This paper presents the outline of the systolic array recursive least-squares (RLS) processor prototyped primarily with the aim of broadband mobile communication applications. To execute the RLS algorithm effectively, this processor uses an orthogonal triangularization technique known in matrix algebra as QR decomposition for parallel pipelined processing. The processor board comprises 19 application-specific integrated circuit chips, each with approximately one million gates. Thirty-two bit fixed-point signal processing takes place in the processor, with which one cycle of internal cell signal processing requires approximately 500 nsec, and boundary cell signal processing requires approximately 80 nsec. The processor board can estimate up to 10 parameters. It takes approximately 35 µs to estimate 10 parameters using 41 known symbols. To evaluate signal processing performance of the prototyped systolic array processor board, processing time required to estimate a certain number of parameters using the prototyped board was comapred with using a digital signal processing (DSP) board. The DSP board performed a standard form of the RLS algorithm. Additionally, we conducted minimum mean-squared error adaptive array in-lab experiments using a complex baseband fading/array response simulator. In terms of parameter estimation accuracy, the processor is found to produce virtually the same results as a conventional software engine using floating-point operations.

A digit-recurrence algorithm for cube rooting is proposed. In cube rooting, the digit-recurrence equation of the residual includes the square of the partial result of the cube root. In the proposed algorithm, the square of the partial result is kept, and the square, as well as the residual, is updated by addition/subtraction, shift, and multiplication by one or two digits. Different specific versions of the algorithm are possible, depending on the radix, the digit set of the cube root, and etc. Any version of the algorithm can be implemented as a sequential (folded) circuit or a combinational (unfolded) circuit, which is suitable for VLSI realization.

In this paper, we present deterministic parallel algorithms for the convex hull of sorted points and their application to a related problem. The algorithms are proposed for the coarse grained multicomputer (CGM) model. We first propose a cost optimal parallel algorithm for computing the problem with a constant number of communication rounds for n/p p2, where n is the size of an input and p is the number of processors. Next we propose a cost optimal algorithm, which is more complicated, for n/p pε, where 0 < ε < 2. From the above two results, we can compute the convex hull of sorted points with O(n/p) computation time and a constant number of communication rounds for n/p pε, where ε > 0. Finally we show an application of our convex hull algorithms. We solve the convex layers for d lines in O((n log n)/p) computation time with a constant number of communication rounds. The algorithm is also cost optimal for the problem.

Given a graph G, a designated vertex r and a natural number k, we wish to find k "independent" spanning trees of G rooted at r, that is, k spanning trees such that, for any vertex v, the k paths connecting r and v in the k trees are internally disjoint in G. In this paper we give a linear-time algorithm to find k independent spanning trees in a k-connected maximal planar graph rooted at any designated vertex.

In recent years, the study of the security of Elliptic Curve Cryptosystems (ECCs) have been received much attention. The MOV algorithm, which reduces the elliptic curve discrete log problem (ECDLP) to the discrete log problem in finite fields with the Weil pairing, is a representative attack on ECCs. Recently Kanayama et al. observed a realization of the MOV algorithm for non-supersingular elliptic curves under the weakest condition. Shikata et al. independently considered a realization of the MOV algorithm for non-supersingular elliptic curves and proposed a generalization of the MOV algorithm. This short note explicitly shows that, under a usual cryptographical condition, we can apply the MOV algorithm to non-supersingular elliptic curves by using the multiplication by constant maps as in the case of supersingular. Namely, it is explicitly showed that we don't need such a generalization in order to realize the MOV algorithm for non-supersingular elliptic curves under a usual cryptographical condition.

We consider a single-vehicle scheduling problem on a tree, where each vertex has a job with a release time and a processing time and each edge has a travel time. There is a single vehicle which starts from a start vertex s and reaches a goal vertex g after finishing all jobs. In particular, s is called a home location if s = g. The objective of the problem is to find a depth-first routing on T so as to minimize the completion time. In this paper, we first show that the minimum completion times of the problem for all home locations s V can be simultaneously computed in O(n) time, once the problem with a specified home location s V has been solved, where n is the number of vertices. We also show that given a specified start vertex s, the minimum completion times for all goal vertices g can be computed in O(n) time.

Since the detection of optical flow (two-dimensional motion field on an image) from image sequences is essentially an ill-posed problem, most of the conventional methods use a smoothness constraint for optical flow heuristically and detect reasonable optical flow. However, little discussion exists regarding the degree of smoothness. Furthermore, to recover the relative three-dimensional motion and depth between a camera and a rigid object, in general at first, the optical flow is detected without a rigid motion constraint, and next, the motion and depth are estimated using the detected optical flow. Rigorously speaking, the optical flow should be detected with such a constraint, and consequently three-dimensional motion and depth should be determined. To solve these problems, in this paper, we apply a parametric model to an optical flow, and construct an estimation algorithm based on this model.

In this paper, we first investigate the problems of the existing branch point algorithms for available bit rate (ABR) multicast connections in ATM networks, and then propose various solutions for resolving those problems. By combining these solutions, we also propose a new efficient and scalable branch point algorithm. In the proposed algorithm, each branch point stores the feedback information on a per-branch basis for each virtual connection and only passes BRM cells returning from the farthest destination. Simulation results show that the proposed algorithm can provide a good fairness, a higher efficiency and an excellent scalability, compared with the existing algorithms.

To reduce an amount of computation of full search algorithm for fast motion estimation, we propose a new and fast matching algorithm without any degradation of predicted images. The computational reduction without any degradation comes from adaptive matching scan algorithm according to the image complexity of the reference block in current frame. Experimentally, we significantly reduce the computational load compared with conventional full search algorithm.

For the purpose of equalisation of rapidly time variant multipath channels, we derive a novel adaptive algorithm, the amplitude banded LMS (ABLMS), which implements a non-linear adaptation based on a coefficient matrix. Then we develop the ABLMS algorithm as the adaptation procedure for a linear transversal equaliser (LTE) and a decision feedback equaliser (DFE) where a parallel adaptation scheme is deployed. Computer simulations demonstrate that with a small increase of computational complexity, the ABLMS based parallel equalisers provide a significant improvement related to the conventional LMS DFE and the LMS LTE in the case of a second order Markov communication channel model.

This paper aims at improving effectiveness of previously proposed hybrid priority lists, {L*i=LdLsi}, that are applied in nonpreemptive 2-processor scheduling of general acyclic SWITCH-less program nets, where Ld and Lsi are dynamic and static priority lists respectively. Firstly, we investigate the effectiveness of Ld through experiments. According to the experimental results, we reconstruct Ld to propose its improved list L1d. Then analyzing the construction methodology of the static priority lists {Lsi}, we propose a substituted list L2d by taking into account of the factor: remaining firing numbers of nodes. Finally, we combine a part of L1d and L2d to propose a new priority list L**. Through scheduling simulation on 400 program nets, we find the new priority list L** can generate shorter schedules, close to ones of GA (Genetic Algorithm) scheduling that has been shown exceedingly effective but costing much computation time.

The k-vertex-connectivity augmentation problem for a specified set of vertices of a graph with degree-unchangeable vertices, kVCA(G,S,D), is defined as follows: "Given a positive integer k, an undirected graph G=(V,E), a specified set of vertices S V and a set of degree-changeable vertices D V, find a smallest set of edges E such that the vertex-connectivity of S in (V,E E) is at least k and E {(u,v) u,v D}. " The main result of the paper is that checking the existence of a solution and finding a solution to 2VCA(G,S,D) or 3VCA(G,S,D) can be done in O(|V|+|E|) or O(|V|(|V|+|E|)) time, respectively.

If there exist any two vertices in G whose distance becomes longer when a vertex u is removed, then u is defined as a hinge vertex. Finding the set of hinge vertices in a graph can be used to identify critical nodes in an actual network. A number of studies concerning hinge vertices have been made in recent years. In general, it is known that more efficient sequential or parallel algorithms can be developed by restricting classes of graphs. For instance, Chang et al. presented an O(n+m) time algorithm for finding all hinge vertices of a strongly chordal graph. Ho et al. presented a linear time algorithm for all hinge vertices of a permutation graph. In this paper, we shall propose a parallel algorithm which runs in O(log n) time with O(n) processors on CREW PRAM for finding all hinge vertices of an interval graph.

This paper describes a unique motion estimation and compensation (ME/MC) hardware architecture for a scene-adaptive algorithm. By statistically analyzing the characteristics of the scene being encoded and controlling the encoding parameters according to the scene, the quality of the decoded image can be enhanced. The most significant feature of the architecture is that the two modules for ME/MC can work independently. Since a time interval can be inserted between the operations of the two modules, a scene-adaptive algorithm can be implemented in the architecture. The ME/MC architecture is loaded on a single-chip MPEG-2 video encoder.

A modified version of the SAGE algorithm is presented for joint delay-azimuth-attenuation parameters' estimation in a multiuser DS-CDMA system. The introduced modification consists of using different time interval lengths when calculating the time correlations for optimizing the different channel parameters. This modification was proposed for the purpose of a further reduction in the algorithm's computational weight in case of receiving sufficiently resolvable waves. Specifically, we found that short interval windows are sufficient for estimating delays and azimuth angles, which is quite effective in reducing the computational burden in their optimization processes. As for the estimation of the attenuation parameters, a longer time window, equal to the preamble length, is considered for more accurate estimation. Also two other estimators are proposed. The first one combining the modified SAGE with a sequential estimation of the attenuation parameters, suitable for slowly varying channels. Another one, similar to the first, and primarily designed to alleviate the influence of present strong interferers. Through a numerical example, the performances of the three presented estimation schemes, in terms of their near-far resistance, are compared. And it is shown that the proposed second combined estimator outperforms the modified SAGE in environments with high MAI levels.

Since the traffic of NetNews is increasing, keeping all articles becomes serious problem from a viewpoint of waste of network bandwidth and the amount of disk usage. In addition, users read not all incoming articles. We have proposed several caching algorithms to overcome this problem and shown that a selective prefetch scheme gives the best system performance among the proposed ones. However, since the selective prefetch scheme employed a simple selecting policy, the scheme gave low hit ratio in some cases. Therefore, this paper intends to improve the selective prefetch scheme from a viewpoint of the amount of disk usage as well as hit ratio. In this paper, we divide the scheme into three factors: reference span, criterion, and threshold in criterion. Through simulation experiments using actual NetNews logs, we investigate the influence of the factors of the reference span and the threshold to system performance. As a result, it is shown that the reference span is more significant factor than the threshold, the selective prefetch scheme with a value around the seven days reference span keeps high hit ratio and reduces the amount of disk usage.

In this paper, we propose a lower bound for the minimum distance of [n,k] linear codes which are specified by generator matrices whose rows are k vectors of a given sequence of n linearly independent vectors over a finite field. The Feng-Rao bound and the order bound give the lower bounds for the minimum distance of the dual codes of the codes considered in this paper. We show that the proposed bound gives the true minimum distance for Reed-Solomon and Reed-Muller codes and exceeds the Goppa bound for some L-type algebraic geometry codes.

In this paper, we examine an optimal reliability assignment/redundant allocation problem formulated as a nonlinear mixed integer programming (nMIP) model which should simultaneously determine continuous and discrete decision variables. This problem is more difficult than the redundant allocation problem represented by a nonlinear integer problem (nIP). Recently, several researchers have obtained acceptable and satisfactory results by using genetic algorithms (GAs) to solve optimal reliability assignment/redundant allocation problems. For large-scale problems, however, the GA has to enumerate a vast number of feasible solutions due to the broad continuous search space. To overcome this difficulty, we propose a hybridized GA combined with a neural-network technique (NN-hGA) which is suitable for approximating optimal continuous solutions. Combining a GA with the NN technique makes it easier for the GA to solve an optimal reliability assignment/redundant allocation problem by bounding the broad continuous search space by the NN technique. In addition, the NN-hGA leads to optimal robustness and steadiness and does not affect the various initial conditions of the problems. Numerical experiments and comparisons with previous results demonstrate the efficiency of our proposed method.

It is well known that based on the structure of a transversal filter, the RLS equaliser provides the fastest convergence in stationary environments. This paper addresses an adaptive transversal equaliser which has the potential to provide more faster convergence than the RLS equaliser. A comparison is made with respect to computational complexity required for each update of equaliser coefficients, and computer simulations are demonstrated to show the superiority of the proposed equaliser.

One major breakthrough on the communication society recently is the extension of networking from wired to wireless networks. This has made possible creating a mobile distributed computing environment and has brought us several new challenges in distributed protocol design. Obviously, wireless networks do have some fundamental differences from wired networks that need to be paid special attention of, such as lower communication bandwidth compared to wired networks, limited electrical power due to battery capacity, and mobility of processes. These new issues make traditional recovery algorithm unsuitable. In this paper, we propose an efficient algorithm with O(nr) message complexity where O(nr) is the total number of mobile hosts (MHs) related to the failed MH. In addition, these MHs only need to rollback once and can immediately resume its operation without waiting for any coordination message from other MHs. During normal operation, the application message needs O(1) additional information when it transmitted between MHs and mobile support stations (MSSs). Each MSS must keep an ntotal_h*n cell_h dependency matrix, where O(ntotal_h) is the total number of MHs in the system and ncell_h is the total number of MHs in its cell. Finally, one related issue of resending lost messages is also considered.