A novel time-hopping (TH) multiple access ultrawideband (UWB) system employing M -ary orthogonal pulse position modulation (PPM) is proposed and investigated. A concept of removing the usage of time slots within a frame period is applied in the proposed TH/M -ary PPM UWB system. The transmitter of each user exploits a pseudorandom TH address to produce the TH-coded symbols, which are inputted t...

The rst Zagreb index of a graph is equal to the sum of the square of the vertex degrees of the graph and the forgotten topological index (Findex) of a graph is de ned as the sum of cubes of the vertex degrees of the graph. These parameters have applications in chemistry and drug structures. For any xed integer d ≥ 2, the d-ary tree is a rooted tree in which each node has no more than d children...

Let Kq(n,R) denote the minimal cardinality of a q-ary code of length n and covering radius R. Recently the authors gave a new proof of a classical lower bound of Rodemich on Kq(n, n−2) by the use of partition matrices and their transversals. In this paper we show that, in contrast to Rodemich’s original proof, the method generalizes to lower-bound Kq(n, n − k) for any k > 2. The approach is bes...

in this paper, a parameter uniform numerical method based on shishkin mesh is suggested to solve a system of second order singularly perturbed differential equations with a turning point exhibiting boundary layers. it is assumed that both equations have a turning point at the same point. an appropriate piecewise uniform mesh is considered and a classical finite difference scheme is applied on t...

The M -ary differential-chaos-shift-keying (M -ary DCSK) system offers a good noise performance over an additive white Gaussian noise (AWGN) channel in the category of non-coherent detection chaotic systems. However, the way that the M -ary DCSK system utilizes the available Walsh codes results in a relatively low bandwidth efficiency. Moreover, the number of delay elements required at the tran...

This paper presents the performance of the Weight-Balanced Testing (WBT) algorithm with multiple testers. The WBT algorithm aims to minimize the expected number of (round of) tests and has been proposed for coding, memory storage, search and testing applications. It often provides reasonable results if used with a single tester. Yet, the performance of the WBT algorithm with multiple testers an...

An analytical study is presented for the performance of fast frequency-hopping (FFH) self-normalized orthogonal -ary frequency-shift-keyed (MFSK) noncoherent receivers in the presence of multitone jamming. The multiple equal-power jamming tones are assumed to correspond to some of the possible FFH/ -ary orthogonal signaling tones. It has been shown that a higher diversity order (the number of h...

We study restricted computation models related to the tree evaluation problem. The TEP was introduced in earlier work as a simple candidate for the (very) long term goal of separating L and LogDCFL. The input to the problem is a rooted, balanced binary tree of height h, whose internal nodes are labeled with binary functions on [k] = {1, . . . , k} (each given simply as a list of k2 elements of ...

Russian Doll Search (RDS) is a clever procedure to solve overconstrained problems. RDS solves a sequence of nested subprob-lems, where two consecutive subproblems diier in one variable only. We present the Specialized RDS (SRDS) algorithm, which solves the current subproblem for each value of the new variable with respect to the previous subproblem. The SRDS lower bound is superior to the RDS l...

We consider algorithms of the Waltz type for computing local consistency (also called arc-consistency) for constraints over numeric domains. Many commonly used propagation rules do not in fact enforce local consistency. We extend the propagation rule given by Falt-ings Faltings, 1994] to the case of ternary constraints. Since any general n-ary continuous constraint can be represented as a colle...