Radio frequency IDentification (RFID) applications in the Internet of Things usually use multiple readers to read multiple tags. In such a practice, reader collisions may critically affect the performance. To obtain better reading schedules for the readers in order to enhance the RFID performance, the authors introduce a new and efficient anti‐collision algorithm – the SwitchTable algorithm – in this study. The authors build the new algorithm over the concepts of the four‐colour theorem and also the switch tables to fix the loopholes in existing algorithms – mainly the practice of variable MaxColor and the broadcast of kick signals. The authors’ SwitchTable algorithm sets MaxColor to four according to the four‐colour theorem, to avoid possible collisions and solve the problem of previous dynamic MaxColor change. It meanwhile uses a colour switch mechanism which works by switch tables and unicasting switch signals (not broadcasting kick signals) to remove the impact of sending kick signals and attain more efficient planned colour change. Extended simulation runs are carried out to evaluate the performance of various anti‐collision algorithms, including DCS, ColorWave, ColorTable and the authors’ SwitchTable. The results show that, with the new features, the authors’ new algorithm produces constantly better transmission success ratios and throughput , particularly in more complex RFID networks.

In vehicular ad‐hoc networks, high mobility tends to break established paths and cause bandwidth waste because of path reconstruction. To improve the situation, this study presents a new position‐based protocol. The new protocol uses control packets to collect approaching‐the‐junction information and, based on the information, lets moving vehicles adapt their routing paths dynamically when arriving at a junction. Compared with existing protocols which pre‐store massive routing paths in a vehicle, the protocol can accurately relay packets to the destination by significantly reduced control packets. Transmission efficiency is therefore enhanced. Performance evaluation exhibits that the proposed protocol is suitable for practice in highly topology‐changing vehicle‐to‐vehicle environments because it can accurately select targets for packet relay at less routing and storage cost.

To conduct secure communications in wireless networks, clients must create safer keys from the recorded less secure passwords -- known as Password-Authenticated Key Exchange (PAKE). As attacker capability has evolved quickly, PAKE protocols must progress with time to fight against possible attacks. This paper makes an analytical survey on current cross-realm client-to-client (C2C) PAKE protocols and based on the Smart Card Framework Agreement develops a new and stronger C2C PAKE protocol to deal with malicious attacks. The new protocol involves client passwords, Smart Card information and server private keys to build a security protection mechanism which maneuvers by Mod calculation, Asymmetric encryption and Diffie-Hellman operations and is able to maintain communication security even when client passwords and server private keys are snatched. To verify the security of various C2C PAKE protocols -- including ours, we employ Yoneyama's Security Model which can verify even Key-Compromise Impersonation (KCI) and Leakage of Ephemeral Private (LEP) attacks. Cost comparisons -- covering calculation times and complexity -- are also provided. The results show that our protocol achieves notably better security at reasonable cost.

Building proper routing protocols for a Mobile Ad-hoc Network (MANET) is a critical challenge because (1) flooding route requests often results in broadcast storm (especially when nodes or connections increase) and (2) re-broadcasting route discovery packets to rebuild or repair a broken path (caused by node mobility) will consume more control packets. To solve such broadcast storm and path damage problems, this paper mixes the ideas of multipoint relaying and 2-hop route repair into a new routing protocol suitable for large-scale MANETs. Simulation results show that the new protocol can effectively repair damaged routes at reduced bandwidth consumption.

This paper presents a novel algorithm for tagging the relationship of test on the learning content called Binary Union-plus Tag (BUT). The proposed algorithm is motivated by the desire of students to re-study unacquainted content after a test. By binary coding items of content, BUT provides the users of an e-Learning system a certain range of content which lacks learning to connect to tests and content. It starts off with one of the content structures as a reference structure. Then, all the mistakes made on the test are mapped to the reference structure to highlight the re-studying area in the learning materials. To evaluate the performance of the proposed method, it has been used on the learning process of two hundred grade students. Moreover, the experimental results show that the proposed algorithm can considerably improve the achievement of students in terms of both locating the essential range of the content and providing the necessary matters.

This paper presents a Bidirectional Hierarchy-based Any cast Routing (BHAR) protocol for collecting data over multi-hop wireless sensor networks (WSNs). The BHAR protocol improves on existing HAR mechanisms to speed up the process of constructing hierarchical trees and repairing routes, and as a result to prolong network lifetime. Different from HAR, BHAR allows sinks and sources to initialize the construction of a hierarchical tree. By knowing only its own parent and neighbor nodes, each node can join a tree, exchange/refresh its routing table, and perform route repair without geographical information or being controlled remotely. Simulation results show that our BHAR performs apparently better than traditional HAR on network construction and route repair.

In this paper, we present a system for predicting the examination result, called automatic score prediction system (ASPS). ASPS builds on the lecture structure created by a teacher or a particular pedagogy a course content tree. Each examination sheet is then derived from this course content tree. Besides, each of the question items in an examination sheet belongs to either a section, a chapter, or a unit The difficulty and authority of the question items are determined by the weighted score. The main task of the system is in the classification of the testing results and in the provision of the learning curves and the remedial courses. The learning achievement and testing results can be summarized as a learning curve to the students. By analyzing the learning accomplishments, not only can ASPS predict the probabilistic result of the next examination, but it can also provide reviews or remedial lessons to the students. The main contributions of the ASPS system described herein are twofold: (1) the system can produce the learning curve based on the examination result, which would make it easy for the students and teachers to understand the learning results. (2) The system can provide the course contents to the students to help them review after the examination. Moreover, it provides suggestions for teaching on the not yet acquainted and confused contents.

Wireless sensor networks (WSNs) usually employ different ranging techniques to measure the distance between an unknown node and its neighboring anchor nodes, and based on the measured distance to estimate the position of the unknown node. This paper presents an effective Particle Swarm Optimization (PSO)-based Localization Scheme using the Radio Signal Strength (RSS) ranging technique. Modified from the iterative multilateration algorithm, our scheme is unique in adopting the location data of remote anchors provided by the closest neighbor anchors of an unknown node to estimate the unknown nodepsilas position and using the PSO algorithm to further reduce error accumulation. The new scheme meanwhile takes in a modified DV-distance approach to raise the success ratios of locating unknown nodes. Compared with related schemes, our scheme is shown through simulations to perform constantly better in increasing localization success ratios and decreasing location errors -- at reduced cost.

This paper presents a thorough performance analysis on various user location tracking strategies, including an enhanced caching strategy of ours. The results confirm favorable performance and reduced cost for our enhanced caching strategy.

We present a new cache invalidation strategy able to maintain data consistency between the server and mobile clients in an efficient way in mobile communications.

A new optimization technique, the genetic annealing algorithm (GAA), is proposed to solve the task matching and scheduling problem in a heterogeneous computing system. The GAA is simple in design; it employs only the stir operation, a novel idea with the annealing concept, to locate optimal solutions. Experimental evaluation shows that compared with the genetic algorithm, simulated annealing and guided evolutionary simulated annealing approaches, the GAA yields constantly favorable performance in terms of speedup, running time, cost and complexity.

Adaptive routing and virtual channels are used to increase routing adaptivity in wormhole-routed two-dimensional meshes. But increasing channel buffer utilization without considering even distribution of the traffic loads tends to cause congestion in the most adaptive routing area. To avoid such traffic congestion, a concept of the restricted area is proposed. The proposed restricted area, defined to be a part of the network where message transmission concentrates, can be located following the region of adaptivity. By properly guiding message routing inside and outside the area, we are able to achieve more balanced buffer utilization and to reduce traffic congestion accordingly. The performance of several routing algorithms with or without using the restricted area is simulated and evaluated under various traffic loads and distribution patterns. The results indicate that routing algorithms with the restricted areas yield constantly larger throughput and smaller latency than routing algorithms without using the concept.

Composed of various topologies, the k-ary n-cube system is desirable for accepting and executing topologically different tasks. To utilize its large amount of processor resources, several allocation strategies have been reported, each with certain restrictions that affect performance. For improvement, we propose a new allocation strategy for the k-ary n-cubes. The proposed strategy is an extension of the TC strategy for hypercubes and is able to recognize all subcubes with different topologies requested by tasks. Complexity analysis and performance comparison between related strategies are provided to demonstrate their advantages and disadvantages. Simulation results show that with full subcube recognition ability and no internal fragmentation, our strategy always exhibits better performance.

Fault diagnosis is important for the immediate elimination of faults in a network. Over the years the diagnosis of faults for a single path network is frequently reported but that for a multipath network remains relatively unattended. The goal of this research is to detect faults in the gamma interconnection network (GIN) and the cyclic gamma interconnection network (CGIN), two multistage interconnection networks (MINs) with multiple paths. Two approaches, the primary fault diagnosis approach and the advanced fault diagnosis approach, are proposed. The primary approach can be employed to detect and locate either a single fault or multiple faults in GINs and CGINs; the advanced approach is able to detect a single fault with much reduced detection time. For better illustration, examples are given following the presentation of each approach for both multipath networks. Extended simulation is conducted to demonstrate the effectiveness of the proposed approaches.

To improve the terminal reliability of the Gamma interconnection network (GIN), we consider altering its connecting patterns between stages to attain multiple disjoint paths between any source and destination pair. The new modified GIN, referred to as a CGIN with connecting patterns between stages exhibiting a cyclic feature, is able to tolerate any arbitrary single fault and to lift up terminal reliability accordingly. If several rows of switching elements are fabricated in one chip using the VLSI technology, a CGIN could lead to reduced cost because the pin count per chip decreases and the layout area taken by connections shrinks. To make routing and rerouting in the CGIN more efficient and simpler to implement, destination tag routing and rerouting is also provided.

To ensure high terminal reliability for the Gamma interconnection network (GIN), we propose a new modified GIN, referred to as CGIN (cyclic Gamma interconnection network) as its connecting patterns between stages exhibit a cyclic feature. The fact that there exist multiple disjoint paths between any communication pair for all types of CGINs makes it possible to tolerate any arbitrary single fault and to accomplish enhanced terminal reliability accordingly. The performance of the CGIN is also evaluated through simulation.

We propose a new processor allocation strategy that applies to any mesh system and recognizes submeshes of arbitrary sizes at any locations in a mesh system. The proposed strategy allocates a submesh of exactly the size requested by an incoming task, completely avoiding internal fragmentation. Because of its efficient allocation, this strategy exhibits better performance than an earlier allocation strategy based on the buddy principle. An efficient implementation of this strategy is presented. Extensive simulation runs are carried out to collect experimental cost and performance measures of interest under different allocation schemes.>

With all of the salient features of hypercubes, the cube-connected cycles (CCC) structure is an attractive parallel computation network suited for very large scale integration (VLSI) implementation because of its layout regularity. Unfortunately, the classical CCC structure tends to suffer from considerable performance degradation in the presence of faults. The authors deal with a fault-tolerant CCC structure obtained by incorporating a spare PE in each cycle and by adding extra links among PE's to realize dimensional substitutes for failed PE's in the immediate lower dimension. A unique feature of this design lies in that a faulty PE and its laterally connected PE are always replaced at the same time by their immediate vertical successor pair, achieving pairwise substitution to elegantly maintain the rigid full CCC structure after faulty PE's arise. The proposed structure improves reliability substantially without incurring large overhead in layout area. This design is compared with earlier fault-tolerant CCC designs in terms of normalized reliability, which takes area overhead into account. An extension to this fault-tolerant structure is also discussed.>

The Gamma interconnection network (GIN) is composed of 3*3 basic building blocks, with interconnecting patterns between stages following the plus-minus-2/sup i/ functions. The authors consider modifications to the GIN by altering the interconnecting patterns between stages so as to achieve high terminal reliability between any source-destination pair, resulting in the reliable GIN (REGIN). A type of REGIN's ensures totally disjoint paths in existence from any source to any destination, thereby capable of tolerating an arbitrary single fault. If several building blocks (i.e., 3*3 switches) are fabricated in one chip with very large scale integrated (VLSI) technology, the layout area and the pin count are less for the REGIN than for its GIN counterpart as a result of the change in the interconnecting patterns, giving rise to potential cost reduction. The terminal reliability of the REGIN is derived and compared with that of a compatible GIN. In addition, the performance of the REGIN is evaluated using simulation.>

Fully recognizing various subcubes in a hypercube computer efficiently is addressed. A method with much less complexity than the multiple-GC strategy in generating the search space, while achieving complete subcube recognition, is proposed. This method is referred to as a dynamic processor allocation scheme because the search space generated is dependent on the dimension of the requested subcube dynamically. The basic idea lies in collapsing the binary tree representations of a hypercube successively so that the nodes which form a subcube but are distant are brought close to each other for recognition. The strategy can be implemented efficiently by using right rotating operations on the notations of the sets of subcubes corresponding to the nodes at a certain level of binary tree representations. Results of extensive simulation runs carried out to collect performance measures for different allocation strategies are discussed. It is shown that this strategy compares favorably in most situations with other known allocation schemes capable of achieving complete subcube recognition.>

A processor allocation strategy is proposed which can apply to any mesh system and recognize submeshes with arbitrary sizes at any location in a mesh system. The proposed strategy allocates a submesh of exactly the size requested by an incoming task, completely avoiding internal fragmentation. Because of its efficient allocation, this strategy exhibits better performance than an earlier allocation strategy based on the buddy principle. An efficient implementation of this strategy is presented. Extensive simulation runs were carried out to collect experimental performance measures of interest under different allocation schemes for comparison.>

Fully recognizing various subcubes in a hypercube computer efficiently is nontrivial due to the specific structure of the hypercube. We propose a method with much less complexity than the multiple-GC strategy in generating the search space, while achieving complete subcube recognition. This method is referred to as a dynamic processor allocation scheme because the search space generated is dependent upon the dimension of the requested subcube dynamically, rather than being predetermined and fixed. The basic idea of this strategy lies in collapsing the binary tree representations of a hypercube successively so that the nodes which form a subcube but are distant would be brought close to each other for recognition. The strategy can be implemented efficiently by using shuffle operations on the leaf node addresses of binary tree representations. Extensive simulation runs are carried out to collect experimental performance measures of interest of different allocation strategies. It is shown from analytic and experimental results that this strategy compares favorably in many situations to any other known allocation scheme capable of achieving complete subcube recognition.