Colombia, September 2013 QoS assessment for mobile speech services including user interfaces in vehicles and hands-free communication Dr.-Ing. H. W. Gierlich Head of Telecom Division CITEL (PCC.I)/ ITU Forum on Information and Communication Technology Service: Quality, Control and Surveillance (Cartagena de Indias, Colombia, September 2013)

Colombia, September Outline Introduction The impact of terminal design on speech quality Assessment methods and standards for mobile terminals Driver distraction and speech services in cars Summary

Users Expectation (QoE) Colombia, September Speech Quality... Sound Quality & Naturalness Intelligibility Talking Effort Conversational Effort Double Talk Performance Expectation Transmission of Background Noise Speech Characteristics Individual Listening Network Conditions Environmental Conditions Listening Effort

Signal Processing in Modern Terminals Colombia, September Modulation / Demodulation H(f ) - NLP CN EC Decoder Coder LoudspeakerDecoder Comfort Noise Mikrofon – (Array) EC AGC/ companding … Coder Noise cancellatio n + NR z.B. GSM/UMTS SE Speech- enhancement speech recognition/ control EQ Important: All signal processing is non-linear, time variant and targeted to speech enhamcement

Speech Quality Colombia, September TESTING …in general should be based on users perception …may be based on simple signals and procedures modelling aspects of users perception (e.g. loudness) …may be based on complex signals and advanced procedures modelling aspects of users perception (e. g. switching and double talk tests) …may be based on perceptual models using psychoacoustically motivated procedures (models of the human hearing) USERS PERCEPTION …is subjective and generally different between subjects …is based on experience …is cultural dependant

Colombia, September Outline Introduction The impact of terminal design on speech quality Assessment methods and standards for mobile terminals Driver distraction and speech services in cars Summary

Speech Quality Evaluation Colombia, September Speech- Quality EchoPerformance Receiving Double Talk Quality of Background Noise Transm. Sending

Terminal Testing Bring the world to the lab: Simulate user Simulate user behaviour Simulate user environments Simulate network and access points Simulate network conditions Valdidate correct NTP access Colombia, September

The Typical Lab Setup Colombia, September Sub- woofer Testsystem Network Simulation Background Noise Simulation

Relevant Standards GPP TS (GSM 11.10) 3GPP TS & TS GPP2 C.S0056 TIA 928 (CDMA/TDMA) CTIA GSMA HDvoice standard For more advanced testing: ETSI TS – TS standard series Colombia, September

Moste Important Test Parameters Enabling a Good QoS Performance Basic acoustic tests e.g. Loudness Ratings (ITU-T P.79), Frequency response tests… Delay and echo tests Speech quality tests – with and without background noise Conversational test including double talk, switching… Important: Test signals are mostly speech based – ITU-T P.501 Colombia, September

The Impcat of Delay on Conversational Dynamics Colombia, September Best case between fixed & mobile network (no satelite): ~150 ms Worst case across networks: >> 500 ms For superior conversational quality: delay < ~150 ms (from the users perspective) Network Terminal A Terminal B 0 ms 150 ms 500 ms

Conversational/Double Talk Test Signal Colombia, September Word fully masked, one speaker continuosly talking Word in partially masked Word conicident with the other channel speaker, Simulating delay and unwanted double talk Double talk sentences Receive Send Male Female Male Female Short isolated words Word in a speech pause

Summary of Quality Parameters Using Quality Pies according to ITU-T P.505 Colombia, September Phone 4 Conv. Quality Phone 3 Conv. Quality Phone 2 Conv. Quality Phone 1 Conv. Quality Background Noise Performance

Colombia, September Outline Introduction The impact of terminal design on speech quality Assessment methods and standards for mobile terminals Driver distraction and speech services in cars Summary

Driver Distraction Colombia, September Physical/manual distraction Manual operation of devices Visual distraction Watching information other than road Auditory distraction Focusing on auditory events not related to the driving task Cognitive distraction Occupied by non driving related tasks

Technology Based Distraction in Cars Colombia, September Car entertainment systems Navigation systems Phones for speech communication Car information systems Text messanging systems Texting while driving :

To be Avoided Colombia, September In general all activities distracting from the driving task, esp.: Visual cues which require different focus than road Non intuitive manual operation of the car Loading the human auditory system by distracting cues Unnatural and low quality dialogs and communications

Driving Task Colombia, September The driving task => Auditory Channel and Speech available mostly occupied: visual system mainly involved: hands and legs involved: auditory system not involved: talking

Speech Based Services in Cars Colombia, September o The main speech applications: Speech recognition systemsSpeech recognition systems Speech dialog systemsSpeech dialog systems Text to speech systemsText to speech systems Speech enhancement for communication systemsSpeech enhancement for communication systems Hands-free communicationHands-free communication Enhanced in-car communication systems between passengersEnhanced in-car communication systems between passengers

Communicational Quality – Drivers Distraction Colombia, September Superior Communication Quality -> Reduced Drivers Distraction Seamless Interaction -> Low Delay, Perfekt Double Talk Performance Perfekt Intelligibility, High Speech Naturalness at the Far End Perfekt Intelligibility, High Speech Naturalness in the Car

Hands-Free in Cars Colombia, September Why hands-free in cars? Reduce phsyical distraction (dialing, holding the phone…) Reduce visual distraction (watching display, keyboard …)

Superior Sound Quality & Intelligibility in the Car Colombia, September o Wideband services in mobile networks available soon-> o Enabling wideband telephony (100 Hz- 8 kHz) in cars Fullband Narrow band (car) Wideband (car) o Efficient use of the high quality audio systems in cars: Getting superior sound quality Increasing speech intelligibility Increasing naturalness of a conversation Reduce drivers distraction due to poor speech sound quality

Colombia, September Bluetooth Link Phone adapter & antenna amplifier Radio Link Hands-free signal processing Car audio system

Car Hands-Free Testing Colombia, September analysis Mobiles Sound Playback System (can be installed in any vehicle) Test System

ITU-T Standards Contributing to Reduced Drivers Distraction Colombia, September ITU-T standards for Hands-Free Communication: ITU-T P.1100 for narrowband hands-freeITU-T P.1100 for narrowband hands-free ITU-T P.1110 for wideband hands-freeITU-T P.1110 for wideband hands-free ITU-T standards work in FG CarCOM: New work on subsystem requirements for Hands-Free Systems in CarsNew work on subsystem requirements for Hands-Free Systems in Cars ITU-T standards for Dialog Systems: P.851: Subj. evaluation of dialog systems P.851: Subj. evaluation of dialog systems Suppl. 24 to P. Rec.: Parameters describing the interaction with spoken dialog systems Suppl. 24 to P. Rec.: Parameters describing the interaction with spoken dialog systems

The Main Section in ITU-T P.1100 & P.1110 Colombia, September Definition of the test arrangement in a car Description of a digital interface concept for development and debugging Microphone test specification for separate microphones in a car Measurement parameters and requirements for hands-free terminals Bluetooth test interface for validation of telephone performance Subjective test strategy for car to car communication

Conclusions and Recommendations Mobile terminal testing is essential to provide sufficient or even superior QoE to the user – many operator have specific terminal standards for their suppliers A variety of parameters contribute to the overall (conversational) speech quality Network conditions have to be considered in the testing Low driver distraction is essential to offer mobile services Speech based operation is the key to the success of mobile services in cars Both, terminals and networks have to be thoroughly engineered and adapted to each other Colombia, September

Tandeming of Signal Processing in Terminals & Networks Colombia, September Base Station EC ES NR Mobile Phone EC ES NR gain Mobile Network Netw. 1 Netw. 2