153 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
Distributed Access Control with Blockchain
The specification and enforcement of network-wide policies in a single
administrative domain is common in today's networks and considered as already
resolved. However, this is not the case for multi-administrative domains, e.g.
among different enterprises. In such situation, new problems arise that
challenge classical solutions such as PKIs, which suffer from scalability and
granularity concerns. In this paper, we present an extension to Group-Based
Policy -- a widely used network policy language -- for the aforementioned
scenario. To do so, we take advantage of a permissioned blockchain
implementation (Hyperledger Fabric) to distribute access control policies in a
secure and auditable manner, preserving at the same time the independence of
each organization. Network administrators specify polices that are rendered
into blockchain transactions. A LISP control plane (RFC 6830) allows routers
performing the access control to query the blockchain for authorizations. We
have implemented an end-to-end experimental prototype and evaluated it in terms
of scalability and network latency.Comment: 7 pages, 9 figures, 2 table
- …