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This paper considers the link-level and network-level performance of code division multiple access (CDMA) pilot interference cancellation (pilot IC) technology, a low-complexity advanced receiver technology being considered for use in commercial third generation (3G) CDMA cellular systems. The concept behind this technology is to estimate and cancel at the handset receiver the interference effects associated with CDMA downlink pilot signals broadcast from the base stations of the network. The canceling of interference at the receiver improves the signal-to-interference/noise ratio (SINR), which enables increased cell capacity or throughput. In this paper, we derive SINR expressions for evaluating the probability of error performance of both the RAKE and pilot IC handset receivers, under conventional random spreading code assumptions. The approach can easily and accurately model a wide variety of transmitter, channel, and receiver conditions, including the effects of channel estimation. We also utilize radio network simulations to illustrate and quantify the capacity gains available for 3G CDMA networks through the use of pilot IC handsets. Network simulations are also used to examine the reduced level of soft-handoff found to be possible in pilot IC-based networks and the increased flexibility available in setting pilot power levels. We further consider the impact of using stronger pilot signals for improving the demodulation performance of sensitive higher-order modulation constellations that are needed to support spectrally efficient high-rate data services. Index Terms--Code division multiple access (CDMA), interference cancellation, multiuser detection, pilot signal, RAKE.

Simple closed-form asymptotic expressions are derived for the Cramer-Rao lower bound to estimate the parameters of an unknown multichannel linear system and solve its identification and deconvolution. The proposed algorithm assumes that the system outputs are observable while the system inputs are non-Gaussian. Lower bounds are also derived on the signal reconstruction performance. System identification/deconvolution performance is dependent on the accuracy of identifying the location and the scale parameters of the input probability density functions from observation of the input signals.

We present a novel scheme that combines decision feedback equalization (DFE) with high-rate error-detection coding in an efficient manner. The proposed scheme is shown to considerably outperform the conventional practice on channels with high SNR, such as those encountered in twisted-pair telephonia systems. In order to analyze the performance of our method, we introduce an approximate mathematical model taking into account the error propagation phenomenon. Based on this model, upper and lower bounds on the overall probability of error are developed. These show that a simple low-redundancy error-detecting code, when properly integrated with the equalizer, can make the overall probability of error several orders of magnitude lower than that obtained with the conventional DFE, or with a DFE followed by an error-correcting code. Computer simulations of the proposed method have been performed for several channels, including the so-called high-bit-rate digital subscriber line (HDSL) test-loop #4, which is known to have a considerable amount of intersymbol interference. For all these channels, our results show that a reduction in the probability of error by more than three orders of magnitude can be obtained using codes of rate 0.96 and above. This, in turn, translates into power savings (coding gain) of 2.5 to 3 dB. Index Terms - Equalization, coding, decision-feedback, inter-symbol interference, trellis, HDSL.

In this article we examine the augmentation of application interfaces with enhanced specifications that include sequencing constraints called protocols. Protocols make explicit the relationship between messages (methods) supported by the […]

The methods for multichannel signal separation depend on the use of second and higher-order statistics. The separation techniques based on statistical independence among the source signals involve higher-order statistical calculations. Closed-form analytical expressions reveal the contribution of different statistics to estimation accuracy. Several simulations and experiments analyze the reliability of the approach.

Statistical independence condition is essential to develop a set of criteria that define signal decoupling in multiple-input-multiple-output linear system. Information regarding the nature of the signal source such as speech, communication or image signals is not essential for the criteria. Algorithms developed to execute the criteria include iterative solutions for linear least square problems.

A proposed method for the blind identification of finite impulse response systems with discrete-alphabet inputs is algebraic and does not depend on the statistical properties of the input and noise. Results show that the algorithm does not exhibit potential dependence on the fine structure of the noise although, with noise-free systems, the exact impulse response is generated.

Organizations increasingly need to build an enterprise-wide capability to leverage technology that is distributed in different business units. Some organizations establish enterprise architecture (EA) standards to enable greater compatibility of information technology (IT) components and integration of applications and data across the enterprise. Through a firm-level survey, we sought to answer two key questions about the use of EA standards: (1) How do different governance mechanisms affect the use of EA standards? and (2) To what extent does the use of EA standards help organizations to improve the sharing and integration of IT resources across the enterprise? We identified four key governance mechanisms for EA standards management and examined how each mechanism affected the use of EA standards. We also examined how the use of EA standards affects the management of IT infrastructure, applications, and data resources across business units. Our empirical results showed that the use of EA standards is effective in helping organizations to better manage their IT resources. Our study also provides detailed insights into how organizations can set up governance mechanisms to facilitate the use of EA standards in achieving enterprise-wide goals. [ABSTRACT FROM AUTHOR]

Byline: Wai Fong Boh, Daniel M. Yellin This paper examines the key managerial factors affecting Service-Oriented Architecture (SOA) implementation in organisations, and whether the implementation of SOA provides benefits to organisations. Based on a cross-sectional survey with 108 organisations, we found that top management support was a significant enabler for SOA implementation. We also found that organisations implementing SOA gained the benefits of improved application integration and the ability to establish external linkages with business partners more quickly.

A two-input two-output noiseless signal is estimated using a novel algorithm based on the minimization of a set of cross-correlations between the reconstructed signals and a nonlinear function of these signals. The proposed algorithm allows the recovery of the inputs from noise-free observations of the outputs. Numerical results show that the performance of the algorithm approximates that of the Cramer-Rao lower bound in the case of optimal choice of the nonlinear function.