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In this two-part article, I trace the history of the Internet. The Internet started in 1969 as an experiment by the Advanced Research Projects Agency (ARPA) of the US Department of Defense to use packet switching on leased telephone lines to connect four mainframe computers. Email was invented in 1971 and it became a "killer application" as it promoted easy interaction among its users. By 1972, fifty computers were connected using leased telephone lines to form what was known as the ARPANET which was successfully demonstrated at an international conference — ICCC 72. ARPANET was followed by Packet Radio Network (PRNET), which connected mobile computers, and Satellite Network (SATNET), which connected computers in Europe with those in the US. A protocol named Transmission Control Protocol/ Internet Protocol (TCP/IP) was invented in 1973 to interconnect ARPANET, PRNET, and SATNET. The success of the TCP/IP protocol in connecting disparate networks paved the way for the development of the Internet. [ABSTRACT FROM AUTHOR]

Optical packet switching is a prominent technology proposing not only a reduction in the energy consumption by the elimination of numerous optical–electrical–optical conversions in electronic switches, but also a decrease in network latencies due to the cut-through nature of packet transmission. However, it is adversely affected by packet contention, preventing its deployment. Solutions have been proposed to tackle the problem: addition of shared electronic buffers to optical switches (then called hybrid opto-electronic switches), customization of TCP protocols, and use of different service classes of packets with distinct switching criteria. In the context of data center networks, we investigate a combination of said solutions and show that the hybrid switch, compared to the optical switch, boosts the performance of the data center network. Furthermore, we show that introducing a "Reliable" service class improves performance for this class not only in the case of the hybrid switch, but also brings the optical switch to performance levels comparable to that of the hybrid switch, all the while keeping other classes' performance on the same level. [ABSTRACT FROM AUTHOR]

With the advent of new technologies, such as software-defined networks (SDN) and fog computing, and the development of communication technology and the vehicular industry, there has been a remarkable growth in intelligent transportation systems (ITS) in recent years. As a main component of ITS, vehicular ad hoc networks (VANETs) suffer from a host of problems, including architectural inflexibility, wireless communication instability, limited range of communications, and frequent topological changes due to the rapid mobility of vehicles. One of the challenges in vehicular ad hoc networks is the lack of efficient and reliable communication between vehicles. Also, given the huge amounts of data production and big data, the communication capabilities of vehicles can be utilized to effectively transmit and communicate data, thus reducing excessive bandwidth usage in internet networks and their infrastructure. The current paper's aim is to present a method for improving the transmission of data packets in inter-vehicle communications. In this regard, software-defined networks and fog-based computing offer substantial benefits. The proposed routing method includes the switching of data packet transmission through the VANET infrastructure and internet transmission. SDN- and Fog computing-based Switchable Routing (SFSR) provides the best path for the inter-vehicle transmission of data packets. When data packet transmission via VANETs is not possible, transmission may be performed via internet. The results of the simulation indicate improved performance of SFSR in terms of the packet delivery ratio, packet loss ratio, end-to-end delay, routing overhead, and routing failure rate. [ABSTRACT FROM AUTHOR]

Internet traffic continues to grow relentlessly, driven largely by increasingly high resolution video content. Although studies have shown that the majority of packets processed by Internet routers are pass-through traffic, they nonetheless have to be queued and routed at every hop in current networks, which unnecessarily adds substantial delays and processing costs. Such pass-through traffic can be better circuit-switched through the underlying optical transport network by means of pre-established circuits, which is possible in a unified packet and circuit switched network. In this paper, we propose a novel convex optimization framework based on a new destination-based multicommodity flow formulation for the allocation of circuits in such unified networks. In particular, we consider two deployment settings, one based on real-time traffic monitoring, and the other relying upon history-based traffic predictions. In both cases, we formulate global network optimization objectives as concave functions that capture the fair sharing of network capacity among competing traffic flows. The convexity of our problem formulations ensures globally optimal solutions. [ABSTRACT FROM AUTHOR]

IPv6 is an Internet protocol with the ability to provide a large number of addresses to allow the connectivity of each existing thing to the global network. It also allows the deployment of many technologies and services of the next generation. One of the major changes that occurred in the IP header with this new version is the addition of the IPv6 flow label field, which was created with the intention of labeling packets that belong to a particular flow to provide an appropriate treatment by routers. However, this field has not been widely exploited yet, and it is being set to zero in almost all IPv6 packets. The main Internet routing problem is that said routing is based on the shortest path algorithm, which leads to the possibility of some paths being congested while others are underused. To solve the congestion problem, many solutions aiming at traffic engineering support have been proposed, but this topic remains an open issue. This paper describes a new solution to support traffic engineering based on the usage of the IPv6 flow label for providing fast packet switching, which we have called PSA-TE6. In this document, we present the PSA-TE6 operation and evaluation regarding the label space reduction, label stacking cost and its minimization. The results show that PSA-TE6 is cheaper compared to the IP/MPLS solution when there is no label stacking, and that PSA-TE6 also outperforms IP/MPLS when the stacking is enabled until achieving a 40% presence of tunnels for encapsulation levels greater than 1. [ABSTRACT FROM AUTHOR]

Function packet set is a dynamic model of information law, which introduces function concept into packet set and improves it; function packet set is a function set pair composed of function internal packet set SF¯ and function outer packet set SF; or, (SF¯,SF) is a function packet set. Packet reasoning is a dynamic reasoning generated from packet set, and it’s composed of internal packet reasoning and outer packet reasoning. This paper introduces function into packet reasoning, improves packet reasoning and gives packet information law reasoning; by cross-penetration of function outer packet set with outer packet information law reasoning, the studies on intelligent fusion of outer packet information law and its outer separating are given. The generating of outer packet information law reasoning of intelligent fusion of outer packet information law, intelligent fusion of outer packet information law with attribute conjunctive reduction theorem, outer separating and reducing of intelligent fusion of outer packet information law and outer separating of intelligent fusion of outer packet information law with discovery-application of unknown information law are given in this paper. [ABSTRACT FROM AUTHOR]

The transmission of haptic data is relatively challenging in multimedia communication. In this research study, the methods are presented for exploiting the properties of human haptic perception for data reduction of haptic data transmission. Packet-switched communication of haptic data is characterized by high packet rates on the communication channel. The quality of the internet-based haptic tele-control/tele-presence systems is highly dependent on the quality of the communication channel between the operator and the remote site, and on the delay jitter in the data exchange. The proposed research work is evaluated experimentally using a Geomagic Touch (previously PHANTOM Sensable Omni) haptic device with a sphere as a virtual model. Four experiments were conducted to evaluate the proposed research study. In the first experiment the JND Weber’s law is applied on sent force values only, while in the second experiment, the force calculation algorithm has been modified to include human movement velocity. The third experiment discusses the use of JND on the sent velocity values. The evaluation of the human’s perception shows that the proposed modification to the basic dead-band approach highly reduces the number of sent packets with minimal disturbance in haptic feeling. Further enhancements using prediction techniques have also been introduced in the fourth experimental evaluation. The linear predictions are added to the above proposed reduction methods. Combining the dead-band approach with a fast, configurable and accurate prediction algorithm enables a significant reduction in the amount of data sent across the network. The reduction is estimated to be 85%, while preserving the original data structure. [ABSTRACT FROM AUTHOR]

A datacenter, which is a highly distributed multiprocessing system, needs to keep accurate track of time across a large number of machines. Precise time synchronization has become a critical component due to stringent requirements of several time critical applications such as real-time big data analytics, high-performance computing, and financial trading. Our study starts with a survey on the most relevant time synchronization techniques for datacenter networks. Then, we propose a zero-overhead microsecond-accuracy solution to synchronize a packet-switched optical network for datacenters. To achieve the desired time accuracy, we consider precision time protocol to synchronize the server clocks with a central controller clock. Zero-overhead is maintained by using data traffic to carry the time messages instead of a separate control channel. Through simulation, we show that microsecond level of time accuracy can be achieved. We also discuss the dependency of the accuracy on different traffic loads, traffic distributions, and packet lengths. [ABSTRACT FROM AUTHOR]

IP traceback using packet marking technique allows direct traceback of attackers. Under this strategy en route routers inject mark into packets which is later used to unambiguously identify the source of an attack. Star coloring approach allows the mark to be reused, thereby saving bit space and at the same time explicitly identify the attacker. As the Internet structure is unknown, in the present work we propose a distributed approach of assigning color (mark) to routers such that the star color template is followed without consideration of the graph structure. An algorithm is proposed to minimize the color assignment conflict. The convergence of the algorithm is also discussed. Simulation study is presented to support the convergence analysis. [ABSTRACT FROM AUTHOR]

Securing mobile ad hoc networks (MANET) has been the interest of researchers recently because of its use in important security sectors such as police, rescue teams, and the military. One method to ensure a secure ad hoc network is to identify malicious nodes (hostile) from good nodes by their reputation based on the past experience of packet delivery. In this paper, we explore by applying reputation in various ways the effect to the throughput of a MANET ad hoc network. We simulate four different scenarios where the node reputation is evaluated to choose the most reliable route and eliminate the effect of malicious nodes performing gray-hole attack. One of the applied scenarios is a hybrid method where a sender node takes in consideration the reputation of all the nodes forming a route to choose the most reliable route. We find that by applying the hybrid method the performance of the network is the best and data packets are more likely to be delivered successfully to the intended destination in a very hostile environment. [ABSTRACT FROM AUTHOR]

Wireless multimedia sensor networks (WMSNs) have emerged as a revolutionary technology, that has shifted the focus of low power wireless sensor networks (WSNs). These networks are aimed at gathering and delivering both scalar and multimedia data from the environment. WMSNs inherit the miniature size, low power, low processing and short range wireless communication traits from WSNs. Addition of multimedia content in WMSNs demands fulfillment of various QoS parameters like low end-to-end delay, acceptable jitter rate, low packet loss rate and higher throughput. Over the past few years, considerable research efforts have been directed towards the fulfillment of these QoS requirements; by proposing new traffic-aware medium access and routing algorithms. However, the issues of rate adaptation and congestion control are still largely unexplored. Congestion in wireless networks is a major cause of packet loss resulting in degraded network performance. In WMSNs congestion is a common occurrence, due to the communication of high data rate, bursty video traffic over lossy wireless link. Therefore, it is critical to adjust the sending rate of source nodes based on network conditions. This work investigates the issue of rate adaptation and congestion control in WMSNs. A traffic-aware congestion control protocol (TACC) is proposed that operates on end-to-end principle at the transport layer. The proposed protocol uses burst loss information to detect congestion at the destination and directs source nodes to adjust reporting rate accordingly. The proposed protocol is evaluated using simulation analysis which shows significant improvement in terms of packet losses, end-to-end delay, packet delivery ratio and received picture quality. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to propose a low complexity Heuristic Based Application Specific Packet Classification (HASPC) algorithm that ensures wire speed packet classification to prevent the delay and loss of multimedia packets. With the exponential growth in the link capacity, diversified services offered by the Internet and the complexities of the packet routing algorithms, wire speed classification in each router has become a bottleneck at high speed interfaces. Embedded, Network Processors (NPs) have emerged as an aid to the router for effectively processing the packets with speed and flexibility. The effectiveness of the proposed algorithm has been verified using Intel's IXP 2400 NP simulator. The improvement in throughput of HASPC with respect to other existing algorithms varies from around 17-86%. The complexity involved is also independent of the packet size. Thus the proposed HASPC has better efficiency in supporting multimedia applications. [ABSTRACT FROM AUTHOR]

A modified memory-space-memory (MSM) Clos-network switch, called MCNS, with a module-level matching packet dispatching scheme, is presented in the paper. The MCNS is a modification of the MSM Clos-network switch proposed to simplify the packet dispatching scheme. In this paper, we evaluate the combinatorial properties of the MCNS, as well as a new module-level matching packet dispatching algorithm. We also show how this algorithm can be implemented in an field-programmable gate array chip. Selected simulation results obtained for the MCNS are compared with the results obtained for the MSM Clos-network switch using other module-level matching algorithms. [ABSTRACT FROM AUTHOR]

Packet filtering allows a network gateway to control the network traffic flows and protect the computer system. Most of the recent research works on the filtering systems mainly concern the performance, reliability and defence against common network attacks. However, since the gateway might be controlled by red an untrusted attacker, who might try to infer the identity privacy of the sender host and mount IP tracking to its data packets. IP spoofing is another problem. To avoid data packets to be filtered in the packet filtering system, the malicious sender host might use a spoofed source IP address. Therefore, to preserve the source IP privacy and provide source IP authentication simultaneously in the filtering system is an interesting and challenging problem. To deal with the problem, we construct a data packet filtering scheme, which is formally proved to be semantic secure against the chosen IP attack and IP guessing attack. Based on this filtering scheme, we propose the first privacy-preserving packet filtering system, where the data packets whose source IP addresses are at risk are filtered, the privacy of the source IP is protected and its correctness can be verified by the recipient host. The analysis shows that our protocol can fulfil the objectives of a data packet filtering system. The performance evaluation demonstrates its applicability in the current network systems. We also presented a packet filtering scheme, where the data packets from one subnet can be filtered with only one filter policy. [ABSTRACT FROM AUTHOR]

An MAODV is an extension of AODV protocol. It's one of the efficient multicast tree structures. So many techniques are used to improve the performance of MAODV protocol such that performance like PDR, latency, energy. In minimum load adhoc networks the multicast route to recovery is effective. Merely, in maximum load network condition large number of packets discarded and poor robustness of the tree based protocols appears. This paper represents a way to improve the packet deliver ratio, latency and energy consumption of the system by using backup paths and to choose the best path among backup paths using genetic algorithm (GA) by using best fitness value for further transmission during route repair occurs. The validity of the tree based multicast protocols is improved by holding a network structure using backup paths. The efficiency of the tree structure is improved by using GA in the mesh structure created by backup paths. It not merely improves the reliability it also reduces the control and data overhead in the multicast tree. The operation of the system is measured by applying the simulation tool NS-2. Ultimately the performance is compared with MAODV protocol and current methods. [ABSTRACT FROM AUTHOR]

This paper presents a survey of data center network architectures that use both optical and packet switching components. Various proposed architectures and their corresponding network operation details are discussed. Electronic processing-based packet switch architectures and hybrid optical-electronic-based switch architectures are presented. These hybrid optical switch architectures use optical switching elements in addition to traditional electronic processing entities. The choice of components used for realizing functionality including the network interfaces, buffers, lookup elements and the switching fabrics have been analyzed. These component choices are summarized for different architectures. A qualitative comparison of the various architectures is also presented. [ABSTRACT FROM AUTHOR]

A method for optimization of parameters of a telecommunication and information network providing data processing and transmission in a mobile two-agent robotic system is considered. The first agent receives a Poisson stream of packets (information blocks) and retransmits them to the second agent for subsequent processing. The first agent loses the input packet if its buffer is overflown; the second agent does not admit the overflow of its buffer by sending a rejection message and requesting packet retransmission. The problem of minimization of input packet loss is solved in the steady-state mode under constraints on the processing time and energy consumption by controlling the transmission rate and rejection probability. Conditions in which the values of the objective and constraint functionals form a convex set are determined. The numerical synthesis of the control is implemented on the basis of the augmented Lagrangian method. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of robust exponential stabilization for sampled-data systems with variable sampling and packet dropouts. It is assumed that the system parameter uncertainties are norm-bounded and appear in both the state and input matrices. An input delay approach is adopted to model the sample-and-hold behavior with a time-varying delayed control input, and a switched system approach is proposed to model the data-missing phenomenon. On this basis, the sampled-data control system with variable sampling and packet dropouts is modeled as a switched system with time-varying delay. The objective is to design a sampled-data controller to guarantee the robust exponential stability of the resulting closed-loop system. Based on a new piecewise time-dependent Lyapunov functional, novel sufficient conditions are derived for the existence of robustly exponentially stabilizing sampled-data controllers. It is shown that the controller gains can be obtained by solving a set of linear matrix inequalities. Two simulation examples are given to demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, we propose an unequal Luby transform (LT) based on block weight shift (ULT-BWS) method as an unequal forward error correction method to minimize video distortion over packet-lossy networks. First, we consider unequal amount of error propagation effects from packet loss in hierarchical prediction structure to give unequal property in an LT codes. For robust video transmission over various channel status, the ULT-BWS method assigns an efficient amount of protection for frame blocks with different error propagation weights by controlling the range of more important blocks in a group of pictures. Simulation results demonstrate that the proposed ULT-BWS method gives robust performance and significantly improved video quality, compared with the conventional ULT schemes. [ABSTRACT FROM AUTHOR]

Throughput imbalances among contending flows are known to occur when any carrier sense multiple access (CSMA)-based protocol is employed in multi-hop wireless networks. These imbalances may vary from slight difference in throughput to complete starvation in which some flows are unable to acquire channel accesses. The root cause of such imbalances is the lack of coordination when CSMA medium access control (MAC) protocols are employed in multi-hop wireless networks. In this paper, we accurately predict per-flow throughput in general multi-hop wireless networks while addressing CSMA's coordination problem. Unlike the previous work, our analytical throughput prediction model can clearly differentiate between links interfering from transmission range and carrier sensing range. Modeling of conditional packet loss probability and busy time sensed by each station is critical for per-flow throughput prediction in arbitrary networks. The calculation of both these parameters largely depends on MAC behavior due to geometrical configuration of interfering stations; we accurately compute conditional packet loss probability and busy time based on geometrical configuration of the interfering stations and predicted per-flow throughput. Our analytical results demonstrate improved accuracy, indicate throughput imbalances, and provide better understanding of CSMA-based protocol behavior in multi-hop wireless networks that can be used to design fair, scalable, and efficient MAC layer protocols. [ABSTRACT FROM AUTHOR]

Vehicular ad hoc networks (VANETs) make the transmission between vehicles possible without infrastructure. However, ad hoc networks also increase the redundancy of networks. To decrease the redundancy of networks and make VANETs more efficient, we introduce the new routing protocol: intersection-based forwarding protocol (IBFP). In urban-area, we set virtual ports (VP) at each intersection. The virtual port is served by stopping vehicle which is waiting for the traffic light in front of the intersection. VP will gather all the packets that need to be forwarded from all passing by vehicles. When VP leaves this intersection, it will transmit all the copies of packets to the next VP. As the movement of VP, packets can be transmitted to every intersection in a very short period of time like the epidemic process. Destination vehicles can receive packets with high success rate. The epidemic process only exists among VPs. Therefore, on the premise of high success rate, the proposed IBFP can transmit packets with less delay and redundancy. [ABSTRACT FROM AUTHOR]

With the popularization of wireless mobile device, mobile social networks (MSNets) have begun to attract more and more attention. In MSNets, mobile social users can communicate with each other by intermittent connectivity. The wireless device moving trajectory reflects the social attribute of the device carrier. In this paper, the relay selection is addressed in terms of both the absolute character and the relative character of node moving trajectory. First, the hot degree of node movement trajectory is defined based on the steady-state node distribution using a semi-markov chain. Moreover, another semi-markov chain is used to predict the future locations of a mobile user, with the predictive location nodes as basis, and the similarity of node movement trajectories is presented. Furthermore, a data forwarding based on node moving trajectory is proposed. Its main idea is to choose a node with higher hot degree of node moving trajectory and lower similarity of movement trajectories between it and a packet carrier to propagate the data packets. The simulation results show that, compared with the Spray and Wait routing and the social groups-based routing, our algorithm can outperform them in the delivery ratio and delivery delay, and apparently reduce network overhead compared with the Epidemic algorithm. Additionally, our algorithm nears the maximum delivery ratio and minimum delivery delay obtained by the Epidemic algorithm in a realistic trace data. [ABSTRACT FROM AUTHOR]

Industrial cyber-physical systems (ICPS) bridge the physical factory floor and the cyber computational space by leveraging the emerging techniques, such as wireless sensor networks for ubiquitous connection and perception, where sensors are deployed to monitor and collect industrial data according to different timeliness requirements. Priority-aware schemes are often used to tackle the differentiated data packet collection. However, it is challenging to coordinate the multichannel access while meeting the priority-aware transmission requirement in ICPS. In this paper, we propose a separate design principle (SDP) for priority-aware packet collection. In SDP, the transmission of each priority class of sensors is separately scheduled by a multichannel superframe which fully uses the available channels. As a result, each time slot on each channel is repeatedly scheduled to sensors of different priorities by different superframes. Then, a priority-aware transmission mechanism is devised to coordinate the transmissions of different sensors in the predefined priority order. Simulation results show that for four priorities, SDP achieves as low as 16, 18, 23, and 36 % of the mean packet transmission delay of non-overlap TDMA scheduling for each priority class, respectively. Moreover, SDP greatly outperforms IEEE 802.15.4e protocol for packet collection with two priorities. We also demonstrate the feasibility of SDP based on the implementation of software-defined radios. [ABSTRACT FROM AUTHOR]

As a kernel function in network routers, packet classification requires the incoming packet headers to be checked against a set of predefined rules. There are two trends for packet classification: (1) to examine a large number of packet header fields, and (2) to use software-based solutions on multi-core general purpose processors and virtual machines. Although packet classification has been widely studied, most existing solutions on multi-core systems target the classic 5-field packet classification; it is not easy to scale up their performance with respect to the number of packet header fields. In this work, we present a decomposition-based packet classification approach; it supports large rule sets consisting of a large number of packet header fields. In our approach, range-tree and hashing are used to search the fields of the input packet header in parallel. The partial results from all the fields are represented in rule ID sets; they are merged efficiently to produce the final match result. We implement our approach and evaluate its performance with respect to overall throughput and processing latency for rule set size varying from 1 to 32 K. Experimental results on state-of-the-art 16-core platforms show that, an overall throughput of 48 million packets per second and a processing latency of 2,000 ns per packet can be achieved for a 32 K rule set. [ABSTRACT FROM AUTHOR]

Wireless sensor-actor networks (WSANs) are applicable in versatile domains ranging from very common to those which demand reliable actions in the event area. The unique characteristics of WSANs and the resource-constrained nature of the constituent sensor nodes give rise to design energy and delay efficient routing protocols. Many researchers have made considerable efforts to meet these challenges by designing energy and delay efficient protocols. In this paper, a comprehensive survey is presented on existing routing protocols for WSAN to analyze and list out their merits and demerits. The study broadly segregates the existing routing protocols into two categories i.e., cluster based and non-cluster based protocols. The cluster based protocols structure the physical network into virtual groups, whereas the non-cluster based protocols either use flooding or broadcasting mechanisms for communication. All the routing protocols under consideration have been simulated in a common simulation platform. Their performances are analyzed with respect to average end-to-end delay, packet delivery ratio, and average energy dissipation in the network individually. In addition, the best protocols among both the categories are compared to derive an overall conclusion. [ABSTRACT FROM AUTHOR]

Modeling and analysis of communication link duration in vehicular ad hoc networks (VANETs) is crucial as it directly affects many performance metrics such as packet delivery ratio, throughput and end-to-end delay. In this paper, we investigate the properties of communication link duration in one-dimensional VANETs for different fading channel conditions. We employ a stochastic microscopic mobility model that takes into account time dependence of the inter-vehicle distance. A discrete-time finite-state Markov chain with state dependent transition probabilities is used to model the inter-vehicle distance. The presence of fading channel conditions will introduce fluctuations in the received signal power. Even when the inter-vehicle distance between a given pair of vehicles is less than their transmission range, poor channel conditions may result in link failure. A modified distance transition probability matrix is derived to describe the combined effects of relative velocity among a pair of vehicles, link failure due to outage, and inter-vehicle distance. The probability distribution of the communication link duration is derived from the modified distance transition probability matrix. The analytical results obtained from the model are validated by extensive simulation results. [ABSTRACT FROM AUTHOR]

A stabilization problem in a networked control system with packet dropouts is studied and dynamic output-feedback control is constructed. Predictive control approach is employed for obtaining plant state estimates at each step k. This eliminates the need for considering explicitly plant state switching when a packet dropout occurs. [ABSTRACT FROM AUTHOR]

Reducing the NoC power is critical for scaling up the number of nodes in future many-core systems. Most NoC designs adopt packet-switching to benefit from its high throughput and excellent scalability. These benefits, however, come at the price of the power consumption and latency overheads of routers. Circuit-switching, on the other hand, enjoys a significant reduction in power and latency of communication by directing data over pre-established circuits, but the relatively large circuit setup time and low resource utilization of this switching mechanism is often prohibitive. In this paper, we address one of the major problems of circuit-switching, i.e. the circuit setup time overhead, by an efficient and fast algorithm based on the time-division multiplexing scheme. We then further improve the performance by reserving circuits for anticipated messages, and hence completely hide circuit setup time. To address the low resource utilization problem, we integrate the proposed circuit-switching into a packet-switched NoC and use unused circuit resources to transfer packet-switched data. Evaluation results show considerable reduction in NoC power consumption and packet latency. [ABSTRACT FROM AUTHOR]

We consider a server serving a time-slotted queued system of multiple packet-based flows, where not more than one flow can be serviced in a single time slot. The flows have exogenous packet arrivals and time-varying service rates. At each time, the server can observe instantaneous service rates for only a subset of flows (selected from a fixed collection of observable subsets) before scheduling a flow in the subset for service. We are interested in queue length aware scheduling to keep the queues short. The limited availability of instantaneous service rate information requires the scheduler to make a careful choice of which subset of service rates to sample. We develop scheduling algorithms that use only partial service rate information from subsets of channels, and that minimize the likelihood of queue overflow in the system. Specifically, we present a new joint subset-sampling and scheduling algorithm called Max-Exp that uses only the current queue lengths to pick a subset of flows, and subsequently schedules a flow using the Exponential rule. When the collection of observable subsets is disjoint, we show that Max-Exp achieves the best exponential decay rate, among all scheduling algorithms that base their decision on the current (or any finite past history of) system state, of the tail of the longest queue. To accomplish this, we employ novel analytical techniques for studying the performance of scheduling algorithms using partial state, which may be of independent interest. These include new sample-path large deviations results for processes obtained by non-random, predictable sampling of sequences of independent and identically distributed random variables. A consequence of these results is that scheduling with partial state information yields a rate function significantly different from scheduling with full channel information. In the special case when the observable subsets are singleton flows, i.e., when there is effectively no a priori channel state information, Max-Exp reduces to simply serving the flow with the longest queue; thus, our results show that to always serve the longest queue in the absence of any channel state information is large deviations optimal. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A new link layer protocol, quality of service hybrid multi channel protocol (QoS-HMCP), that takes into account the need for QoS support in multi-channel multi-interface wireless mesh networks (MCMI-WMNs) is proposed in this paper. QoS-HMCP protocol retains most properties of enhanced distributed channel access (EDCA) mechanism, defined by the 802.11 standard, as well as the basic mechanisms of HMCP protocol. To achieve good network performances with QoS-HMCP protocol in MCMI network, it was necessary to precisely define the channel coordination and procedure for the medium competition of EDCA functions (EDCAFs) after the expiration of interval of time within which a particular EDCAF has the right to initiate data exchange sequences onto the wireless medium-transmission opportunity. Taking into consideration the previously defined conditions, four versions of QoS-HMCP protocol are proposed in this paper. These versions were compared with each other and with basic HMCP with regard to the throughput of user data and delay through the network. The four versions of the QoS-HMCP protocol, multi channel routing (MCR) protocol and chosen metric were implemented in Glomosim simulator. The results have shown that implementation of QoS-HMCP protocol in MCMI-WMN resulted in a very small delay for voice and video traffic, while low-priority traffic categories (best effort and background) were still able to access the media. [ABSTRACT FROM AUTHOR]

Communication specialists around the world are facing the same problem: shifting from circuit switching (CS) to packet switching (CS). Communication service providers are favoring 'Allover-IP' technologies hoping to boost their profits by providing multimedia services. The main stakeholder in this field of the paradigm shift is the industry itself: packet switching hardware manufacturers are going to earn billions of dollars and thus pay engineers and journalists many millions for the promotion of the new paradigm. However, this drive for profit is tempered by life itself. This article is devoted to the discussion of the telecommunications development strategy. We will provide examples to illustrate the difficulties that complicate the transition from CS to PS and make us question the feasibility of shifting the telecommunications paradigm. We will consider two examples: [ABSTRACT FROM AUTHOR]

Conventional shortest path routing mechanisms in low power and lossy networks (LLNs) impose excessive traffic load on some nodes and cause their early battery depletion. Load balancing via multipath routing is a promising solution to increase lifetime. This idea is practised by some algorithms, mostly through limited number of disjoint paths, to reduce inter-path interference. In this paper a proactive multipath routing algorithm called MRPL is proposed, based on the recent standard routing protocol for LLNs. The algorithm tries to distribute the traffic load through a set of braided paths, with the objective of maximizing the network lifetime and minimizing total transmission cost. The traffic distribution mechanism is formulated by a linear program and a heuristic method is proposed to implement it in a distributed manner. Simulation results provide enough evidence for energy and cost efficiency of the proposed routing mechanism. [ABSTRACT FROM AUTHOR]

A link level reliable multicast requires a channel access protocol to resolve the collision of feedback messages sent by multicast data receivers. Several deterministic media access control protocols have been proposed to attain high reliability, but with large delay. Besides, there are also protocols which can only give probabilistic guarantee about reliability, but have the least delay. In this paper, we propose a virtual token-based channel access and feedback protocol (VTCAF) for link level reliable multicasting. The VTCAF protocol introduces a virtual (implicit) token passing mechanism based on carrier sensing to avoid the collision between feedback messages. The delay performance is improved in VTCAF protocol by reducing the number of feedback messages. Besides, the VTCAF protocol is parametric in nature and can easily trade off reliability with the delay as per the requirement of the underlying application. Such a cross layer design approach would be useful for a variety of multicast applications which require reliable communication with different levels of reliability and delay performance. We have analyzed our protocol to evaluate various performance parameters at different packet loss rate and compared its performance with those of others. Our protocol has also been simulated using Castalia network simulator to evaluate the same performance parameters. Simulation and analytical results together show that the VTCAF protocol is able to considerably reduce average access delay while ensuring very high reliability at the same time. [ABSTRACT FROM AUTHOR]

Packet delay control in mobile ad hoc networks (MANETs) is critical to support delay-sensitive applications in such networks. By combining erasure coding and packet redundancy techniques, this paper proposes a general two-hop relay algorithm 2HR- $$(x,\tau ,f)$$ for a flexible control of packet delivery delay in MANETs, where a group of x packets in source node are first encoded into $$x\cdot \tau$$ encoded packets based erasure coding, and each encoded packet is then delivered to at most f distinct relay nodes ( f-cast) that will help to forward the encoded packet to destination node. To understand the delay performance in a 2HR- $$(x,\tau ,f)$$ MANET, we then develop a discrete time multi-dimensional Markov chain model to depict the packet delivery process in the network, based on which closed-form results on mean and variance of packet delivery delay are further derived. Finally, extensive simulation and theoretical results are provided to illustrate the efficiency of our delay models as well as the capability of the 2HR- $$(x,\tau ,f)$$ algorithm in delay control. [ABSTRACT FROM AUTHOR]

Reliable data transmission is a fundamental challenge in resource-constrained wireless sensor networks. In current implementations, a single bit error requires retransmitting the entire frame. This incurs extra processing overhead and power consumption, especially for large frames. Frame fragmentation into small blocks with individual error detection codes can reduce the unnecessary retransmission of the correctly received blocks. The optimal block size, however, varies based on the wireless channel conditions. In this paper, we propose an interference-aware frame fragmentation scheme called iFrag. iFrag dynamically adjusts the number of blocks inside a frame based on current channel conditions, and effectively addresses all challenges associated with such dynamic partitioning. Through analytical and experimental results, we show that iFrag achieves up to $$3\times$$ improvement in goodput when the channel is noisy, while reducing the delay by 12 % compared to other static fragmentation approaches. On average, it shows a 13 % gain in goodput across all channel conditions used in our experiments. Our testbed results also show that iFrag lowers the energy consumed per useful bit by 60 %, as improved data transmission reliability reduces the number of frame retransmissions which increases the motes energy efficiency. [ABSTRACT FROM AUTHOR]

This paper presents and studies objective video quality evaluation techniques for a network where frame losses can be considered independent, for example a best effort not heavy loaded packet switching network. The total or partial loss of a frame's information affects the quality of video playback, as the frame cannot be decoded and other frames that depend on it cannot be correctly decoded too. Therefore, during some time the video playback has errors in the image and the user will perceive them as interruptions. In this paper, the total number of decoded frames and the video playback interruptions duration will be considered important parameters to quantify the video quality. The analytical formulation for them will be presented and the importance of considering them together will be highlighted. [ABSTRACT FROM AUTHOR]

As current mobile core network systems are expected to evolve into all-IP networks, packet switching will be a prerequisite for all mobile applications. Next-generation mobile networks, as envisioned by ITU-T, are packet-based networks capable of providing consistent and ubiquitous service to end users, independent of the network, access technology, and device used. This study discusses the differentiated packet forwarding performance of four major types of mobile network traffic under the proposed mobile network priority-based queueing (MPQ) scheme with two queueing buffer allocations, namely dynamic queueing buffer (DQB) allocation and overflow queueing buffer (OQB) allocation. As different queueing buffer allocations are adopted to store arriving packets in DQB and OQB, the MPQ scheme shows different packet forwarding performance under these two methods. In this study, we use ns2 (Network Simulator version 2) as the simulation platform to simulate several scenarios. The simulation results show that the MPQ scheme is able to support differentiated packet forwarding behavior for mobile traffic with both DQB and OQB allocations in a mobile core network. Some issues were identified in the MPQ scheme with both DQB and OQB allocation, which will need to be addressed. [ABSTRACT FROM AUTHOR]

Wireless Mesh Network (WMN) is regarded as a viable solution to provide broadband Internet access flexibly and cost efficiently. Improving the performance of Transmission Control Protocol (TCP) in WMNs is an active research area in the networking community. The existing solutions proposed for improving the TCP performance has concentrated on differentiating the DATA packet drops in the forward direction induced by both network congestion as well as transmission errors. However, the recent studies show that in WMNs packet drops occur not only in the forward direction but also in the reverse direction particularly due to hidden terminal, hidden capture terminal, link asymmetry etc. The loss of ACK packets in the reverse direction cause frequent retransmission timeouts subject to needless retransmissions and unnecessary slowing down the growth of congestion window, which causes the performance degradation of TCP. In this paper, we introduce a sender side TCP algorithm, called detection of packet loss (DPL), which is capable to distinguish the type of packet drops either DATA or ACKs caused by transmission errors as well as network congestion based on one-way queuing delay and react accordingly. To justify our contributions, we implement DPL in Qualnet simulator and compare its performance against existing TCP solutions via extensive simulations. Our simulation results show that the proposed algorithm can accurately distinguish the type of packet drops whether it is a DATA or ACK caused by transmission error or congestion and can significantly improve the performance under a wide range of scenarios in WMNs. [ABSTRACT FROM AUTHOR]

Proportional fairness is a widely accepted form of allocating transmission resources in communication systems. For wired networks, the combination of a simple probabilistic packet marking strategy together with a scheduling algorithm aware of two packet classes can meet a given proportional vector of n loss probabilities, to an arbitrary degree of approximation, as long as the packet loss gap between the two basic classes is sufficiently large. In contrast, for wireless networks, proportional fairness is a challenging problem because of random channel variations and contention for transmitting. In this paper, we show that under the physical model, i.e., when receivers regard collisions and interference as noise, the same packet marking strategy at the network layer can also yield proportional differentiation and nearly optimal throughput. Thus, random access or interference due to incoherent transmissions do not impair the feasibility of engineering a prescribed end-to-end loss-based proportional fairness vector. We consider explicitly multihop transmission and the cases of Markovian traffic with a two-priority scheduler, as well as orthogonal modulation with power splitting. In both cases, it is shown that sharp differentiation in loss probabilities at the link layer is achievable without the need to coordinate locally the transmission of frames or packets among neighboring nodes. Given this, a novel distributed procedure to adapt the marking probabilities so as to attain exact fairness is also developed. Numerical experiments are used to validate the design. [ABSTRACT FROM AUTHOR]

The analytical modeling and performance analysis of the 802.11 network in all its various extensions (802.11b, 802.11a, 802.11g, 802.11e, 802.11n, etc.) have already been widely explored over the past years. However, the packet fragmentation mechanism (PFM), which is proposed by the IEEE work group to reduce the impact of bit error rate (BER) on the packet error rate (PER), has not been considered in the analytical models proposed in the literature. Yet, the PFM constitutes a key parameter to achieve the best performances of 802.11 networks. In this paper, we extend the Bianchi's Markov chain model with the PFM and the PER. Then, we analyze the performance improvement level achieved with the PFM in an IEEE 802.11 network under the impact of BER and packet length. The proposed analysis has been applied on the basic access method of 802.11b network in saturated traffic conditions. So, we have analyzed the throughput and the mean response time of the 802.11 network. The obtained theoretical results are validated by simulation. [ABSTRACT FROM AUTHOR]

The rigid delay constraint is one of the most challenging issues in real-time video delivery over wireless networks. The expired video packets will become useless for the decoding and display even if they are received correctly at the receiver. Because the significance of each video packet is different, the schedulers have to take into account not only the urgency of the packet but also its importance in the real-time video applications. However, the existing QoS-based IEEE 802.11e MAC protocol leaves the urgency and the importance of video packets out of consideration. This paper proposes a Priority and Delay Aware Packet Management Framework (PDA-PMF) to improve the transmission quality of real-time video streaming over IEEE 802.11e WLANs. In the MAC layer, this framework estimates the delay of each video packet. Subsequently, video packets are sent or dropped according to both the significance of the video packets and the estimation value of the delay. Simulation results show that the proposed scheme can not only reduce the packet losses, but also protect the more important video packets, so as to improve the received video quality effectively. [ABSTRACT FROM AUTHOR]

Efficient video content adaptation requires techniques for content analysis and understanding as well as the development of appropriate mechanisms for content scaling in terms of the network properties, terminal devices characteristics and users' preferences. This is particularly evident in industrial surveillance applications, due to the huge amount of data needed to be stored, delivered and handled. In this paper, we address both issues by incorporating (a) computer vision tools that allows efficient tracking of salient visual objects for long time regardless of the dynamics of the visual environment -via a self initialized tracking algorithm-and (b) an adaptive optimal rate distortion scheme able to allocate different priorities for each detected video object with respect to users' needs, network platforms capabilities and terminal characteristics. The self initialized tracker firstly appropriately describes visual content, secondly incorporates adaptive mechanisms for automatically update the tracker to adjust to the current conditions and thirdly includes an efficient decision mechanism that estimates the time instances in which adaptation should be activated. For the rate distortion algorithm, an optimal adaptive framework is adopted which is capable of allocating the desired quality to objects of users' interest without violating the target bit rate of the sequence. The Wavelet Packet Transform (WPT) is adopted towards this purpose. The advantage of the WPT is that it localizes the frequency components of each video object and therefore it offers additionally content adaptability according to video object texture coding. The WPT tree is transmitted only at the first frame of each shot and thus dew bits are required for its encoding. Experimental results and comparisons with other approaches are presented to illustrate the good performance of the proposed architecture. The results cover real-world and complex industrial environments. [ABSTRACT FROM AUTHOR]

This paper investigates the performance of multicast cooperative ARQ (MCARQ) in wireless networks for reducing the system's waiting time and the sum energy, where the delay and energy analytical model are proposed under equivalent service time and ideal Nyquist pulse. The packet transmission process is modulated by a three-state Markov chain, then the steady-state distribution of the MCARQ is obtained by solving the Markov chain. Further, the queue waiting time and energy efficiency of the multicast ARQ (MARQ) and MCARQ are obtained respectively. Theoretical analysis and simulation results demonstrate that the MCARQ protocol has a better performance than the MARQ in delay and energy efficiency. The presented model has potentially applications in practical systems, e.g. Multi-user MIMO communications. [ABSTRACT FROM AUTHOR]

Recently, by using vehicle-to-vehicle and vehicle-to-infrastructure communications for VANET/ITS, the cooperative active safety driving (ASD) providing vehicular traffic information sharing among vehicles significantly prevents accidents. Clearly, the performance analysis of ASD becomes difficult because of high vehicle mobility, diverse road topologies, and high wireless interference. An inaccurate analysis of packet connectivity probability significantly affects and degrades the VANET/ITS performance. Especially, most of related studies seldom concern the impact factors of vehicular accidents for the performance analyses of VANET/ITS. Thus, this paper proposes a two-phase approach to model a distributed VANET/ITS network with considering accidents happening on roads and to analyze the connectivity probability. Phase 1 proposes a reliable packet routing and then analyzes an analytical model of packet connectivity. Moreover, the analysis is extended to the cases with and without exhibiting transportation accidents. In phase 2, by applying the analysis results of phase 1 to phase 2, an adaptive vehicle routing, namely adaptive vehicle routing (AVR), is proposed for accomplishing dynamic vehicular navigation, in which the cost of a road link is defined in terms of several critical factors: traffic density, vehicle velocity, road class, etc. Finally, the path with the least path cost is selected as the optimal vehicle routing path. Numerical results demonstrate that the analytical packet connectivity probability and packet delay are close to that of simulations. The yielded supreme features justify the analytical model. In evaluations, the proposed approach outperforms the compared approaches in packet connectivity probability, average travel time, average exhausted gasoline. However, the proposed approach may lead to a longer travel distance because it enables the navigated vehicle to avoid traversing via the roads with a higher traffic density. [ABSTRACT FROM AUTHOR]

Systematic packet collisions constitute a major problem in wireless flooding, which is a key mechanism for information dissemination in wireless mesh and multi-hop ad hoc networks. Since this cannot be solved only through classic MAC collision avoidance mechanisms, the IETF has proposed and standardized in RFC 5148 jittering techniques to handle it. These techniques are widely used in protocols for wireless communication such as OLSR, AODV or LOAD, and have proven useful for reducing collisions. They lead however some undesirableside effects that may harm substantially the flooding performance. To the best of our knowledge, no research effort has been deployed to understand and analyze these effects. This paper addresses this issue. It motivates and introduces a theoretical model of flooding with jitter in a wireless interface, as specified in RFC 5148, and explores the probabilistic characterization of additional flooding delay caused by jitter. It mostly provides two analytical bounds for the per-interface additional jitter delay. Presented results, which are validated by way of a discrete-event simulation, enable a better understanding of the performance trade-offs (between packet collisions and additional delay, in particular) underlying the use of jitter in wireless flooding. [ABSTRACT FROM AUTHOR]

According to the store-carry-forward packet transmission method, nodes can communicate with each other in intermittently connected mobile network flexibly. As can be seen, the successful transmission of packets is assisted by multiple copies injected into the network. Therefore, the limited buffer should be utilized reasonably in this situation. In this paper, an adaptive buffer scheduling mechanism is proposed with the aid of packet transmission status estimation. According to the activity degree of node and the number of packet copies, the status of packet transmission in the network can be evaluated. Furthermore, with the estimated outcome of packet redundancy, the packets in the buffer are scheduled dynamically. Numerical results show that the activity degree can be estimated accurately, especially when the networks become larger. The number of packet copies can be proved that it follows normal distribution. Compared with other buffer scheduling mechanisms, our mechanism displays better performance, e.g., the packet delivery probability is enhanced by 21–50 %, and the latency is reduced by 15–23 %. [ABSTRACT FROM AUTHOR]

Biologically-inspired packet switched network on chip (NoC) based hardware spiking neural network (SNN) architectures have been proposed as an embedded computing platform for classification, estimation and control applications. Storage of large synaptic connectivity (SNN topology) information in SNNs require large distributed on-chip memory, which poses serious challenges for compact hardware implementation of such architectures. Based on the structured neural organisation observed in human brain, a modular neural networks (MNN) design strategy partitions complex application tasks into smaller subtasks executing on distinct neural network modules, and integrates intermediate outputs in higher level functions. This paper proposes a hardware modular neural tile (MNT) architecture that reduces the SNN topology memory requirement of NoC-based hardware SNNs by using a combination of fixed and configurable synaptic connections. The proposed MNT contains a 16:16 fully-connected feed-forward SNN structure and integrates in a mesh topology NoC communication infrastructure. The SNN topology memory requirement is 50 % of the monolithic NoC-based hardware SNN implementation. The paper also presents a lookup table based SNN topology memory allocation technique, which further increases the memory utilisation efficiency. Overall the area requirement of the architecture is reduced by an average of 66 % for practical SNN application topologies. The paper presents micro-architecture details of the proposed MNT and digital neuron circuit. The proposed architecture has been validated on a Xilinx Virtex-6 FPGA and synthesised using 65 nm low-power CMOS technology. The evolvable capability of the proposed MNT and its suitability for executing subtasks within a MNN execution architecture is demonstrated by successfully evolving benchmark SNN application tasks representing classification and non-linear control functions. The paper addresses hardware modular SNN design and implementation challenges and contributes to the development of a compact hardware modular SNN architecture suitable for embedded applications [ABSTRACT FROM AUTHOR]

In this paper, an effective algorithm for detecting the sector ID and ICFO together via the PSS-matching process is presented. In the conventional scheme, the commonly used differential correlation for PSS detection in frequency domain is applied. Its performance is compromised by the squaring noise. To remedy this shortcoming, a partial correlation scheme for PSS detection, including the theoretical deduction and analysis, is proposed. Compared with conventional schemes, the proposed scheme can detect both the sector ID and ICFO with higher accuracy and much lower complexity. The performance superiority of the proposed scheme is confirmed by the simulation results. The performance of the techniques discussed is compared through simulation, as well as through considerations of their relative computational complexity. [ABSTRACT FROM AUTHOR]