Minimum Cross-correlation Research Articles

Design of Differential Space-Time Trellis Codes

This paper presents the performance analysis and code design for differential space-time trellis code (DSTTC) when no channel state information (CSI) is available at neither the transmitter nor receiver. Upper bounds on the pairwise error probability of DSTTC over fast fading and quasi-static fading channels are derived and new design criteria are proposed based on these bounds. It is shown that the performance of DSTTC is determined by the minimum weighted square product distance (WSPD) over independent fast fading channels, and by the minimum cross correlation distance (CCD) over quasi-static fading channels. New DSTTCs are found by a systematic code search. Simulation results show that under the same spectral efficiency the proposed coding scheme has a superior performance and lower complexity compared to other existing differential space time coding schemes

Bias-current dependence of anticorrelation polarization dynamics in vertical-cavity surface-emitting lasers with long external cavity

The bias-current dependence of anticorrelation polarization dynamics in vertical-cavity surface-emitting lasers with long external cavity has been studied experimentally. With fixed optical feedback strength, the minimum cross-correlation coefficient exhibits exponential decay with the bias current. Strong anticorrelation is obtained at frequencies lower than 1GHz for all bias currents. Near the relaxation oscillation frequency good correlation is found at higher bias current but poor correlation is found at lower bias currents.

Differential Label-free Quantitative Proteomic Analysis of Shewanella oneidensis Cultured under Aerobic and Suboxic Conditions by Accurate Mass and Time Tag Approach

We describe the application of LC-MS without the use of stable isotope labeling for differential quantitative proteomic analysis of whole cell lysates of Shewanella oneidensis MR-1 cultured under aerobic and suboxic conditions. LC-MS/MS was used to initially identify peptide sequences, and LC-FTICR was used to confirm these identifications as well as measure relative peptide abundances. 2343 peptides covering 668 proteins were identified with high confidence and quantified. Among these proteins, a subset of 56 changed significantly using statistical approaches such as statistical analysis of microarrays, whereas another subset of 56 that were annotated as performing housekeeping functions remained essentially unchanged in relative abundance. Numerous proteins involved in anaerobic energy metabolism exhibited up to a 10-fold increase in relative abundance when S. oneidensis was transitioned from aerobic to suboxic conditions.

Large Set of CI Spreading Codes for High-Capacity MC-CDMA

In this letter, a large set of spreading codes that doubles capacity in multicarrier code-division multiple-access (MC-CDMA) systems without any cost in bandwidth and with negligible cost in performance is introduced. This large set is comprised of: 1) complex spreading codes instead of conventional real-valued spreading codes and 2) two sets, each made up of orthogonal complex spreading codes, with minimum cross correlation between sets. Simulations performed over Rayleigh fading channels demonstrate 100% gains in terms of MC-CDMA capacity with negligible loss in performance.

Polychromatic pattern recognition using the non-zero-order joint transform correlator with cross-correlation peak optimization

A multi-channel polychromatic non-zero-order joint transform correlator (NOJTC) with minimum average cross-correlation energy is introduced. The system is implemented using a general JTC scheme with additional power-spectrum subtraction strategy and the design of an ideal reference function with a Lagrange multipliers technique. As the zero-order part is removed, the desired correlation peaks can be quite distinctive and sharp. The correlator also shows the advantage of better detection ability over monochromatic systems.

Ocean Currents from Successive Satellite Images: The Reciprocal Filtering Technique

Abstract Cross-correlation analyses of successive satellite images of the ocean surface can provide estimates of surface currents by tracking features of temperature or ocean color. While the technique successfully identifies many true vectors, it also can produce a large number of “rogue” vectors through the erroneous matching of similar-shaped surface features. Several techniques have been suggested to detect these rogue vectors and eliminate them from the analyses. These include nearest-neighbor matching, velocity filtering, and limits on the minimum cross-correlation coefficient that is acceptable. A pair of concurrent Advanced Very High Resolution Radiometer (AVHRR) images of the Leeuwin Current off the west coast of Australia is used to show that a new technique, based on reciprocity, outperforms other techniques in many situations. The reciprocal technique allows a low correlation coefficient threshold to be set thereby increasing the number of good vectors obtained while also removing those vector...

Statistical analysis of fiber-optic CDMA communication systems. II. Incorporating multiple optical amplifiers

For pt. I see ibid., vol.20, no.8, p.1304-16 (2002). In this paper, we study and elaborate on the architectural consideration of using multiple optical amplifiers in an all-optical fiber-optic code-division multiple-access (FO-CDMA) network. Our study and considerations are based on obtaining the statistical characteristic functions for photon-counts of a string of output pulses that constitutes the address code in a FO-CDMA network. Optical orthogonal codes (OOCs) with minimum auto-and cross correlation are employed as the address or signature sequence codes. Our analysis is based on chip-synchronous interference only, which provides an upper bound on the system performance. Shot noise, thermal noise, and extinction ratio are considered in this analysis. Bit error rate (BER) results are obtained using two methods, namely, saddle-point and Gaussian approximations. From our BER analysis, we develop some insight into the optimum distribution of optical amplifiers and their corresponding gain setting parameter. Moreover, the effects of source power, code weight, number of users, bit rate, and amplified spontaneous emission noise are investigated.

Optimal synthesis of a real‐valued template for synthetic aperture radar pattern recognition

AbstractFor distortion‐invariant radar image recognition with a hybrid electrical and optical signal processing technique, the design of the nonzero‐order joint transform correlator to achieve minimum average cross‐correlation energy has been studied. In this work, as we require the desired cross‐correlation peak to be real valued for all real‐valued training images, the optimized reference function will be real valued as well, although the reference function is optimized in the frequency domain with the method of Lagrange multipliers. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 91–95, 2002.

Non-zero order joint transform correlator with an optimized real-valued reference function

In order to achieve distortion invariant image recognition, the design of the non-zero order joint transform correlator with minimum average cross-correlation energy has been studied. In this work, we prove that the optimal reference function is real-valued if the desired cross-correlation peak is also set to be real for every image in a training set. The recognition effectiveness is demonstrated by an example, where the genuine seal-imprint can be detected as compared with the invalid, although very similar one.

A New Method for Static Load Modeling Based on the Normal Operating Data and the Correlation Analysis Theory

Abstract This paper elucidates the closed loop structure of 'Load-System' and the characteristics ofrandom signals hi power system, and presents the minimum cross-correlation function method, an on-line identification method for static load modeling. This method is essentially different from the current least squares fitting method in the main idea, and is suitable for the static load modeling under the normal operating conditions with low noise-to-signal ratio. The simulation and field data modeling of this method are carried out and the effects, of this method are also compared with the least squares fitting method.

Binary Sequences with Good Autocorrelation and Cross Correlation Properties

A numerical optimization technique is developed for designing pairs of binary sequences suitable for radar and communication systems. Application of this method yields sequences with near uniform autocorrelation sidelobes and cross-correlation values both of approximately 1.3?N, where N is the sequenuce length. A lower bound of the minimum cross-correlation peak value has been estimated to be ?N when a uniform probability distribution is assumed.