117 research outputs found
Channel Characterization for Chip-scale Wireless Communications within Computing Packages
Wireless Network-on-Chip (WNoC) appears as a promising alternative to
conventional interconnect fabrics for chip-scale communications. WNoC takes
advantage of an overlaid network composed by a set of millimeter-wave antennas
to reduce latency and increase throughput in the communication between cores.
Similarly, wireless inter-chip communication has been also proposed to improve
the information transfer between processors, memory, and accelerators in
multi-chip settings. However, the wireless channel remains largely unknown in
both scenarios, especially in the presence of realistic chip packages. This
work addresses the issue by accurately modeling flip-chip packages and
investigating the propagation both its interior and its surroundings. Through
parametric studies, package configurations that minimize path loss are obtained
and the trade-offs observed when applying such optimizations are discussed.
Single-chip and multi-chip architectures are compared in terms of the path loss
exponent, confirming that the amount of bulk silicon found in the pathway
between transmitter and receiver is the main determinant of losses.Comment: To be presented 12th IEEE/ACM International Symposium on
Networks-on-Chip (NOCS 2018); Torino, Italy; October 201
Fault Tolerance in Programmable Metasurfaces: The Beam Steering Case
Metasurfaces, the two-dimensional counterpart of metamaterials, have caught
great attention thanks to their powerful control over electromagnetic waves.
Recent times have seen the emergence of a variety of metasurfaces exhibiting
not only countless functionalities, but also a reconfigurable or even
programmable response. Reconfigurability, however, entails the integration of
tuning and control circuits within the metasurface structure and, as this new
paradigm moves forward, new reliability challenges may arise. This paper
examines, for the first time, the reliability problem in programmable
metamaterials by proposing an error model and a general methodology for error
analysis. To derive the error model, the causes and potential impact of faults
are identified and discussed qualitatively. The methodology is presented and
instantiated for beam steering, which constitutes a relevant example for
programmable metasurfaces. Results show that performance degradation depends on
the type of error and its spatial distribution and that, in beam steering,
error rates over 10% can still be considered acceptable
Impact of transient CSMA/CA access delays on active bandwidth measurements
Proceedings of: 9th ACM SIGCOMM Conference on Internet Measurement Conference (IMC'09), November 4–6, 2009, Chicago, IllinoisWLAN devices based on CSMA/CA access schemes have become
a fundamental component of network deployments. In
such wireless scenarios, traditional networking applications,
tools, and protocols, with their built-in measurement techniques,
are usually run unchanged. However, their actual
interaction with the dynamics of underlying wireless systems
is not yet fully understood. A relevant example of such
built-in techniques is bandwidth measurement. When considering
WLAN environments, various preliminary studies
have shown that the application of results obtained in wired
setups is not straightforward. Indeed, the contention for
medium sharing among multiple users inherent to CSMA/CA
access schemes has remarkable consequences on the behavior
of and results obtained by bandwidth measurement techniques.
In this paper, we focus on evaluating the effect
of CSMA/CA-based contention on active bandwidth measurement
techniques. As a result, it presents the rate response
curve in steady state of a system with both FIFO
and CSMA/CA-based contending cross-traffic. We also find
out that the distribution of access delay shows a transient
regime before reaching a stationary state. The duration of
such transient regime is characterized and bounded. We
also show how dispersion-based measurements that use a
short number of probing packets are biased measurements
of the achievable throughput, the origin of this bias lying on
the transient detected in the access delay of probing packets.
Overall, the results presented in this paper have several
consequences that are expected to influence the design of bandwidth measurement tools as well as to better understand
the results obtained with them in CSMA/CA links.European Community's Seventh Framework ProgramThis work has been partially funded by the COST Action
IC0703 "Data Traffic Monitoring and Analysis", by the Spanish
Ministry of Science and Innovation under grant number
TEC2008-06826/TEC (project ARTICO), and by the Catalan
Regional Government under grants 2009SGR-1140 and
2009SGR-940Publicad
Building a Graph-based Deep Learning network model from captured traffic traces
Currently the state of the art network models are based or depend on Discrete
Event Simulation (DES). While DES is highly accurate, it is also
computationally costly and cumbersome to parallelize, making it unpractical to
simulate high performance networks. Additionally, simulated scenarios fail to
capture all of the complexities present in real network scenarios. While there
exists network models based on Machine Learning (ML) techniques to minimize
these issues, these models are also trained with simulated data and hence
vulnerable to the same pitfalls. Consequently, the Graph Neural Networking
Challenge 2023 introduces a dataset of captured traffic traces that can be used
to build a ML-based network model without these limitations. In this paper we
propose a Graph Neural Network (GNN)-based solution specifically designed to
better capture the complexities of real network scenarios. This is done through
a novel encoding method to capture information from the sequence of captured
packets, and an improved message passing algorithm to better represent the
dependencies present in physical networks. We show that the proposed solution
it is able to learn and generalize to unseen captured network scenarios.Comment: 8 pages, 4 figure
- …