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Abstract

Content


Introduction

Users of mobile networks need in high data rates. The reason for this is the Internet. Mobile phones have penetrated very much in the daily lives of many users, so they can be a convenient tool to access the Internet. For this rate increase is not only necessary but also to ensure the required quality of service (QoS). As a result, the group has developed a 3GPP mobile standard third-generation (UMTS).

1. Theme urgency

During the construction of a UMTS network using various methods to optimize the main parameters of air interface HSDPA. Optimization involves improving the quality of the entire network. In the radio resource management algorithms include handover, power control, packet scheduling, access control and load [1].

Type of Service and the channel model defines the boundary of the allowable number of user channels. This sets a limit load factor of the cell. So, the optimization of the load factor of the cell of a UMTS network plays an important role in the allocation of the total power of the base station.

2. Goal and tasks of the research

Objective of research is develop a method for optimizing the main parameters of the network UMTS/HSDPA to improve the construction and operation of third generation mobile UMTS.

Main tasks of the research:

1. Identification of basic energy-velocity relations for the radio interface UMTS.

2. Analyze and evaluate the parameters of network HSDPA.

3. To analyze the features of construction of the access network based on HSDPA air interface

4. Development of a method allowing for the optimization of energy relations for the air interface HSDPA.

Research object: air interface High Speed Downlink Packet Access (HSDPA).

Research subject: the load factor of the cell in the network UMTS/HSDPA.

3. Review of sources

Semenova O., Semenov A., Wozniak O. active development of methods to control access to UMTS networks using the phase of neural technologies, which enable the network to avoid congestion in the Vinnytsia National Technical University [2]. Veduta V. suggested in his paper a method for optimizing a digital communication system with the code channels [3]. Application of multiobjective optimization in the planning of cellular networks have been proposed Bezruk V. and Chebotareva D. (Kharkov National University of Radio Electronics) [4]. Bezruk V., Tikhonov V., Kudryavtsev A., Chebotarev D. demonstrated a description of the mathematical model of network traffic, third generation mobile communication [5].

4. Development of a method of optimization of the cell load factor in the network UMTS/HSDPA

UMTS – third generation mobile communication, which is developed by the European Telecommunications Standards Institute (ETSI).

For UMTS defined three basic access technologies:

– Broadband Multiple Access CDMA;

– Wireless global mobile communications with data transmission GSM/EDGE;

– Additional Services – access to wireless local area network WLAN [6].

The main features of the technology HSDPA.

– The presence of high-speed downlink channel HS-RDSCH (High Speed Downlink Shared Channel) (Fig. 1).


Figure 1 - Visualization of multiplexing user data channel HS-PDSCH

Figure 1 - Visualization of multiplexing user data channel HS-PDSCH

(animation: 9 frames, delay  1 s, repeat 7, size 88 Kbyte, Easy GIF Animator)


– Constant output power base station.

– Lack of handover.

– Limitations of available channel codes for the organization of HS-SCCH and the DPCH.

Skrynnikov V. engaged of energy-velocity relations UMTS/HSDPA in [7]. He showed the dynamic nature of the change of energy-velocity relationship in the radio network UMTS:


Equation (1) in the form:

To optimize load factor of the cell using the method of Hooke-Jeeves. It is easy to calculus, and there are no derivatives [8]. As objective function we take the expression (2). Full power base stations and signal/noise ratio will be changed.

After optimization were obtained by two dependencies: the load factor of the total cell capacity of the base station (Fig. 2) and the dependence of the load cell from the signal/noise ratio (Fig. 3).



Figure 2 - The load factor of the total cell capacity of the base station



    Figure 3 - The dependence of the load cell from the signal/noise ratio

    Conclusion

    At the stage of pre-planning network UMTS/HSDPA is important to choose the most optimal values of the coefficient of load cell. After investigating the power-velocity relationships can be seen that to maintain the optimal values of the load cell is sufficient change in the total power of the base station at fixed other parameters of the radio interface. This enables operators to quickly and easily control the quality of service high speed data transmission in the downlink.

    References

    1. Планирование пропускной способности и зоны обслуживания. [Электронный ресурс]. – Режим доступа: URL: http://wcdma3g.ru/index.php?topic=glava8&page=3. – Название с экрана.
    2. Семенова О.О., Семенов А.О., Возняк О.В. Керування доступом до UMTS мереж за допомогою фазі-нейронних технологій. // Вісник Хмельницького национального университету. Хмельницьк–2011. Випуск 3. С. 249–254.
    3. Ведута В.О. Оптимізація систем зв’язку з кодовими каналами. // Електроніка та системи управління. 2009. Випуск 2 (20). С. 18–26.
    4. Безрук В.М., Чеботарева Д.В. Применение методов многокритериальной оптимизации при планировании сетей сотовой связи. // Харьковский национальный университет радиоэлектроники. 2008. С. 117–126.
    5. Безрук В., Тихонов В., Кудрявцева Н., Чеботарева Д. Математические модели сетевого трафика мобильной связи третьего поколениия. // Харьківський національний університет радіоелектроніки. Харків–2012. С. 194–207.
    6. Кааранен Х. Сети UMTS. Архитектура, мобильность, сервисы ⁄ Х. Кааранен, А. Ахтиайнен, Л. Лаитинен, С. Найян, В. Ниеми. – М.: Техносфера, 2008 – 468 с.
    7. Скрынников В.Г. Предварительная оценка параметров сети UMTS/HSDPA. // Электросвязь. №3. 2008.
    8. Банди З.Б. Методы оптимизации. Основной курс: Пер. с англ. – М.: Радио и связь, 1988 – 128 с.: ил.

    Important note

    This master’s work has not been completed yet. Final completion: December 2012. The full version of the work and materials on the topic can be obtained from the author or his scientific supervisor after this date.