gsm voice quality
DESCRIPTION
GSM voice quality. Final report. Customer: Tunisiana. Tunis, 15 th of July 2004. Company profile (MCI). MCI: Management Conseil et Ingénierie. Telecommunications and IT Know-How in: Training Commissioning and Maintenance (OAM) Network Planing Radio coverage tests - PowerPoint PPT PresentationTRANSCRIPT
GSM voice quality
Final report
Tunis, 15th of July 2004
Customer: Tunisiana
Telecommunications and IT Know-How in: Training Commissioning and Maintenance (OAM) Network Planing
Radio coverage tests Traffic measurements and analysis
Company profile (MCI)
MCI: Management Conseil et Ingénierie
Traditional approach for GSM radio link test:
• Protocol analysers (RXQUAL)Data useful in network maintenance but not for the estimation of the Quality of Service (QoS) as viewed by the mobile phone user (perception!!).
RXQUAL does not represent “real life” conditions. The following slides discuss inherent problems of RXQUAL and demonstrate that the measurement cannot be related to perceived speech quality in an accurate and reliable way.
Why voice QoS
In today’s competitive environment, it is
important for GSM operators to be able to
accurately assess performance and
voice quality of their networks in order to
maintain or extend market position.
From a subscriber’s point of view, the
relevant performance measure are:
• Call success rate
• Speech quality
QoS is critical to success
• RXQUAL does not consider the varying efficiency of interleaving and bit error correction under different environmental conditions (fading or frequency hopping)
• RXQUAL does not consider quality degradation caused by stolen speech frames (Handover: TCH becomes FACCH for 0,2s)
• RXQUAL does not detect any PSTN quality impairing effects (echo, crosstalk or noise in the analogue part of the network)
• Speech quality is the only parameter to detect defects within voice processing circuits
Arguments for Speech Quality
• RXQUAL does not recognise whether bad speech frame indication (BFI) failed
• Downlink RXQUAL may Fail in Detecting QoS degradation in Uplink Direction
• RXQUAL does not consider acoustical power level variations
Arguments for Speech Quality
Objectives of the study
Evaluation of the quality of service for the telecom operator:
Orascom Telecom TunisiaOrascom Telecom Tunisia
Location: Tunis
Training of the agents
• Identification of the typical noise (echo, metallic or robot voice, lost syllables, etc…) ;• Evaluation of the voice quality (recorded audio samples)
MCI used a software tool for recording and editing of voice messages
Training of the agents
The agents were trained on :
• Use of MCI Hotline
• Numbers to be called
• Itineraries to follow
• Manipulation of topographical maps
• Use of the test forms
Equipment used
Test types
• Outdoor : Outside buildings (pedestrian)• Indoor : Inside buildings, underground
excluded:• Close to doors or windows• Far from doors and windows
• Incar : Inside a car also called drive test
Measured parameters
• Call success rate / Call failure:• Due to network saturation• Due to missed coverage
• Call drop rate / Call completion rate
• Voice quality noted 1 to 4: • Excellent quality• Some noise but still good quality• Some words are not understood but the conversation is still OK• Bad quality. The conversation is not understood
Speech quality relates to:Intelligibility: Quality of perception of the meaning or information content of what the talker said;Naturalness: Degree of fidelity to the talker’s voice;Loudness: Absolute loudness level at the listener’s side.
Sample of the study
Totally 2706 calls:
- Outdoor: 1236- Indoor: 1226- Incar: 244
Tunis was divided into:- 6 regions- 79 sectors with different sizes
Incar calls: all main roads tested, also bidirectionally
R E S U L T S
O F T H E
S T U D Y
Major Indoor points
Liste of the indoor points (365 points):Libellé NombreMunicipalités 18Aéroport de Tunis Carthage 1Banques 5Centres commerciaux 19Souks et marchés 7Petits commerces 20Cafés et salons de thé 17Délégations 7Hôpitaux, cliniques et dispensaires 24Hôtels 4Immeubles 101Ecoles, lycées et collèges 18Habitations 17Magasins et supermarchés 7Autres locaux 2Postes 21Sociétés privées 18Universités 23Autres administrations 36
Constitution of the sample
Distribution of the calls by regions
Sector Region Total Nr.of calls Note 1 Note 2 Note 3 Note 4
407 75 7 782.06% 15.12% 1.41% 1.41%
222 48 2 2
81.02% 17.52% 0.73% 0.73%
313 78 6 2
78.45% 19.55% 1.50% 0.50%
91 23 6
75.83% 19.17% 5.00%
251 79 8 174.04% 23.30% 2.36% 0.30%
685 109 7 6
84.88% 13.51% 0.87% 0.74%
Frequency of notation
A Tunis Centre 496
B La Marsa, SidiBou Saïd,Carthage LaGoulette
274
C Ben Arous,Megrine, Radès,El Mourouj
399
D Ezzahra, Hammam Lif,Hamma Chatt
120 -
E Manouba 339
F Ariana/El Menzah/ Ennasr,Bardo
807
Speech quality by regions (1)
Speech quality by regions (2)
Distribution of the the notes 3 and 4 by regions
DATA ON GISArcView
Sample on ArcView (1)
Habib Bourguiba Avenue
Sample on ArcView (2)
Ariana City Center
Data for a sample on ArcView
Data stored on GIS for each measurement
End