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Eroshkina Daria

Daria Eroshkina

Faculty: Computer Information Technologies and Automation
Speciality: Telecommunication Systems and Networks
Theme of the Master's Work: Research of reliability ensuring methods in information transfer of WiMAX-based networks
Scientific Adviser: Aleksander Horhordin

Autobiography Resume

Abstract of the master's work


Research of reliability ensuring methods in information transfer of WiMAX-based networks


Introduction

Tendencies of development of telecommunications in the world are linked with the emergence of new services, so to existing networks demand more. To date, some providers can not provide high speed data transmission and reliability. Recently, for solving these problems technology of WiMAXhas been applied, which provides wireless communication over long distances.


Relevance

The development of scientific and technological progress in modern society is so fast that technologies relevant today may take a back seat tomorrow. The technology of wireless broadband access WiMAX enables data transmission over long distances. Its feature is to work in the absence of a direct line of sight, which is especially important in urban areas with dense buildings and the presence of tall buildings.

Environment for signal propagation in the WiMAX network is the air space. It can cause interference that would distort the data signal, so wireless protection problem of signals from the harmful effects is important.


Aims and objectives

Aim of the work: research of methods to ensure the reliability of information in the WiMAX networks, and the application of the chosen method to achieve specified level of reliability of information transmission.

To achieve this goal, following tasks should be solved:

  • Analyze the causes of interference in wireless networks WiMAX
  • Develop a model of interaction of signal interference and estimate the probability of bit error rate under different settings of model parameters
  • Select and justify a method to ensure reliability of data transmission
  • Apply the chosen method to achieve a given level of confidence.

Expected scientific innovation

Master's thesis focused on the construction and study the characteristics of the model channel network of WiMAX, which takes into account the negative impact caused by interference in the medium of signal propagation. It is also necessary to select and apply the method that most closely to correct the interference at reliability of the information.


Survey of research

Among the masters DonNTU study issues related to technology WiMAX, engaged Shapovalova L. in the "Research and development model data in the radio access network based on WiMAX in terms of quality and safety" and Kusov R. in "Research and development of transmission path radio channel access to modern telecommunication networks based on wireless broadband technology WiMAX".

This topic is represented in the work of the world's scientists, such as Nuaimi L., Shepard S., Ortman F., Smith K., Perik D.

Among the scientists of Ukraine and neighboring countries to address issues relating to the wireless broadband WiMAX, engaged Vishnevsky V., Shakhnovich I., Tailor C., Vasilyev V.


Summary of results

Since WiMAX is a wireless, then transmision via radio links formed between the antenna devices. Two kinds of signal are of particular interest: in a direct line of sight and in its absence.

In the line of sight the quality of the received signal is influenced by such factors as:

  • losses in free space
  • losses due to state of the atmosphere
  • presence of reflective objects
  • Doppler Effect
  • impact of noise

One of the main features of the 802.16 WiMAX standard is that it provides high-speed connections over long distances, even without direct line of sight of the object. Reflection of the signal makes it possible to operate in dense urban areas, but the phenomenon can occur multipath interference signals..

Рисунок 1

Picture 1 - Multipath interference of signals. Gif-animation: 121kb, 6 frames, 6 repetition cycles


To combat the noise is often used excessive coding, diversity reception, the application of adaptive antennas with radiation pattern, adaptive equalization technology and orthogonal frequency division multiplexed OFDM.

To study the dependence of modulation type and size of bit error rate of signal to noise ratio in wireless networks, WiMAX has been used a model system of data transmission standard, IEEE 802.16-2004. The simulation was performed with the application package Matlab. The initial data for modeling is the SNR (Signal / Noise Ratio, dB), which is specified in the parameters block AWGN Channel, and the output you get value bit error (Bit Error Rate) and Rate ID, which corresponds to the type of modulation, as defined in the parameters model. Data obtained by simulation are summarized in Table 1.


Table 1 - Simulation results

Таблица 1

The data obtained suggest that when the signal to noise ratio not only changes the probability of bit-errors, but also the type of modulation

The standard laid adaptive-code design, which allows you to adjust to the characteristics of the channel at a time. Depending on the SNR, the system selects the modulation method, which achieves the required quality of information transfer and stable operation of the communication system WiMAX.


Conclusion

In the future I plan to create a model of channel network of WiMAX, which allows to take into account the negative impact of the propagation of signals in the absence of a direct line of sight. With the help of the resulting model a method for reducing the effect of noise on the communication system and improvement of the information reliability will be selected and carried out.


References

  1. Шаповалова Л.В. Исследование и разработка модели передачи данных в сети радиодоступа по технологии WiMAX с учетом качества и безопасности [Электронный ресурс] / Портал магистров ДонНТУ, - Режим доступа: http://masters.donntu.ru/2010/fkita/shapovalova/diss/index.htm


  2. Гепко И.А., Олейник В.Ф., Чайка Ю.Д., Бондаренко А.В. Современные беспроводные сети: состояние и перспективы развития [Электронный ресурс] / Современные беспроводные сети, - Режим доступа: http://wireless-networks.vikenia.com/Modern%20Wireless%20Networks.pdf


  3. Пахомов С. Скоростная связь без проводов, или Стандарт 802.16 [Электронный ресурс] / Электронный журнал "КомпьютерПресс", - Режим доступа: http://www.compress.ru/article.aspx?id=9948&iid=415


  4. Сюваткин В. С., Есипенко В. И., Ковалев И. П., Сухоребров В. Г. WiMAX – технология беспроводной связи: теоретические основы, стандарты, применение. – СПб.: БХВ – Петербург, 2005. – 368 с.


  5. Терентьев С.В., Тихвинский В.О. Оценка параметров качества услуг в сетях WiMAX [Электронный ресурс] / Электронный журнал "T-Comm - Телекоммуникации и Транспорт", - Режим доступа: http://www.media-publisher.ru/cgi-bin/stats.cgi?page=5-6/09


  6. Гепко И.А., Олейник В.Ф., Чайка Ю.Д., Бондаренко А.В. Современные беспроводные сети: состояние и перспективы развития [Электронный ресурс], - Режим доступа: http://www.compress.ru/article.aspx?id=9948&iid=415


  7. Коржов В. Беспроводные технологии передачи данных - стандарт радиодоступа WiMAX [Электронный ресурс] / Журнал "Computerworld", - Режим доступа: http://www.rmt.ru/articles.html?article=101


  8. Силаков Н. На пути к широкому эфиру [Электронный ресурс] / Журнал "СЕТИ и Телекоммуникации", - Режим доступа: http://www.seti-ua.com/?in=seti_show_article&seti_art_ID=65&SearchString=wimax&by_id=3


  9. Коржов В. Беспроводные технологии передачи данных - стандарт радиодоступа WiMAX [Электронный ресурс] / Журнал "Computerworld", - Режим доступа: http://www.rmt.ru/articles.html?article=101


  10. Васильев В.Г Технология фиксированного широкополосного беспроводного доступа WiMAX [Электронный ресурс], - Режим доступа: http://ebookee.org/-WiMAX_386923.html


Important note

By the time of writing of the abstract Graduate work is not completed yet. Final results were obtained in December 2011. You can take full text of the research from the author or supervisor after this date.


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