Per-Arne Wiberg

Bluetooth in industrial environment

An initial study of the use of Bluetooth in an industrial environment is presented. The tests have been performed at a paper mill, and in an office environment at Halmstad University. It shows the possibility to use Bluetooth for wireless short range communication in an industrial environment.

Wireless technology in industry-applications and user scenarios

We draw a map of the wireless technology landscape, and place different industrial applications in this context. It is clear that in order to implement wireless communication in safety critical applications more research is needed. We describe one approach aiming at the very low bit error rates of these applications.

Deadline dependent coding-a framework for wireless real-time communication

A framework for real-time communication over a wireless channel is proposed. The concept of deadline dependent coding (DDC), previously suggested by the authors, is further developed using soft decision decoding of block codes to maximize the probability of delivering information before a given deadline. The strategy of DDC is to combine different coding and decoding methods with automatic repeat request (ARQ) in order to fulfil the application requirements. These requirements are formulated as two quality of service (QoS) parameters: deadline (t/sub DL/) and probability of correct delivery before the deadline (Pd), leading to a probabilistic view of real-time communication. An application can negotiate these QoS parameters with the DDC protocol, thus creating a flexible and dependable scheme.

An architecture comparison between a wireless sensor network and an active RFID system

In This work a new hardware platform for active RFID and wireless sensor network is presented. Furthermore a comparison of these two architectures is performed, i.e., the singlehop and the multihop architecture. The comparison reveals important issues regarding the utilization and energy consumption for the singlehop as well as for the multihop architecture.

Graphical programming of time-deterministic real-time systems

In this paper we present the Picasso programming language and the underlying design philosophy. Our goal is to provide programmers working with distributed embedded real-time systems with a tool to manage the complexity of this class of systems. The proposed tool allows easy and safe changes of the system software and hardware at any time during the lifetime of the system. This means that even during operation the system can be changed safely. This is not only important for enhancing the design process but is also necessary for a class of systems that need to be in service at all times. We have chosen to call this approach Change-Orientation. The most characteristic properties of the language are that it is graphical and that it shows time explicitly. All processing is described as functional transformations. These transformations are called processes. A very direct way of implementing a process is possible because the semantics of the description maps directly on the computation model of the processor.

Capacity limitations in wireless sensor networks

It is expected that wireless sensor network will be used in home automation and industrial manufacturing in the future. The main driving forces for wireless sensor networks are fault tolerance, energy gain and spatial capacity gain. Unfortunately, an often forgotten issue is the capacity limits that the network topology of a wireless sensor network represents. In this paper we identify gains, losses and limitations in a wireless sensor network, using a simplified theoretical network model. Especially, we want to point out the stringent capacity limitations that this simplified network model provide. Where a comparison between the locality of the performed information exchange and the average capacity available for each node is the main contribution.

Protocol for wireless real-time systems

A protocol and a communication mechanism intended for time and safety critical applications using a radio channel for information transport are considered jointly. The protocol is based on a scheme of retransmissions done on demand within a given time window. Each retransmission is coded with a varying number of redundant symbols. The set of blocks used for retransmission is controlled by two quality-of-service parameters: deadline for the transmission and the probability that the correct decoded message will reach the recipient before this deadline. Analysis of a protocol model indicates that it is possible to transmit time critical information in a mobile wireless system with very low error probabilities in an industrial environment.

An active backscatter wake-up and tag identification extraction protocol for low cost and low power active RFID

In this paper we present a Radio Frequency Identification (RFID) protocol used to wake up and extract the ID of every tag (or a subset thereof) within reach of a reader in an active backscatter RFID system. We also study the effect on tag energy cost and read-out delay incurred when using the protocol, which is based on a frequency binary tree. Simulations show that, when using the 2.45 GHz ISM band, more than 1500 tags can be read per second. With a population of 1000 tags, the average read-out delay is 319 ms, and the expected lifetime of the RFID tags is estimated to be more than 2.5 years, even in a scenario when they are read out very often.

An Implementation of a 3-tier Hierarchical Wireless Sensor Network

In this paper an implementation of a wireless sensor network is described. The aim with the implementation is to investigate if present design patterns are applicable on wireless sensor networks. A 3-tier model is adopted as a possible candidate for the software as well as for the network architecture. The implemented wireless sensor network consists of a heterogeneous set of hardware devices such as sensors, sensor hubs, beepers, PDAs and connectors. Most of the hardware components are COTS and most of the software is GNU licensed. All these form a 3-tier hierarchical network architecture.

T4 - telematics for totally transparent transports

Transports can be made safer, more secure and efficient by help of telemetry and tracking on-line in real time. T4 is a system architecture aimed to support the development of telematic services for transparent tracking and surveillance monitoring of goods transported by different means on a global scale. The main idea is to focus on the transported pallets or parcels instead of the vehicles moving them. To enable rapid response to new customer requirements and to support remote management of field equipment, software implemented services are designed, packaged, deployed and mediated using XML, Java and the OSGi software technology standards.