| 1. |
- Flärdh, Oscar, et al.
(författare)
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A Control Framework for Online Error Control Adaptation in Networked Applications
- 2006
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Ingår i: Proceedings of IEEE Second International Symposium on Control, Communications, and Signal Processing.
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Konferensbidrag (refereegranskat)abstract
- For many real-time applications running over packet-switched networks, it is important to maintain delivered data quality using a limited amount of network resources. It is therefore natural to employ cost functions that allow online trade-off between the experienced application quality and the resource usage. However, minimizing such cost functions requires perfect knowledge of the network state at the transmission side, while, in general, such information is only partially available. In this paper, we introduce a new adaptive error correction algorithm that optimizes the amount of redundancy based on the available information from the application and the network. An extremum-seeking control algorithm is employed to deal with the high level of uncertainty in the network models. The validity of our approach is illustrated in simulations with varying network loads and loss correlation.
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| 2. |
- Flärdh, Oscar, et al.
(författare)
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Analysis of a simple feedback scheme for error correction over a lossy network
- 2007
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Ingår i: 2007 IEEE INTERNATIONAL CONFERENCE ON NETWORKING, SENSING, AND CONTROL. - : IEEE. - 9781424410750 ; , s. 261-266
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Konferensbidrag (refereegranskat)abstract
- A control theoretic analysis of a simple error correction scheme for lossy packet-switched networks is presented. Based on feedback information from the error correction process in the receiver, the sender adjusts the amount of redundancy using a so called extremum-seeking controller, which do not rely on any accurate model of the network loss process. The closed-loop system is shown to converge to a limit cycle in a neighborhood of the optimal redundancy. The result are validated using packet-based simulations with data from wireless sensor network experiments.
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| 3. |
- Witrant, Emmanuel, et al.
(författare)
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Predictive control over wireless multi-hop networks
- 2007
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Ingår i: Proceedings Of The 2007 Ieee Conference On Control Applications. - : IEEE. - 9781424404438 ; , s. 1037-1042
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Konferensbidrag (refereegranskat)abstract
- Remote control over wireless multi-hop networks is considered. Time-varying delays for the transmission of sensor and control data over the wireless network are caused by a randomized multi-hop routing protocol. The characterstics of the routing protocol together with lower-layer network mechanisms give rise to a delay process with high variance and stepwise changing mean. A new predictive control scheme with a delay estimator is proposed in the paper. The estimator is based on a Kalman filter with a change detection algorithm. It is able to track the delay mean changes but efficiently attenuate the high frequency jitter The control scheme is analyzed and its implementation detailed. Network data from an experimental setup are used to illustrate the efficiency of the approach.
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| 4. |
- Bao, Lei, et al.
(författare)
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Optimized Rate Allocation for State Estimation over Noisy Channels
- 2009
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Ingår i: 2009 IEEE INTERNATIONAL SYMPOSIUM ON INFORMATION THEORY. - NEW YORK : IEEE. ; , s. 2684-2688
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Konferensbidrag (refereegranskat)abstract
- Optimal rate allocation in a networked control system with limited communication resources is instrumental to achieve satisfactory overall performance. In this paper, a practical rate allocation technique for state estimation in linear dynamic systems over a noisy channel is proposed. The method consists of two steps: (i) the overall distortion is expressed as a function of rates at all time instants by means of high-rate quantization theory, and (ii) a constrained optimization problem to minimize the overall distortion is solved by using Lagrange duality. Monte Carlo simulations illustrate the proposed scheme, which is shown to have good performance when compared to arbitrarily selected rate allocations.
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| 5. |
- Bao, Lei, et al.
(författare)
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Optimized rate allocation for state feedback control over noisy channels
- 2009
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Ingår i: Decision and Control, 2009 held jointly with the 2009 28th Chinese Control Conference. CDC/CCC 2009. Proceedings of the 48th IEEE Conference on. - : IEEE. - 9781424438716 ; , s. 573-578
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Konferensbidrag (refereegranskat)abstract
- Optimal rate allocation in a networked control system with highly limited communication resources is instrumental to achieve satisfactory overall performance. In this paper, we propose a rate allocation technique for state feedback control in linear dynamic systems over a noisy channel. Our method consists of two steps: (i) the overall distortion is expressed as a function of rates at all time instants by means of high-rate quantization theory, and (ii) a constrained optimization problem to minimize the overall distortion is solved. We show that a non-uniform quantization is in general the best strategy for state feedback control over noisy channels. Monte Carlo simulations illustrate the proposed scheme, which is shown to have good performance compared to arbitrarily selected rate allocations.
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| 6. |
- Bao, Lei, et al.
(författare)
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Rate allocation for quantized control over noisy channels
- 2009
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Ingår i: Final Proceedings of the 2009 7th International Symposium on Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks. - 9781424449200 ; , s. 595-603
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Konferensbidrag (refereegranskat)abstract
- To achieve satisfactory overall performance, optimal rate allocation in a networked control system with highly limited communication resources is instrumental. In this paper, a rate allocation technique for state feedback control in linear dynamic systems over a noisy channel is proposed. The method consists of two steps: (i) the overall cost is expressed as a function of rates at all time instants by means of high-rate quantization theory, and (ii) a constrained optimization problem to minimize the overall distortion is solved. It is shown that a non-uniform quantization is in general the best strategy for state feedback control over noisy channels. Monte Carlo simulations illustrate the proposed scheme, which is shown to have good performance when compared to arbitrarily selected rate allocations.
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