Multiple-packet Transmission Research Articles

Sliding-Mode Predictive Control of Networked Control Systems Under a Multiple-Packet Transmission Policy

This paper addresses the output feedback stabilization problem for a class of networked control systems (NCSs) under a multiple-packet transmission policy. To compensate the time delays and packet losses, a sliding-mode predictive controller is constructed by taking full advantage of network transmission capacity. A Kalman predictor is used to estimate the current and predict the future plant states, while sliding-mode control (SMC) is employed to compute the control sequences. The estimated state errors are transformed into a system disturbance, and the stability of the closed-loop NCSs is guaranteed by constructing the robust stabilizing SMC controller. Simulation and experimental results are given to demonstrate the effectiveness of the proposed approach.

ATM Switch Implementation for NGN using DWDM

In global communications the demand for higher bandwidth is increasing phenomenally due to the spread of Internet in particular and other domain applications in general. Legacy networks are existing networks which are in implementation. Continuity can be achieved through Optical backbone networks only, even though other media, such as satellite are available in public switched telephone networks, the interface between client and network is an optical Asynchronous Transfer Mode (ATM) switch. Wavelength division multiplexing provides efficient bandwidth utilization. Dense wavelength division multiplexing uses multiplexers at the transmitter at different wavelengths. Availability of contiguous wavelength in the route should be considered for optimum utilization of routing algorithm. In terms of routing packets in optical domain, QOS parameters that need to be considered for optimization are Packet Size, Throughput, Traffic Density, Data Rates and BER. This paper deals with understanding the parameters for various algorithms for duplex/bidirectional multiple packet transmission through asynchronous transfer mode (ATM) protocol. Here ATM acts as a switch for routing algorithm. Fixed Size ATM Packets are transmitted to optimize throughput in the network. NETLOGO software is used for simulation and analysis.

Symbol-level reliable broadcasting of sensitive data in error-prone wireless networks

Reliable packet transmission over error-prone wireless networks has received a lot of attention from the research community. In this paper, instead of using simple packet retransmissions to provide reliability, we consider a novel retransmission approach, which is based on the importance of bits (symbols). We study the problem of maximizing the total gain in the case of partial data delivery in error-prone wireless networks, in which each set of bits (called symbols) has a different weight. We first address the case of one-hop single packet transmission, and prove that the optimal solution that maximizes the total gain has a round-robin symbol transmission pattern. Then, we extend our solution to the case of multiple packets. We also enhance the expected gain using random linear network coding. Our simulation results show that our proposed multiple packets transmission mechanism can increase the gain up to 60%, compared to that of a simple retransmission. Moreover, our network coding scheme enhances the expected total gain up to 15%, compared to our non-coding mechanism.

Rate Monotonic Scheduling Analysis for Stability Constraints in Network Control System

The Feedback control system connected to a real time network through which the control process takes place are called network control system(NCSs).Features of NCS is the information like reference input, plant output, control input is exchanged between sensors, controllers, actuator using a network like CAN bus. The system wiring is reduced, easy to maintain and increases the system reliability. In the conventional control theories uses some ideal assumptions like equal distance sensing, synchronized control and non-delayed sensing and actuation. But in time varying systems this assumption fails due to transmission delay or packet dropout. In this paper Stability of NCS is analysed by considering transmission delay for a computer controlled system using scheduling algorithm The In direct digital control systems, computerized control replaced all analog instrumentation for the process control. Example system is shown in the figure 1 with a summary of several modular manufacturing system integrated control networks like FireWire, DeviceNet and Ethernet. In the example system, FireWire are used for the job requires high data throughput and high bandwidth. DeviceNet are used for the jobs which require low bandwidth like short, periodic messages signals transmission. Ethernet is preferred for the job like information exchange between the upper supervisory workstation and the controller is high volume but not time critical. Sensors with analog outputs and actuators with analog inputs are point to point connection with the digital computers. Sensing, actuating and control signal are deadline based since speed of all digital control CNC machines are high due to accuracy of the product manufacture in the system. Some of the constraints in the design of the system which affects the performance is choosing good scheduling algorithm, either constant or time varying network induced delay between the sensor to controller and controller to actuator in the shared medium, unreliable transmission path, packet dropouts due to packet size, bandwidth and busy path. Depending on the systems environmental condition while analysing some parameter are kept constant. Fundamental issues like time varying transmission period, network scheduling, network induced delay, single packet or multiple packet transmission of plant inputs and output and dropping of the network packets are basic problems in NCSs. In this paper we have considered time delay factor as variable since message transmitted between devices are either control data, which is time critical or information data which only needs guaranteed delivery.

Performance analysis of CSMA/CA protocols with multi-packet transmission

Wireless objects equipped with multiple antennas are able to simultaneously transmit multiple packets by exploiting the channel’s spatial dimensions. In this paper, we study the benefits of such Multiple Packet Transmission (MPT) approach, when it is used in combination with a Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol for fully interconnected networks, addressing the interactions between the two mechanisms and showing the performance gains that can be achieved. To this end, a very simple Media Access Control (MAC) protocol that captures the fundamental properties and tradeoffs of a CSMA/CA channel access protocol supporting MPT is introduced. Using this protocol as a reference, a new analytical model is presented for the case of non-saturated traffic sources with finite buffer space. Simulation results show that the analytical model is able to accurately characterize the steady-state behavior of the reference protocol for different number of antennas and different traffic loads, providing a useful tool for understanding the performance gains achieved by MAC protocols supporting MPT.

Dynamic Observer-Based <i>H</i><sub>∞</sub> Control for Networked Control Systems in Multiple-Packet Transmission with Random Delays

Dynamic observer-based H∞ control for NCSs in multiple-packet transmission with random delays was discussed. The non-convex problem was converted into an LMI with matrix equation constraint. The H∞ control design which guarantees exponential mean-square stability and the H∞ performance level of the closed-loop system were given. The result shows that a numerical example presented here illustrates the effectiveness of the proposed method.

<i>H<sub>∞</sub></i> Controller Design for Networked Control Systems in Multiple-Packet Transmission with Random Delays

Discrete-time NCSs in multiple-packet transmission with random delays were discussed. The random delays from the sensors to the controllers and from the controllers to the actuators were considered. A novel random delay model in multiple-packet transmission was proposed and the relationship of the delays and the system performance was studied. The state feedback H∞ controller can be constructed via solving a linear matrix inequality, such that the closed-loop system with random delays exponentially mean-square stable and with a prescribed H∞ performance bound. The result shows that an example presented here illustrates the effectiveness of the proposed method.

Efficient RTSP-based multiple buffering and packet transmission methods for delivering OMA PoC Box service

OMA (Open Mobile Alliance) PoC (Push-to-talk over Cellular) integrates group voice-video communications, internet services, and multimedia services for use at terminals. It allows the use of PoC Box for users who cannot participate in PoC sessions for a variety of reasons such as absence, emergency situations, and battery discharge. The PoC standard recommends that RTSP (Real Time Streaming Protocol) be used when media is transmitted from a PoC Box to a PoC terminal. While for a RTSP-based VOD service a large packet size is used to take advantage of fast wired networks, a RTSP-based transmission method that takes into account the nature of wireless communication environments is needed for the PoC service. To enable a user to effectively access important information in in-transit media via playback control and to reduce playback delay, this paper proposed buffering and packet transmission methods, the performance and adequacy of which were verified through testing. The buffering methods are Alternating Double Buffering, Advance Partition Multiple Buffering, and On-Demand Multiple Buffering, while the packet transmission methods are Same-Priority Packet Transmission and Priority-based Packet Transmission.

Redundant data transmission in control/estimation over lossy networks

In lossy networks the probability of successful communication can be significantly increased by transmitting multiple copies of a same message through independent channels. In this paper we show that communication protocols that exploit this by dynamically assigning the number of transmitted copies of the same data can significantly improve the control performance in a networked control system with only a modest increase in the total number of transmissions. We develop techniques to design communication protocols that exploit the transmission of multiple packets while seeking a balance between stability/estimation performance and communication rate. An average cost optimality criterion is employed to obtain a number of optimal protocols applicable to networks with different computational capabilities. We also discuss stability results under network contention when multiple nodes utilize these protocols.

Controller Design for Systems With Multipacket Transmissions

This paper investigates the problem of stability analysis and state-space-equation controller design for a type of nonlinear systems in which measurement data of the sensors and the control signals are communicated through independent communication channels via a multiple-packet transmission policy. The packet delays (and dropouts) at the sensors side and the actuators side are assumed to be different in properties and are treated separately. A framework of stability analysis and controller design under multiple-packet transmission policy is derived by simultaneous consideration of quantization effect, successive packet delays, dropouts, and noises. The main results are obtained by constructing a new Lyapunov functional and using a new tight bounding technique without introducing any free-weighting matrices. As a general tool for designing state-space-equation controllers for networked control systems, the presented method is less conservative with reduced number of variables and larger upper bounds of time-delays, which is shown by numerical examples.

Decentralized control and communication

In this paper, the past and current issues involved in the design of decentralized networked control systems are reviewed. The basic models of interconnected systems described as continuous-time linear time-invariant systems in the time domain serve as a framework for the inclusion of communication channels in the decentralized feedback loop. The I/O-oriented models and the interaction oriented models with disjoint subsystems and interactions are distinguished. The overview is focused on packet dropouts, transmission delays, and quantization effects which are included in the time-driven design of feedback loop components. Single- and multiple-packet transmissions are considered in this contents. The design of decentralized state feedback gain matrices with delayed feedback uses the methodology of sampled-data feedback design for continuous-time systems, while the decentralized H∞ quantizer design is based on the static output controller. The Liapunov stability approach results in computationally efficient decentralized control design strategies described by using linear matrix inequalities.

Mean square detectability of multi-output systems over stochastic multiplicative channels

This study addresses the mean square detectability problem for multi-output networked systems via single packet or multiple packets transmission, where a multiplicative white noise model the unreliability of output channels. For the single packet case, by adopting the bisection technique, the authors give the critical value (lower bound) of mean square capacity for ensuring mean square detectability. For the m -parallel multiple packets transmission strategy, a necessary and sufficient condition on overall mean square capacity for mean square detectability in terms of the Mahler measure or topological entropy of the plant is presented, under the assumption that the given network resource can be allocated among all the output channels. Applications in erasure-type channel and channel with stochastic sector-bounded uncertainty are provided to demonstrate the results.

An entropy approach to filtering for networked control systems

This paper is concerned with minimum error entropy filter design for non-linear Networked Control Systems (NCSs) with multiple-packet transmission mechanism. Since the error of the filter in NCSs is generally non-Gaussian, the filter is designed under the information theoretic learning frame. The convergent condition of the proposed filter is established. A simulation example shows that the proposed approach is feasible and effective.

Capacity Analysis and Call Admission Control in Distributed Cognitive Radio Networks

In this paper, homogeneous voice traffic in a single-channel cognitive radio network (CRN) is considered. We analyze the constant-rate voice capacity of a fully-connected network with slot-ALOHA and round-robin channel access, and propose two call admission control (CAC) algorithms for a non-fully-connected network with slot-ALOHA channel access. Different from the existing work in literature, transmission of multiple packets in a single time-slot is considered. Two discrete-time Markov chain based approaches are used for the capacity analysis of the two channel access schemes, respectively. It is shown that the number of voice packets that can be transmitted in a time-slot has a significant impact on the system capacity. The capacity analysis results of the slot-ALOHA scheme is used to develop a CAC procedure when all the voice flows have an identical statistical delay requirement. Further, two CAC algorithms (A1 and A2) are developed for a network with voice traffic flows having different delay requirements in which one (A1) is based on the theory of effective capacity and is considered as a benchmark to compare with the other. Simulation results demonstrate that algorithm A2 performs better than algorithm A1, and that a relaxed delay requirement leads to an increase in the network capacity.

Adaptive Sending Rate Over Wireless Mesh Networks Using SNR

Wireless Mesh Networks (WMNs) have emerged as a key technology for the next generation of wireless networking. Instead of being another type of ad-hoc networking, WMNs diversify the capabilities of ad-hoc networks. Several protocols that work over WMNs include IEEE 802.11a/b/g, 802.15, 802.16 and LTE-Advanced. To bring about a high throughput under varying conditions, these protocols have to adapt their transmission rate. This paper proposes a scheme to improve channel conditions by performing rate adaptation along with multiple packet transmission using packet loss and physical layer condition. Dynamic monitoring, multiple packet transmission and adaptation to changes in channel quality by adjusting the packet transmission rates according to certain optimization criteria provided greater throughput. The key feature of the proposed method is the combination of the following two factors: 1) detection of intrinsic channel conditions by measuring the fluctuation of noise to signal ratio via the standard deviation, and 2) the detection of packet loss induced through congestion. The authors show that the use of such techniques in a WMN can significantly improve performance in terms of the packet sending rate. The effectiveness of the proposed method was demonstrated in a simulated wireless network testbed via packet-level simulation.

Separation principle for networked control systems with multiple-packet transmission

The authors investigate a class of observer-based discrete-time networked control systems (NCSs) with multiple-packet transmission where random packet dropouts occur independently in both the sensor-to-controller (S/C) and controller-to-actuator (C/A) channels. The authors first propose and prove the separation principle for the NCSs where packet dropouts in the C/A and S/C channels are governed by two independent Markov chains, respectively. Secondly, the authors derive a sufficient condition, in terms of linear matrix inequalities (LMIs), for stabilisation control of the Markov chain-driven NCSs. The authors also derive the necessary and sufficient condition for stabilisation control of the memoryless process-driven NCSs as a special case. A numerical example is provided to illustrate the effectiveness of our method.

A new approach to controller design for networked control systems with multiple-packet transmissions

Stabilisation and robust stabilisation problems of Networked Control Systems (NCSs) with multiple-packet transmissions are addressed. We focus our attention on the case that the packets are transmitted over token-passing bus networks, and model the systems as periodically switched systems based on the exact network timing property. Furthermore, by using Elimination lemma, we present stabilising conditions which provide less conservative evaluation for stabilising domains, as well as a novel design method for state feedback controllers. Several numerical examples and simulations are worked out to demonstrate the effectiveness of the proposed design technique.

Decentralized H∞ Quantizers Design for Networked Complex Composite Systems

AbstractThe objective of the paper is to propose an approach to decentralized networked quantized state feedback H∞ controller design for a class of complex symmetric composite continuous-time systems. The effect of data-packet dropouts and communication delays between the plant and the local controller as well as quantizers design are included in the design of asymptotically stabilizing controller and quantizer parameters. Local quantizers are located between the subsystem and the local controller. It is shown how the reduced-order control design of sampled quantized delayed feedback combined with the multiple packet transmissions approach can lead to an effective decentralized control design of the overall closed-loop system.

Robust ℋ ∞ control for networked control systems with uncertainties and multiple-packet transmission

A class of networked control systems is investigated where the plant has time-varying norm-bounded parameter uncertainties and both the sensor-to-controller and controller-to-actuator channels implement multiple-packet transmission and experience random packet dropouts. Sufficient conditions for synthesis of robust stochastic stabilisation and design of robust ℋ∞ controller are derived in the form of linear matrix inequalities. An example is provided to demonstrate the effectiveness of the proposed method.

Stabilization of Networked Systems under Information Structure Constraints

The objective of this paper is to propose a systematic approach to decentralized stabilization with sampled-data delayed feedback for basic models of networked continuous-time complex systems. Single-packet transmissions and multiple-packet transmissions are considered for the I/O-oriented systems as well as the interconnected systems with disjoint structure of subsystems and their interconnections. The Liapunov-Razumikhin based method is used. An attention is focused on the effect of data-packet dropout and communication delays between the plant and the controller to design stabilizing decentralized controllers. It is shown how this methodology can lead to a decentralized control design with time-varying delays in the input. For such a purpose, a delay-dependent approach is considered in order to obtain decentralized controllers asymptotically stabilizing closed-loop networked control systems.