Search results for "Link layer"
showing 7 items of 7 documents
Adaptive Medium Access Control for Distributed Processing in Wireless Sensor Networks
2019
Signal and information processing tasks over Wireless Sensor Networks can be successfully accomplished by means of a distributed implementation among the nodes. Existing distributed schemes are commonly based on iterative strategies that imply a huge demand of one-hop transmissions, which must be efficiently processed by the lower layers of the nodes. At the link layer, general purpose medium access (MAC) policies for wireless communications usually focus on avoiding collisions. These existing approaches result in a reduction of the number of simultaneous transmissions, and an underutilization of the channel as a consequence. This leads to a decrease in the performance of the distributed ta…
Filecasting for streaming content delivery in IP datacast over DVB-H systems
2008
In this paper we investigate the potential gain that can be obtained in DVB-H by delivering streaming content as a succession of time-constrained flies using Application Layer - Forward Error Correction (AL-FEC) for improving the reception for mobile terminals. Compared to the conventional approach with link layer MPE-FEC, this technique allows to increase the robustness of the DVB-H transmission not only as a function of the capacity devoted for error repair (FEC overhead), but also as a function of the number of data bursts coded jointly ("file" or, source data block, size). The main drawback of this approach is an increase of the network latency proportional to the source block size, tha…
Nanoseconds Timing System Based on IEEE 1588 FPGA Implementation
2019
Clock synchronization procedures are mandatory in most physical experiments where event fragments are readout by spatially dislocated sensors and must be glued together to reconstruct key parameters (e.g. energy, interaction vertex etc.) of the process under investigation. These distributed data readout topologies rely on an accurate time information available at the frontend, where raw data are acquired and tagged with a precise timestamp prior to data buffering and central data collecting. This makes the network complexity and latency, between frontend and backend electronics, negligible within upper bounds imposed by the frontend data buffer capability. The proposed research work describ…
How the Atmospheric Variables Affect to the WLAN Datalink Layer Parameters
2010
There are many issues that affect to WLAN connections (walls, vegetation, rain, objects in the Fresnel zone, etc.). Network designers and telecommunication practitioners must take them into account when they are planning wireless connections between devices. Some studies have demonstrated the implication of the atmospheric variables in the frequency attenuation and in the line of sight of the waves. But, to the extend of our knowledge, there is not any work published that relates the atmospheric variables with the datalink layer parameters of the WLANs. We must take into account that the datalink layer allows us to measure quite more parameters than the physical layer. After a review of the…
The RAMON module: architecture framework and performance results
2003
A design study of a Re-configurable Access Module for Mobile Computing Applications is described. After a presentation of its cross-layered architecture, Control Parameters (CPs) of the module are introduced. The set of CPs both describes the functional state of the communication process in relation to the time-varying transport facilities and provides, as input of suitable Algorithms, the control information to re-configure the whole protocol stack for facing modified working conditions. The paper also presents the structure of the simulator realized to demonstrate the feasibility of the design guidelines and to evaluate reconfigurability performances.
Performance evaluation of the MPE-iFEC Sliding RS Encoding for DVB-H streaming services
2008
This article studies the performance of the Sliding RS Encoding (SRSE) in the transmission of streaming services in DVB-H (Digital Video Broadcasting - Transmission System for Handheld Terminals) networks. The SRSE forms part of a set of specifications called MPE-iFEC which has been recently defined in the DVB-SH (Digital Video Broadcasting - Satellite Services to Handheld Devices) standard and is fully compatible with the link layer of DVB-H. MPE-iFEC is capable of encoding information related to different datagram bursts in a jointly manner in order to counteract the long signal blockages expected in satellite reception. This is what is usually referred to as Multi-Burst Encoding (MBE) an…
Application Layer FEC for Mobile TV Delivery in IP Datacast Over DVB-H Systems
2009
In this paper we investigate the potential gain that can be obtained in DVB-H using application layer forward error correction (AL-FEC) to perform a multi-burst protection of the transmission for improving the reception of streaming services for mobile terminals. Compared to the conventional approach with link layer multi protocol encapsulation FEC (MPE-FEC), this technique allows to increase the robustness of the DVB-H transmission not only as a function of the capacity devoted for error repair (FEC overhead), but also as a function of the number of bursts jointly encoded. The main drawback of this approach is an increase of the network latency, that can be translated into a larger service…