198 research outputs found
Network layer solutions for a content-centric internet
Nowadays most people exploit the Internet to get contents such as web pages, music or video files. These users only value āwhatā they download and are not interested about āwhereā content is actually stored. The IP layer does the opposite and cares about the āwhereā and not about the āwhatā. This contrast between the actual usage of the Internet and the service offered by the IP layer is deemed to be the source of several problems concerning usability, performance, security and mobility issues. To overcome this contrast, research on the Future Internet is exploring novel so-called content-centric architectures, where the network layer directly provides users with contents, instead of providing communication channels between hosts. In this paper, we identify the main functionalities of a content-centric network (CONET), we discuss pros and cons of literature proposals for an innovative, content-centric network layer and we draw our conclusions, stating some general requirements that, in our opinion, a CONET should satisfy
Will the Proliferation of 5G Base Stations Increase the Radio-Frequency 'Pollution'?
A common concern among the population is that installing new 5G Base Stations (BSs) over a given geographic region may result in an uncontrollable increase of Radio-Frequency 'Pollution' (RFP). To face this dispute in a way that can be understood by the layman, we develop a very simple model, which evaluates the RFP at selected distances between the user and the 5G BS locations. We then obtain closed-form expressions to quantify the RFP increase/decrease when comparing a pair of alternative 5G deployments. Results show that a dense 5G deployment is beneficial to the users living in proximity to the 5G BSs, with an abrupt decrease of RFP (up to three orders of magnitude) compared to a sparse deployment. We also analyze scenarios where the user equipment minimum detectable signal threshold is increased, showing that in such cases a (slight) increase of RFP may be experienced
Streaming H.264 scalable video over data distribution service in a wireless environment
The Data Distribution Service (DDS) middleware is enjoying a rapid adoption in high-performance, mission-critical networks. At the same time, the H.264 Scalable Video Coding (SVC) has been recently standardized and it is deemed to be an effective solution for video streaming over a channel with time-varying bandwidth, like the wireless one. In these conditions, it is critical to adapt the video bit-rate to the actual wireless capacity, and bit-rate adaptation is extremely simple for a H.264 SVC video. In this paper we devise, evaluate and demonstrate a technique for streaming H.264 SVC video over a DDS middleware. The contribution is threefold: i) we design a structure of the DDS data-unit able to carry H.264 SVC video-units; ii) we devise a receiver-driven rate-control mechanism based on our DDS data-unit and exploiting specific DDS functionality; iii) we implement and show the effectiveness of our mechanism in an 802.11 wireless scenario, comparing our proposal with other solution
Check before storing: what is the performance price of content integrity verification in LRU caching?
In some network and application scenarios, it is useful to cache content in network nodes on the ļ¬y, at line rate. Resilience of in-network caches can be improved by guaranteeing that all content therein stored is valid. Digital signatures could be indeed used to verify content integrity and provenance. However, their operation may be much slower than the line rate, thus limiting caching of cryptographically veriļ¬ed objects to a small subset of the forwarded ones. How this aļ¬ects caching performance? To answer such a question, we devise a simple analytical approach which permits to assess performance of an LRU caching strategy storing a randomly sampled subset of requests. A key feature of our model is the ability to handle traļ¬c beyond the traditional Independent Reference Model, thus permitting us to understand how performance vary in diļ¬erent temporal locality conditions. Results, also veriļ¬ed on real world traces, show that content integrity veriļ¬cation does not necessarily bring about a performance penalty; rather, in some speciļ¬c (but practical) conditions, performance may even improve
Is It Safe Living in the Vicinity of Cellular Towers? Analysis of Long-Term Human EMF Exposure at Population Scale
We focus on the ElectroMagnetic Field (EMF) exposure safety for people living in the vicinity of cellular towers. To this aim, we analyze a large dataset of long-term EMF measurements collected over almost 20 years in more than 2000 measurement points spread over an Italian region. We evaluate the relationship between EMF exposure and the following factors: (i) distance from the closest installation(s), (ii) type of EMF sources in the vicinity, (iii) Base Station (BS) technology, and (iv) EMF regulation updates. Overall, the exposure levels from BSs in the vicinity are below the Italian EMF limits, thus ensuring safety for the population. Moreover, BSs represent the lowest exposure compared to Radio/TV repeaters and other EMF sources. However, the BS EMF exposure in proximity to users exhibits an increasing trend over the last years, which is likely due to the pervasive deployment of multiple technologies and to the EMF regulation updates. As a side consideration, if the EMF levels continue to increase with the current trends, the EMF exposure in proximity to BSs will saturate to the maximum EMF limit by the next 20 years at a distance of 30 meters from the closest BS
'Pencil Beamforming Increases Human Exposure to ElectroMagnetic Fields': True or False?
According to a very popular belief-very widespread among non-scientific communities-the exploitation of narrow beams, a.k.a. 'pencil beamforming', results in a prompt increase of exposure levels radiated by 5G Base Stations (BSs). To face such concern with a scientific approach, in this work we propose a novel localization-enhanced pencil beamforming technique, in which the traffic beams are tuned in accordance with the uncertainty localization levels of User Equipment (UE). Compared to currently deployed beamforming techniques, which generally employ beams of fixed width, we exploit the localization functionality made available by the 5G architecture to synthesize the direction and the width of each pencil beam towards each served UE. We then evaluate the effectiveness of pencil beamforming in terms of ElectroMagnetic Field (EMF) exposure and UE throughput levels over different realistic case-studies. Results, obtained from a publicly released open-source simulator, dispel the myth: the adoption of localization-enhanced pencil beamforming triggers a prompt reduction of exposure w.r.t. other alternative techniques, which include e.g., beams of fixed width and cellular coverage not exploiting beamforming. The EMF reduction is achieved not only for the UE that are served by the pencil beams, but also over the whole territory (including the locations in proximity to the 5G BS). In addition, large throughput levels-adequate for most of 5G services-can be guaranteed when each UE is individually served by one dedicated beam
Massive measurements of 5G exposure in a town: methodology and results
We target the problem of performing a large set of measurements over the territory to characterize the exposure from a 5G deployment. Since using a single Spectrum Analyzer (SA) is not practically feasible (due to the limited battery duration), in this work we adopt an integrated approach, based on the massive measurement of 5G metrics with a 5G smartphone, followed by a detailed analysis done with the SA and an ElectroMagnetic Field (EMF) meter in selected locations. Results, obtained over a real territory covered by 5G signal, reveal that 5G exposure is overall very limited for most of measurement locations, both in terms of field strength (up to 0.7 [V/m]) and as share w.r.t. other wireless technologies (typically lower than 15%). Moreover, our approach allows easily spotting measurement outliers, e.g., due to the exploitation of Dynamic Spectrum Sharing (DSS) techniques between 4G and 5G. In addition, the exposure metrics collected with the smartphone are overall a good proxy of the total exposure measured over the whole 5G channel. Moreover, the sight conditions and the distance from 5G base station play a great role in determining the level of exposure. Finally, a maximum of 130 [W] of power radiated by a 5G base station is estimated in the scenario under consideration
How Much Exposure From 5G Towers Is Radiated Over Children, Teenagers, Schools and Hospitals?
The rolling-out of 5G antennas over the territory is a fundamental step to provide 5G connectivity. However, little efforts have been done so far on the exposure assessment from 5G cellular towers over young people and 'sensitive' buildings, like schools and medical centers. To face such issues, we provide a sound methodology for the numerical evaluation of 5G (and pre-5G) downlink exposure over children, teenagers, schools and medical centers. We then apply the proposed methodology over two real scenarios. Results reveal that the exposure from 5G cellular towers will increase in the forthcoming years, in parallel with the growth of the 5G adoption levels. However, the exposure levels are well below the maximum ones defined by international regulations. Moreover, the exposure over children and teenagers is similar to the one of the whole population, while the exposure over schools and medical centers can be lower than the one of the whole set of buildings. Finally, the exposure from 5G is strongly lower than the pre-5G one when the building attenuation is introduced and a maturity adoption level for 5G is assumed
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