Salem Hasnaoui

Coupling Latency Time to the Throughput Performance Analysis on Wireless CAN Networks

CAN networks, called controller area networks, can be used in the framework of real-time distributed industrial applications. Wireless CAN gives a solution when industrial mobile stations under certain constraints should continue to use the CAN protocol as a frame exchange protocol. In wireless CAN, we adopt the use of the RTS/CTS mechanism to gain access to the medium in a first step and to exchange ordinary CAN frames in a second step. We focus, in this paper, on the performance evaluation of wireless CAN by coupling the two criteria: the throughput and the latency time. After analyses, we deduce that when we increase the payload, the latency time along with the throughput increase respectively. Thus, in this way our work, in this paper, consists in computing the throughput-latency time couple that would guarantee a maximum throughput and minimum latency time in the case of WCAN

DESIGN AND IMPLEMENTATION OF A GLOBAL SCHEDULING STRATEGY FOR DATA DISTRIBUTION OVER CAN-BASED NETWORKS

Abstract The data distribution service (DDS) standard enables heterogeneous applications to interact in real-time distributed systems with high-performance requirements. Real-time networking must provide predictable latencies in its messaging mechanisms, in order to allow participants to perform its schedulability analysis. However, there is a lack of support for scheduling DDS applications over real-time networks. This paper describes the design and implementation of a real-time data distribution strategy that uses the object management group DDS and real-time network facilities to ensure the on-time and temporally valid delivery of data. This strategy implements an algorithm, called the LifeSpan-based consistent data delivery algorithm to determine scheduling parameters that will ensure that data that arrives at a requesting target is valid. This implementation introduces a global scheduling solution that manages the distribution and transmission activities in order to ensure the respect of DDS entities deadlines.

Workflow for multi-core architecture: From MATLAB/Simulink models to hardware mapping/scheduling

Programming multicore based Digital Signal Processors (DSP) becomes increasingly complex. This complexity is related to the rapid evaluation of Telecommunication and multimedia systems accompanied by a rapid increase of user requirements in terms of latency, power computation, consumption, etc. Workflow showed to be a successful approach for programming the applications based on multi-cores DSP platforms. The main goal of this work is the design of a hardware/software system in an automated manner. In this paper, we present our proposed workflow taking as entry point a MATLAB/Simulink application. This workflow allows an automatic transformation from a Simulink model to synchronous dataflow (SDF) model, followed by a mapping and scheduling steps in order to obtain the C code to be executed by each core within the designed platform. Our approach is based on the synchronous and hierarchical behaviour of both Simulink and SDF, aiming to simplify the generation of a compatible C code. We present also a performance analysis to find an optimal number of cores to be used for a configured MIMO OFDM LTE that we give as example.

OFDM synchronization errors and effects of phase noise on WLAN transceivers

This work aims at frequency synchronization in OFDM IEEE 802.11g Transceivers. The degradation of performance results from the detrimental effects introduced by frequency offset and phase noise. First, we present a robust method to detect and synchronize the OFDM signal with severe noise and interference corruption based on calculating the accumulated phase difference for each subcarrier. Then, we present a simple architecture to implement the proposed methods. These methods are simulated and analyzed by computer. Finally, we propose many algorithms to correct the common phase error (CPE) of the phase noise and track well its variation.

An All-Detailed Architecture of a RF Wireless Transmitter

It is widely known that (FHSS) frequency-hopped spread spectrum is the mostly used spread technique which uses multilevel modulation and cover both infrastructure field and Ad-Hoc networks. This paper presents the architecture and implementation of a FHSS RF radio transmitter. The complete radio transmitter chain was implemented in which a direct digital frequency synthesize (DDFS) was used for fast frequency hopping and FSK modulation. The radio transmits data in the 900 MHz ISM band at a rate of up to 160 kbps using frequency shift keying (FSK) modulation with frequency hopping at a rate of up to 80 khops/sec. The transmitter is also designed to take part of a detailed transceiver chain, to be modular and reusable in other wireless communication systems.

Hard Real Time Communication Using the CANIOP Protocol

Distributed computer control in complex embedded systems oversees diverse electronic control units connecting hundreds or thousands of analogue and digital sensors and actuators. These systems are also called today sensors networks. In an emrging class of open distributed real time and embedded (DRE) systems with stringent but dynamic QoS requirements, there is a need to propagate QoS parameters and enforce task QoS requirements across multiple endsystems in a way that is simultaneously efficient and adaptable. Consequently, this paper presents an inter-ORB protocol, which makes efficient use of the advantages of controller area network (CAN) and maps the CAN priorities to a band of CORBA priorities. Our definition of this protocol is bound closely to the features of RT-CORBA, the OMG data acquisition from industrial systems(DAIS) RFP and the CAN bus, well known as a real-time underlying network . We give the criteria of the definition of the priority field and show how prioritization of messages over the physical CAN network can be achieved, when adopting the use of RT-CORBA scheduling service which implements a dynamic scheduling policy.