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This article presents the structure and the composition of a newly developed multifaceted test battery for the measurement of creativity within scientific and artistic domains. By integrating existing procedures for the evaluation of creativity, the new battery promises to become a comprehensive assessment of creativity, encompassing both domain-general and domain-specific components. In particular, the test battery was designed for the measurement of the 2 main stages of the creative thinking process: ideation and evaluation. The test battery also includes 2 measures of creative achievement and can be used to assess professional levels of creativity in artistic and scientific creativity, as well as everyday creativity. Because creative thinking is not an isolated phenomenon in human behavior, the battery includes the measurement of 2 constructs, intelligence and personality, both of which are highly relevant for creativity. Preliminary results from a vast administration campaign of this test battery are presented.

Broadband satellite services to fixed terminals are currently offered in the forward link by the 2nd Generation (2G) Digital Video Broadcasting Satellite (DVB-S2) standard. For this standard the use of powerful Low-Density Parity-Check (LDPC) error correcting codes has been adopted performing within approximately 1 dB from the Shannon capacity limit. This paper studies and compares for the first time in a systematic manner different approximation methods used in check node update computation of DVB-S2 LDPC decoding with the aim of reducing computational complexity. Various performance evaluation resuits are presented for a wide range of DVB-S2 parameters, such as LDPC codeword size, coding rate, modulation format and including several decoding algorithms. It is shown that the proposed check node update approximations have a robust behavior, i.e. the resulting performance is quite independent of the DVB-S2 modulation and coding parameters. It is further shown that these approximations perform very close to the optimal Sum-Product Algorithm (SPA) in degradation, which is less than 0.2 dB. Despite this small degradation, the reduction in computational complexity compared to the optimal SPA is significant and can be as high as 40% in computational time savings. Index Terms--Broadcasting, iterative decoding, Low-Density Parity-Check (LDPC) codes.

Acquisition of the code timing in a direct-sequence code-division multiple-access (DS-CDMA) system at the base station must take place before signal detection and decoding is possible. Code acquisition under severe multiple-accessinterference (MAI) conditions with time-varying codes makes the task even more difficult. Inefficient designs lead to a large number of false alarms and/or missed detections. This requirement is needed for conventional single-antenna (l-D) designs, as well as for multielement antenna (2-D) designs. This paper details a powerful code-acquisition technique for the uplink of DS-CDMA systems under high-loaded situations for both 1-D and 2-D schemes, where the number of users is greater than the processing gain. Under this high-MAI condition, the DS-CDMA acquisition problem becomes very difficult, and conventional search methods simply fail. The method discussed utilizes soft data from a multiuser detector to reduce the interference received by the acquisition unit. Analytical performance is compared to simulation results in terms of the number of users, processing gain, interferer-signal power, cancellation factor, antenna configuration, and noise variance. Numerical results validate performance under realistic conditions with amplitude, phase, and frequency impairments. Index Terms--Antenna arrays, cochannel interference, code-division multiple-access (CDMA), multiuser channels, synchronization.

In a recent paper, the modified Gardner detector has been proposed for advanced symbol-timing recovery of M-ary phase-shift keying signals. Compared with the original algorithm, the self-noise jitter can be considerably reduced for highly bandlimited systems and smaller values of M. In this letter, a completely different approach is investigated, which improves the self-noise performance for larger values of M, as well. Index Terms--Digital receivers, Gardner (GA) detector, symbol-timing recovery.

The performance of a class of generalized-selection combining (GSC) receivers operating over independent but nonidentically distributed Weibull fading channels is studied. We consider the case where the two branches with the largest instantaneous signal-to-noise ratio (SNR), from a total of L available, GSC(2, L) are selected. By introducing a novel property for the product of moments of ordered Weibull random variables, convenient closed form expressions for the moments of the GSC(2,L) output SNR are derived. Using these expressions, important performance criteria, such as average output SNR and amount of fading, are obtained in closed form. Furthermore, employing the Pade approximants theory and the moment-generating function approach, outage and bit-error rate performance are studied. An attempt is also made to identify the equivalency between the Weibull and the Rice fading channel, which is typically used to model the mobile satellite channel. We present various numerical performance evaluation results for different modulation formats and channel conditions. These results are complemented by equivalent computer simulated results which validate the accuracy of the proposed analysis. Index Terms--Amount of fading ([A.sub.F]), bit-error rate (BER), generalized-selection combining (GSC), land-mobile satellite, moment-generating function (MGF), ordered statistics, outage probability, Pade approximants, Weibull fading channels.

This paper applies the theoretical framework for the evaluation of code acquisition in the presence of fading developed in the companion Part I paper. Code synchronization for code-division multiple-access (CDMA) cellular networks, such as IS-95 and cdma2000, is considered. A multidwell testing procedure is adopted. Notably, a procedure for the optimization of the multidwell parameters (number of dwells, dwell lengths, thresholds) to achieve minimum acquisition time is introduced and enforced. The effects of fading, interchip interference (ICI), frequency offset, multiple-access interference, and noise are taken into account in the determination of false alarm and detection probabilities. In particular, anomalous ICI despreading and internal interference-cancellation effects are described. Numerical and simulation results, in terms of time for correct acquisition, confirm the accuracy of the proposed approach and show how it can be effectively used in the design and evaluation of a code-acquisition subsystem. Index Terms--Code acquisition, code-division multiple access (CDMA), fading, IMT-2000, IS-95, spread spectrum.

This paper deals with the analysis of the code-acquisition process performed by a mobile terminal in a code-division multiple-access cellular system. The fundamental contribution is the setting of a theoretical framework for code-acquisition analysis, accounting for the presence of fading and shadowing with specified coherence time. A multidwell architecture is considered, accounting for different verification strategies. The MAX/TC detection criterion is used, and the acquisition performance is analyzed, following both the direct and flow-graph approaches. Expressions for the acquisition time probability density function under different assumptions are given, as well as closed-form expressions for the mean and variance of the acquisition time. Practical applications and numerical results are reported in the Part II companion paper. Index Terms--Code-division multiple access (CDMA), code acquisition, fading, IMT-2000, IS-95, spread spectrum.

New bounds are proposed for the Marcum Q-function, which is defined by an integral expression where the Oth-order modified Bessel function appears. The proposed bounds are derived by suitable approximations of the Oth-order modified Bessel function in the integration region of the Marcum Q-function. They prove to be very tight and outperform bounds previously proposed in the literature. In particular, the proposed bounds are noticeably good for large values of the parameters of the Marcum Q-function, where previously introduced bounds fail and where exact computation of the function becomes critical due to numerical problems. Index Terms--Marcum Q-function, modified Bessel function of the first kind, upper and lower bounds.

The paper addresses the analysis of multidimensional trellis-coded M-ary phase shift keying (MPSK) modulation over a Rice-lognormal fading channel model, applicable to a variety of environments and to both terrestrial and satellite mobile communications. Bounds to the bit error probability are derived and applied to the analysis of a few selected trellis-coded modulation (TCM) schemes. The results, confirmed by simulation, show that on the Rice channel there exists a threshold in bit energy-to-noise density ratio above which the effective code length is the dominant parameter, while the free distance is dominating below. However, the influence of both parameters is mitigated when shadowing is present.

This letter addresses performance evaluation in a nonselective fading channel modeled by a combination of Rice and lognormal (RLN) statistics. The RLN model is valid under widely different environmental conditions, both for terrestrial cellular and for satellite personal communication systems. The letter provides semianalytical expressions for the average error probability in the RLN channel for coherent M-ary phase shift keying (PSK) and noncoherent M-ary orthogonal transmissions, then it highlights the relationship between outage probability and cell coverage for macro and microcellular systems, and finally it provides some error probability results for nongeostationary (non-GEO) satellite systems.

The paper introduces a statistical channel model which is a combination of Rice and lognormal statistics, and is suitable in principle to all types of environment (rural, suburban, urban) simply by tuning the model parameters. The model validity is confirmed by comparisons with measurement data collected in the literature. Empirical formulas are derived for the model parameters to fit measured data over a wide range of elevation angles. In particular, the model is applied to nongeostationary satellite channels, such as low-Earth orbit and medium-Earth orbit channels, in which for a given user located in a generic site the elevation angle changes continuously. Finally, examples of average bit error probability evaluations in the channel are provided.