We investigated luminescent properties in combination of red emissive europium complex of tris(dibenzoylmethane)-mono(4,7-dimethylphenanthroline)europium(III) [Eu(dbm)3phen] and blue phosphorescent molecule of bis[(4,6-difluorophenyl)-pyridinato-N,C2'] (picolinate) iridium (III) (FIrpic) doped in poly(N-vinyl-carbazole) (PVK). A sharp red emission from Eu(dbm)3phen was observed in photoluminescence (PL) measurement, whereas, in the case of electroluminescence (EL), emission from FIrpic and Eu compound were observed. The difference of the PL and EL spectra indicates that different energy transfer processes between Eu(dbm)3phen and FIrpic are suggested.

A novel method to simplify decision functions of support vector machines (SVMs) is proposed in this paper. In our method, a decision function is determined first in a usual way by using all training samples. Next those support vectors which contribute less to the decision function are excluded from the training samples. Finally a new decision function is obtained by using the remaining samples. Experimental results show that the proposed method can effectively simplify decision functions of SVMs without reducing the generalization capability.

Assume that G(D) is a k0n0 canonical generator matrix. Let G(L)(D) be the generator matrix obtained by integrating L consecutive trellis-modules associated with G(D). We also consider a modified version of G(L)(D) using a column permutation. Then take notice of the corresponding minimal trellis-module T(L). In this paper, we show that there is a case where the minimum number of states over all levels in T(L) is less than the minimum attained for the minimal trellis-module associated with G(D). In this case, combining with a shifted sectionalization of the trellis, we can construct a trellis-module with further reduced number of states. We actually present such an example. We also clarify the mechanism of state-space reduction. That is, we show that trellis-module integration combined with an appropriate column permutation and a shifted sectionalization of the trellis is equivalent to shifting some particular bits of the original code bits by L time units.

This letter develops theoretical analysis of the normalized LMS algorithm (NLMSA) for use in complex-domain adaptive filters in the presence of impulse noise at filter input. We propose a new "stochastic" model for such impulse noise, and assume that filter reference input process is a white process, e.g., digital QAM data, White & Gaussian process, etc. In the analysis, we derive a simple difference equation for mean square tap weight misalignment (MSTWM). Experiment is carried out to demonstrate effectiveness of the NLMSA in robust filtering in the presence of the impulse noise at the filter input. Good agreement between simulated and theoretically calculated filter convergence, in a transient phase as well as in a steady-state, proves the validity of the analysis.

A brief review of metamaterials and their applications to antenna systems is given. Artificial magnetic conductors and electrically small radiating and scattering systems are emphasized. Single negative, double negative, and zero-index metamaterial systems are discussed as a means to manipulate their size, efficiency, bandwidth, and directivity characteristics.

In this paper we study relationships between the linear complexities of a sequence when treated as a sequence over two distinct fields. We obtain bounds for one linear complexity in the form of a constant multiple of the other, where the constant depends only on the fields, not on the particular sequence.

Reduced-complexity maximum a posteriori probability (MAP) signal detection is a promising technique for multiple-input multiple-output space division multiplexing (MIMO-SDM) transmission. These detectors avoid exhaustive searches for all possible transmitted symbol vectors by generating a set of candidate symbol vectors. One problem with the reduced-complexity MAP detectors when used in conjunction with soft input decoders is the inaccuracy of log likelihood ratio (LLR) values since they are computed from a handful of candidate symbol vectors, which degrades the subsequent decoding process. To rectify this weakness, this paper proposes an LLR computation scheme for reduced complexity MAP detectors. The unique feature of the proposed scheme is that it utilizes the statistical property of the MIMO channel metric to narrow down further the number of candidate symbol vectors. Toward this goal, metric selection is performed to select only a statistically "good" portion of the candidate symbol vectors. Computer simulation results show that the proposed LLR computation scheme is more effective than the existing schemes especially when the number of candidate symbol vectors becomes smaller in reduced-complexity MAP detection.

This letter describes two low complexity receiver structures over a multi-broadcast channel of an orthogonal frequency division multiple access (OFDMA) multi-user system. The first is a one-group occupied receiver structure, whose complexity is much lower than that of a conventional OFDMA receiver structure. The other one, a multi-group occupied receiver structure, exploits multiple groups for one user, by which users' down-link data rate can be adaptively controlled by a base station (BS). Unlike unchangeable complexity of an OFDMA receiver structure that performs full-size of a fast Fourier transform (FFT) operation although only a few subcarriers are taken, its complexity linearly increases with the number of occupied subcarrier groups. The proposed receiver structures can meet the possible high-rate demand in the down-link and will become one of the strong candidates in next generation mobile communication systems.

Similar to algebraic decoding schemes, the (23, 12, 7) Golay code can be decoded by applying the step-by-step decoding algorithm. In this work, a modified step-by-step algorithm for decoding the Golay code is presented. Logical analysis yielded a simple rule for directly determining whether a bit in the received word is correct. The computational complexity can be reduced significantly using this scheme.

We have been investigating an orthogonal frequency division multiple access (OFDMA) based cellular system that is called "dynamic parameter controlled orthogonal frequency and time division multiple access (DPC-OF/TDMA)" for the development of beyond third generation (B3G) mobile communication systems. Moreover, we have already proposed a time alignment control (TAC) to compensate propagation delays that induce a multiple-access interference (MAI) in the uplink OFDMA. However, that TAC includes a large amount of computations. This means that it is quite difficult for the OFDMA systems to implement TAC into volume-limited hardware devices such as field programmable gate array (FPGA). Thus, we propose a new complexity-reduced TAC (CRTAC) in this paper. CRTAC can be implemented into such devices easily. In this paper, we show some computer simulation results, and then evaluate the error rate performances of DPC-OF/TDMA employing CRTAC. Moreover, we also show the benefit of the reasonable level of the implementation complexity made by CRTAC.

It is known that any chordal graph can be uniquely decomposed into simplicial components. Based on this fact, it is shown that for a given chordal graph, its automorphism group can be computed in O((c!n)O(1)) time, where c denotes the maximum size of simplicial components and n denotes the number of nodes. It is also shown that isomorphism of those chordal graphs can be decided within the same time bound. From the viewpoint of polynomial-time computability, our result strictly strengthens the previous ones respecting the clique number.

Intercarrier interference will cause the loss of subchannel orthogonality and increase the error floor in proportion to the Doppler frequency. In this paper, we firstly analyze the generation mechanism of intercarrier interference in OFDM. Then we propose an O(N log2N) complexity ICI equalizer for OFDM systems in the presence of double selective fading which is mainly bases on FFT operation. Simulation result shows that with only 6 iterations LCD-FFT can achieve better performance than the LS-equalizer. After 10 iterations LCD-FFT performs almost the same as MMSE equalizer.

This paper investigates the accepting powers of two-way alternating Turing machines (2ATM's) with only existential (universal) states which have inkdots and sublogarithmic space. It is shown that for sublogarithmic space-bounded computations, (i) multi-inkdot 2ATM's with only existential states and the ones with only universal states are incomparable, (ii) k-inkdot 2ATM's are better than k-inkdot 2ATM's with only existential (universal) states, k ≥ 0, and (iii) the class of sets accepted by multi-inkdot 2ATM's with only existential (universal) states is not closed under complementation.

This paper proposes a new architecture for multibit complex bandpass ΔΣAD modulators with built-in Switched-Capacitor (SC) circuits for application to Low-IF receivers such as used for Bluetooth and WLAN. In the realization of complex bandpass ΔΣAD modulators, we face the following problems: (i) SNR of AD converter is deteriorated by mismatches between internal analog I and Q paths. (ii) Layout design becomes complicated because of signal lines crossing by complex filter and feedback from DAC for I and Q paths in the complex modulator, and this increases required chip area. We propose a new structure for a complex bandpass ΔΣAD modulator which can be completely divided into two paths without layout crossing, and solves the problems mentioned above. The two parts of signal paths and circuits in the modulator are changed for I and Q while CLK is changed for High/Low by adding multiplexers. Symmetric circuits are used for I and Q paths at a certain timing, and they are switched by multiplexers to those used for Q and I paths at another timing. Therefore the influence from mismatches between I and Q paths is reduced by dynamic matching. As a result, the modulator is divided into two separate parts without crossing signal lines between I and Q paths and its layout design can be greatly simplified compared with conventional modulators. We have conducted MATLAB simulations to confirm the effectiveness of the proposed structure.

A novel frequency domain training sequence and the corresponding carrier frequency offset (CFO) estimator are proposed for orthogonal frequency division multiplexing (OFDM) systems over frequency-selective fading channels. The proposed frequency domain training sequence comprises two types of pilot tones, namely distinctively spaced pilot tones with high energies and uniformly spaced ones with low energies. Based on the distinctively spaced pilot tones, integer CFO estimation is accomplished. After the subcarriers occupied by the distinctively spaced pilot tones and their adjacent subcarriers are nulled for the sake of interference cancellation, fractional CFO estimation is executed according to the uniformly spaced pilot tones. By exploiting a predefined lookup table making the best of the structure of the distinctively spaced pilot tones, computational complexity of the proposed CFO estimator can be decreased considerably. With the aid of the uniformly spaced pilot tones generated from Chu sequence with cyclically orthogonal property, the ability of the proposed estimator to combat multipath effect is enhanced to a great extent. Simulation results illustrate the good performance of the proposed CFO estimator.

This letter presents the characteristics of complex antenna factors of a resistor loaded dipole antenna with a balun consisting of two coaxial feeders (coaxial cable balun). The resistor loading is used to realize dipole antennas with higher fidelity than unloaded dipole equivalents. The complex antenna factor for a resistor loaded dipole antenna with coaxial cable balun is derived by extending the power loss concepts. The numerical results show that the series resistor loaded dipole antenna offers higher fidelity than the unloaded dipole. The result of the calculated complex antenna factors are in good agreement with that of the measured results.

In order to reduce the computational complexity of the DWT domain on-line signature verification, the authors propose to utilize the pen-movement vector as an input parameter. Experimental results indicate that the verification rate obtained using the pen-movement vector parameter is equivalent to that obtained by the conventional method, although the computational complexity of the proposed method is approximately half that of the conventional method.

In this letter, we propose a cdma2000 based MC-CDMA scheme which inherits the same architecture and bandwidth of forward link packet data channel of cdma2000 1x EV-DV. The system utilizes no cyclic prefix, and it uses the bandwidth efficient iterative technique [6] to recover cyclicity of OFDM symbol of the MC-CDMA system to achieve backward compatibility with 1x EV-DV system. We report that the link-level performance of our proposed system is significantly better than previous equalizer-based scheme [7] in frequency selective fading channels.

In this paper, we discuss a new property, named dead, of (dataflow) program nets. We say that a node of a program net is dead iff the node cannot fire once in any possible firing sequence, and furthermore the program net is partially dead. We tackle a problem of deciding whether a given program net is partially dead, named dead problem. Program nets can be classified into four subclasses: general, acyclic, SWITCH-less, and acyclic SWITCH-less nets. For each subclass, we give a method of solving dead problem and its computation complexity. Our results show that (i) acyclic SWITCH-less nets are not partially dead; (ii) for SWITCH-less nets, dead problem can be solved in polynomial time; (iii) for acyclic nets and general nets, dead problem is intractable.

H.264 video coding standard has a significant performance better than the other standards are the adoption of variable block sizes, multiple reference frames, and the consideration of rate distortion optimization within the codec. However, these features incur a considerable complexity in the encoder for motion estimation. As for the multiple reference frames motion estimation, the increased computation is in proportion to the number of searched reference frames. In this paper, a fast multiple frame reference frames selection method is proposed for H.264 video coding. The proposed algorithm can efficiently determine the best reference frame from the allowed five reference frames. As determine the number of reference frames to search the motion using the correlation of the different block between the block of current frame and that of previous frame, this scheme can efficiently reduce the computational cost while keeping the similar quality and bit-rate. Simulation results show that the speed of the proposed method is faster than that of the original scheme adapted in JVT reference software JM95 while keeping the similar video quality and bit-rate.