IEEE Journal of Selected Topics in Signal Processing

Periodic constant-amplitude zero-autocorrelation (CAZAC) waveforms u are analyzed in terms of the discrete periodic ambiguity function A _u. Elementary number-theoretic considerations illustrate that peaks in A_u are not stable under small perturbations in its domain. Further, it is proved that the analysis of vector-valued CAZAC waveforms depends on met... View full abstract»

In this paper, a method for the design of nonlinear phase, full-band, ultra-wideband (UWB) pulses that satisfy the Federal Communications Commission's effective isotropic radiation power spectrum mask, or more generally, any other given mask, is introduced. The method uses convex programming in each step of the iterative procedure that updates the phase distribution of the goal function. Thanks to... View full abstract»

In this paper, we address the design of an optimal transmit signal and its corresponding optimal detector for a radar or active sonar system. The focus is on the temporal aspects of the waveform with the spatial aspects to be described in a future paper. The assumptions involved in modeling the clutter/reverberation return are crucial to the development of the optimal detector and its consequent o... View full abstract»

In this paper, we use an information theoretic approach to design radar waveforms suitable for simultaneously estimating and tracking parameters of multiple extended targets. Our approach generalizes the information theoretic water-filling approach of Bell to allow optimization for multiple targets simultaneously. Our paper has three main contributions. First, we present a new information theoreti... View full abstract»

The dynamic adaptation of waveforms for transmission by active radar has been facilitated by the availability of waveform-agile sensors. In this paper, we propose a method to employ waveform agility to improve the detection of low radar-cross section (RCS) targets on the ocean surface that present low signal-to-clutter ratios due to high sea states and low grazing angles. Employing the expectation... View full abstract»

This paper investigates the advantages of adaptive waveform amplitude design for estimating parameters of an unknown channel/medium under average energy constraints. We present a statistical framework for sequential design (e.g., design of waveforms in adaptive sensing) of experiments that improves parameter estimation (e.g., unknown channel parameters) performance in terms of reduction in mean-sq... View full abstract»

For dynamic spectrum allocation (DSA), distributed game has emerged as an attractive approach that enhances radio spectrum utilization efficiency at scalable complexity in network size. Cognitive radios act as game players to judiciously decide their transmission power spectrum density (TPSD) based on channel state information (CSI), which is generally estimated independently from the DSA games an... View full abstract»

The majority of active sonar systems detect and classify a target based on the amplitude of the received echo strength or the induced Doppler shift. However, additional classification information is available from the phase shift introduced by some targets as a result of the acoustic boundary conditions. For example, reverberation returns from the sea surface and from the swimbladders of various f... View full abstract»

Cognitive radar is a recently proposed approach in which a radar system may adaptively and intelligently interrogate a propagation channel using all available knowledge including previous measurements, task priorities, and external databases. A distinguishing characteristic of cognitive radar is that it operates in a closed loop, which enables constant optimization in response to its changing unde... View full abstract»

By exploiting the reflective and refractive nature of high-frequency (HF) radiowave propagation through the ionosphere or the conducting sea surface, over-the-horizon radar (OTHR) systems perform wide-area surveillance at long range well beyond the limit of the horizon of conventional line-of-sight (LOS) radars. Improved characterizations of the targets can be achieved by using multiple OTHRs oper... View full abstract»

In this paper, a system for automatically recognizing radar waveforms is introduced. This type of techniques are needed in various spectrum management, surveillance and cognitive radio or radar applications. The intercepted radar signal is classified to eight classes based on the pulse compression waveform: linear frequency modulation (LFM), discrete frequency codes (Costas codes), binary phase, a... View full abstract»

The recently proposed Multistatic Adaptive Pulse Compression (MAPC) algorithm has been shown to successfully suppress both range sidelobes and interference from multiple radars operating in the same spectrum, thus enabling shared-spectrum multistatic radar. In this paper, we present a method to increase the overall information capacity of the MAPC algorithm by performing joint adaptive pulse compr... View full abstract»

We consider the problem of minimax robust waveform design for multiple-input multiple-output (MIMO) radar based on mutual information (MI) and minimum mean-square error (MMSE) estimation for target identification and classification. Recognizing that a single, precise characterization of target power spectral density (PSD) is rare in practice, we assume the PSD lies in an uncertainty class of spect... View full abstract»

Emerging advances in reconfigurable radio-frequency (RF) front-ends and antenna arrays are enabling new physical modes for accessing the radio spectrum that extend and complement the notion of waveform diversity in wireless communication systems. However, theory and methods for exploiting the potential of reconfigurable RF front-ends are not fully developed. In this paper, we study the impact of r... View full abstract»

Multiple-Input Multiple-Output (MIMO) radar has been shown to provide enhanced performance in theory and in practice. MIMO radars are equipped with the ability to choose freely their transmitted waveforms at each aperture. In conventional radar systems Woodward's ambiguity function is used to characterize waveform resolution performance. In this paper we extend the idea of waveform ambiguity funct... View full abstract»

In this work, we consider the problem of designing space-time-frequency linear dispersion (LD) codes in wideband multiple-input multiple-output (MIMO) antenna systems employing orthogonal-frequency-division-multiplexing (OFDM). Three criteria are presented and discussed in detail, which involve: 1) minimizing the average uncoded block error rate, 2) maximizing the ergodic mutual information, and 3... View full abstract»

In this paper, we present an adaptive algorithm for interference avoidance, which can be applied in a distributed manner by active users in a CDMA wireless system to obtain optimal codewords and powers for specified target signal-to-interference plus noise ratio (SINR). The algorithm is derived using a game-theoretic approach in which separable cost functions with respect to codeword and power are... View full abstract»

Fourth-generation (4G) communication systems will likely support multiple capabilities while providing universal, high-speed access. One potential enabler for these capabilities is software-defined radio (SDR). When controlled by cognitive radio (CR) principles, the required waveform diversity is achieved through a synergistic union called CR-based SDR. This paper introduces a general framework fo... View full abstract»