Early Packet Research Articles

Coherent transient exciton transport in disordered polaritonic wires

Abstract Excitation energy transport can be significantly enhanced by strong light–matter interactions. In the present work, we explore intriguing features of coherent transient exciton wave packet dynamics on a lossless disordered polaritonic wire. Our main results can be understood in terms of the effective exciton group velocity, a new quantity we obtain from the polariton dispersion. Under weak and moderate disorder, we find that the early wave packet spread velocity is controlled by the overlap of the initial exciton momentum distribution and its effective group velocity. Conversely, when disorder is stronger, the initial state is nearly irrelevant, and red-shifted cavities support excitons with greater mobility. Our findings provide guiding principles for optimizing ultrafast coherent exciton transport based on the magnitude of disorder and the polariton dispersion. The presented perspectives may be valuable for understanding and designing new polaritonic platforms for enhanced exciton energy transport.

Satisfying strict deadlines for cellular Internet of Things through hybrid multiple access

AbstractLatency‐constrained aspects of cellular Internet of Things (IoT) applications rely on Ultra‐Reliable and Low Latency Communications (URLLC), which highlight research on satisfying strict deadlines. In this study, we address the problem of latency‐constrained communications with strict deadlines under average power constraint using Hybrid Multiple Access (MA), which consists of both Orthogonal MA (OMA) and power domain Non‐Orthogonal MA (NOMA) as transmission scheme options. We aim to maximize the timely throughput, which represents the average number of successfully transmitted packets before deadline expiration, where expired packets are dropped from the buffer. We use Lyapunov stochastic optimization methods to develop a dynamic power assignment algorithm for minimizing the packet drop rate while satisfying time average power constraints. Moreover, we propose a flexible packet dropping mechanism called Early Packet Dropping (EPD) to detect likely to become expired packets and drop them immediately. Numerical results show that Hybrid MA improves the timely throughput compared to conventional OMA by up to and on average by more than . With EPD, these timely throughput gains improve to and , respectively.

Towards a real-time IoT: Approaches for incoming packet processing in cyber–physical systems

Embedded real-time devices for monitoring, controlling, and collaboration purposes in cyber–physical systems are now commonly equipped with IP networking capabilities. However, the reception and processing of IP packets generates workloads in unpredictable frequencies as networks are outside of a developer’s control and difficult to anticipate, especially when networks are connected to the internet. As of now, embedded network controllers and IP stacks are not designed for real-time capabilities, even when used in real-time environments and operating systems.Our work focuses on real-time aware packet reception from open network connections, without a real-time networking infrastructure. This article presents two experimentally evaluated modifications to the IP processing subsystem and embedded network interface controllers of constrained IoT devices. The first, our software approach, introduces early packet classification and priority-aware processing in the network driver. In our experiments this allowed the network subsystem to remain active at a seven-fold increase in network traffic load before disabling the receive interrupts as a last resort. The second, our hardware approach, makes changes to the network interface controller, applying interrupt moderation based on real-time priorities to minimize the number of network-generated interrupts. Furthermore, this article provides an outlook on how the software and hardware approaches can be combined in a co-designed packet receive architecture.

Secure Communication Channel Establishment: TLS 1.3 (over TCP Fast Open) versus QUIC

Secure channel establishment protocols such as Transport Layer Security (TLS) are some of the most important cryptographic protocols, enabling the encryption of Internet traffic. Reducing latency (the number of interactions between parties before encrypted data can be transmitted) in such protocols has become an important design goal to improve user experience. The most important protocols addressing this goal are TLS 1.3, the latest TLS version standardized in 2018 to replace the widely deployed TLS 1.2, and Quick UDP Internet Connections (QUIC), a secure transport protocol from Google that is implemented in the Chrome browser. There have been a number of formal security analyses for TLS 1.3 and QUIC, but their security, when layered with their underlying transport protocols, cannot be easily compared. Our work is the first to thoroughly compare the security and availability properties of these protocols. Toward this goal, we develop novel security models that permit “layered” security analysis. In addition to the standard goals of server authentication and data confidentiality and integrity, we consider the goals of IP spoofing prevention, key exchange packet integrity, secure channel header integrity, and reset authentication, which capture a range of practical threats not usually taken into account by existing security models that focus mainly on the cryptographic cores of the protocols. Equipped with our new models we provide a detailed comparison of three low-latency layered protocols: TLS 1.3 over TCP Fast Open (TFO), QUIC over UDP, and QUIC[TLS] (a new design for QUIC that uses TLS 1.3 key exchange) over UDP. In particular, we show that TFO’s cookie mechanism does provably achieve the security goal of IP spoofing prevention. Additionally, we find several new availability attacks that manipulate the early key exchange packets without being detected by the communicating parties. By including packet-level attacks in our analysis, our results shed light on how the reliability, flow control, and congestion control of the above layered protocols compare, in adversarial settings. We hope that our models will help protocol designers in their future protocol analyses and that our results will help practitioners better understand the advantages and limitations of secure channel establishment protocols.

On the Minimum Average Age of Information in IRSA for Grant-Free mMTC

We consider the optimal design of the frame-based irregular repetition slotted ALOHA (IRSA) protocol for minimizing the average age of information (AAoI) in grant-free massive machine-type communications (mMTC). To this end, we first characterize the AAoI as a function of the number of user elements (UEs), the frame duration, and the repetition distribution of IRSA. We present this characterization for IRSA schemes with packet recovery at the end of frame and packet generation either at the beginning of the frame or just in time before first transmission in a frame. We also propose and characterize the AAoI of a novel early packet recovery method which further reduces the average age of information. In all cases, the analysis reveals that, as a function of normalized channel traffic (defined as the ratio of number of UEs to frame duration), the AAoI first decreases linearly due to more frequent updates received from the UEs, and increases sharply beyond a critical point due to packet recovery failures caused by collisions. We then consider the problem of minimizing AAoI by optimizing over the normalized channel traffic and repetition distribution for all the proposed sampling and recovery schemes. The optimization problem is challenging since the objective function is semi-analytical and can only be completely characterized using simulations. In an asymptotic regime where the number of UEs as well as the frame size is large, we characterize the AAoI using upper and lower bounds. We also obtain a locally optimal normalized channel traffic and repetition distribution using differential evolution. Based on the insights obtained from the asymptotic analysis, we also propose a pragmatic approach to obtain a normalized channel traffic and repetition distribution for AAoI reduction in the non-asymptotic case. Finally, we empirically show that our AAoI minimizing schemes outperform conventional throughput optimal schemes.

IMPACT OF AN EARLY PREGNANCY EDUCATION PACKET ON PATIENT QUESTION VOLUME

To determine whether providing an evidence-based early pregnancy education packet (EPEP) to newly pregnant patients with a prior diagnosis of infertility impacts the volume of patients’ pregnancy-related questions.

Hybrid mechanism towards network packet early acceptance and rejection for unified threat management

Recent network architectures utilise many types of security appliances to combat blended attacks. However, managing multiple separate security appliances can be overwhelming, inefficient and expensive. Thus, multiple security features are needed to be integrated into unified security architecture resulting in an unified threat management system (UTM). In most current UTM systems, whenever a security feature is needed, the corresponding module is just ‘attached or added on’. This approach of adding on may reduce the UTM performance dramatically, especially when security features such as IDS/IPS are enabled. In this study, a hybrid mechanism is proposed to solve UTM redundant packet classification problem. The mechanism is based on the use of splay tree filters and pattern-matching algorithms to enhance packet filtering and deep packet inspection (DPI) performance. The proposed mechanism uses network traffic statistics to dynamically optimise the order of the splay tree filters, allowing early acceptance and rejection of network packets. In addition, DPI signature rules are reordered according to their matching frequencies, allowing early packets acceptance. The authors demonstrate the merit of their mechanism through simulations performed on firewall and snort as independent packet manipulation systems compared with the proposed hybrid mechanism that uses unified communication between them.

An Efficient Low-Power MAC Protocol for Wireless Body Sensor Networks

The battery of a sensor node in a wireless body sensor network is small, and therefore has a short lifetime. In consequence, intensive research is being conducted on schemes to efficiently utilize the energy of a sensor node. This paper proposes a new scheme to combine a transmission power control (TPC) model, which is a technology used to heighten energy efficiency in existing body sensor networks, with a low power medium access control (MAC) protocol. This model integrates the short preamble scheme of the existing X-MAC protocol and the TPC model, by combining an early ACK packet and a transmission power control packet. Our scheme efficiently transmits data by predicting the appropriate transmission power before transmitting data packets. We experiment with a TPC algorithm, and analyze the result in order to evaluate the performance of the proposed scheme.

Network Traffic Processing With PFQ

This paper presents Packet Family Queue (PFQ), a high-performance framework for packet processing designed to flexibly handle network applications parallelism and making traffic processing safe and easy. PFQ is an open-source module for the Linux kernel that combines software-accelerated packet I/O to in-kernel early stage packet processing and fine-grained distribution to network applications and physical devices. PFQ does not require any modification to network device drivers and exposes programming interfaces to multi-threaded applications natively designed to run on top of it, as well as to legacy monitoring tools using the pcap library. The results show that the flexibility and the backward compatibility provided by PFQ do not impact its processing performance that, in fact, reaches line rate figures in the cases of pure speed tests and real practical monitoring use cases on 10+ Gb/s links.

Statistical dynamic splay tree filters towards multilevel firewall packet filtering enhancement

Network Firewalls are considered to be one of the most important security components in today's IP network architectures. Performance of firewalls has significant impact on the overall network performance. Firewalls should be able to sustain a very high throughput and ensure network services availability. In this paper, we propose an analytical dynamic multilevel early packet filtering mechanism to enhance firewall performance. The proposed mechanism uses statistical splay tree filters that utilize traffic characteristics to minimize packet filtering time. The statistical splay tree filters are reordered according to the network traffic divergence upon certain threshold qualification (Chi–Square Test). That is, the proposed mechanism is able to decide whether or not there is a need to update the dynamic splay tree filters' order for filtering the next network traffic window and predict the best order pattern. Furthermore, the importance of optimizing packet rejection and acceptance is done through the multilevel packet filtering process; where in each level, unwanted packets are rejected as early as possible. The proposed mechanism can also be considered as a device protection mechanism against denial of service (DoS) attacks targeting the default filtering rule. Early packet acceptance is done using the splay tree data structure which adapts dynamically according to network traffic flows. Consequently, repeated packets will have less memory accesses and therefore reduce the overall packets filtering time as demonstrated in the evaluation section.

Opportunistic Flooding in Low-Duty-Cycle Wireless Sensor Networks with Unreliable Links

Flooding service has been investigated extensively in wireless networks to efficiently disseminate network-wide commands, configurations, and code binaries. However, little work has been done on low-duty-cycle wireless sensor networks in which nodes stay asleep most of the time and wake up asynchronously. In this type of network, a broadcasting packet is rarely received by multiple nodes simultaneously, a unique constraining feature that makes existing solutions unsuitable. In this paper, we introduce Opportunistic Flooding, a novel design tailored for low-duty-cycle networks with unreliable wireless links and predetermined working schedules. Starting with an energy-optimal tree structure, probabilistic forwarding decisions are made at each sender based on the delay distribution of next-hop receivers. Only opportunistically early packets are forwarded via links outside the tree to reduce the flooding delay and redundancy in transmission. We further propose a forwarder selection method to alleviate the hidden terminal problem and a link-quality-based backoff method to resolve simultaneous forwarding operations. We show by extensive simulations and test-bed implementations that Opportunistic Flooding is close to the optimal performance achievable by oracle flooding designs. Compared with Improved Traditional Flooding, our design achieves significantly shorter flooding delay while consuming only 20-60% of the transmission energy.

Dynamic rule and rule‐field optimisation for improving firewall performance and security

A novel approach is presented to improve firewall packet filtering through optimising the order of firewall rules for early packet acceptance as well as the order of rule-fields for early packet rejection. The proposed approach is based on the calculation of the histograms of packet matching rules and of packet not matching rule-fields. These histograms are able to effectively monitor firewall performance in real-time and to predict the patterns of packet filtering in terms of rules order and rule-fields order. Furthermore, the proposed approach becomes even more significant when firewall is heavily loaded with burst traffic. A comparison of the proposed approach and the other conventional approaches, including static rule order approach and dynamic rule order approach is presented. The numerical results obtained by simulations demonstrate that the proposed approach is able to significantly improve the firewall efficiency in terms of cumulative processing time compared to other conventional approaches. Furthermore, the proposed scheme also has the capability to significantly reduce the effect of many common network attacks on firewall performance.

New jitter-aware network coding approach for packet selection in wireless mesh network using Jacobsen

Article history: Received June 10, 2014 Accepted 20 November 2014 Available online November 23 2014 Network coding (NC) is an approach for increasing the throughput of communication networks. NC has been derived from the idea of combining packets and forwarding them to achieve higher throughputs. From the very beginning, NC has attracted the attentions of scholars since they could improve the throughput of wired networks. Previous works have focused on the improvement of network throughput. Some methods add artificial delay to send packets. The methods are used in order to gain coding time and to increase throughput but they could not be used in immediate applications. However, early packets dispatch or adding delay to packets, for increasing coding time, can influence on the jitter of sent data. On the other hand, jitter is an important parameter in determining multimedia broadcasting time. Unlike previous methods, this paper provides a jitter-based coding algorithm using Jacobsen method. In the proposed method, the selection priority is based on packets jitter so that a packet with the minimum jitter is considered as the first priority for coding. Related computations are performed through Jacobson algorithm. According to simulation results, selecting a proper coding pattern for jitter can improve jitter by 30% while the throughput of this method shows no considerable change compared with that of available methods. Growing Science Ltd. All rights reserved. 4 © 201 Coding model Network coding Quality of service Source routing algorithm Wireless networks

KREONET 기반의 광역 규모 오픈플로우 네트워크 구축 및 성능 분석

최근 네트워크 가상화 기능 및 망에 대한 프로그래밍의 용이성을 제공해 줄 수 있는 기반 기술로 오픈플로우 기술이 주목 받고 있다. 국내에서는 캠퍼스 실험실 수준의 로컬 망에서 오픈플로우 기술의 적용 및 Layer 3을 경유한 캠퍼스 망 간의 연동이 이뤄지고 있지만 IP 계층에서의 네트워크 지연 등으로 인한 성능 저하가 문제되고 있다. 본 논문에서는 로컬 망 수준이 아닌 국가과학기술연구망 기반의 광역 규모 오픈플로우 망을 순수 Layer 2상에서 설계 및 구축하고 종단간 Round-trip Time 측정, TCP/UDP 성능 테스트를 통해 오픈플로우 망과 오픈플로우 적용 전 일반 망의 성능을 비교 분석한다. 분석 결과, 광역 규모의 오픈플로우 망은 일반 망과 비교할 때, UDP 스트림에 대한 초반 패킷 손실 문제를 제외하고 대등한 수준의 성능을 보였다. 또한, 초반 UDP 패킷 손실로 인한 성능 저하 현상은 컨트롤러 상에 반복 유입되는 동일한 "Packet_in" 이벤트에 대한 예외 처리를 구현함으로써 개선시킬 수 있었다. Recently, OpenFlow has been paid attention to as a fundamental technology which provides a function of virtualization and programmability in network. In Korea, deployment of OpenFlow networks in campuses and the interconnection between them through tunneling in layer 3 has been performed. However, the performance of the interconnected networks is decreased due to delay in IP layer. In this paper, we design and deploy nation-wide, not local, OpenFlow networks in a pure layer 2 environment over KREONET. After that, we do end-to-end Round-trip Time measurements and TCP/UDP performance tests in OpenFlow and normal networks, and do comparison and analysis on the test results. The results show that the nation-wide OpenFlow networks provide equal performance to normal networks except for the initial packet loss for UDP streaming. In regards to the performance decrease due to early UDP packet loss, we can mitigate it by implementing exceptional procedures in a controller which deal with the same continuous "Packet_in" events.

Design and analysis of a model predictive controller for active queue management

Model predictive (MP) control as a novel active queue management (AQM) algorithm in dynamic computer networks is proposed. According to the predicted future queue length in the data buffer, early packets at the router are dropped reasonably by the MPAQM controller so that the queue length reaches the desired value with minimal tracking error. The drop probability is obtained by optimizing the network performance. Further, randomized algorithms are applied to analyze the robustness of MPAQM successfully, and also to provide the stability domain of systems with uncertain network parameters. The performances of MPAQM are evaluated through a series of simulations in NS2. The simulation results show that the MPAQM algorithm outperforms RED, PI, and REM algorithms in terms of stability, disturbance rejection, and robustness.

X.25 Virtual Circuits - TRANSPAC IN France - Pre-Internet Data Networking [History of communications

The following article , by Remi Despres, is the second on the history of X.25 systems to appear in this column. As noted by Dr. Despres, the previous article focused on the Canadian Datapac system. Earlier articles on packet switching in this column have included one on the history of the Arpanet/Internet and one on early British packet switching systems. What makes this article particularly distinctive, aside, of course, from the fact that it focuses on the major contributions of French engineers to the development of packet switching as well as to X.25 standardization, is that it carefully outlines the reasons for the choice of connection-oriented virtual circuits for the Transpac network, as contrasted with datagram-based packet switching adopted for Arpanet. Interestingly, Dr. Despres notes that the idea of using virtual-circuit connection-oriented packet switching in the Transpac development came from the British packet switching activity. It is to be noted that early commercial packet switching networks in the United States, such as Tymnet and Telenet, also adopted the virtual circuit paradigm.

Intelligent Stale-Frame Discards for Real-Time Video Streaming over Wireless Ad Hoc Networks

This paper presents intelligent early packet discards (I-EPD) for real-time video streaming over amultihop wireless ad hoc network. In a multihop wireless ad hoc network, the quality of transferring real-time video streams could be seriously degraded, since every intermediate node (IN) functionally like relay device does not possess large buffer and sufficient bandwidth. Even worse, a selected relay node could leave or power off unexpectedly, which breaks the route to destination. Thus, a stale video frame is useless even if it can reach destination after network traffic becomes smooth or failed route is reconfigured. In the proposed I-EPD, an IN can intelligently determine whether a buffered video packet should be early discarded. For the purpose of validation, we implement the I-EPD on Linux-based embedded systems. Via the comparisons of performance metrics (packet/frame discards ratios, PSNR, etc.), we demonstrate that video quality over a wireless ad hoc network can be substantially improved and unnecessary bandwidth wastage is greatly reduced.

The early history of packet switching in the UK [History of Communications

In this issue of the History Column we bring you an article by Prof. Peter Kirstein, one of the original contributors to early packet switching. We are probably all familiar with the history of the Internet, beginning with its genesis in the American-developed ARPAnet of the late 1960s and early 1970s. We may be less familiar with the contributions of British researchers, as well as those in other countries such as France, at about the same period of time, who worked closely with American researchers as well as independently in developing the packet-switching technology so fundamental to the Internet. Prof. Kirstein recounts the early activities by British engineers, led by Donald Davies of the National Physical Laboratory, the British Post Office, those of his own group at University College London, and others as well. He also ties this work into ongoing activities in the United States at the time. In future History Columns we plan to have similar articles by U.S. packet-switching pioneers on their own early activities in the field. This series of articles on the genesis of the Internet should be of great interest to all communication engineers. We commend the article following to your attention.

The early history of packet switching in the UK

In this issue of the History Column we bring you an article by Prof. Peter Kirstein, one of the original contributors to early packet switching. We are probably all familiar with the history of the...

Enhanced Predictive Handover for Fast Proxy Mobile IPv6

Proxy Mobile IPv6 (PMIPv6) has been proposed in order to overcome the limitations of host-based mobility management in IPv6 networks. However, packet losses during doing handover are still a problem. To solve this issue, several schemes have been developed, and can be classified into two approaches: predictive and reactive handover. Both approaches commonly use bi-directional tunnel between mobile access gateways (MAGs). In predictive schemes especially, mobility support for a mobile node (MN) is triggered by simplified link signal strength. Thereafter, the MN sends handover notification to its serving MAG, and is then able to initiate packet forwarding. Therefore, if the MN moves toward an unexpected MAG that does not have any pre-established tunnel with the serving MAG, it may lead to packet losses. In this paper, we define this problem as Early Packet Forwarding (EPF). As a solution, we propose an enhanced PMIPv6 scheme using two-phase tunnel control based on the IEEE 802.21 Media Independent Handover (MIH).