40 times that of a (1, 1) system at the same total radiated transmitter power and bandwidth. Moreover, in some applications, n could be much larger than 8. In striving for significant fractions of such huge capacities, the question arises: Can one construct an (n, n) system whose capacity scales linearly with n, using as building blocks n separately coded one-dimensional (1-D) subsystems of equal capacity? With the aim of leveraging the already highly developed 1-D codec technology, this paper reports just such an invention. In this new architecture, signals are layered in space and time as suggested by a tight capacity bound.
With the technological growth of broadband wireless technology like CDMA and UWB , a lots of development efforts towards wireless communication system and Imaging radar system are well justified. Efforts are also being imparted towards a Convergence Technology.. the convergence between a communication and radar technology which will result in ITS (Intelligent Transport System) and other applications. This encourages present authors for this development. They are trying to utilize or converge the communication technologies towards radar and to achieve the Interference free and clutter free quality remote images of targets using DS-UWB wireless technology.
IntroductionPrinciple of Space-time SpreadingSystem ModelDetection of Space-time Spreading W-CDMA SignalsBER PerformanceAdaptive Space-time SpreadingChapter Summary and Conclusion
Broadband wireless systems play an increasingly important role in intelligent transportation systems (ITS). These systems provide high-speed wireless links between many ITS subsystems. As the demand for voice, data and video services on these networks grows, the need to improve coverage range, capacity, data rate and quality of service becomes very important. Smart antenna can greatly enhance the performance of wireless systems. However, there are many different flavors of smart antennas. It is important for ITS designers to understand the different types of smart antennas and choose the appropriate one for the intended operating environment. In this paper we first take a look at how wireless technologies might be used in ITS. We then introduce the different types of smart antennas. Finally we present performance results of practical state-of- the-art smart antenna systems
This paper describes an idealized spread-spectrum communication system. The processing gain concept is developed as a measure of a well-designed system's robust performance against independent wide-sense stationary interference. Multipath and repeater jammer rejection, partial correlation problems, and security requirements are related to spread-spectrum code properties.
The proposed method of moments is an approximation scheme consisting of a simple iteration algorithm which converges to the network's point-to-point blocking probabilities. The following are the key steps. First, the total traffic stream (obtained by combining the individually offered overflow and Poissonian streams under the assumption of independence) offered to any trunk (channel) group in the network is approximated by a renewal process of a specific type.The total overflow from the trunk group is obtained using the generalized Erlang loss function. After suitably apportioning the lost load among the individually offered streams, each stream's blocking on the trunk group is computed. Finally, a point-to-point probability linear graph is constructed from the alternate routing scheme and the point-point-to-point blocking is computed assuming independent blocking in the links. Numerical results are presented for a simple three-node network with Poissonian point-to-point demand and comparison is made between the three-moment methods and simulation. The results indicate that the three-moment method is sufficiently accurate for engineering purposes.
The characteristics of spread-spectrum systems that account for their growing use are examined. They offer low probability of intercept, signal hiding, and jammer rejection. Spread spectrum also provides a measure of immunity to multipath interference and multiple access capability, making it ideal for radar, telephone, local area networks, and many other applications. The two primary techniques commonly used frequency hopping and direct sequence, are described along with their advantages and disadvantages.< >
A small solid-state radar combined with a microprocessor makes possible collision-mitigation braking and automatic headway control in cars of the future. The collision-mitigation function involves the application of antiskid brakes under conditions where, based on radar and other sensor inputs, it is certain that a severe collision will take place. The decision-making algorithm is optimized to prevent the unjustified application of the brakes from false alarms. The automatic headway-control function keeps the car at a safe distance with respect to other vehicles on the road ahead. In the absence of other cars the system operates as a conventional cruise control.
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