Showing papers on "Transmission delay published in 2013"

A Delay System Method for Designing Event-Triggered Controllers of Networked Control Systems

Abstract: This note is concerned with event-triggered H∞ controller design for networked control systems. A novel event-triggering scheme is proposed, which has some advantages over some existing schemes. A delay system model for the analysis is firstly constructed by investigating the effect of the network transmission delay. Then, based on this model, criteria for stability with an H∞ norm bound and criteria for co-designing both the feedback gain and the trigger parameters are derived. These criteria are formulated in terms of linear matrix inequalities. Simulation results have shown that the proposed event-triggering scheme is superior to some existing event-triggering schemes in the literature.

Modeling and Optimization of the IEEE 802.15.4 Protocol for Reliable and Timely Communications

Abstract: Distributed processing through ad hoc and sensor networks is having a major impact on scale and applications of computing. The creation of new cyber-physical services based on wireless sensor devices relies heavily on how well communication protocols can be adapted and optimized to meet quality constraints under limited energy resources. The IEEE 802.15.4 medium access control protocol for wireless sensor networks can support energy efficient, reliable, and timely packet transmission by a parallel and distributed tuning of the medium access control parameters. Such a tuning is difficult, because simple and accurate models of the influence of these parameters on the probability of successful packet transmission, packet delay, and energy consumption are not available. Moreover, it is not clear how to adapt the parameters to the changes of the network and traffic regimes by algorithms that can run on resource-constrained devices. In this paper, a Markov chain is proposed to model these relations by simple expressions without giving up the accuracy. In contrast to previous work, the presence of limited number of retransmissions, acknowledgments, unsaturated traffic, packet size, and packet copying delay due to hardware limitations is accounted for. The model is then used to derive a distributed adaptive algorithm for minimizing the power consumption while guaranteeing a given successful packet reception probability and delay constraints in the packet transmission. The algorithm does not require any modification of the IEEE 802.15.4 medium access control and can be easily implemented on network devices. The algorithm has been experimentally implemented and evaluated on a testbed with off-the-shelf wireless sensor devices. Experimental results show that the analysis is accurate, that the proposed algorithm satisfies reliability and delay constraints, and that the approach reduces the energy consumption of the network under both stationary and transient conditions. Specifically, even if the number of devices and traffic configuration change sharply, the proposed parallel and distributed algorithm allows the system to operate close to its optimal state by estimating the busy channel and channel access probabilities. Furthermore, results indicate that the protocol reacts promptly to errors in the estimation of the number of devices and in the traffic load that can appear due to device mobility. It is also shown that the effect of imperfect channel and carrier sensing on system performance heavily depends on the traffic load and limited range of the protocol parameters.

Event-based fault detection for networked systems with communication delay and nonlinear perturbation

Abstract: This paper is concerned with the event-based fault detection for the networked systems with communication delay and nonlinear perturbation. We propose an event-triggered scheme, which has some advantages over existing ones. The sensor data is transmitted only when the specified event condition involving the sampled measurements of the plant is violated. An event-based fault detection model is firstly constructed by taking the effect of event-triggered scheme and the network transmission delay into consideration. The main purpose of this paper is to design an event-based fault detection filter such that, for all unknown input, communication delay and nonlinear perturbation, the error between the residual signal and the fault signal is made as small as possible. Sufficient conditions for the existence of the desired fault detection filter are established in terms of linear matrix inequalities. Based on these conditions, the explicit expression is given for the designed fault detection filter parameters. A numerical example is employed to illustrate the advantage of the introduced event-triggered scheme and the effectiveness of the proposed method.

Multimedia-aware quality-of-service and error correction provisioning

Abstract: Methods and apparatus for associating each data packet in a media stream with logic corresponding to a particular quality-of-service (QoS) and/or error correction requirement. In an exemplary embodiment, each packet in the media stream is assigned a frame tag which designates a particular quality-of-service and/or error correction scheme for the corresponding packet. At least a portion of each packet is encoded according to the packet's designated quality-of-service as indicated by the frame tag. A receiver accesses the frame tags from within the transmitted media stream in order to determine the appropriate means for processing or decoding the encoded portion of each packet. In this manner, each packet within the media stream can have its own quality-of-service and/or error correction requirements and processing, thereby enhancing link efficiency and better enforcing QoS policy across the system.

Delay-based back-pressure scheduling in multihop wireless networks

Abstract: Scheduling is a critical and challenging resource allocation mechanism for multihop wireless networks. It is well known that scheduling schemes that favor links with larger queue length can achieve high throughput performance. However, these queue-length-based schemes could potentially suffer from large (even infinite) packet delays due to the well-known last packet problem, whereby packets belonging to some flows may be excessively delayed due to lack of subsequent packet arrivals. Delay-based schemes have the potential to resolve this last packet problem by scheduling the link based on the delay the packet has encountered. However, characterizing throughput optimality of these delay-based schemes has largely been an open problem in multihop wireless networks (except in limited cases where the traffic is single-hop). In this paper, we investigate delay-based scheduling schemes for multihop traffic scenarios with fixed routes. We develop a scheduling scheme based on a new delay metric and show that the proposed scheme achieves optimal throughput performance. Furthermore, we conduct simulations to support our analytical results and show that the delay-based scheduler successfully removes excessive packet delays, while it achieves the same throughput region as the queue-length-based scheme.

Stateless load balancer in a multi-node system for transparent processing with packet preservation

Abstract: Stateless load balancing of network packets within a system avoids detection by a network client or end user for deep packet inspection or other bump-in-the-wire applications At least one header field of a received packet is used in generating a hash value The hash value is used to identify a processing resource within the system for processing the received packet Before being sent to the identified resource, the received packet is encapsulated with a new header that includes an indication of ingress port The encapsulation does not modify the original packet On a return path from the identified processing resource, the ingress port is determined from the encapsulated packet, the encapsulated packet is decapsulated to obtain a recovered packet that is identical to the received packet, and the recovered packet is forwarded to the network through an egress port as determined from the recovered ingress port

Method and apparatus for accelerating forwarding in software-defined networks

Abstract: A network element acting as a forwarding plane within a software-defined network to reduce negative effects of slow-path packet processing is described. The network element, upon receiving a first packet, determines whether it matches any flow entry within a set of flow tables. When the first packet does not match any flow entry of the set of flow tables, the network element performs a miss procedure including inserting at least a portion of the first packet into a packet miss table of the network element, which is accessed by a controller. The controller may access the packet miss table using a pull mechanism. The miss procedure may also include accessing a configurable default rule table of the network element, which includes rules enabling limited forwarding for those packets that do not match any entry of the set of flow tables.

H"~ control of networked control systems with time delay and packet disordering

Abstract: The article is concerned with the design of H ∞ controller for networked control systems (NCSs) with both time delay and packet disordering. Analyzing and establishing the relation between time delay and packet disordering, the NCS with both time delay and packet disordering is transformed into the model with multi-step time delays. Given the time delays, we can easily obtain the action time of the control signals without calculating the disorder number. Moreover, a new notion of effective value of transmission packets (EVTP) is proposed in this paper to better study the phenomenon of packet disordering. The bigger the EVTP, the better the NCS will be stabilized, that is, the less negative influence is resulted from packet disordering. By Lyapunov functional method and linear matrix inequality approach, a sufficient criterion for robust stability of NCSs is presented. Finally, numerical examples and simulations are used to illustrate the effectiveness and validity of the proposed method.

Expanding network functionalities for openflow based split-architecture networks

Abstract: A method enables a switch in a split-architecture network to provide high speed packet processing and enhanced network functionalities that are not supported by the OpenFlow. The switch receives a packet from a network through an input port of the switch, and matches header fields in the packet against table entries in flow tables to identify an action to be taken. The flow tables are part of an OpenFlow pipeline. The identified action is to direct the packet to a designated processing unit in the switch. The OpenFlow pipeline forwards the packet to the designated processing unit via a communication channel in the switch. The designated processing unit processes the packet with the enhanced network functionalities, and injects the packet back to one of the flow tables before transmission of the packet to the network through an egress port of the switch.

A Traffic Distribution Technique to Minimize Packet Delivery Delay in Multilayered Satellite Networks

Abstract: Multi-Layered Satellite Networks (MLSNs) have enormous potential to provide a ubiquitous wireless environment due to their advantages, such as extensive coverage, high network capacity, and lower delay performance. Since MLSNs are flexible and can be expanded easily to construct useful communication networks, researchers have paid a great deal of attention to find out how to use them efficiently. However, traffic congestion may occur in such networks since the distribution of MLSN users is heavily influenced by geographical restrictions, and they may often lead to severe communication delay and throughput degradation. Traditional research has proposed a counter-measure for avoiding traffic congestion caused by traffic flow on each layer. However, they do not consider congestion due to the inter-layer traffic that may, indeed, occur in MLSNs. Therefore, to effectively resolve the problem of traffic congestion, we propose a new MLSN model by envisioning a method to distribute the flow of packets between the two layers of the considered MLSNs for minimizing the packet delivery delay of the network. Moreover, we analyze the effect of the method on the packet delivery delay by considering propagation and queuing latencies. The analysis clearly shows the advantage of our proposed model. Furthermore, computer-based simulation results validate our analysis and demonstrate the effectiveness of our proposed model.

Mobility increases the connectivity of wireless networks

Abstract: In this paper, we investigate the connectivity for large-scale clustered wireless sensor and ad hoc networks. We study the effect of mobility on the critical transmission range for asymptotic connectivity in k-hop clustered networks and compare to existing results on nonclustered stationary networks. By introducing k -hop clustering, any packet from a cluster member can reach a cluster head within k hops, and thus the transmission delay is bounded as Θ(1) for any finite k. We first characterize the critical transmission range for connectivity in mobile k-hop clustered networks where all nodes move under either the random walk mobility model with nontrivial velocity or the i.i.d. mobility model. By the term nontrivial velocity, we mean that the velocity of a node v is ω(r(n)), where r(n) is the transmission range of the node. We then compare with the critical transmission range for stationary k-hop clustered networks. In addition, the critical number of neighbors is studied in a parallel manner for both stationary and mobile networks. We also study the transmission power versus delay tradeoff and the average energy consumption per flow among different types of networks. We show that random walk mobility with nontrivial velocities increases connectivity in k-hop clustered networks, and thus significantly decreases the energy consumption and improves the power-delay tradeoff. The decrease of energy consumption per flow is shown to be Θ([(logn)/(nd)]) in clustered networks. These results provide insights on network design and fundamental guidelines on building a large-scale wireless network.

Adaptive packet deflection to achieve fair, low-cost, and/or energy-efficient quality of service in network on chip devices

Abstract: Methods and apparatus for provision of adaptive packet deflection to achieve fair, lowcost, and/or energy-efficient Quality of Service (QoS) in Network-on-Chip (NoC) devices are described. In some embodiments, it is determined whether a target port of a packet has reached a threshold utilization value and the packet is routed to an alternate port in response to a deflection probability value that is to be determined based on a utilization value of the target port and a priority level value of the packet. Other embodiments are also claimed and/or disclosed.

Communication method, node, and network system

Abstract: A communication method executed by a node in an ad hoc network having multiple nodes, includes receiving from a neighboring node of the node in the ad hoc network, a first packet that includes a sender address of the neighboring node and a first packet transmission count of packet transmissions from the neighboring node; extracting the first packet transmission count from the first packet; receiving from the neighboring node and after reception of the first packet, a second packet that includes the sender address of the neighboring node and a second packet transmission count of packet transmissions from the neighboring node; extracting the second packet transmission count from the second packet; determining whether the second packet is an invalid packet, based on the first packet transmission count and the second packet transmission count; and discarding the second packet upon determining the second packet to be an invalid packet.

Wireless Device Transmission Power

Abstract: A wireless device transmits a first packet in subframe n of a first cell of a first cell group and transmits a second packet in subframe n+1 of a second cell of a second cell group overlapping in time with the transmission of the first packet. The wireless device reduces a subframe transmission power of at least one of the first packet and the second packet if a power parameter is more than an allowable transmission power. A calculation for the power parameter considers transmission power of the first packet and the second packet according to a pre-configured rule.

An Interacting Stochastic Models Approach for the Performance Evaluation of DSRC Vehicular Safety Communication

Abstract: In this paper, an analytic model is proposed for the performance evaluation of vehicular safety related services in the dedicated short range communications (DSRC) system on highways. The generation and service of safety messages in each vehicle is modeled by a generalized M/G/1 queue. The overall model is a set of interacting M/G/1 queues, one queue for each vehicle. The interaction is that the server is shared as it is the contention medium. To make the model scalable, we use semi-Markov process (SMP) model to capture the shared server's behavior from one tagged vehicle's perspective, where the medium contention and back off behavior for this vehicle and influences from other vehicles are considered. Furthermore, this SMP interacts with the tagged vehicle's own M/G/1 queue through fixed-point iteration. The proof for the existence, uniqueness and convergence of the fixed point is provided. Based on the fixed-point solution, performance indices including mean transmission delay, packet delivery ratio (PDR), and packet reception ratio (PRR) are derived. Analytic-numeric results are verified through extensive simulations under various network parameters. Compared with the existing models, the proposed SMP model facilitates the impact analysis of hidden terminal problem on the PDR and PRR computation in a more precise manner.

OAM and Time Slot Control in a Deterministic ARC Chain Topology Network

Abstract: In one embodiment, a network of nodes is configured to communicate according to a configuration of Available Routing Construct (ARC) chains as well as monitoring communication in the network, and/or selectively controls whether or not provisioned particular links will be used. One embodiment colors nodes of the network (e.g., a wireless deterministic network) along different paths through the network and marks packets with the color of each traversed node to track a path taken by a packet. One embodiment sends a particular packet through the network and marks over which links the packet traverses and aggregates these traversed links of other copies of the particular packet. One embodiment controls whether or not the provisioned time slots are used based on flooding a control packet through the network with enable or disable information for each of these links.

Multi-level iSCSI QoS for target differentiated data in DCB networks

Abstract: In an embodiment, a method can include setting metadata of a first data packet to have a first priority level based on a first internal classifier of the first data packet and setting metadata of a second data packet to have a second priority level based on a second internal classifier of the second data packet. The first data packet and second data packet can be of the same traffic type (e.g., iSCSI). The method can further include sub-classifying (e.g., the same traffic type), based on the first and second priority levels, to direct the first data packet into a first data channel and second data packet into a second data channel for the same traffic type.

Network service slotting

Abstract: Exemplary methods, apparatuses, and systems of packet processing utilize an ordered sequence of packet processing services to process a packet having a destination. The packet is a native, non-proprietary network packet that uses a standard network protocol and standard packet format. The packet processing services include a plurality of physical and/or virtual services. The ordered sequence is determined by applying one or more policy rules. A virtual service insertion platform manages routing of the packet to each service in the ordered sequence of services until all services have processed the packet, then the packet is forwarded to the packet destination.

Mitigating Receiver's Buffer Blocking by Delay Aware Packet Scheduling in Multipath Data Transfer

Abstract: Reliable in order multipath data transfer under asymmetric heterogeneous network conditions has known problems related to receiver's buffer blocking, caused by out of order packet arrival. Several mitigation techniques have been proposed to address this issue mostly by using various packet retransmission schemes, load-balancing and bandwidth-estimation based mechanisms. In comparison to the existing reactive techniques for buffer block mitigation, we propose a novel and yet simpler to implement, delay aware packet scheduling scheme for multipath data transfer over asymmetric network paths, that proactively minimizes the blocking inside receiver's buffer. Our initial simulation results show that, in comparison to the default round robin packet scheduler, by using our proposed delay aware packet scheduling scheme, we can significantly improve overall performance while notably minimizing the receiver's buffer usage, which is also beneficial for multi-homed hand-held mobile devices with limited buffering capacity, which, due to their multi-homing and heterogeneous wireless network features (i.e. availability of 3G and Wi-Fi) are also one of the most common use cases for multi-path transport.

Mac header compression in long-range wireless local area networks

Abstract: A method includes receiving, at or from a station STA, a plurality of packets. Each packet includes a set of flag bits, and a MAC header containing at least a first address field specifying a receiver address and a second address field specifying a transmitter address. The method also includes determining whether each set of flag bits indicates that the STA was associated with an AP when the respective packet was generated, and processing the MAC header of each packet. Processing the MAC header of each packet includes processing a third address field in each packet for which it is determined that the respective set of flag bits indicates that the STA was not associated with an AP when the respective packet was generated. The third address field contains a MAC address of the STA.

Spectrum Assignment and Sharing for Delay Minimization in Multi-Hop Multi-Flow CRNs

Abstract: This paper investigates the problem of spectrum assignment and sharing to minimize the total delay of multiple concurrent flows in multi-hop cognitive radio networks. We first analyze the expected per-hop delay, which incorporates the sensing delay and transmission delay characterizing the PU activities and spectrum capacities. Then we formulate a minimum delay optimization problem with interference constraints, and propose an approximation algorithm termed MCC to solve the problem. According to our theoretical analysis, MCC has a bounded performance ratio and a low computational complexity. Finally, we exploit the minimum potential delay fairness in spectrum sharing to mitigate the inter-flow contentions. Extensive simulation study has been performed to validate our design and to compare the performance of our algorithms with that of the state-of-the-art.

Switched Ethernet-Based Real-Time Networked Control System with Multiple-Client–Server Architecture

Abstract: This paper experimentally verifies that a multiple-client-server architecture based on switched Ethernet can be used as a real-time communication standard for possible applications in factory automation, by observing the effects of packet delays, network congestion, and packet loss on the performance of a networked control system (NCS). The NCS experimental setup used in this research involves real-time feedback control of multiple plants connected to one or more controllers over the network. A multiclient-multiserver (MC-MS) architecture on a local area network (LAN) was developed using user datagram protocol as the communication protocol. In the single-client-single-server (SC-SS) system, as the Ethernet link utilization increased over 82%, the average packet delays and steady-state error of a dc motor speed-control system increased by 2231% and 304%, respectively. As the link utilization increased beyond the threshold, employing an additional server in the NCS reduced average packet delays and also overcame the negative effects of Ethernet's flow control mechanism. The MC-MS architecture is tested with artificially generated random packet loss. The standard deviation of steady-state error (SSE) at 80% utilization with packet loss is found to be 70.2% less than SC-SS and 200% less than multiclient-single-server architecture. The MC-MS architecture remained stable till 70% of control or measurement packet loss.

Methods and Systems for Managing Distributed Media Access Control Address Tables

Abstract: Methods, systems, and computer programs are presented for switching a network packet. One method includes operations for receiving a packet having a media access control (MAC) address, and for switching the packet by a first packet switching device (PSD) when the MAC address is present in a first memory. Further, the method includes operations for transferring the packet to a second PSD when the MAC address is absent from the first memory and present in a second memory associated with the second PSD, and for transferring the packet to a third PSD when the MAC address is absent from the first memory and the second memory.

Cross-Layer Performance Analysis of Recirculation Buffers for Optical Data Centers

Abstract: Recirculation buffer modules combining arrayed waveguide gratings (AWGs), tunable wavelength converters (TWCs), and fiber delay lines (FDLs) have been proposed to bypass the existing switching bottlenecks in massive-scale data centers. Performance studies of such subsystems are devoted exclusively to either the network layer or the physical layer aspects. Network layer studies consider packet drops only due to limited buffering capacity and ignore the critical role of the physical layer in degrading signal quality. Purely physical layer studies, on the other hand, are oblivious to contention-based drops and load transients. As a result, neither approach is able to estimate accurately the performance characteristics of buffer modules as key elements in optical data centers. In this theoretical work, we integrate the network layer and the physical layer effects into a single analysis framework to compare various recirculation buffer module designs in terms of throughput, delay, signal quality, and complexity. We primarily compare the designs in terms of two metrics: maximum operating load and Q-factor degradation impact. Our Monte Carlo simulations indicate that Q-factor degradation has the dominant role in determining the buffer module performance over a wide range of load values, resulting in significant bandwidth limitations. In order to implement optical packet switching in data centers, tradeoffs between physical layer quality requirements and forward error correction (FEC) overheads should be carefully investigated.

On the performance of a large-scale optical packet switch under realistic data center traffic

Abstract: High-speed, submicrosecond-latency, large-port-count (thousands) optical packet switches (OPSs) for intercluster communication networks can become a key element in the deployment of cloud-oriented large-scale data centers. In this work we numerically investigate the performance of a large-port-count wavelength-division multiplexing (WDM) OPS based on a Spanke-type architecture with highly distributed control. We analyze it under a data center traffic modelto determine its suitability for this type of environment. Results indicate that the proposed architecture can be scaled to 4096 ports while providing packet loss below 10-6 and latency under 1 μs, with a total switching capacity over 55 Tbits/s. Additionally, we propose and analyze two WDM OPS architectures. The first one detects and processes small and large-sized Ethernet packets with two parallel switches. The second architecture includes multiple receivers to decrease packet losses and latency while using very limited electronic buffers. Results indicate that both techniques can lead to substantial improvements. In terms of packet loss and latency, they allow up to 40% higher input load with respect to the original WDM OPS architecture.

Method of data reliable transmission with user datagram protocol (UDP) in communication network

Abstract: The invention provides a method of data reliable transmission with a user datagram protocol (UDP) in a communication network. The method comprises that firstly, connecting handshake is carried out between a data packet sending end and a data packet receiving end, a communication layer of the data packet sending end informs an application layer that a reliable transmission channel is built; in a data packet transmission process, the communication layer of the data packet sending end detects a channel state of the transmission channel through a heartbeat mechanism, and if the channel state changes, the application layer is informed. The method has strong adaptability and can be used for the communication network which is large in transmission delay difference. A mutual-informing mode is used between the application layer and the communication layer of the sending end, the application layer and the communication layer are in mutual independence and also a unified whole, data reliable transmission is achieved, and meanwhile the problem that when the transmission channel is in fault, the uninformed application layer sends data to the communication layer continuously and resources are consumed is avoided. According to the method, the communication layer of the receiving end transmits a data packet to the application layer directly according to protocol header information to activate task scheduling, and the method has more advantages than a polling scheduling strategy and a callback scheduling strategy.