In this paper, we propose a periodic reactance time function for 2-element electronically steerable passive array radiator (ESPAR) antennas applicable to the receivers of both single-input multiple-output (SIMO) and multiple-input multiple-output (MIMO) systems with 2 outputs. Based on the proposed function, we evaluate the power patterns of the antenna for various distances between two antenna elements. Moreover, for the distances, we discuss the correlation properties and the strength of the two outputs to find the appropriate distance for the receiver. From the discussions, we can conclude that distances from 0.1 to 0.35 times the wavelength are effective in terms of receive diversity.

In this paper, a new and an accurate symbol error probability's analytical model of Rectangular Quadrature Amplitude Modulation in α-µ fading channel is presented for single-user single-input multi-output environment, which can be easily extended to generalized fading channels. The maximal-ratio combining technique is utilized at the receiving end and unified moment generating functions are used to derivate the results. The fading mediums considered are independent and non-identical. The mathematical model presented is applicable for slow and frequency non-selective fading channels only. The final expression is presented in terms of Meijer G-function; it contains single integrals with finite limits to evaluate the mathematical expressions with numerical techniques. The beauty of the model will help evaluate symbol error probability of rectangular quadrature amplitude modulation with spatial diversity over various fading mediums not addressed in this article. To check for the validity of derived analytical expressions, comparison is made between theoretical and simulation results at the end.

In this paper, we present an FPGA hardware implementation for a phylogenetic tree reconstruction with a maximum parsimony algorithm. We base our approach on a particular stochastic local search algorithm that uses the Progressive Neighborhood and the Indirect Calculation of Tree Lengths method. This method is widely used for the acceleration of the phylogenetic tree reconstruction algorithm in software. In our implementation, we define a tree structure and accelerate the search by parallel and pipeline processing. We show results for eight real-world biological datasets. We compare execution times against our previous hardware approach, and TNT, the fastest available parsimony program, which is also accelerated by the Indirect Calculation of Tree Lengths method. Acceleration rates between 34 to 45 per rearrangement, and 2 to 6 for the whole search, are obtained against our previous hardware approach. Acceleration rates between 2 to 36 per rearrangement, and 18 to 112 for the whole search, are obtained against TNT.

Cache memories are the major application of high-speed SRAMs, and they are frequently installed in high performance logic VLSIs including microprocessors. This paper presents a 4-way set-associative, SOI cache-tag memory. To obtain higher operating speed with less power dissipation, we devised an I/O-separated memory cell with a dual-rail wordline, which is used to transmit complementary selection signals. The address decoding delay was shortened using CMOS dual-rail logic. To enhance the maximum operating frequency, bitline's recovery operations after writing data were eliminated using a memory array configuration without half-selected cells. Moreover, conventional, sensitive but slow differential amplifiers were successfully removed from the data I/O circuitry with a hierarchical bitline scheme. As regards the stored data management, we devised a new hardware-oriented LRU-data replacement algorithm on the basis of 6-bit directed graph. With the experimental results obtained with a test chip fabricated with a 0.25-µm CMOS/SIMOX process, the core of the cache-tag memory with a 1024-set configuration can achieve a 1.5-ns address access time under typical conditions of a 2-V power supply and 25°C. The power dissipation during standby was less than 14 µW, and that at the 500-MHz operation was 13-83 mW, depending on the bit-stream data pattern.

In this paper, we present a maximum a posteriori probability (MAP) approach to the problem of blind estimation of single-input, multiple-output (SIMO), finite impulse response (FIR) channels. A number of methods have been developed to date for this blind estimation problem. Some of those utilize prior knowledge on input signal statistics. However, there are very few that utilize channel statistics too. In this paper, the unknown channel to be estimated is assumed as the frequency-selective Rayleigh fading channel, and we incorporate the channel prior distributions (and hyperprior distributions) into our model in two different ways. Then for each case an iterative MAP estimator is derived approximately. Performance comparisons over existing methods are conducted via numerical simulation on randomly generated channel coefficients according to the Rayleigh fading channel model. It is shown that improved estimation performance can be achieved through the MAP approaches, especially for such channel realizations that have resulted in large estimation error with existing methods.

Equivalent Transmission Path (ETP) model-based BER map method was proved to be used in fast estimating Bit Error Rate (BER) of Single-Input Single-Output Orthogonal Frequency Division Multiplexing (SISO-OFDM) system, where the delay spreading exceeds the guard interval. In this paper, we propose a method for evaluating transmission characteristics of Single-Input Multiple-Output Orthogonal Frequency Division Multiplexing (SIMO-OFDM) system with application to maximum ratio combining diversity at the reception. The simulation results show that the proposed approximation method is able to be used in estimating trasmission characteristics with high accuracy not only for SISO-OFDM system but also for SIMO-OFDM system.

In this letter, we focus on the spectrum sharing cognitive radio system, wherein a single-input multi-output cognitive fading channel is considered. Subject to the joint average interference constraint and peak interference constraint at the primary receiver, the outage capacity of the cognitive channel involving joint beamforming and power control is analyzed. We derive the optimal beamforming and power control strategy and deduce the closed-form expression for the outage capacity under Rayleigh fading model, the functional regions of two kinds of interference constraints are discussed as well. Furthermore, considering zero-outage transmission, we investigate the delay-limited capacity and introduce a new concept called the zero-outage average interference wall. Extensive simulations corroborate our theoretical results.

In this letter, we consider a diversity precoding scheme for signal detection in ultra-wideband (UWB) multiple input single output (MISO) systems, which consists of linear diversity prefilters in the transmitter. For a UWB MISO system, the BER performance of a linear transmit diversity precoding system with imperfect channel estimation is presented in IEEE 802.15.3a UWB multipath channels and also compared with that of a linear receive diversity postcoding approach. It is shown that the diversity precoding UWB MISO system offers the performance equivalent to the diversity postcoding scheme for single input multiple output (SIMO) systems while making the mobiles low-cost and low-power.

This paper proposes a Inter-symbol Interference (ISI) suppressing method For Orthogonal Frequency Division Multiplexing (OFDM) system. In the environments where the delay spread exceeds the guard interval, the occurrence of ISI results in a degradation of system performance. A receiving method based on the Equivalent Transmission Path (ETP) model is proposed for Single-Input Multiple-Output (SIMO) OFDM system. Compared to the receiving scheme using Maximal Ratio Combining (MRC) method, the proposed one shows better performance in suppressing errors due to ISI. The paper also points out that the ETP-based model can be used for detecting the desired signal in the multi-user OFDM system. Simulation results of the system performance show the effectiveness of the proposed method over the conventional OFDM system in suppressing ISI.

Orthogonal frequency-division multiplexing (OFDM) systems often use a cyclic prefix (CP) to simplify the equalization design at the cost of bandwidth efficiency. To increase the bandwidth efficiency, we study the blind equalization with linear smoothing [1] for single-input multiple-output (SIMO) OFDM systems without CP insertion in this paper. Due to the block Toeplitz structure of channel matrix, the block matrix scheme is applied to the linear smoothing channel estimation, which equivalently increases the number of sample vectors and thus reduces the perturbation of sample autocorrelation matrix. Compared with the linear smoothing and subspace methods, the proposed block linear smoothing requires the lowest computational complexity. Computer simulations show that the block linear smoothing yields a channel estimation error smaller than that from linear smoothing, and close to that of the subspace method. Evaluating by the minimum mean-square error (MMSE) equalizer, the block linear smoothing and subspace methods have nearly the same bit-error-rates (BERs).

We propose a new two-stage blind separation and deconvolution strategy for multiple-input multiple-output (MIMO)-FIR systems driven by colored sound sources, in which single-input multiple-output (SIMO)-model-based ICA (SIMO-ICA) and blind multichannel inverse filtering are combined. SIMO-ICA can separate the mixed signals, not into monaural source signals but into SIMO-model-based signals from independent sources as they are at the microphones. After the separation by the SIMO-ICA, a blind deconvolution technique for the SIMO model can be applied even when each source signal is temporally correlated and the mixing system has a nonminimum phase property. The simulation results reveal that the proposed algorithm can successfully achieve separation and deconvolution of a convolutive mixture of speech, and outperforms a number of conventional ICA-based BSD methods.

The effect of a cavity on the third-order optical nonlinearity, is studied for a two-level system with excitation frequency ω0, as a function of the Q factor, coupling constant g, and longitudinal (γ1) and pure transverse (γ2) damping constants. The largest enhancement is found in the strong-coupling regime with γ1+2γ2=ω0/2Q. Large enhancement is also achieved in the weak-coupling regime satisfying the condition , and the intensity depends on damping constants only. The calculation is based on the cavity QED because the semiclassical treatment of the cavity quasimode leads to incorrect optical nonlinearity.

The exact calculation of the ergodic and outage capacity for Rayleigh fading single-input multiple-output (SIMO) channels in the presence of unequal-power Rayleigh fading interferers is mathematically quite challenging due to the complicated distribution of the capacity. In this paper, a SIMO system with M receive antennas and N interferers is considered. Based on some statistical results, the closed-form upper and lower bound for the ergodic and outage capacity are derived respectively. These bounds are shown to be simple to compute and appear to be quite tight.

In this paper, we address the blind separation problem of binaural mixed signals, and we propose a novel blind separation method, in which a self-generator for initial filters of Single-Input-Multiple-Output-model-based independent component analysis (SIMO-ICA) is implemented. The original SIMO-ICA which has been proposed by the authors can separate mixed signals, not into monaural source signals but into SIMO-model-based signals from independent sources as they are at the microphones. Although this attractive feature of SIMO-ICA is beneficial to the binaural sound separation, the current SIMO-ICA has a serious drawback in its high sensitivity to the initial settings of the separation filter. In the proposed method, the self-generator for the initial filter functions as the preprocessor of SIMO-ICA, and thus it can provide a valid initial filter for SIMO-ICA. The self-generator is still a blind process because it mainly consists of a frequency-domain ICA (FDICA) part and the direction of arrival estimation part which is driven by the separated outputs of the FDICA. To evaluate its effectiveness, binaural sound separation experiments are carried out under a reverberant condition. The experimental results reveal that the separation performance of the proposed method is superior to those of conventional methods.

A hybrid beamformer composed of a direction-of-arrival (DOA) based scheme and maximal ratio combining (MRC) is proposed to overcome the degradation caused by inaccurate channel estimation due to insufficient pilot power, which happens in conventional single-input, multiple-output (SIMO) Code Division Multiple Access (CDMA) reverse link. The proposed scheme can provide more accurate channel estimation and interference reduction at the expense of diversity gain in the spatially correlated SIMO channel. As a result, the hybrid scheme outperforms conventional MRC beamformers for six or more antennas in the channel environment, in which the angle-of-spread (AOS) is within 30.

In this paper, single-input multiple-output (SIMO)-model-based blind source separation (BSS) is addressed, where unknown mixed source signals are detected at microphones, and can be separated, not into monaural source signals but into SIMO-model-based signals from independent sources as they are at the microphones. This technique is highly applicable to high-fidelity signal processing such as binaural signal processing. First, we provide an experimental comparison between two kinds of SIMO-model-based BSS methods, namely, conventional frequency-domain ICA with projection-back processing (FDICA-PB), and SIMO-ICA which was recently proposed by the authors. Secondly, we propose a new combination technique of the FDICA-PB and SIMO-ICA, which can achieve a higher separation performance than the two methods. The experimental results reveal that the accuracy of the separated SIMO signals in the simple SIMO-ICA is inferior to that of the signals obtained by FDICA-PB under low-quality initial value conditions, but the proposed combination technique can outperform both simple FDICA-PB and SIMO-ICA.

This paper introduces an efficient affine projection algorithm (APA) using iterative hyperplane projection. The inherent effectiveness against the rank deficient problem has led APA to be the preferred algorithm to be employed for various applications over other variety of fast converging adaptation algorithms. However, the amount of complexity of the conventional APA could not be negligible because of the accomplishment of sample matrix inversion (SMI). Another issue is that the "shifting invariance property," which is typically exploited for single channel case, does not hold ground for space-time decision-directed equalizer (STDE) application deployed in single-input-multi-output (SIMO) systems. Therefore, fast adaptation schemes, such as fast traversal filter based APA (FTF-APA), becomes impossible to utilize. The motivation of this paper deliberates on finding an effective algorithm on the basis of APA, which yields low complexity while sustaining fast convergence as well as excellent tracking ability. The performance of the proposed method is evaluated under wireless SIMO channel in respect to bit error rate (BER) behavior and computational complexity, and upon completion, the validity is confirmed. The performance of the proposed method is evaluated under wireless SIMO channel in respect to bit error rate (BER) behavior and computational complexity, and upon completion, the validity is confirmed.

We newly propose a novel blind separation framework for Single-Input Multiple-Output (SIMO)-model-based acoustic signals using an extended ICA algorithm, SIMO-ICA. The SIMO-ICA consists of multiple ICAs and a fidelity controller, and each ICA runs in parallel under the fidelity control of the entire separation system. The SIMO-ICA can separate the mixed signals, not into monaural source signals but into SIMO-model-based signals from independent sources as they are at the microphones. Thus, the separated signals of SIMO-ICA can maintain the spatial qualities of each sound source. In order to evaluate its effectiveness, separation experiments are carried out under both nonreverberant and reverberant conditions. The experimental results reveal that the signal separation performance of the proposed SIMO-ICA is the same as that of the conventional ICA-based method, and that the spatial quality of the separated sound in SIMO-ICA is remarkably superior to that of the conventional method, particularly for the fidelity of the sound reproduction.

We have developed advanced SOI n- and p-MOSFETs with strained-Si channel on insulator (strained-SOI) structure fabricated by SIMOX (separation-by-implanted-oxygen) technology. The characteristics of this strained-SOI substrate and electrical properties of strained-SOI MOSFET's have been experimentally studied. Using strained-Si/relaxed-SiGe epitaxy technology and usual SIMOX process, we have successfully formed the layered structure of fully-strained-Si (20 nm)/fully-relaxed-SiGe film (290 nm) on uniform buried oxide layer (85 nm) inside SiGe layer. Good drain current characteristics have been obtained in strained-SOI MOSFET's. It is found that both electron and hole mobility is enhanced in strained-SOI MOSFET's, compared to the universal mobility in an inversion layer and the mobility of control SOI MOSFET's. These mobility enhancement factors are almost the same as the theoretical results.

A low-voltage 6-GHz-band monolithic LC-tank VCO has been fabricated using 0.2-µm CMOS/SIMOX process technology. The VCO features a tuning-range switching technique to achieve a wide tuning range. The output frequency range is between 5.71 and 6.21 GHz owing to the tuning-range switch. With the tuning-range switch on or off, the phase noise is about -100 dBc/Hz at 1-MHz offset and about -120 dBc/Hz at 10-MHz offset frequency at the supply voltage of 2 V.