INESC-ID

About: INESC-ID is a nonprofit organization based out in Lisbon, Portugal. It is known for research contribution in the topics: Field-programmable gate array & Control theory. The organization has 932 authors who have published 2618 publications receiving 37658 citations.

Modelling and implementation of virtual radio resources management for 5G Cloud RAN

Abstract: The virtualisation of Radio Access Networks (RANs) is one of the goals in designing 5G mobile networks. This paper aims at presenting a proof of concept for the virtualisation of radio resources using Open Air Interface (OAI), a software-based Long-Term Evolution (LTE) eNodeB physical emulator. OAI was extended to support multi-tenancy, representing diverse Virtual mobile Network Operators (VNOs) with different Service Level Agreements (SLAs). A comprehensive analytical model for managing the virtual radio resources has been proposed, with two key parts: estimation of available radio resources and their allocation to different VNOs. The estimation is performed by the model, and the allocation is managed by OAI scheduling. Various scenarios and use cases are studied in this virtual RAN environment, network performance being evaluated for different situations, by varying guaranteed levels, serving weights, and used services. Results show that the proposed approach offers almost the same capacity to guaranteed VNOs regardless of other existing VNOs, experiencing at worst a degradation of 32% of its initial allocated data rate, without violation of the guaranteed data rate. The data rate allocated to best effort VNOs may decrease up to 7% of its initial value, which is acceptable, to guarantee other more demanding SLAs.

Asymmetric transistor sizing targeting radiation-hardened circuits

Abstract: This article proposes a technique to improve the dependability of circuits under energetic particle irradiation by resizing transistors in the most critical paths. First, the SET vulnerability of a mapped circuit is analyzed to identify the most sensitive nodes. The sensitivity of the circuit is defined by the logical and electrical masking. Once the most critical nodes are selected, a transistor sizing algorithm is able to resize the pull-up and pull-down transistors separately. The asymmetric resizing offers interesting area and performance trade-off in comparison with gate sizing and gate duplication techniques. Results show very small area and performance penalties for circuits operating at ground level for a 130-nm technology process.

A Wireless Sensor and Actuator Network for improving the electrical power grid dependability

Abstract: This paper presents an overview of a Wireless Sensor and Actuator Network (WSAN) used to monitor an electrical power grid distribution infrastructure. The WSAN employs appropriate sensors to monitor key grid components, integrating both safety and security services, which improve the grid distribution dependability. The supported applications include, among others, video surveillance of remote secondary substations, which imposes special requirements from the point of view of quality of service and reliability. The paper presents the hardware and software architecture of the system together with performance results.

A low-noise CMOS front-end for TOF-PET

Abstract: An analogue CMOS front-end for triggering and amplification of signals produced by a silicon photomultiplier (SiPM) coupled to a LYSO scintillator is proposed. The solution is intended for time-of-flight measurement in compact Positron Emission Tomography (TOF-PET) medical imaging equipments where excellent timing resolution is required ( ≈ 100ps). A CMOS 0.13μm technology was used to implement such front end, and the design includes preamplification, shaping, baseline holder and biasing circuitry, for a total silicon area of 500x90 μm. Waveform sampling and time-over-threshold (ToT) techniques are under study and the front-end provides fast and shaped outputs for time and energy measurements. Post layout simulation results show that, for the trigger of a single photoelectron, the time jitter due to the pre-amplifier noise can be as low as 15 ps (FWHM), for a photodetector with a total capacitance of 70 pF. The very low input impedance of the pre-amplifier ( ≈ 5Ω) allows 1.8 ns of peaking time, at the cost of 10 mW of power consumption.

RepWeb: replicated Web with referential integrity

Abstract: Replication of web content, through mirroring of web sites or browsing off-line content, is one of the most used techniques to increase content availability, reduce network bandwidth usage and minimize browsing delays in the world-wide-web.The world-wide-web does not support referential integrity, i.e., broken links do exist. This has been considered, for some years now, one of the most serious problems of the web. This is true in various fields, e.g.: i) if a user pays for some service in the form of web pages, he requires such pages to be reachable all the time, and ii) archived web resources, either scientific, legal or historic, that are still referenced, need to be preserved and remain available.Current approaches to the broken-link problem are not able to preserve referential integrity on the web and, simultaneously, support replication and minimize storage waste due to memory leaks. Some of them also impose specific authoring and management systems. Thus, the limitations of current systems reside in three issues: transparency, completeness and safety.We propose a system, RepWeb, comprised of an application to access and manage replicated web content and an implementation of an acyclic distributed garbage collection algorithm for wide-area replicated memory, that satisfies all these requirements. It supports replication, enforces referential integrity on the web and minimizes storage waste.