Set Of Packets Research Articles

A corpuscular picture of electrons in chemical bond.

We introduce a theory of chemical bond with a corpuscular picture of electrons. It employs a minimal set of localized electron wave packets with "floating and breathing" degrees of freedom and the spin-coupling of non-orthogonal valence-bond theory. Its accuracy for describing potential energy curves of chemical bonds in ground and excited states of spin singlet and triplet is examined.

Packet Fragmentation and Reassembly in Molecular Communication.

This paper describes packet fragmentation and reassembly to achieve reliable molecular communication among bionanomachines. In the molecular communication described in this paper, a sender bionanomachine performs packet fragmentation, dividing a large molecular message into smaller pieces and embedding into smaller molecular packets, so that molecular packets have higher diffusivity to reach the receiver bionanomachine. The receiver bionanomachine then performs packet reassembly to retrieve the original molecular message from a set of molecular packets that it receives. To examine the effect of packet fragmentation and reassembly, we develop analytical models and conduct numerical experiments. Numerical results show that packet fragmentation and reassembly can improve the message delivery performance. Numerical results also indicate that packet fragmentation and reassembly may degrade the performance in the presence of drift in the environment.

Effective interference level‐based packet transmission for multiple‐input multiple‐output systems with hybrid automatic repeat request

A packet transmission strategy for multiple-input multiple-output systems with interference cancellation detection and hybrid automatic repeat request (HARQ) processes is proposed. The error probability and throughput of such a system depend on the choice of the set of packets to be transmitted in each packet transmission time interval, but there are no existing implementable strategies to optimise such choice of packets. In this study, the authors first define a concept of the effective interference level (EIL) and establish the relationship between the EIL and the effective signal-to-interference-plus-noise ratio. Then they show that choosing the set of packets that minimises the EIL successively from the lowest to the highest HARQ round leads to a lower packet error and higher system throughput than conventional HARQ, which is verified by simulation. Also, the proposed EIL-based scheme uses only the acknowledgement feedback messages like a conventional HARQ scheme, because the number of HARQ rounds of each packet is the only required information to calculate the EIL. Simulation results show that the proposed scheme outperforms the conventional scheme in terms of throughput with the signal-to-noise ratio gain of about 4.2 dB at maximum.

Coded Cooperative Data Exchange Problem for General Topologies

We consider the coded cooperative data exchange problem for general graphs, both undirected and directed. In this problem, given a graph $G=(V,E)$ representing clients in a broadcast network, each of which initially hold a (not necessarily disjoint) set of information packets; one wishes to design a communication scheme in which eventually all clients will hold all the packets of the network. Communication is performed in rounds, where in each round a single client broadcasts a single (possibly encoded) information packet to its neighbors in $G$ . The objective is to design a broadcast scheme that satisfies all clients with the minimum number of broadcast rounds. The coded cooperative data exchange problem has seen significant research over the last few years; mostly when the graph $G$ is the complete broadcast graph in which each client is adjacent to all other clients in the network, but also on general topologies, both in the fractional and integral setting. In this paper, we focus on the integral setting in general topologies $G$ , both undirected and directed. For undirected graphs, we tie the coded cooperative data exchange problem on $G$ to variants of the dominating set problem and in such show that solving the problem exactly or even approximately within a multiplicative factor of $\log {|V|}$ is intractable (i.e., NP-hard). We then turn to study efficient data exchange schemes for undirected topologies yielding a number of communication rounds comparable with our intractability result. Last, we tie the coded cooperative data exchange problem for directed topologies to the directed Steiner tree problem, yielding efficient data exchange approximation schemes. Our communication schemes do not involve encoding, and in such yield bounds on the coding advantage in the setting at hand.

The generation of band information law and the dynamic hiding of information law

Function packet sets (P-sets) is a novel model with law and dynamic characteristics, which is composed of function internal P-set $$S^{{\bar{F}}}$$ and function outer P-set $$S^{F}$$ . Using the structure, law and dynamic characteristic of function P-sets, we present the concepts of P-information law and band information law and their generation. Subsequently, the attribute theorem of P-information, the hiding and hiding theorem of P-information in band information law and the recovery theorem of information law are studied. Based on the above theory results, an application example of information law hiding is given and validated.

Delay Optimization Via Packet Scheduling for Multi-Path Routing in Wireless Networks

In this paper, the delay optimization problem of multi-path routing in wireless networks is studied. We propose a packet scheduling algorithm weighted shortest delay (WSD) for multi-path routing with the objective minimizing the total weighted delay of a set of packets. To solve the issue of differentiated quality of service, WSD algorithm assigns a nonnegative weight for each packet of every kind of wireless network application. At each network node along the path from source to destination, whenever a link of the node becomes idle, WSD algorithm transmits the packet with largest ratio of its weight to packet length among available packets which have arrived but not yet transmitted. Theoretical analysis proves that WSD algorithm is asymptotically optimal for the total weighted delay of transmitted packets if the arrival times, weights and transmission times of packets are bounded. Real experiment results further verify that WSD algorithm can enhance the delay performance of multi-path routing protocol profoundly.

English

The main aim of this paper is to investigate the performance of multi-carrier code division multiple access (MC-CDMA) technique, which has gain much attention due to its high frequency spectrum efficiency and high data rate transmission and makes the wireless communication more reliable and efficient. MC-CDMA technique is the combination of both orthogonal frequency division multiplexing (OFDM) and code division multiple access (CDMA), which found to be very effective to mitigate the effect of fading channels and to improve the system performance. In this paper, we investigate the performance of conventional MC-CDMA system, orthogonal wavelet packet based MC-CDMA system (WP-MC-CDMA), and Huang Hilbert Transformation (HHT) based MC-CDMA system. However, the conventional MC-CDMA has already been discussed in the literature, and used as a benchmark for other two schemes. In addition, the orthogonal wavelet packet based MC-CDMA technique is designed with a set of wavelet packets and used as the modulation waveforms in a multicarrier CDMA system. The WP-MC-CDMA shows their superiority over conventional MC-CDMA in terms of bit error rate (BER), and helps to mitigate the effects of interference and channel fading. Moreover, we also investigate the performance of Huang Hilbert Transformation based MC-CDMA. This scheme outperforms than that of other two techniques. This is due to Huang Hilbert Transformation based MC-CDMA is based on the knowledge of the instantaneous channel state information and instantaneous imperfect channel estimates. Therefore, by the knowledge of their instantaneous channel gains, it shows their superiority over of conventional MC-CDMA and WP-MC-CDMA in terms of spectral efficiency and data rate transmission. Furthermore, we also present the comparison all three techniques in terms of BER. Finally, our numerical and simulation results validate our proposed theoretical findings.

Automatic Test Packet Generation

Networks are getting larger and more complex, yet administrators rely on rudimentary tools such as ping and traceroute to debug problems. We propose an automated and systematic approach for testing and debugging networks called “Automatic Test Packet Generation” (ATPG). ATPG reads router configurations and generates a device-independent model. The model is used to generate a minimum set of test packets to (minimally) exercise every link in the network or (maximally) exercise every rule in the network. Test packets are sent periodically, and detected failures trigger a separate mechanism to localize the fault. ATPG can detect both functional (e.g., incorrect firewall rule) and performance problems (e.g., congested queue). ATPG complements but goes beyond earlier work in static checking (which cannot detect liveness or performance faults) or fault localization (which only localize faults given liveness results). We describe our prototype ATPG implementation and results on two real-world data sets: Stanford University's backbone network and Internet2. We find that a small number of test packets suffices to test all rules in these networks: For example, 4000 packets can cover all rules in Stanford backbone network, while 54 are enough to cover all links. Sending 4000 test packets 10 times per second consumes less than 1% of link capacity. ATPG code and the data sets are publicly available.

Efficient Rostering of Mobile Nodes in Intermittently Connected Passive RFID Networks

This paper focuses on the problem of rostering in intermittently connected passive RFID networks. It aims to report a list of tagged mobile nodes that appear in given interested area(s) and time interval(s). Such rostering faces several unique challenges. First, the network consists of two dramatically different types of nodes: powerful static readers and extremely resource-constrained mobile tags. Communication can be established from a reader to a tag only, but not tags to tags or readers to readers. Therefore, the connectivity is very low and intermittent. Besides connectivity, the tag's computation power is also intermittent. It is available only for a short interval when the tag is powered up by a nearby reader, rendering any continuous functions impossible. Moreover, the capacity of tags is so limited that it becomes the critical network resource and communication bottleneck. To address the above challenges, we propose a rostering algorithm that employs a dynamic space-efficient coding scheme to construct hypothetic packet candidates, appraises their values according to information redundancy and tag mobility, and establishes a 0-1 Knapsack model to choose the best set of packets, which together maximize their total (redundancy-excluded) value, but do not exceed the capacity of a tag. We carry out experiments that involve 38 volunteers for nine days and perform large-scale simulations to evaluate the proposed rostering scheme.

When 3G Meets VANET: 3G-Assisted Data Delivery in VANETs

In this paper, we consider a sensory data gathering application of a vehicular ad hoc network (VANET) in which vehicles produce sensory data, which should be gathered for data analysis and making decisions. Data delivery is particularly challenging because of the unique characteristics of VANETs, such as fast topology change, frequent disruptions, and rare contact opportunities. Through empirical study based on real vehicular traces, we find an important observation that a noticeable percentage of data packets cannot be delivered within time-to-live. In this paper, we explore the problem of 3G-assisted data delivery in a VANET with a budget constraint of 3G traffic. A packet can either be delivered via multihop transmissions in the VANET or via 3G. The main challenge for solving the problem is twofold. On the one hand, there is an intrinsic tradeoff between delivery ratio and delivery delay when using the 3G. On the other hand, it is difficult to decide which set of packets should be selected for 3G transmissions and when to deliver them via 3G. In this paper, we propose an approach called 3GDD for 3G-assisted data delivery in a VANET. We construct a utility function to explore the tradeoff between delivery ratio and delivery delay, which provides a unified framework to reflect the two factors. We formulate the 3G-assisted data delivery as an optimization problem in which the objective is to maximize the overall utility under the 3G budget constraint. To circumvent the high complexity of this optimization problem, we further transition the original optimization problem as an integer linear programming problem (ILP). Solving this ILP, we derive the 3G allocation over different time stages. Given the 3G budget at each time stage, those packets that are most unlikely delivered via the VANET are selected for 3G transmissions. We comprehensively evaluate our 3GDD using both synthetic vehicular traces and real vehicular 3G traces. Evaluation results show that our approach outperforms other schemes under a wide range of utility function deflations and network configurations.

Attribute Dependence of P-Information Law and its Application

Function P-sets (function packet sets) is a novel mathematics structure and model. P-information law is generated by function P-sets, which is an information law pair composed of internal P-information law and outer P-information law . Using the generation and structure of P-information law, the attribute dependence, attribute dependence measurement and attribute dependence theorem of P-information law are presented. Based on the results, the application of P-information attribute dependence is given.

Inverse Packet Sets and Information Mining-discovery of Intelligent Fusion

Inverse Packet Sets and Information Mining-discovery of Intelligent Fusion

�� Operations on Packet Sets and the Significance of Application

�� Operations on Packet Sets and the Significance of Application

Packet Sets and Identification of Inward-convergence Information

Packet Sets and Identification of Inward-convergence Information

Systematic Structural Testing of Firewall Policies

Firewalls are the mainstay of enterprise security and the most widely adopted technology for protecting private networks. As the quality of protection provided by a firewall directly depends on the quality of its policy (i.e., configuration), ensuring the correctness of firewall policies is important and yet difficult. To help ensure the correctness, we propose a systematic structural testing approach for firewall policies. We define structural coverage (based on coverage criteria of rules, predicates, and clauses) on the firewall policy under test. To achieve high structural coverage effectively, we have developed four automated packet generation techniques: the random packet generation, the one based on local constraint solving (considering individual rules locally in a policy), the one based on global constraint solving (considering multiple rules globally in a policy), and the one based on boundary values. We have conducted an experiment on a set of real policies and a set of faulty policies to detect faults with generated packet sets. Generally, our experimental results show that a packet set with higher structural coverage has higher fault-detection capability (i.e., detecting more injected faults). Our experimental results show that a reduced packet set (maintaining the same level of structural coverage with the corresponding original packet set) maintains similar fault-detection capability with the original set.

Prepare Tone: Enhancing Broadcast-Packet Transmission of Multiple Rendezvous Mac Performance in Multiple-Channel Ad Hoc Network

Multiple Rendezvous approaches utilized multi-channel which was only with a single transceiver radio may enhance Mac throughputs of multi-channel ad hoc network no less than that of other approaches which need extra radios or hardware for time synchronization. However, for the media-access methods of Multiple Rendezvous, nodes in ad hoc network should be listening on different channels to preserve the control packets of any data transmission with noneinterference each other. Therefore, for any broadcast data packet or multicast data packet, it should be transmitted to its destinations like a set of single-cast data packets. And then other performances of ad hoc network as routing may be reduced by the high overload of broadcast packet. In order to reduce the transmission number of a broadcast packet, a method of using prepare tones (single-cast tone and broadcast tone) before data-packet transmission is presented, we called it PTMC (Prepare Tone for Media-access Control). In the method of PTMC, any broadcast packet will be send out only once to preserve it can reach any idle destination, which is not sending or receiving any data-packets at that time, nevertheless any single-cast packet will be matched and send out just as MAXM done. Simulation results among PTMC, MAXM and SSCH show: If every broadcast packet was send to potential receivers one by one, the throughputs of ad hoc network routed by AODV and media controlled by MAXM or SSCH may not be improved as the available channel number is increasing, for reasons of the routing discovery time increasing. Using PTMC to solve this problem, whatever data-traffics or available channels are provided, the throughput of PTMC will be better than the other two. Thus with available channels increasing, the throughput of PTMA is improved.

Design and Analysis of Relay-aided Broadcast using Binary Network Codes

We consider a base-station broadcasting a set of order-insensitive packets to a user population over packet-erasure channels. To improve efficiency we propose relay-aided transmission using instantaneously-decodable binary network coding. The proposed coding schemes have the benefits of minimal decoding delay and low complexity. We further analyze the performance of the resulting broadcast schemes, and show that significant improvements in transmission efficiency are obtained as compared to previously proposed ARQ and network-coding-based schemes.

Compound-Fault Diagnosis of Bearing Based on Order Tracking Wavelet Packet and Rough Sets

The diagnosis of compound-fault is always a difficult point, and there is not an effective method in equipment diagnosis field, then a new method of compound-fault diagnosis was presented. The vibration signals at start-up in the gearbox are non-stationary signals, and traditional ways of diagnosis have low precision. Order tracking and wavelet packet and rough sets theory are introduced in the compound-fault diagnosis of bearing. First, the vibration signals at start-up were resampled using computer order tracking arithmetic and equal angle distributed vibration signals were obtained, and wavelet packet has been used for equal angle distributed vibration signals decomposition and reconstruction. Then, energy distribution of every frequency band can be calculated according to normalization process. A new feature vector can be obtained, then clear and concise decision rules can be obtained by rough sets theory. Finally, the result of compound-fault example proves that the proposed method has high validity and more amplitude appliance foreground.

Function P-sets

P-sets (packet sets) is improved by introducing function into it, and the concept and structure of function P-sets (function packet sets) is proposed, which is a set pair composed of the function internal P-set \( S^{{\bar{F}}} \)(function internal packet set \( S^{{\bar{F}}} \)) and the function outer P-set SF (function outer packet set SF). Function P-sets has dynamic characteristics and law characteristics. Under certain conditions, function P-sets can return to the “origin” of function ground sets S. In the paper, it is proved that function P-sets is extension of P-sets, conversely, P-sets is special case of function P-sets. Applications of function P-sets in discovery of unknown information laws hidden information systems, are provided. Function P-sets is a new theory and a new method to research dynamic information laws for information systems.

Quantum and quasiclassical state-to-state dynamics of the NH + H reaction: Competition between abstraction and exchange channels

Quantum and quasiclassical state-to-state dynamics for the NH + H' reaction at high collision energies up to 1.6 eV was studied on an accurate ab initio potential energy surface. Both of the endothermic abstraction (NH + H' → N + HH') and thermoneutral exchange (NH + H' → H + NH') channels were investigated from the same set of wave packets using an efficient coordinate transformation method. It is found that the abstraction represents a minor reaction channel in the energy range studied, primarily due to endothermicity. The cross section for the abstraction reaction increases monotonically with the collision energy, while that for the exchange reaction is relatively energy insensitive. As a result, the thermal rate constant for the abstraction reaction follows the Arrhenius law, where that for the exchange reaction is nearly temperature independent. Finally, it is shown that the quantum mechanical results can be reasonably reproduced by the Gaussian-binning quasiclassical trajectory method and to a lesser extent by a quantum statistical model.