Nicolas Krommenacker

A design process of switched Ethernet architectures according to real-time application constraints

Ethernet networks are based on a medium access method which is not deterministic. The use of such networks in factory environments (which are strongly time constraints) can absolutely not guarantee that the applications requirements will be respected. This paper presents a method based on genetic algorithms to minimize end-to-end delays by providing a good distribution of the devices on the network switches. The objective function is defined by using the network calculus which is a deterministic theory and enables to determine bounded delays. In this paper, a case study is described: theoretical results are verified by a real experimentation and compared with results obtained with a network simulator.

IEEE 802.11 Load Balancing: An Approach for QoS Enhancement

With the 802.11 WLAN multimedia applications (Video, Audio, real-time voice over IP,…) increasing, providing Quality of Service (QoS) support becomes very important since the original standard doesn’t take QoS into account. The standard offers access to the wireless users only regarding physical considerations. This can lead to overloaded access points (AP) and considerable degradation of the QoS. This paper deals with this problem. It focuses on the presentation of a QoS management solution for wireless communication systems. It mainly defends that a balanced distribution of mobile stations among the available access points leads to better performances of the Wireless LAN. Some OPNET simulations of the proposed approach are presented to show a better resources allocation and efficiency on QoS metrics. A protocol structure between mobiles and APs is also specified for the implementation of this approach. An SDL description and MSC simulation of this protocol is provided as a first step in its development.

Genetic algorithms for industrial ethernet network design

The Ethernet network is increasingly being used for industrial communications which are strongly time-constrained. This kind of network is intrinsically nondeterministic and does not guarantee that communication end-to-end delays will be bounded. Nevertheless, from the observed traffic between industrial devices, some network topologies improving the availability and temporal performances can be designed. This paper describes the use of a genetic algorithm approach for the optimisation and design of industrial control networks. We propose to solve the combinatorial problem which consists of finding the best distribution of industrial devices on a switched Ethernet architecture with GA techniques, so that the required quality of service is provided.

Using genetic algorithms to design switched Ethernet industrial networks

The Ethernet network is increasingly used for industrial communications which are strongly time-constrained. This kind of network is intrinsically nondeterministic and does not enable to guarantee the communication end-to-end delays to be bounded. Nevertheless, from the traffic observed between the industrial devices, some network topologies improving the availability and the temporal performances can be designed. This paper describes the use of the genetic algorithm approach for the optimisation and the design of industrial control networks. We propose to solve the combinatorial problem which consists of finding the best distribution of the industrial devices on a switched Ethernet architecture with GA techniques.

Building industrial communication systems based on IEEE 802.11g wireless technology

Industrial communication systems (ICS) are specifically designed for deterministic communication between sensors, actuators, programmable logic controllers, monitoring systems, and operator workstations. These networks are traditionally based on wired technology and a deterministic medium access control. Nowadays, the emerging trend is the availability of wireless technology for ICS, since this leads to more flexible and mobile equipments at reduced cost. This article presents a performance analysis of wireless ICS based on the IEEE 802.11g standardized technology, considering the infrastructure mode with both distributed and point coordination functions. The time-critical messages are handled during the contention free period. The performance analysis allows to validate the ability of 802.11g technology to support time-critical traffic required by wireless ICS, being given the scheduling and characteristics of the messages. In addition, the configuration parameters of access points can be easily derived from the performance analysis

A new location system for an underground mining environment using visible light communications

In this paper we introduce a novel localization algorithm based on visible light communications (VLC) and the trilateration technique. The new algorithm can be used for tracking people or machinery in an underground mining environment. The proposed method utilizes the concept of reference points in order to reduce the location estimation error. The proposed algorithm outperforms the LANDMARC (location identification based on dynamic active radio frequency identification (RFID) calibration) algorithm, which uses RFID tags to determine the location of an object, in terms of the location estimation error.

Performance study of IEEE 802.15.4 for industrial maintenance applications

Nowadays, a growing number of enterprises are adopting wireless technologies. However, field communications induce real-time constraints and those networks should at least fulfill those requirements. In this paper, we study IEEE 802.15.4 performances in order to support industrial real-time traffic. This analysis brings out a comparative analysis of IEEE 802.15.4 medium access methods. It provides also some limitations of that standard concerning cycle duration and amount of messages per cycle.

Energy consumption analysis of a simple image transmission protocol in wireless sensor networks

This paper proposes and evaluates a simple energyaware image transmission protocol suitable for wireless sensor networks. Energy saving is achieved through the use of a wavelet image transform and a semi-reliable transmission. On the one hand, wavelet image transform provides data decomposition in multiple levels of resolution, so the image can be divided into packets with different priorities. On the other hand, semi-reliable transmission enables priority-based packet discarding by intermediate nodes according to their battery’s state-of-charge. Such approach provides a graceful trade-off between the image quality played out and the sensor nodes lifetime. An analytical performance evaluation in terms of mean dissipated energy is performed. Results show up to 90% reduction in the energy consumption achieved by our proposal compared to a non energy-aware transmission.

Designing Suitable Switched Ethernet Architectures Regarding Real-Time Application Constraints

Abstract Since the Ethernet network is not deterministic, its use in factory environments (which are strongly time constraints) can not absolutely guarantee that the applications requirements will be respected. This paper presents a method based on genetic algorithms to minimise end-to-end delays, by providing a good distribution of the devices on the network switches. The objective function is defined by using the network calculus, which is a deterministic theory and enables to bound these delays. A case study is described. The results are compared with those obtained by using a network simulator.

Containers monitoring through the Physical Internet: a spatial 3D model based on wireless sensor networks

The Physical Internet concept was developed to address the current unsustainability problem of logistic systems. The key elements are the encapsulation and the handling of world-standard smart green modular containers (π-containers) throughout an open global logistic infrastructure. Logistic processes such as partial loading/unloading or splitting/merging of π-containers play an important role for a successful Physical Internet. However, the large variety of transformation processes can introduce desynchronisation between the physical and informational flows, i.e. the real composition of a composite π-container (a set of stacked π-containers) can differ of the information stored in the supply chain management system. To overcome this problem, this paper proposes a system to generate and maintain automatically a virtual three-dimensional layout reflecting the spatial distribution of π-containers. The proposed approach uses smart π-containers equipped with wireless sensor nodes. The relative position of π-containers can be determined by the neighbourhood relationships between the sensor nodes. From this information, a constraint set is formulated in a Constraint Satisfaction Problem where each solution is a potential loading pattern. The methodology is developed and computational experiments are proposed, as a proof-of-concept. The results show that our proposed method yields quick and satisfactory results.