In a variety of communication systems, the multipath propagation due to various reflections is often encountered. In this paper, the directions-of-arrival (DOA) estimation of the cyclostationary coherent signals is investigated. A new approach is proposed for estimating the DOA of the coherent signals impinging on a uniform linear array (ULA) by utilizing the spatial smoothing (SS) technique. In order to improve the robustness of the DOA estimation by exploiting the cyclic statistical information sufficiently and handling the coherence effectively, we give a cyclic algorithm with multiple lag parameters and the optimal subarray size. The performance of the presented method is verified and compared with the conventional methods through numerical examples.

Recently, a great deal of effort has been devoted to the design problem of "constrained least squares M-D FIR filter" because a significant improvement of the squared error is expected by a slight relaxation of the minimax error condition. Unfortunately, no design method has been reported, which has some theoretical guarantee of the convergence to the optimal solution. In this paper, we propose a class of novel design methods of "constrained least squares M-D FIR filter. " The most remarkable feature is that all of the proposed methods have theoretical guarantees of convergences to the unique optimal solution under any consistent set of prescribed maximal error conditions. The proposed methods are based on "convex projection techniques" that computes the metric projection onto the intersection of multiple closed convex sets in real Hilbert space. Moreover, some of the proposed methods can still be applied even for the problem with any inconsistent set of maximal error conditions. These lead to the unique optimal solution over the set of all filters that attain the least sum of squared distances to all constraint sets.

A constant modulus adaptive array algorithm is derived using analysis and synthesis filter banks to permit adaptive digital beamforming for wideband signals. The properties of the CMA adaptive array using the filter banks are investigated. This array would be used to realize adaptive digital beamforming when this is difficult by means of ordinary (that is, non-subband) processing due to the limited speed of signal processor operations. As an actual application, we present a beamspace adaptive array structure that combines the analysis and synthesis filter banks with RF-domain multibeam array antennas, such as those utilizing optical signal processing.

In this paper, we extend the Gnaedig's results on termination of order-sorted rewriting. Gnaedig required a condition for order-sorted signatures, called minimality, for the termination proof. We get rid of this restriction by introducing a transformation from a TRS with an arbitrary order-sorted signature to another TRS with a minimal signature, and proving that this transformation preserves termination.

In this paper, we present a hierarchical technique for simultaneous pin assignment and global routing during floorplanning based on the minimum cost maximum integer flow algorithm with several heuristic cost functions. Furthermore, our algorithm handles feedthrough pins and equi-potential pins taking into account global routes. Our algorithm allows various user specified constraints such as pre-specified pin positions, wiring paths, wiring widths and critical nets. Experimental results including Xerox floorplanning benchmark have shown the effectiveness of the heuristics.

Non-uniform traffic can affect communications quality in microcell systems, and this disparity in communications quality between base stations (BSs) lowers the system efficiency in CDMA systems. If traffic distribution and propagation conditions are already known during the introduction of a CDMA system, it is desirable to design cell areas according to the non-uniformity of traffic distribution and BS locations. Cell area is determined by the transmission power of the pilot-signal from the BS and it is necessary to control the transmission power of mobile stations in the uplink, which is determined by the desired power level at the BS, according to the cell area. The disparity in communications quality can be rectified by optimally designing the two parameters of the pilot-signal power and desired power level. This paper describes an algorithm for setting both the pilot-signal power and the desired power level during the cell design stage in CDMA systems. The proposed algorithm operates that the communications qualities of all BSs in the system converge to average quality by adjusting the two parameters. The parameters of all BSs in the whole system can be determined through computer calculation. Through performance evaluations, we confirmed that the average SIRs of all BSs attained almost the same value and the variance between the BSs was less than half by adopting the cell design algorithm when there was dispersion in BS placement. This algorithm is also effective using the actual measured SIR after a system has been established.

This paper presents a design of CMOS Chua-type analog chaos circuit by using a signal-flow-graph (SFG) method. In this circuit, the transmittance of a nonlinear element is realized by an OTA with a feedback resistor, and other linear elements are realized by op-amp based circuits. The proposed circuit is insensitive to the finite admittance of OTA's and to the parasitics of resistors except a feedback resistor in the nonlinear element. The performance and chaotic behavior of the proposed circuit are confirmed by SPICE simulations.

We have developed a new type of phase interpolation DDS with a digitally controlled delay generator. The new DDS is similar to a sine output DDS in that it produces low spurious signals, but it does not require a sine look-up table. Periodic jitter in the MSB of the DDS accumulator is reduced with the digitally controlled delay generator. Experimental results confirm successful frequency synthesizer operation in which the spurious signal level is successfully reduced to less than that the MSB of the accumulator.

This letter proposes a method to transform normalized ARMA lattice filters, which are originally realized for signal analysis, into signal synthesis lattice filters. Although the transformation method has been proposed for normalized ARMA lattice filters with the MA order which is greater than or equal to the AR order, it has not been done when the AR order is greater than the MA order. With the proposed method, once an ARMA lattice filter with the AR order greater than the MA order is realized, then it can be transformed to the signal synthesis filter.

We present a high-level synthesis scheme that considers weak testability of generated register-transfer level (RTL) data paths, as well as their area and performance. The weak testability, proposed in our previous work, is a testability measure of RTL data paths for non-scan design. In our scheme, we first extract a condition on resource sharing sufficient for weak testability from a data flow graph before synthesis, and treat the condition as design objectives in the following synthesis tasks. We propose heuristic synthesis algorithms which optimize area and the design objectives under the performance constraint.

We will present a partial scan design method based on n-fold line-up structures in order to achieve high fault efficiency and reduce test pattern generation time for practical LSIs. We will also present a partial scan design method based on the state justification of pure load/hold FFs in order to achieve high fault efficiency and reduce the number of scan FFs for practical LSIs with lots of load/hold FFs. Experimental results for practical LSIs show that our presented methods can achieve high fault efficiency (more than 99%) and reduce the number of scan FFs for the LSI with lots of load/hold FFs.

For mobile telecommunication systems, it is important to accurately predict the propagation-path loss in terms of the estimation of the radiowave coverage area. The propagation-path loss has been estimated in a median obtained spatially from many received amplitudes (envelopes) within a region of several tens times as long as the wavelength, rather than in the envelopes themselves. Although ray tracing can obtain the envelopes and their median that reflect the site-dependent characteristics, the estimated median sometimes does not agree with the measured one. Therefore, the accuracy improvement has been expected. In this paper, an accuracy improvement is achieved by substituting a median with random phases for the median obtained spatially from many envelopes. The characteristic function method is used to obtain the cumulative distribution function and the median analytically where the phases are randomized. In a multipath environment, the phase-estimation error accompanying the location error of the ray tracing input influences the spatially obtained median. The phase-randomizing operation reduces the effects of the phase-estimation error on the median prediction. According to our estimation, improvements in accuracy of 4. 9 dB for the maximum prediction error and 2. 9 dB for the RMS prediction error were achieved. In addition, a probability-based cell-design method that takes the radiowave arrival probability and the interference probability into consideration is possible by using the percentiles obtained by the characteristic function method and the cell-design examples are shown in this paper.

In this paper, we propose a novel power distribution method which can be adopted in case of the nonuniform distribution for mobiles in DS/CDMA distributed power cellular system. DS/SS distributed power cellular system has been proposed for achieving RAKE reception in micro-cellular environment. In forward link of this system, optimum power distribution method which can minimize the required total transmitting power has been discussed. The performance of this system has been shown in case of the uniform distribution for mobiles. In this paper, first, we propose a novel method in case of the nonuniform distribution. In the proposed method, replacing the path and its combinations of signals from base stations successively, we can find a new condition of less power distribution which is passed over in a conventional distribution method. We adopt simple distribution models for mobiles and compare the proposed method with the other methods by computing the total transmitting power and the quantity of calculations. As a result, we show that it is possible to almost obtain optimum power distribution by using the proposed method. Next, we adopt a nonuniform distribution model, in which the difference of the number of users exists only in the center cell. Using this model, we compare the proposed method with the other methods by computing the total transmitting power, the quantity of calculations, and a probability of impossible power distribution. Finally, in order to simplify and decrease the quantity of calculations of the proposed method, we propose a modified calculation algorithm which is applicable in case of that a new mobile station has increased. And we show the performance of this algorithm.

The advantage of random testing is that test application can be performed at a low cost in the BIST scheme. However, not all circuits are random pattern testable due to the existence of random pattern resistant faults. In this paper, we present a method for improving the random pattern testability of logic circuits by partial circuit duplication approach. The basic idea is to detect random pattern resistant faults by using the difference between the duplicated part of a circuit and the original part. Experimental results on benchmark circuits show that high fault coverage can be achieved with a very small amount of hardware overhead.

Personal communication systems are increasingly required to accommodate not only voice traffic, but also various types of data traffic. Generally speaking, voice traffic is symmetric between uplink and downlink, while data traffic can be highly asymmetric. It is therefore inefficient to accommodate data in a conventional TDMA/TDD system with fixed TDD boundary. In this paper, focusing on the continuous data traffic which requires multi-slots in a circuit based TDMA/TDD system, an algorithm is proposed in which the TDD boundary are moved adaptively to accommodate data traffic efficiently. Comparing with the boundary-fixed conventional algorithm, computer simulations confirm that the proposed algorithm has superior performance in the excessive transmission delay of data while maintaining the performance of voice. The intercell interference between mobiles due to different TDD boundaries is also confirmed to be negligible. Moreover, almost the similar performance improvements of the proposed algorithm are confirmed for two different average message sizes of data calls.

The increasing activity at millimeter wave frequency band and the growing demand for waveguide components to be applied for integrated circuit purpose have promoted the need for applying the field-theory-based approaches to the design procedure. In this paper, genetic algorithms (GA's) are applied to accurately design the iris-coupled waveguide filters based on network-boundary element method (NBEM). GA's model the natural selection and evolve towards the global optimum, thus avoid being trapped in local minima. Network-boundary element method, which combines boundary element method with network analysis method, derives the network parameters of the guided wave structures with less storage location and central processing unit time. Therefore, NBEM is a feasible and efficient field-theory-based approach for the GA optimization of waveguide filters. With NBEM performing the task of evaluating the performance of the filter designs optimized by the GA, rigorous and optimal designs of the waveguide filters are realized. The obtained analysis and optimization results are compared to a number of reference solutions to demonstrate the validity and accuracy of the proposed approach.

We present a realization of the transparent wave absorber effective for the use at V-band frequency. First, we propose a structure of the transparent wave absorber consisting of spacer (polycarbonate) and two transparent resistive sheet (polyethylene terephtalate deposited with Indium Tin Oxide) used as a reflection film and an absorption film. Second, a design chart for this type of wave absorber is shown. Third, a design method and manufacturing process of the transparent wave absorber are described particularly for V-band frequency. As a result, the measurement of reflection loss of the absorber indicate that a peak absorption of 32-38 dB is attained at a target frequency of 60 GHz.

This paper describes a new high resolution algorithm for the two-dimensional (2-D) frequency estimation problem, which, in particular, is noise insensitive in view of the fact that in many practical applications the contaminated noise may not be white noise. For this purpose, the approach is set in the context of higher-order statistics (HOS), which has demonstrated to be an effective approach under a colored noise environment. The algorithm begins with the consideration of the fourth-order moments of the available 2-D data. Two auxiliary matrices, constituted by a novel stacking of the diagonal slice of the computed fourth-order moments, are then introduced and through which the two frequency components can be precisely determined, respectively, via matrix factorizations along with the subspace rotational invariance (SRI) technique. Simulation results are also provided to verify the proposed algorithm.

A mobility management scheme that reduces signaling traffic load and connection setup time is a pivotal issue in designing future personal communication service (PCS) networks to satisfy Quality of Services requirements and use network resources efficiently. Particularly, required is scalable mobility management, to meet the explosive growth in number of users for the current second-generation wireless communication systems, and to materialize PCS concepts such as terminal, personal, and service mobility. Many mobility management schemes have been proposed for the reduction of signaling traffic. However, these schemes have not been sufficiently compared using a unified performance measure that is free of assumptions as to mobility model or database architecture. In this paper, we categorize the various mobility management schemes for advanced PCSs in distributed environments into four types and clarify the appropriate domain for each type. To do this, we settled on the number of signals at connection setup and location registration as a unified performance measure, since this value closely relates to connection setup time and network efficiency. We found two kinds of schemes with replicating and caching functions of user information that are extremely effective for reducing signaling load and hence connection setup time. These schemes are appropriate when the probability that a user is in his/her home area is relatively small or the connection setup rate is relatively high compared to the location registration rate. These are the most likely situations in the advanced PCS for global environments.

The matrix decomposition of transformation associated with the Kronecker product not only provides a thoughtful structure in hardware realization but also bestows a skillful tool for complexity evaluation. Hence, there are several fast algorithms developed to achieve efficient computation of two-dimensional (2-D) discrete cosine transform (DCT) with matrix decomposition techniques. However, we found that their derivations associated with their computation structures were not shown formally. In this paper, we propose formal derivations to remedy their deficiencies to achieve more structural 2-D DCT and inverse DCT (IDCT) algorithms. Furthermore, we also show that the remedied algorithms are with less computational complexity and more regular structure for realization.