Early submissions deadline:

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Upcoming Events
Event Dates

22nd FRUCT

09.04 - 13.04

AMICT'2018

11.04 - 13.04

CFP: 5th CEE-SECR 2009 conference

The 5th Eastern and Central European Software Engineering Conference in Russia (CEE-SECR) is the major software event that attracts 500+ participants from local industry.The conference employs a double-blind review process producing a high quality program, which includes globally-recognized software "gurus / founding fathers" as keynote speakers such as Grady Booch, Lars Bak, Yuri Gurevich and others.

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Connect2Earth campaign: Make history

This December world leaders meet in Copenhagen to decide how we deal with climate change. Do you want to be part of this historical event? You can… Sign up and participate in the discussions on connect2earth and you could be selected to go alongside WWF and IUCN to Copenhagen. Enter the competition now and help shape the future! (www.connect2earth.org/introduction) This is a unique opportunity as the talks are closed to the general public.

Russian Mobile VAS Awards

Welcome to participate at the Russian Mobile VAS Awards'2009 competition. Entry deadline: October 16, 2009. The Awards winners will be announced at the VI Mobile VAS Conference gala dinner and Awards Ceremony on November 19. Russian Mobile VAS Awards'2009 categories:

FRUCT training registration

Please, choose training you would like to participate:

Qt training
Mobile Trust Computing
M3 Smart Spaces

Common information:

First and Last Name:

Email:

Education:

Speciality (Student, PhD student, Specialist, PhD etc.):

University (IT, Telecommunications, Math etc.):

Questionnaire for participants in Qt training:

Do you have some GUI development experience?

Which GUI libraries/tools have you used?


Specify your knowledge about GNU/make:

Other:

Why are you going to participate in training? What's your goal?

Select one most important thing which you prefer to focus during the training:

Please write your wishes about Qt training for organizers:


Would you like to use the computer class PC or own laptop?

 

Resource allocation in OFDMA

For last few decades, Orthogonal Frequency Division Multiplexing has been recognized not only as an efficient modulation format but also as an effective way of supporting multiple access. The orthogonal frequency division multiple access (OFDMA) principle employs assignment of orthogonal sub-carrier sets to a number of the network users and has been adopted in Metropolitan Area Networks (IEEE 802.16.std), Wide Area Networks such as Ultra Mobile Broadband for 3GPP Long Term Evolution.

Whenever an OFDMA operates in a time-frequency dispersive radio channel the link adaptation provides a benefit in terms of any system performance metric by employing time, frequency and multi-user diversities. The aim of the project is elaboration of low complexity (practical) link adaptation algorithms with QoS constraints (such as fairness, delay etc.) for OFDMA.

Contacts


Contact person: Natalia Ermolova

Polar Modulation and Transmitters Power Efficiency

Introduction


High peak-to-average signals play a key role in the modern wireless communications. More over OFDM technology being applied to the initially constant envelope signal like QPSK, makes it distribution Gaussian with theoretically infinite crest factor. Such signals are very sensitive to the nonlinear distortions.
Quadrature (I/Q) modulation is a most popular technique of baseband signal spectrum translation to the radio frequency (RF) bands. From the mathematical point of view this way provides one of two forms of the complex numbers representation as real and imaginary parts. Practical realization of this method is very convenient and therefore widely used both for BPSK, QPSK GMSK and QAM modulation constellations. But among a lot of advantages it has one serious drawback. In the case of non constant amplitude signal modulation schemes (including OFDM technology) it requires high transmitter linearity. As a result power efficiency suffers. 
Polar modulation is alternative way of complex envelope forming. In this case angle and amplitude but not real and imaginary variations are applied to the carrier signal. It corresponds to the polar representation of complex envelope. Polar modulation realization allows nonlinear operation of RF transmitter. Even high efficiency switching classes of operation of power amplifiers are appropriated. Amplitude component of signal modulation is introduced at the last stage of power amplifier in this case.
Difficulties of practical realization of such approach quite clear – it is necessary to provide sufficient accuracy of amplitude and angle variations during modulation. 
The purpose of the project is practical polar modulation development, hardware prototype elaboration, its experimental research and numerical estimation of the power efficiency improving.

Environment


Experimental set consists of the next blocks:

  • bit stream source;
  • digital processor (modulator);
  • RF transmitter;
  • RF receiver;
  • digital demodulator;
  • BER tester.

Standard measurement equipment is also necessary for a purpose of prototypes tuning and experiments providing:

  • vector generator;
  • spectrum analyzer;
  • digital oscilloscope.

Research Directions


  1. Amplitude modulation technique at power amplifiers, operating in the different classes, including switched regimes.
  2. Combined angle and amplitude modulation accuracy and its distortions due to hardware imperfection.
  3. Development of the polar modulation signals digital processing for a popular communication standards like 802.11, 802.16.

Project Stages


  1. Literature analysis. Different classes operation of the power amplifiers simulation. Polar modulation technique simulation. Calculation of achievable modulation parameters and limitations.
  2. Choice of practical realization variants. Electronic components analysis. Development of prototypes and its fabrication. Signal processing special algorithms development.
  3. Prototypes tuning and parameters measurement. Complete experiments wit different modulation formats. Experimental results summarizing and analysis.

Contacts


Team leader: Vladimir Prikhodko

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