[Κινητές και Δορυφορικές] Γενικές απορίες κι ανακοινώσεις/επικαιρότητα 2013/2014

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[Ανεβάζετε τα θέματα των εξετάσεων στον τομέα Downloads]

Είσαι πρωτοετής;... Καλώς ήρθες! Μπορείς να βρεις πληροφορίες εδώ. Βοήθεια για τους καινούργιους μέσω χάρτη.

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Ανεβάζετε τα θέματα των εξετάσεων στον τομέα Downloads με προσοχή στα ονόματα των αρχείων!

[Admins]

Για αλλαγή του public name σας, επικοινωνήστε με έναν από τους Admins.

[ampoulog]

Ποιες τεχνολογίες φέρνει το LTE-A;

http://www.tekna.no/ikbViewer/Content/787700/18%20LTE-Advanced%20Overview%20-%20Tor%20Leif%20Aarland.pdf

[ampoulog]

Further Along the Road to 4G:  An update on LTE and LTE-Advanced

http://www.home.agilent.com/upload/cmc_upload/All/Further_Along_the_Road_to_4G_an_Update_ond_LTE-Advanced_V2.pdf?cmpid=1-4254376024

[ampoulog]

[Free Tutorial]

Intelligent Transportation Systems: Advanced Communications Technologies & Applications



Abstract: Intelligent Transportation Systems (ITS) based on wireless communications, the Internet, GPS, and sensor networks are emerging.  The central idea in an ITS system is to deliver useful information to all kinds of motorists, such as ordinary drivers, emergency vehicles, transit and service vehicles. The goal is to shorten driving time, make driving safer, speed law and medical assistance and others, and contribute to a better environment.

Engineers and researchers are identifying key issues to address to enable successful Intelligent Transportation Systems. This presentations provides an open discussion on recent research results on a broad range of topics relevant to ITS architecture, network support, communication-based technologies and application development.

link: https://www.comsoc.org/form/tutorial-registration-intelligent-transportation-systems-advanced-communications-technologies-a

[ampoulog]

Ιστορικά 

FCC: POTS is History

The FCC gave the go ahead for a next-gen telephone network sending digitized voice and data through the internet rather than copper-based Plain Old Telephone Service and central offices.



AT&T and Verizon received a nod to test moving telephone services from existing circuit-switch technology to Internet protocol to see how the change may affect consumers.
The experiments would not test the new technology – it is already being used. The trials would seek to establish, among other things, how consumers welcome the change and how new technology performs in emergency situations, including in remote locations.

The IP transition tests allow companies that offer landline phone services to ultimately replace their old copper wires with newer technology like fiber or wireless.

“We cannot continue requiring service providers to invest in both old networks and new networks forever,” Commissioner Ajit Pai, a Republican, said.

More than a third of adults use cellphones as their only form of phone service, up from just 5 percent a decade ago. Federal regulations require phone companies to maintain the plain, old telephone system even as they continue building out advanced networks that imposes costs and slows investment.

Meanwhile, consumer advocates caution that moving too quickly to an IP-based phone network could leave some Americans behind.

link: http://www.dailywireless.org/2014/01/31/fcc-pots-is-history/

άλλα χρήσιμα:
[1] http://www.fcc.gov/document/fcc-oks-voluntary-experiments-testing-impact-technology-transitions
[2] http://en.wikipedia.org/wiki/Plain_old_telephone_service
[3] http://www.washingtonpost.com/blogs/the-switch/wp/2014/01/30/the-fcc-is-beta-testing-a-next-gen-telephone-network/
[4] http://www.reuters.com/article/2014/01/30/usa-fcc-iptransition-idUSL2N0L414G20140130

[ampoulog]

REGENERATIVE PAYLOADS IN SATELLITE COMMUNICATIONS

http://www.dlr.de/rd/Portaldata/28/Resources/dokumente/RA/Rodriguez.pdf

[ampoulog]

Συνοπτικές σημειώσεις από MIT για Satellite Communications!

http://ocw.mit.edu/courses/aeronautics-and-astronautics/16-851-satellite-engineering-fall-2003/lecture-notes/l21satelitecomm2_done.pdf

[ampoulog]

A guide to communication satellites:

http://www.eutelsat.com/files/contributed/news/media_library/brochures/guide-to-satellites.pdf

[ampoulog]

Tech Focus - Signal Processing in Communications

Free Access to papers on Signal Processing from recent IEEE Communications technical conferences, magazines, and journals.

Partial list includes:

• Signal Processing Communications Protocols
  
• Comprehensive sensing framework for signal processing in heterogeneous cellular networks
• Spectral efficiency in signal processing radios in interference limited environments
• Signal processing advances in speech recognition
• 100-Gb/s optical transport in employing digital signal processing
• An analysis of uplink base station cooperation with practical constraints
• Optimized scheduling algorithm for LTE downlink systems
• Multi-user Pre-processing in multi-antenna OFDM TDD systems with non-reciprocal transceivers
• DSP-based optical access approaches for enhancing NG-PON2 Systems

https://www.comsoc.org/form/tech-focus-registration-signal-processing-in-communications

[ampoulog]

Τηλεπικοινωνιακά νέα 

Vehicle-to-Vehicle Communications Tech Will Be Mandatory, say Feds

By Lucas Laursen
Posted 4 Feb 2014 | 19:41 GMT


Illustration: U.S. Department of Transportation


The National Highway Traffic Safety Administration (NHSTA) will soon propose rules for vehicle to vehicle (V2V) communications on U.S. roads, it announced yesterday. The agency is now finalizing a report on a 2012 trial with almost 3000 cars in Ann Arbor, Michigan, and will follow that report with draft rules that would "require V2V devices in new vehicles in a future year."

A car changing lanes, for example, might get a warning from its V2V system that another car is fast approaching in the driver's blind spot. NHTSA, which has been researching V2V since 2002, claims that such systems could prevent three quarters of road crashes. A public-private partnership in Europe has been testing V2V technologies since 2008, IEEE Spectrum reported at the time.

As envisioned by NHTSA, vehicles equipped with V2V would send position and speed data to one another ten times per second over an ad hoc wireless network. Onboard computers could then calculate whether nearby vehicles are a threat and alert drivers. Future protocols might incorporate information from the sort of onboard sensors that are growing more popular among carmakers, creating a road-spanning network of sensors and alerting cars to problems up or down the road. That kind of data ubiquity would help drivers avoid one another, and is a step toward more autonomy for self-driving cars.

As usual, there are tradeoffs. The agency wrote that V2V data would not identify vehicles, but added that, "vehicles would be identifiable through defined procedures only if there is a need to fix a safety problem" without defining those procedures. That implies that some sort of identifying information is in the system.

Drivers might as well accept that modern vehicles are no more capable of protecting their personal information, including location, than are mobile phones, as a Ford executive's comments made clear last month. The NHTSA also notes on its V2V website that, "Anonymous data from connected vehicles will be open to the public and can be used for a myriad of new safety, mobility and environmental applications." The paranoid will not take comfort in that: computer scientists have shown again and again that identifying individuals from anonymized data is easy.

David Friedman, the NHTSA's acting administrator, put a positive spin on his announcement, writing that future generations will remember this as the moment that, "the historical arc of transportation safety considerably changed for the better." Not the smoothest of people to people communications, but then again, this is about cars.

Source: http://spectrum.ieee.org/tech-talk/green-tech/advanced-cars/vehicle-to-vehicle-tech-will-be-mandatory-say-feds

[ampoulog]

Το LTE1800 είναι αυτό που χρησιμοποιούν οι εταιρίες που παρέχουν υπηρεσίες κινητής στην Ελλάδα (Cosmote και Vodafone).

Για περισσότερες πληροφορίες, μπορείτε να δείτε στα

[1] http://www.gsma.com/spectrum/wp-content/uploads/2012/03/lte1800mhzwhitepaper0.9.pdf
[2]https://d1dmfej9n5lgmh.cloudfront.net/gsmonline/article_attachments/attachments/33985/original/martin_ljungberg_ericsson_mwc_barcelona_2011.pdf?1353374287

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Heterogeneous Networks

Anders Furuskär from Ericsson Research talks about Heterogeneous Networks, also known as HetNets. Heterogeneous networks are an attractive means of expanding mobile network.

<a href="https://www.youtube.com/watch?v=vTCYvbwmgEA" target="_blank">http://www.youtube.com/watch?v=vTCYvbwmgEA</a>

http://www.youtube.com/watch?v=vTCYvbwmgEA

Διάρκεια: 4:01

[ampoulog]

Heterogeneous Networks in LTE

by Jeanette Wannstrom, masterltefaster.com and Keith Mallinson, WiseHarbor

Effective network planning is essential to cope with the increasing number of mobile broadband data subscribers and bandwidth-intensive services competing for limited radio resources. Operators have met this challenge by increasing capacity with new radio spectrum, adding multi-antenna techniques and implementing more efficient modulation and coding schemes. However, these measures alone are insufficient in the most crowded environments and at cell edges where performance can significantly degrade. Operators are also adding small cells and tightly-integrating these with their macro networks to spread traffic loads, widely maintain performance and service quality while reusing spectrum most efficiently.

One way to expand an existing macro-network, while maintaining it as a homogeneous network, is to “densify” it by adding more sectors per eNB or deploying more macro-eNBs. However, reducing the site-to-site distance in the macro-network can only be pursued to a certain extent because finding new macro-sites becomes increasingly difficult and can be expensive, especially in city centres. An alternative is to introduce small cells through the addition of low-power base stations (eNBs, HeNBs or Relay Nodes (RNs)) or Remote Radio Heads (RRH) to existing macro-eNBs. Site acquisition is easier and cheaper with this equipment which is also correspondingly smaller.

Small cells are primarily added to increase capacity in hot spots with high user demand and to fill in areas not covered by the macro network – both outdoors and indoors. They also improve network performance and service quality by offloading from the large macro-cells. The result is a heterogeneous network with large macro-cells in combination with small cells providing increased bitrates per unit area. See Figure 1.




Η συνέχεια στο: http://www.3gpp.org/technologies/keywords-acronyms/1576-hetnet

[ampoulog]

LTE-A PHY Layer Overview &  Femto Design Challenges

http://sites.cttc.es/femtoschool/images/presentations/5_mariuspesavento_tudarmstadt_lteaphylayer.pdf

[ampoulog]

Και το video της παραπάνω παρουσίασης:
http://lteworld.org/video/lte-phy-layer-overview-femto-design-challenges

[ampoulog]

Telecommunications Satellites

Satellite telecommunication is the most mature of space applications. Starting 50 years ago with the launch of Telstar in 1962 and Syncom in 1963, satcom has continued to grow ever since.

At first, satellite performance was very limited. To compensate for this, very large ground stations with dish antennas more than 20 metres in diameter were required to establish links with them. The use of satellites was limited to long distance telephony and to the transport of television signals between studios.

By 1990, two out of every three intercontinental telephone calls were transmitted by telecommunication satellites. Satellites proved particularly useful for communicating with many of the countries in the less developed parts of the world.
 
New technology and different kinds of demand have changed the way communications satellites are used. More powerful satellites and the use of higher frequencies have made it possible for many people to receive direct signals from the sky. At the beginning of the 21st century, more than 100 million European homes were able to watch television programmes transmitted by satellites, either by direct reception or through cable distribution systems.

Satcom: Where space meets daily life
Today telecommunications satellites are part of our daily lives. Many everyday activities rely on telecommunication satellites that are in orbit, almost 36 000 kilometres above our heads.

Did you know that:

When you listen to the radio, it is very likely that the signal you are receiving has been distributed from the central studios by satellite?
Many newspapers and magazines are produced locally but printed centrally? The content of the paper is sent to the printing plants using satellite links.
Even when a news or sports event shown on television is taking place just a few kilometres away from the studios, it has probably been transmitted via satellite?
Most news agencies use satellites to distribute text, audio and video to their affiliates?
In many countries, access to the Internet is by satellite communication? Internet service providers often link their servers to the core of the Internet network by satellite. With the emergence of very powerful broadband satellites, users – equipped with their own broadband interactive satellite terminals – will get access to the Internet regardless of their distance from the nearest terrestrial node.

http://www.esa.int/Our_Activities/Telecommunications_Integrated_Applications/Telecommunications_satellites