[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!

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Η αντιστοίχηση εργασίας με ομάδα βρίσκεται στο συνημμένο. Το eThmmy για κάποιο λόγο δεν με αφήνει να μπω, οπότε το ανεβάζω εδώ.

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Στο παρακάτω link μπορείτε να βρείτε μία παρουσίαση για OFDM που κάνει αναφορά και σε Synchronization

http://bwrcs.eecs.berkeley.edu/Classes/EE225C/Lectures/Lec16_ofdm.pdf

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Και για Channel Estimation:

http://herkules.oulu.fi/isbn9789514298578/isbn9789514298578.pdf

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Καλή Χρονιά!!! Χρόνια Πολλά σε όλους μας...

Εύχομαι το 2014 να πραγματοποιήσει κάθε σας επιθυμία και να σας χαρίσει ότι περισσότερο έχετε ανάγκη...

Υγεία, Χαρά, Αγάπη, Τύχη και γενικά ό,τι δεν ήρθε το 2013   

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[Tutorial] Advances in Coordinated Multi-Cell Multi-User MIMO Systems

Abstract

The tutorial begins with a discussion of multiuser MIMO (MU-MIMO) antenna techniques in a point-to-point single-cellular environment. The presenter explains how multi-user scheduling techniques can exploit the degree of freedom in the user domain to enhance the coverage and capacity of MIMO systems simultaneously.

Next, point-to-multipoint MU-MIMO broadcast systems are covered with an emphasis on the limited feedback issue and beamforming design techniques for MU-MIMO broadcast systems. An explanation covers how the MU-MIMO broadcast techniques can be applied to improve performance of the multi-cellular MIMO systems in an interference-limited environment.

Last, the presenter introduces the state of art coordinated multi-point transmission (CoMP) techniques in 3GPP LTE-advanced or called the collaborative MIMO (Co-MIMO) techniques in IEEE 802.16m WiMAX, and concludes this tutorial by discussing the open issues in this field.

link: https://www.comsoc.org/form/tutorial-registration-advances-coordinated-multi-cell-multi-user-mimo-systems

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Υπενθύμιση!

Οι  παρουσιάσεις  των  εργασιών  από  τις  ομάδες  θα  γίνουν  την  Τρίτη  14/01/2014.

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Τηλεπικοινωνιακά Νέα! 

Scientists have created a molecular communication system that will allow us to send messages and data while we are in tunnels, pipelines and underwater.

Text message using vodka: Molecular communication can aid communication underground, underwater or inside the body



Scientists have created a molecular communications system for the transmission of messages and data in challenging environments such as tunnels, pipelines, underwater and within the body.
The technique has a wide range of applications in environments where electromagnetic waves cannot be used, for example in underground structures such as tunnels, pipelines or in underwater environments.
Molecular signalling is a common feature of the plant and animal kingdom – insects for example use pheromones for long-range signalling - but to date continuous data have not been transmitted.
Researchers at the University of Warwick in the UK and the York University in Canada have developed the capability to transform any generic message into binary signals, which in turn is 'programmed' into evaporated alcohol molecules to demonstrate the potential of molecular communications. Their results are published in the open access journal PLOS ONE.
The first demonstration signal was performed in Canada and was 'O Canada,' from the Canadian national anthem. It was sent several metres across open space before it was decoded by a receiver. The hardware is made from off-the-shelf electronics and costs around $100. The scientists believe the simple system could have a wide variety of applications, ranging from communication in hostile underground environments to nanotechnology.

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"We believe we have sent the world's first text message to be transmitted entirely with molecular communication, controlling concentration levels of the alcohol molecules, to encode the alphabets with single spray representing bit 1 and no spray representing the bit 0," says York U doctoral candidate Nariman Farsad, who led the experiment.
Dr Weisi Guo from the School of Engineering at the University of Warwick said: "Imagine sending a detailed message using perfume – it sounds like something from a spy thriller novel, but in reality it is an incredibly simple way to communicate.
" Of course people have achieved short ranged signalling using chemicals, but we have gone to the next level and successfully communicated continuous and generic messages over several metres.
"Signalling or cues are something we see all the time in the natural world - bees for example use chemicals in pheromones to signal to others when there is a threat to the hive.
"In the modern human world, our method won't replace electromagnetic waves which transmit the bulk of our data, but there are some areas where conventional communications systems are not particularly well-adapted.
"For example, inside tunnels, pipelines or deep underground structures, chemical signals can offer a more efficient way of transmitting sensor data, such as those collected to monitor the health of structures and processes.
"Potential targeted applications include wireless monitoring of sewage works and oil rigs. This could prevent future disasters such as the bus-sized fatberg found blocking the London sewage networks in 2013, and the Deepwater Horizon oil spill in 2010."
"They can also be used to communicate on the nano scale, for example in medicine where recent advances mean it's possible to embed sensors into the organs of the body or create miniature robots to carry out a specific task such as targeting drugs to cancer cells.
"On these tiny scales and in special structural environments, there are constraints with electromagnetic signals such as the ratio of antenna size to the wavelength of the signal, which chemical communication does not have.
"Molecular communication signals are also biocompatible and require very little energy to generate and propagate."
The team will now set up a company which aims to bring a range of academic and industrial products to the market.


Read more at: http://phys.org/news/2013-12-messages-molecules-aid-underground-underwater.html#jCp


link: http://phys.org/news/2013-12-messages-molecules-aid-underground-underwater.html

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Τηλεπικοινωνιακά Νέα! 

LTE-Advanced Is the Real 4G

More network capacity, faster data speeds, and better coverage will come from LTE-Advanced mobile technologies.




Read more at: http://spectrum.ieee.org/telecom/standards/lte-advanced-is-the-real-4g

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Οι παρουσιάσεις των εργασιών θα γίνουν την Τρίτη 14/01/2014 και ώρα 13:00-15:00 στην Αίθουσα Α7.


Όσοι κάνουν εργασία θα πρέπει να παραδώσουν την αναφορά τους έως την ημερομηνία εξέτασης του μαθήματος.

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Μάθημα Δευτέρα 13/01/2014

Τη Δευτέρα θα γίνει μάθημα μόνο την πρώτη ώρα (11:00 - 11:45) και θα ξεκινήσει 11:00 ακριβώς, με θέμα: "Απώλειες στις Δορυφορικές Επικοινωνίες", από τον Α. Μπουλογεώργο.

Τη 2η ώρα, μπορείτε να παρακολουθήσετε την δημόσια υποστήριξη του διδακτορικού του Β. Καπινά που θα γίνει στην αίθουσα Γενικών Συνελεύσεων και σχετίζεται με MIMO συστήματα.

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Τηλεπικοινωνιακά Νέα! 

Greening the Cloud Using Renewable-Energy-Aware  Service Migration


link: http://www.comsoc.org/sites/default/files/webfm/freearticle/free.pdf

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CES 2014 Trends: Wireless Networks Need to Learn to Cooperate

As the demand for bandwidth increases, wireless engineers are trying to figure out how to efficiently use all available networks, without sacrificing privacy and security


The big trends this year were an increased focus on cooperation and hand-offs between networks, an increased focus on privacy and security, and questions about how to make money from it all.


Transcript:

Josh Romero: Hi, I’m Josh Romero for IEEE Spectrum’s “Techwise Conversations”.  Today we’ll be talking with Stephen Cass who’s part of IEEE Spectrum’s team that’s live in Las Vegas covering CES 2014.  He’s here to talk about the latest trends in wireless.  Good morning Stephen—how’s Las Vegas?

Stephen Cass: Busy.  It’s only 8:00 in the morning, and already the place is getting pretty crazy, so it’s going to be another big day here at CES.

Josh Romero: I want to know what’s next and new with wireless systems. What have been the trends you’ve been hearing about the most this year, what are the themes emerging from the show?

Stephen Cass:  The big trend is everybody having to get their wireless technologies working together.  I think, in the past, you had one device and it might have one or maybe two wireless technologies.  If you had a cellular phone, it might have just had a 3G or 4G connection and Bluetooth; if you had a laptop it had Wi-Fi. And I think now we’re moving to a world where every device will be expected to negotiate multiple wireless systems, so you can move very seamlessly from place to place.  The reason why everybody—from device manufacturers to the cellphone carriers—are interested in this, is being able to deal with huge amounts of traffic. The idea is the ability to offload traffic.  Most traffic occurs in buildings, so if you’re on a cellphone and you’re doing a streaming video call, there’s not really a need to send that traffic to a cellphone tower down the block. Instead, why not pick it up inside the building, where all the other people who are trying to do video calls are.  So it’s really about how to very seamlessly hand off between these different technologies. Of course, a big challenge with that is the interference; now you’re combining multiple radios into one board or one chip, and with five or six radios you’re talking about interference within the device. And then you’ve got to deal with huge amounts of interference between users on the scale of city block.  So that’s kind of the big technical challenge, but there does seem to be huge momentum to overcome this.

Josh Romero:  So there’s increased cooperation between these previously separate networks at this point?

Stephen Cass: Yes exactly.  So for instance, the Wi-Fi Alliance now is in talks with the near-field communications community to talk about ways that you could maybe tap with your phone and get access to a wireless point.  The cellular people are also talking with operators of commercial Wi-Fi access points, like the type you might find in airports and hotels, again about how to seamlessly hand-off between the cellular network and the local Wi-Fi network.

Josh Romero: This is kind of an evolution of the wireless trends that we’ve been seeing for a couple years, but is there anything particularly new or distinctive that stood out to you at this year's show?

Stephen Cass: Yeah. I think one is the emphasis on control and privacy. In the past, it has always been, “Sure it’s there,” but it’s only imagined that very paranoid, or hardcore, or sort of techies would want to use it.  I think that recent concerns about surveillance has changed that. So everyone is taking security and privacy very seriously.  And how do you guarantee that, especially when you’re moving from all these different technologies and all these different networks?  How do you expose that control to users in a way that makes sense, that they don’t feel that things are being done underneath the hood that they don’t like, while at the same time not making it completely overwhelming so that every two seconds you’re hitting an “I agree to this” or “I agree to that” or "OK these terms of services" notice on your phone.  So that’s been a big issue.

So one issue where you have all these things working together, of course, is monetization and “How do we create a business model?”  Another issue that I asked about is net neutrality.  In the past, wireless mobile, because of it’s limited spectrum, has always made a play for saying that the rules of network neutrality shouldn’t quite apply to them, that there should be exceptions, they should be allowed to do  traffic shaping, so that everybody can make their cellphone call without getting swamped by one person doing a Bit Torrent.  So there are still elements of that idea, that spectrum is very scarce and very constrained but it will be interesting to see how it plays out when I move from fixed wireless systems like Wi-Fi, or the new system called Wi-Gig which is emerging in the next few years, onto cellular network and how that traffic is handled.  I think there’s a lot of work to be done, both technically, and with the business models and some of the technical administration models.

Josh Romero: So it sounds like the big trends this year were increased focus on cooperating and handoffs between networks, and increased focus on privacy and security—is that about right?

Stephen Cass:  I think that’s about right—and also an increased emphasis on how you would make money off it all.

Josh Romero: Great, thanks Stephen. We’ll look forward to hearing more of your reporting from the rest of the show.

Stephen Cass: Thanks Josh.

Josh Romero: We’ve been talking with Stephen Cass, who’s part of IEEE Spectrum’s team covering CES 2014.  For all CES coverage, check out the website.

For Techwise Conversations I’m Josh Romero.

This interview was recorded 8 January 2014.

Audio engineer: Francesco Ferorelli

Image: iStock

NOTE: Transcripts are created for the convenience of our readers and listeners and may not perfectly match their associated interviews and narratives. The authoritative record of IEEE Spectrum’s audio programming is the audio version.

Highlights from ”Wi-Fi to NFC: What’s Next for Wireless“ Session


Source: http://spectrum.ieee.org/podcast/telecom/wireless/ces-2014-trends-wireless-networks-need-to-learn-to-cooperate

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LTE Advanced—Leading in chipsets and evolution

link: http://www.qualcomm.com/sites/default/files/document/files/wireless-networks-lte_advanced-leading_in_chipsets_and_evolution.v6.20130827.pdf

Στο παραπάνω link μπορείτε να βρείτε μία παρουσίαση της Qualcomm σχετικά με LTE-Advanced
και τεχνικές, όπως:
- Carrier Aggrigation
- MIMO κ.α.
σε Heterogeneous Networks (Ετερογενή δίκτυα), που χρησιμοποιούνται για αύξηση των:
- data rate
- spectal efficiency κ.α.

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Extending the benefits of LTE Advanced to unlicensed spectrum

Description:

For operators to meet the anticipated 1000x increase in data traffic, deploying more small cells and utilizing all spectrum resources are key. Although licensed spectrum is the foundation, bandwidth-rich unlicensed spectrum around 5 GHz band can be used to effectively augment the capacity. The question is how to best opportunistically utilize it.

Extending the benefits of LTE Advanced to unlicensed spectrum brings its basic tenets of high-efficiency and robust mobility, while also making it a seamless extension of the larger LTE Advanced network. That means higher performance for operators and better broadband experience for users, and a common unified network for all spectrum types.

Presentation link: http://www.qualcomm.com/media/documents/extending-benefits-lte-advanced-unlicensed-spectrum

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Σχετικά με την Εργασία και την Παρουσίαση

Η παρουσίαση την Τρίτη 13.00 - 15.00 είναι υποχρεωτική και δεν μπορεί να υπάρξει αναβολή. Οι ομάδες θα πρέπει να έχουν ετοιμάσει μία παρουσίαση διάρκειας 10-15' το πολύ (~10-15 διαφάνειες) στις οποίες αν δεν έχουν ολοκληρώσει την εργασία θα συμπεριλάβουν τα:
- πρόβλημα που εξετάζουν και ανάγκη επίλυσης (π.χ. Ποια η ανάγκη για Channel Estimation ή Sychronization)
- μοντέλο του συστήματος που εξετάζουν (SISO OFDM με block που θα δείχνουν που θα εφαρμόσουν (-ζουν) τις διάφορες τεχνικές)
- σύντομη παρουσίαση των καναλιών που έχουν και πως τα υλοποίησαν
- τεχνικές που θα χρησιμοποιήσουν και τι έχουν υλοποιήσει από αυτές
- ότι αποτελέσματα έχουν πάρει
Καλό είναι να αναφερθούν σε "κολλήματα" και προβλήματα που έχουν τόσο στις τεχνικές όσο και στην υλοποίηση, ώστε να γίνει συζήτηση και να βρεθούν λύσεις που θα σας βοηθήσουν να ολοκληρώσετε την εργασία.

Το παραπάνω αποτελεί μία γενική πρόταση στο πως μπορείτε να δομήσετε την παρουσίαση σας. Μπορείτε να ξεφύγετε όσο θέλετε.