Mobiliojo tinklo paslaugų kokybės vertinimo ir gerinimo būdų tyrimas ; Investigation of evaluation and improvement methods of service quality in mobile networks

V.Batkauskas

Sujets

• General Packet Radio Service
• GSM
• Universal Mobile Telecommunications System

Informations

• Publié par: vilnius_gediminas_technical_university
• Publié le: 01 janvier 2006
• Nombre de lectures: 45
• Poids de l'ouvrage: 2 Mo

Extrait

VILNIUS GEDIMINAS TECHNICAL UNIVERSITY





Vaidas Batkauskas

INVESTIGATION OF EVALUATION AND
IMPROVEMENT METHODS OF SERVICE
QUALITY IN MOBILE NETWORKS

Doctor dissertation
Technological science, Electrical Engineering and Electronics – 01T






Vilnius, 2006
VILNIAUS GEDIMINO TECHNIKOS UNIVERSITETAS






Vaidas Batkauskas

MOBILIOJO TINKLO PASLAUGŲ KOKYBĖ S
VERTINIMO IR GERINIMO BŪ DŲ TYRIMAS

Daktaro disertacija
Technologijos mokslai, elektros ir elektronikos inžinerija – 01T






Vilnius, 2006 Doctor dissertation was prepared at Vilnius Gediminas Technical University in 2002 – 2006.

The Scientific Supervisor:
Prof Dr Habil Algimantas Kajackas (Vilnius Gediminas Technical University,
Technological science, Electrical engineering and Electronics – 01T) CONTENTS

1. INTRODUCTION........................................................................................................... 6
2. QUALITY OF ACCESS AND RECEIVED SERVICES OF USERS IN THE GSM
NETWORK..................................................................................................................... 10
2.1. The Global System of Mobile Communications...................................................... 11
2.2. Coverage and capacity of the GSM network............................................................ 12
2.2.1. Planning of coverage and capacity of the GSM network.................................. 13
2.2.2. Impact of Uplink/Downlink power control and discontinuous transmission
on capacity of GSM network............................................................................. 14
2.2.3. Use of the AMR HR codec for expanding of capacity of the network............. 18
2.2.4. Frequency hopping technology for expanding of capacity of the network....... 19
2.2.5. Calculation of the maximum capacity of the GSM network in Vilnius city..... 20
2.2.6. Results of measurements of dropped call rate in the Omnitel GSM network... 22
2.3. Impact of electromagnetic interference on QoS in cellular networks...................... 23
2.3.1. Measurement of interference............................................................................. 24
2.3.2. A proposed method of C/I estimation ............................................................. 26
2.4. Rating of individual QoS for voice services in cellular networks............................ 28
2.4.1. Existing methods of evaluation of QoS received by the user. 29
2.4.2. Arguments for adopting a new concept of individual QoS............................... 30
2.5. A proposed concept for rating of individual QoS.................................................... 32
2.5.1. Call set-up and dropping................................................................................... 32
2.5.2. Radio link performance..................................................................................... 33
2.5.3. Estimating impairments to the voice quality..................................................... 34
2.5.4. Relating voice quality impairment factors to the measured radio channel
parameters.......................................................................................................... 37
2.6. Chapter conclusions.................................................................................................. 37
3. DEVELOPING A MODEL OF THE GPRS/EDGE DATA CHANNEL FOR THE
INDIVIDUAL USER.................................................................................................... 39
3.1. Analysis of the GPRS/EDGE mobile data network ................................................ 39
3.1.1. Infrastructure of the GPRS/EDGE mobile data network................................... 40
3.1.2. Transmission of data packets in the GPRS/EDGE network.............................. 41
3.1.3. Coding of GPRS and EDGE radio data packets. 43
3.1.4. Multislot classes of a MS.................................................................................. 45
3.1.5. Dependency of usage of a coding scheme on quality of radio environment..... 45 3.2. Experimental measurement results........................................................................... 47
3.3. Resources of a GSM/GPRS network radio connection of an individual user.......... 54
3.4. A model of distribution of common resources among voice and data users............ 56
3.4.1. A model of delay of mobile data packets.......................................................... 59
3.4.2. Creating a model in Matlab – Simulink............................................................ 60
3.4.3. Estimation of model input data.......................................................................... 61
3.5. Modelling results...................................................................................................... 62
3.6. Comparison of modelling results with the results of the research of the real
GSM/GPRS system................................................................................................. 66
3.7. Chapter conclusions.................................................................................................. 68
4. INVESTIGATION OF PARALLEL MOBILE DATA CHANNELS............................ 70
4.1. Combination of mobile data channels...................................................................... 71
4.2. Experimental investigation of possibility to combine mobile data channels........... 74
4.2.1. Investigation of existing load balancing technologies of IP channels............... 76
4.2.2. Use of the EIGRP protocol for load balancing of data channels....................... 77
4.2.3. Use of the TEQL protocol for load balancing of data channels........................ 81
4.2.4. Possibility to use the existing protocols for load balancing of data channels... 83
4.3. Investigation of a possibility to access several base stations.................................... 84
4.4. Influence of combining technology of data channels on QoS of an individual user 87
4.5. Chapter conclusions.................................................................................................. 89
5. GENERAL CONCLUSIONS......................................................................................... 91
ABBREVIATIONS............................................................................................................. 92
REFERENCES.................................................................................................................... 95 1. INTRODUCTION

Relevance of the dissertation. GSM mobile networks are very widely used in the
9world and the number of GSM users exceeds 10 . In the last decade, the GSM/GPRS network
has been rapidly expanded in Lithuania as well. Coverage of the network has reached 99 % of
territory of the country. Load of the network in largest cities reaches up to several hundred
Erlangs for square kilometre. The voice traffic still generates the largest part of the network
load, however the mobile data traffic also grows rapidly. Radio interface between the user of
mobile services and the network is not stationary. The received quality of service (QoS) of
every user in different places is different. Even in a single cell radio link characteristics differ
in different parts of the cell. The signal level may easily vary about 10–20 dB just within
several or tens of meters. Moreover, a mobile user experiences different link conditions while
moving in the natural environment within or between cells. However, historically,
characteristics of QoS of mobile services are measured and evaluated like the ones of the
fixed network using statistical methods. Statistically calculated characteristics of QoS do not
include information about the received quality of mobile telecommunication services of every
individual user.
Conception of the received quality of services of individual users (individual QoS –
iQoS) in the GSM/GPRS network has not been analysed before. QoS should be measured not
only at the network level, as it is done today, but also individually in every user terminal.
Possible ways of measurement and evaluation of the received voice and data QoS by an
individual user need to be investigated. This would increase satisfaction of users, allow
implementation of service level agreements for cellular network customers and introduce new
value-added services of high benefit to users (such as quality dependent billing).

The objective and tasks of the dissertation. The objective of the dissertation is to
investigate methods of measurement, evaluation and improvement of iQoS of data and voice
users in mobile telecommunication networks.
The tasks for achieving this objective:
1. to create and present a conception of individual quality of services (iQoS) of the user
in mobile telecommunication networks and offer a method of measurement of iQoS;
2. to develop a system adequate simulation model that will evaluate needs of users and
predict the necessary network expansion and the QoS an individual user will receive;
3. for improvement of iQoS for mobile data users to investigate a possibility of
transmitting data of users using parallel mobile data channels.
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