Antoine Fraboulet

Worldsens: development and prototyping tools for application specific wireless sensors networks

In this paper we present Worldsens, an integrated environment for development and rapid prototyping of wireless sensor network applications. Our environment relies on software simulation to help the designer during the whole development process. The refinement is done starting from the high level design choices down to the target code implementation, debug and performance analysis. In the early stages of the design, high level parameters, like for example the node sleep and activity periods, can be tuned using WS- Net, an event driven wireless network simulator. WSNet uses models for applications, protocols and radio medium communication with a parameterized accuracy. The second step of the sensor network application design takes place after the hardware implementation choices. This second step relies on the WSim cycle accurate hardware platform simulator. WSim is used to debug the application using the real target binary code. Precise performance evaluation, including real-time analysis at the interrupt level, are made possible at this low simulation level. WSim can be connected to WSNet, in place of the application and protocol models used during the high level simulation to achieve a full distributed application simulation. WSNet and WSNet+WSim allow a continuous refinement from high level estimations down to low level real-time validation. We illustrate the complete application design process using a real life demonstrator that implements a hello protocol for dynamic neighborhood discovery in a wireless sensor network environment.

Automatic phase detection for stochastic on-chip traffic generation

(NoC) prototyping is used for adapting NoC parameters to the application running on the chip. This prototyping is currently done using traffic generators which emulate the SoC components (IPs) behavior: processors, hardware accelerators, etc. Traffic generated by processor-like IPs is highly non-regular, it must be decomposed into program phases. We propose an original feature for NoC prototyping, inspired by techniques used in processor architecture performance evaluation: the automatic detection of traffic phases. Integrated in our NoC prototyping environment, this feature permits to have a completely automatic toolchain for the generation of stochastic traffic generators. We show that our traffic generators emulate precisely the behavior of processors and that our environment is a versatile tool for networks-on-chip prototyping. Simulations are performed in a SystemC-based simulation environment with a mesh network-on-chip (DSPIN) and a processor running MP3 decoding applications.

Long-range dependence and on-chip processor traffic

Long-range dependence is a property of stochastic processes that has an important impact on network performance, especially on the buffer usage in routers. We analyze the presence of long-range dependence in on-chip processor traffic and we study the impact of long-range dependence on networks-on-chip. long-range dependence in communication traces of processorips at the cycle-accurate level. We also study the impact of long-range dependence on a real network-on-chip using the SocLib simulation environment and traffic generators of our own. Our experiments show that long-range dependence is not an ubiquitous property of on-chip processor traffic and that its impact on the network-on-chip is highly correlated with the low level communication protocol used.

Worldsens: a fast and accurate development framework for sensor network applications

In this article, we present Worldsens, a fast and accurate development framework for sensor network applications. World-sens offers an integrated platform for the design, development, performance evaluation and profiling of applications. It relies on two simulators, WSNet and WSim, which are used throughout the application design and implementation, from the high level design choices to the implementation validation. WSNet is a modular event-driven wireless network simulator while WSim is a full platform hardware simulator which takes the target binary code as input and uses instruction cycles as time reference. WSNet and WSim can be used in conjunction to offer a distributed simulation of sensor networks with instruction and radio byte accuracy.

eSimu: a Fast and Accurate Energy Consumption Simulator for Real Embedded System

This paper presents a performance and energy consumption simulator for deeply embedded hardware platforms such as sensor network nodes. These tools are based on cycle accurate simulation of complete hardware platforms executing the real application code. This allows designers to get fast performance and consumption estimations without deploying software on target hardware, while being independent of any compilation tools or software components such as network protocols or operating systems.

Cycle accurate simulation model generation for SoC prototyping

We present new results concerning the integration of high level designed ips into a complete System on Chip. We first introduce a new computation model that can be used for cycle accurate simulation of register transfer level synthesized hardware. Then we provide simulation of a SoC integrating a data-flow ip synthesized with MMAlpha and the SocLib cycle accurate simulation environment. This integration also validates an efficient generic interface mechanism for data-flow ips.

Virtual Machine for Software Defined Radio: Evaluating the Software VM Approach

We study the impact of using a virtual machine for the configuration of radio physical layer protocols on a real hardware platform: the Magali chip. The virtual machine is programmed in software on the ARM processor present on the platform. We evaluate the additional cost of the virtual machine layer on the effective implementation of telecommunication physical layer protocols. The results, obtained using the mixed SystemC/VHDL cycle accurate simulator of the Magali platform, show that, although the proof of concept is valid and functional, extra optimizations, such as additional hardware mechanisms, will be necessary to obtain real-time performance.

Worldsens: from lab to sensor network application development and deployment

We present Worldsens, a prototyping and development framework for wireless sensor protocols and applications. Our environment relies on two simulators, WSim and WSNet, and proposes a full simulation and performance estimation of embedded platforms with instruction and radio byte accuracy. During this demo, we propose to demonstrate the interest of the two simulators in stand-alone and in cooperative use.

Two demos using SensLAB: Very large scale open WSN testbed

We present SensLAB, a very large scale wireless sensor network testbed1. SensLAB is distributed among 4 sites having different topologies and consists of 1024 wireless nodes based on open source hardware & software. Within a given site, each one of the 256 nodes is able to communicate via its radio interface (868Mhz or 2.4Ghz) to its neighbors. Furthermore, every sensor node is potentially configurable as a sink node and can exchange data with any other sink node of the whole SensLAB testbed and/or Internet application. The testbed is designed to achieve reproducibility of experimentation, while also supporting evaluation of protocols and applications in real world settings. It allows to monitor transparently, i.e., without any insertion/modification within the code, any deployed application in terms of energy consumption or radio activity. The main benefits of SensLAB for the users are to reduce the costs in terms of: infrastructure investment, maintenance cost and operating cost. With SensLAB you can be up and running minutes after you are assigned an account! SensLABs main and most important goal is to offer an accurate open access multi-users scientific tool to support the design, development, tuning, and experimentation of real large-scale sensor network applications. During this demo, we propose to demonstrate the interests of the SensLAB testbed by developing and running two experimental scenarii that highlight the services offered by SensLAB.

The Radio Virtual Machine: A solution for SDR portability and platform reconfigurability

Instead of a single circuit dedicated to a particular physical (PHY) layer standard, a Software Defined Radio (SDR) platform embeds several hardware accelerators which enable it to support different modulation schemes. In this study we propose an architecture for a SDR PHY layer based on the Virtual Machine (VM) concept. Once a program is compiled in a portable byte-code, the VM can then execute it to manage the desired PHY layer. We demonstrate the feasibility of the proposed architecture through a case study and a proof-of-concept implementation.