An eigenanalysis interference canceler

Eigenanalysis methods are applied to interference cancellation problems. While with common array processing methods the cancellation is effected by global optimization procedures that include the interferences and the background noise, the proposed technique focuses on the interferences only, resulting in superior cancellation performance. Furthermore, the method achieves full effectiveness even for short observation times, when the number of samples used for processing is of the the order of the number of interferences. Adaptive implementation is obtained with a simple, fast converging algorithm     

MIMO Radar with Widely Separated Antennas

MIMO (multiple-input multiple-output) radar refers to an architecture that employs multiple, spatially distributed transmitters and receivers. While, in a general sense, MIMO radar can be viewed as a type of multistatic radar, the separate nomenclature suggests unique features that set MIMO radar apart from the multistatic radar literature and that have a close relation to MIMO communications. This article reviews some recent work on MIMO radar with widely separated antennas. Widely separated transmit/receive antennas capture the spatial diversity of the target's radar cross section (RCS). Unique features of MIMO radar are explained and illustrated by examples. It is shown that with noncoherent processing, a target's RCS spatial variations can be exploited to obtain a diversity gain for target detection and for estimation of various parameters, such as angle of arrival and Doppler. For target location, it is shown that coherent processing can provide a resolution far exceeding that supported by the radar's waveform.     

Performance of parallel concatenated space-time codes

We study a channel turbo-coding scheme that consists of parallel concatenated systematic space-time codes and is referred to as turbo space-time coded modulation (turbo-STCM). The scheme features full rate and simulation results shows that it also provides full diversity. Performance with recursive versus nonrecursive space-time constituent codes is investigated. The advantage of recursive component codes is demonstrated by simulations for a four state 4-PSK turbo-STCM scheme operating over a Rayleigh block-fading channel. It is also shown that the turbo-STCM performs better than conventional space-time codes of similar complexity     

A moving horizon approach to Networked Control system design

This paper presents a control system design strategy for multivariable plants where the controller, sensors and actuators are connected via a digital, data-rate limited, communications channel. In order to minimize bandwidth utilization, a communication constraint is imposed which restricts all transmitted data to belong to a finite set and only permits one plant to be addressed at a time. We emphasize implementation issues and employ moving horizon techniques to deal with both control and measurement quantization issues. We illustrate the methodology by simulations and a laboratory-based pilot-scale study.     

EXIT charts for turbo trellis-coded modulation

In this letter, we extend the previously proposed extrinsic information transfer charts (EXIT) method to the analysis of the convergence of turbo codes to turbo trellis-coded modulation (TTCM) schemes. The effectiveness of the proposed method is demonstrated through examples. The proposed method provides a convenient way to systematically compare between schemes and thus can be used as a tool in the design of TTCM.     

Multiple-symbol differential detection for MPSK space-time block codes: decision metric and performance analysis

Approximately 3 dB signal-to-noise ratio (SNR) loss is always paid with conventional differential space-time block codes (STBCs), compared with coherent STBCs. In this paper, a multiple-symbol differential detection (MSDD) technique is proposed for M-ary phase-shift keying (PSK) STBCs. The new scheme can greatly narrow the 3-dB performance gap by extending the observation interval for differential decoding. The technique uses maximum-likelihood sequence detection instead of traditional symbol-by-symbol detection, and is carried out on the slow, flat Rayleigh fading channel. A generalized decision metric is derived for an observation interval of arbitrary length. It is shown that for a moderate number of symbols, MSDD provides approximately 1.5 dB performance improvement over conventional differential detection. In addition, a closed-form pairwise error probability and approximate bit-error probability (BEP) are derived for multiple-symbol differential binary PSK STBC. Results show that the theoretical BEP matches simulation results well. The BEP is shown to converge asymptotically with the number of symbols in the observation interval to that of the differential scheme with coherent detection.     

Performance of cellular CDMA with cell site antenna arrays,Rayleigh fading, and power control error

The performance of code-division multiple-access (CDMA) systems is affected by multiple factors such as large-scale fading, small-scale fading, and cochannel interference (CCI). Most of the published research on the performance analysis of CDMA systems usually accounts for subsets of these factors. In this work, it is attempted to provide a comprehensive analysis which joins several of the most important factors affecting the performance of CDMA systems. In particular, new analytical expressions are developed for the outage and bit-error probability of CDMA systems. These expressions account for adverse effects such as path loss, large-scale fading (shadowing), small-scale fading (Rayleigh fading), and CCI, as well as for correcting mechanisms such as power control (compensates for path loss and shadowing), spatial diversity (mitigates against Rayleigh fading), and voice activity gating (reduces CCI). The new expressions may be used as convenient analysis tools that complement computer simulations. Of particular interest are tradeoffs revealed among system parameters, such as maximum allowed power control error versus the number of antennas used for spatial diversity     

Exact bit-error probability for optimum combining with a Rayleighfading Gaussian cochannel interferer

We derive expressions for the exact bit-error probability (BEP) for the detection of coherent binary phase-shift keying signals of the optimum combiner employing space diversity when both the desired signal and a Gaussian cochannel interferer are subject to flat Rayleigh fading. Two different methods are employed to reach two different, but numerically identical, expressions. With the direct method, the conditional BEP is averaged over the fading of both signal and interference, With the moment generating function based method, expressions are derived from an alternative representation of the Gaussian Q-function     

Systematic ultimate bound computation for sampled-data systems with quantization

We present a novel systematic method to obtain componentwise ultimate bounds in perturbed sampled-data systems, especially when the perturbations arise due to quantization. The proposed method exploits the system geometry as well as the perturbation structure, and takes intersample behavior into account. The main features of the method are its systematic nature, whereby it can be readily computer coded, without requiring adjustment of parameters for its application, and its suitability for dealing with highly structured perturbation schemes, whereby the information on the perturbation structure is directly taken into account. The latter feature distinguishes the method from other approaches that require a bound on the norm of the perturbation and thus disregard information on the perturbation structure. We apply the method to a numerical example taken from the literature to illustrate its simplicity and potential.     

Target localisation techniques and tools for multiple-input multiple-output radar

This study presents a comparative study of coherent and non-coherent target localisation techniques for multiple-input multiple-output (MIMO) radar systems with widely distributed elements. Performance is evaluated based on closed-form solutions developed for the best linear unbiased estimator (BLUE) for each of the localisation methods. These estimators afford insights into the relation between radar locations, target location and localisation accuracy. In particular, the means squared error of the BLUE is factored into a term dependent on signal and processing characteristics and a term dependent on sensor locations. The latter is referred to as geometric dilution of precision (GDOP). The best achievable accuracy for the coherent case is obtained, and a comparative study with the non-coherent case is presented. MIMO radar systems with coherent processing are shown to benefit from a gain because of coherent processing among sensors. This gain is referred to as coherent localisation gain, and it is proportional to the ratio of the signal carrier frequency to the effective bandwidth (a large ratio for typical signals). The footprint of multiple transmit/ receive sensors results in a gain, referred to as MIMO gain, for both processing techniques. The MIMO gain is proportional to the product of the number of transmitting and receiving sensors. Analysis of the MIMO gain through the use of GDOP contour maps demonstrate the achievable accuracy at various target locations for a given layout of sensors.