Test Report. 3 rd ITU Test Event: Performance Assessment of Mobile Phones as Gateways to Car Hands-free Systems November 2016

Transcription

1 Test Report rd ITU Test Event: Performance Assessment of Mobile Phes as Gateways to Car Hands-free Systems November 216 ITU 217

2 Test Report: Performance Assessment of Mobile Phes as Gateways to Car Hands-free Systems Background In ctinuati of the 1 st and 2 nd Test Event in May 21 and May 216, respectively, ITU has organized a rd Test Event Performance assessment of mobile phes as gateways to car hands-free systems. The test event was held during the ITU Telecom World 216 in Bangkok, Thailand November 15 and 16, 216. This event as well as the previous events is organized according to the request received from automotive industry to test mobile phes against ITU-T Recommendatis which specify the transmissi performance requirements for mobile phes cnected with Hands-free Telephe system (HFT) using Short-Range Wireless (SRW) interface. The key goal of such event is to draw attenti of mobile phe vendors to some issues, which relate to the phe cfigurati in wireless cnecti and quality of voice communicati in and from a car, and to request them to make relevant updates in their mobile phes, if necessary. ITU updates the List of mobile phes compliant with chapter 12 of ITU-T P.11 and ITU-T P.111. The events further provide the possibility to compare the performance of the sample of mobile phes to those measured during the 1 st and 2 nd Test Events. The tests were performed by HEAD acoustics GmbH, based the Chapter 12 tests of Recommendatis ITU-T P.11 and ITU-T P.111, standards for narrow-band and wideband communicatis involving motor vehicles. The test requirements, the methodology and results are fed back into an going process to refine the standards. This report was written by HEAD acoustics which is respsible for the test cducti and the analysis of the test results. Test results have been anymized in this report. Ctact perss: Mr Denis Andreev, denis.andreev@itu.int, Tel Mr Marc Lepage, marc.lepage@head-acoustics.de, Tel Mr Frank Kettler, frank.kettler@head-acoustics.de, Tel ii -

3 Test Report: Performance Assessment of Mobile Phes as Gateways to Car Hands-free Systems Table of Ctents 1. Motivati Summary Cascaded Algorithms.... Test Descripti....1 Test Setup....2 Requirements of Revised Test Criteria for the Test Event Result Representati Analyses Results Overview - Narrowband Overview - Wideband Individual Summary Narrowband Individual Summary Wideband Cross-Cnecti Tests (Informative results) References iii -

4 Test Report: Performance Assessment of Mobile Phes as Gateways to Car Hands-free Systems 1. Motivati Car manufacturers spend high effort to tune HFT systems in their vehicles to provide high quality communicati in vehicles and need to csider the individual influence of mobile phes, as their performance is still far from being uniform. In the typical use case, the driver uses his mobile phe and links it via wireless communicati to the vehicle s hands-free system. Thus, the mobile phe provides the mobile network access. It acts as an audio gateway between the vehicle hands-free system and the mobile network and should provide fully transparent voice transmissi in uplink and downlink. The relevant signal processing is performed solely by the vehicle s hands-free system; mandating that the signal-processing functiality of a mobile phe be disabled while the phe is mounted a hands-free system. The wireless cnecti, typically realized via Bluetooth today, can be ctrolled via appropriate AT commands [7]. However, even if the AT command exchange between handsfree system and mobile phe works properly and the mobile phe replies with ok, it is not always guaranteed that the mobile phe behaves transparently and ly provides gateway functiality. If speech processing algorithms (such as echo cancellati or noise reducti), signal amplificati or attenuati or equalizers are not disabled in the mobile phe, the phe may significantly degrade the quality of the whole system. Recommendatis ITU-T P.11 [1] and ITU-T P.111 [2] describe correspding speech quality tests for verificati of transparency in Chapter 12 ( Verificati of the transmissi performance of short-range wireless (SRW) transmissi enabled phes ). These tests have been used during the previous and the current test event. Mobile phes which successfully pass the tests are listed by ITU in the List of mobile phes [8]. The list is generated and updated based results of the ITU Test Events. ITU provided the opportunity to test mobile phes during the rd Test Event during the ITU Telecom World 216 in Bangkok, Thailand. Following the discussi of these results between vendors, car manufactures, test house and ITU, the current Recommendatis ITU-T P.11/P.111 were updated by more clearly describing mandatory and optial parameters, the relevant criteria of the Chapter 12 of these Recommendatis have been revised accordingly [], []. Tests were repeated with updated software versis the phes. The most important cclusis are drawn in Chapter 2 of this report. Chapter gives brief background informati about the influence of cascaded algorithms. The setup together with a short introducti of the tests itself and the result representati is given in Chapter. Chapter 5 analyses the results. References can be found in Chapter

5 Test Report: Performance Assessment of Mobile Phes as Gateways to Car Hands-free Systems 2. Summary The most important findings can be summarized as follows: 6 mobile phes were tested, e device in narrowband mode ly (wideband not enabled), e device in wideband mode ly ( -the-go tests). Thus, a total number of 1 tests was cducted, 5 in narrowband and 5 in wideband mode. Ne of the tested mobile phes at the rd test event met the requirements of the ITU-T P.11 [1] / P.111 [2] (215). However, some phes were very close to the requirements and passed most of the tests. Vendors reacted to these outcomes for these mobile phes with updated Software and retests were scheduled. In parallel, the results were fed back into the standardizati process requesting an improvement of the current Recommendatis ITU-T P.11/P.111 by more clearly describing mandatory and optial parameters. Mandatory requirements in general identify pass/fail criteria for such kind of testing. The relevant criteria of the Chapter 12 of these Recommendatis have been revised accordingly. As of now, new versis of the ITU-T P.11 [] and ITU-T P.111 [] are available the ITU web page. After the scheduled retests, these mobile phes completely met the requirements of the ITU-T P.11 and ITU-T P.111 (217) respectively. As already seen during the 1 st and 2 nd test event [5], [6], all tested mobile phes in NB and WB mode respd with ok to the AT+= command, indicating that the internal signal processing (noise reducti, echo cancellati) is disabled. One device significantly exceeded the round-trip delay requirement in narrowband mode. The measured delay of more than ms is far out of range and will likely hamper communicati quality. Such outliers have been seen during the events in the past and indicate that this topic is not always in focus during development. All tested devices disable noise reducti and echo cancellati. All devices show almost level transparent transmissi in narrowband and wideband mode in both transmissi directis. Listening speech quality degradatis were measured for e device in narrowband mode. Informative cross cnecti tests in WB Bluetooth cnecti in combinati with WB and NB network access indicate the expected inband level transparency for all WB capable devices. The limited number of tested devices is not exhaustive, but the same could already be observed during the 2 nd event, whereas the results from the 1 st test event still indicated at least some devices with strg inband level mismatch. An additial informative aspect covers the fact that Bluetooth headsets communicating with mobile phes also via the hands-free profile [7], often rely the phe s signal processing. The phe should therefore keep signal processing active, when the AT+= command is not sent. Tests during previous events show, that many devices disable echo cancellati, although it is not (!) requested by the accessories. All phes tested now, except e, kept echo cancellati and noise reducti enabled in this test case, as recommended

6 Test Report: Performance Assessment of Mobile Phes as Gateways to Car Hands-free Systems. Cascaded Algorithms According to the Hands-free Profile V1.7 [7], a vehicle mounted hands-free system may request the mobile phe to disable the internal signal processing, such as echo cancellati and noise reducti, in order to avoid cascaded algorithms and cversatial quality impairments. Figure.1 shows the different compents, i.e. mobile network, the mobile phe, which acts as audio gateway between network and hands-free system (HFT), the HFT itself, the audio playback system and the HFT microphe system in the vehicle. The cnecti between the HFT system and mobile phe is today typically realized via Bluetooth. Receiving directi Sending directi Fig..1: Principle block diagram and definiti of transmissi directis Fig..2: Cascaded signal processing Figure.2 shows the typical signal processing compents in this set-up. In principle, both, the HFT and the mobile phe, provide the same signal processing, i.e. echo cancellati (), the additial processing to suppress residual echo compents (echo suppressi ES ), noise reducti ( ) and gain adjustment including possible automatic gain ctrol ( AGC ). This may lead to cascaded signal processing, if they are not bypassed or disabled in the mobile phe. This should, under all circumstances, be avoided as the compents in the HFT system are already optimized the acoustic envirment in each vehicle. Tandem and ES may significantly hamper the very important double talk performance. Cascaded noise reducti algorithms () degrade speech transmissi quality, especially if the driver is talking from the driving car. Driver s voice sounds artificial, unnatural, metallic or sharp. Additial signal gain (e.g. automatic gain ctrol, static gain) introduced by the mobile phe may lead to signal saturati or too low voice signal in case of attenuati. - -

7 Test Report: Performance Assessment of Mobile Phes as Gateways to Car Hands-free Systems. Test Descripti The SRW cnecti was realized as a Bluetooth cnecti, representing the most comm use case cnecting a mobile phe to a vehicle hands-free system today..1 Test Setup The tests the mobile phes are carried out between two electrical interfaces as shown in figure.1. The phe is cnected to a mobile network simulator the far end side and a Bluetooth reference interface (MFE XI, Measurement frtend provided by HEAD acoustics) the near end side. The MFE XI communicates via the hands-free profile to the mobile phe. A narrowband and wideband Bluetooth cnecti can be setup if the mobile phe supports the both optis. Wideband Bluetooth cnecti uses the msbc codec, a narrowband cnecti the CVSD speech codec. On the network side a network simulator (CMW5, Rohde & Schwarz) was used providing the capability of establishing a narrowband or wideband cnecti to the mobile phe. In narrowband mode, the AMR codec operated at 12.2 kbit/s was used, the AMR- WB codec at kbit/s was used in WB mode. The Bluetooth reference interface MFE XI is directly cnected to the test system ACQUA. The network simulator is cnected via unbalanced analog input and output cnectors to the MFE VI.1 to the ACQUA measurement system (see test setup in figure.1). The clocks between both frtends, MFE XI and MFE VI.1 are synchrized via a digital AES/EBU cnecti. Definiti of transmissi directis: - - Fig..1: Test setup, mobile phe cnected to Bluetooth reference frtend MFE XI and network simulator Sending directi (see also fig..1): The sending directi (uplink) represents the transmissi from the Bluetooth interface (representing the car hands-free unit) via the mobile phe to the network simulator. Receiving directi (see also fig..1): The receiving directi (downlink) is defined as the transmissi from the network simulator through the mobile phe to the Bluetooth interface representing the hands-free unit in a vehicle. In order to verify the echo performance of the mobile phes in such a simulated Bluetooth cnecti, an echo path can be simulated in the MFE XI. This is indicated in figure.1. In this case, the downlink signal received via Bluetooth at the MFE XI is coupled back in sending directi of the Bluetooth cnecti with defined echo attenuati. The test setup guarantees an automatic test run for all devices under all test cditis.

8 Test Report: Performance Assessment of Mobile Phes as Gateways to Car Hands-free Systems.2 Requirements of Revised Test Criteria for the Test Event After the results of the test event were fed back into the standardizati process requesting an improvement of the current Recommendatis ITU-T P.11/P.111 by more clearly describing mandatory and optial parameters, the relevant criteria of the Chapter 12 of these Recommendatis have been revised accordingly. Recommendatis ITU-T P.11 (/217) and P.111 (/217) established the following limits for the test parameters: Parameters Limit in accordance with Rec. ITU-T P.11 Limit in accordance with Rec. ITU-T P.111 Delay 19 ms 1) 19 ms 1) JLR SND ± 2 db ± 2 db JLR RCV ± 2 db 2) ± 2 db 2) JLR SND ± 2 db JLR SND ± 2 db JLR RCV ± 2 db JLR RCV ± 2 db Tolerance scheme Tolerance scheme Tolerance scheme Tolerance scheme Noise Reducti disabled (± db) disabled (± db) MOS-LQOn,w SND. MOS-LQOn.8 MOS-LQOw MOS-LQOn,w RCV. MOS-LQOn.8 MOS-LQOw Echo Canceller disabled (TCLw 2 ± 2 db) disabled (TCL 2 ± 2 db) 1) Performance objective: < 15 ms 2) No additial volume ctrol shall be active Additial tests were performed an informative basis: Double talk test in SND In additi to the echo ctrol test an automatic double talk type test according to ITU-T P.52 Amendment 1 Appendix was informatively performed in SND in order to double check the disabled state of the echo ctrol signal processing. Tests with new service level cnecti and without sending the AT+= command. In order to verify that the deactivati of the and signal processing is really triggered by the dedicated AT command AT+= (and not by other indicators, e.g. the detecti of a Bluetooth cnecti), a subset of tests is repeated after setting up a new service level cnecti and WITHOUT sending the AT+= command: - 5 -

9 Test Report: Performance Assessment of Mobile Phes as Gateways to Car Hands-free Systems Delay SND/RCV JLR SND/RCV Sensitivity frequency respse SND/RCV Noise reducti test in SND Verificati of disabled echo ctrol Automatic double talk test in SND These tests are of special importance for accessories like headsets using the hands-free profile to cnect to mobile phes but relying the phes signal processing. Cross cnecti tests (Recommendati ITU-T P.111 ly) Codec negotiati mechanisms between the SRW (Bluetooth ) side and the mobile network side of mobile phes are not clearly defined. Csidering the assumpti, that in most cases today the head units in vehicles are wideband capable the Bluetooth link, intercnecti tests are limited to wideband cnecti the Bluetooth side (ITU-T P.111 test case). The additial test is performed as follows: SRW cnecti in wideband mode and mobile network cnecti in wideband mode, JLR (JLR SRWsnd and JLR SRWrcv) and frequency respse measurements in both directis (test cases 12.2 and 12..) Test repetiti in SRW wideband cnecti and mobile network cnecti in narrowband mode. Comparis of measured JLR and frequency respses to test 12.2 and 12. results

10 Test Report: Performance Assessment of Mobile Phes as Gateways to Car Hands-free Systems. Result Representati AT+ = A two-page test report was generated for each mobile phe and test run including a Quality Pie chart summary according to Recommendati ITU-T P.55 [11] of the most important results. A summary of the most important findings is given together with graphs for the sending and receiving frequency respses, the noise reducti performance and the spectral echo attenuati tested with a 2 db simulated echo path and frequency respse curves without sending the AT+= command. In case of wideband, the reports are further extended by the results and curves from the informative cross cnecti tests. One example for the Quality Pie chart according to Recommendati ITU-T P.55 from the test event together with a short descripti of the selected parameters and requirements is shown in figure.2. The Quality Pie slices represent the following parameters and requirements (clockwise): ms Fig..2: Quality Pie Chart according to Recommendati ITU-T P.55 The AT+= pie slice indicates the reply of the mobile phe this command from the reference Bluetooth interface. The pie slice is scaled between and. The round-trip delay slice is scaled in ms (with the 19 ms wideband limit). The pie slice. is also digitally scaled between and. The volume ctrol the mobile phe should not influence the sensitivity of the Bluetooth cnecti, independent if the remote volume ctrol feature is supported by the hands-free unit or not. In case the hands-free unit supports this feature, it is expected, that the volume ctrol adjustment the mobile phe may ctrol the hands-free unit playback volume. However, the mobile phes volume ctrol should not influence the sensitivity of the Bluetooth link itself. The very important verificati, if the implemented noise reducti in the mobile phe is still active in the Bluetooth cnecti after sending the AT+= command, is indicated by the pie slice. The slice represents two possible states, disabled as expected ( in the Quality Pie) or enabled ( ). The verificati of the active echo cancellati algorithm in the mobile phe after receiving the AT+= command from the Bluetooth reference interface is scaled in a similar way. Again, two different stages, (as required) or are represented in the correspding pie slice ( ). Informatively the influence of implemented signal processing double talk performance is represented by the DT pie slice. Two different stages are possible, the pie slice is scaled between transparent (as recommended) or not transp.. - / -1 / 1-1/1-1/1 1 ms 2 ms -1 / 1 - / DT - 7 -

11 Test Report: Performance Assessment of Mobile Phes as Gateways to Car Hands-free Systems The sending sensitivity expressed by the measured Juncti Loudness Rating ( ) is scaled in db. The limit, given by the inner red circle, represents an attenuati or amplificati of 2 db (JLR range ± 2 db). The Quality Pie slice is also scaled in db. It represents the violati of the suggested tolerance by the measured sending frequency respse () in db. The pie slice indicates the gain adjustment (amplificati or attenuati) introduced in sending directi by the mobile phe, when applying different test signal levels. This pie slice is scaled in db, the inner red circle represents the minimum requirement of ± 2 db. Listening speech quality measured in sending directi using the Recommendati ITU-T P.86 POLQA method is used for scaling of the pie slice. The scale directly represents the measured MOS-LQO n or MOS-LQO w scores. The limit represented by the inner red circle is given by the numerical value.8 (. in the narrowband case). The receiving sensitivity (Juncti Loudness Rating ( ) is scaled in db. The inner red circle represents attenuati or amplificati of 2 db (JLR ± 2 db). The Quality Pie slice (receiving frequency respse) is scaled in db and indicates the violati of the suggested tolerance by the measured curve. The pie slice indicates the gain adjustment (amplificati or attenuati) introduced in receiving directi by the mobile phe, when applying different test signal levels. This pie slice is scaled in db, the inner red circle represents the minimum requirement of ± 2 db. Listening speech quality in receiving directi is given by the pie slice. The limit represented by the inner red circle is given by the numerical value.8 (wideband), and. respectively (narrowband) as described above (see Chapter.2)

12 Test Report: Performance Assessment of Mobile Phes as Gateways to Car Hands-free Systems 5. Analyses Results 5.1 Overview - Narrowband The measured delay values in sending directi (uplink, UL), receiving directi (downlink, DL) and the round-trip delay (RT) are analyzed in figure 5.1a to 5.1c. The delay introduced by the test setup (frtend delay, network simulator) is csidered and subtracted. Both eway delays are informative in figure 5.1a and 5.1b. The limit of 19 ms is verified in figure 5.1c for the round-trip delay as indicated in chapter.2. Fig. 5.1a: Sending (uplink) delay T AG,UL, narrowband (informative) Fig. 5.1b: Receiving (downlink) delay T AG,DL, narrowband (informative) Fig. 5.1c: Round trip delay T AG,RT, narrowband, 5 tested mobile phes devices meet the round-trip delay requirement of 19 ms in narrowband mode whereas e device significantly exceeds the limit. The measured result of > ms is significantly too high. Such outliers have been seen during previous events in the past and indicate that this topic is not always in focus during development. Figure 5.2 analyzes 1 individual parameters in order to provide an overview about the 5 mobile phes tested in narrowband mode. The green segments of each bar represent the number of mobile phes meeting the limits for each specific parameter. Vice versa the red segments indicate the number of limit violatis

13 Test Report: Performance Assessment of Mobile Phes as Gateways to Car Hands-free Systems Fig. 5.2: Narrowband test result overview, 5 tested mobile phes The two blue bars the right-hand side represent the additial informative tests carried out without sending the AT+= command. They represent the verificati of enabled noise reducti or echo cancellati (, ). Without sending the AT+= command, both algorithms are supposed to be enabled. The following cclusis can be drawn: The 5 phes all respd with Ok to the AT+= command. All parameters are within the recommended limits except the MOS-LQO scores of e device in sending and receiving directi ( and ( MOS-LQO RCV )). The two additial test results in figure 5.2 measured without sending the AT command show, that e device disables echo cancellati, although the AT command is not sent. This device obviously disables this signal processing block triggered by the detecti of a Bluetooth link independent if the AT command is received or not. This has already been seen for a number of devices in previous events. Bluetooth headsets without own implemented signal processing may rely the algorithms in the paired mobile phe. Csequently, echo disturbances and a low communicati quality in noisy envirment may occur. 5.2 Overview - Wideband The measured delay values in wideband mode are analyzed in figure 5.a to 5.c. Both e-way delays are informative ly and the suggested limit of 2 ms is ly applicable for - 1 -

14 Test Report: Performance Assessment of Mobile Phes as Gateways to Car Hands-free Systems the round-trip delay in figure 5.c. Again, the delay introduced by the test setup is csidered in these analyses. Fig. 5.a: Sending (uplink) delay T AG,UL, wideband (informative) Fig. 5.b: Receiving (downlink) delay T AG,DL, wideband (informative) Fig. 5.c: Round trip delay T AG,RT, wideband, 5 tested mobile phes All 5 tested phes show a delay around 15 ms in wideband cnecti. The round-trip delay limit of 2 ms is met

15 Test Report: Performance Assessment of Mobile Phes as Gateways to Car Hands-free Systems Fig. 5.: Wideband test result overview, 5 tested mobile phes The wideband results in figure 5. show, that all devices respd with Ok to the AT+= command, disable the relevant signal processing and can be regarded as transparent. The cross-cnecti tests were carried out for of 5 devices, as e was ly tested in wideband mode. All tests showed the expected level transparency in the cross-cnecti tests. The frequency respses mainly differ in the band limitatis. Audible level ctrasts are not expected e.g. if the mobile network codec dynamically switches from wideband to narrowband mode during an going audio cnecti. The test results without sending the AT command (blue bars) also show that the tested mobile phes keep noise reducti and echo cancellati active, as expected. Again, this is important in cjuncti with Bluetooth enabled headsets without own implemented signal processing. Disabled algorithms in this setup may lead to echo disturbances and a low communicati quality, e.g. if the headset is used in noisy envirment

16 Test Report: Performance Assessment of Mobile Phes as Gateways to Car Hands-free Systems 5. Individual Summary Narrowband -/ -/ /6-1/1 -/ AT+ = /6 * Informative result -/ -/ /6-1/1 -/ * Informative result -/ -/ /6-1/1 -/ * Informative result -/ -/ /6-1/1 -/ * Informative result -1/1 12ms 2ms AT+ = /6 -/ -1/1 DT * 12ms 2ms AT+ = /6 -/ 12ms 2ms -1/1 AT+ = /6 -/ 12ms 2ms -1/1 -/ DT * DT * DT * Device: 1-NB Volume ctrol disabled and disabled, transparent double talk performance Uplink and downlink sensitivities in recommended range MOS-LQO values sufficiently high transparent device, high speech quality w/o sending AT+= Device: 2-NB Volume ctrol disabled Noise reducti: enabled Echo canceller: enabled and disabled, transparent double talk performance Uplink and downlink sensitivities in recommended range MOS-LQO values sufficiently high transparent device, high speech quality w/o sending AT+= Device: -NB Volume ctrol disabled Noise reducti: enabled Echo canceller: enabled and disabled, transparent double talk performance Uplink and downlink sensitivities in recommended range MOS-LQO values sufficiently high transparent device, high speech quality w/o sending AT+= Device: -NB Volume ctrol disabled Noise reducti: enabled Echo canceller: enabled and disabled, transparent double talk performance Uplink and downlink sensitivities in recommended range MOS-LQO values sufficiently high transparent device, high speech quality w/o sending AT+= Noise reducti: enabled Echo canceller: enabled

17 Test Report: Performance Assessment of Mobile Phes as Gateways to Car Hands-free Systems -/ -/ /6-1/1 -/ * Informative result AT+ = /6-1/1 12ms 2ms -/ DT * Device: 5-NB Volume ctrol disabled, very high round trip delay and disabled, transparent double talk performance Uplink and downlink sensitivities in recommended range MOS-LQO values slightly low not transparent, high delay hampers communicati quality w/o sending AT+= Noise reducti: enabled Echo canceller: disabled 5. Individual Summary Wideband - / -1 / 1 AT+ = * Informative result - / -1 / 1 ms -1/1-1/1-1 / 1 1 ms 2 ms AT+ = * Informative result ms -1/1-1/1 - / 1 ms 2 ms -1 / 1 - / DT * DT * Device: 1-WB Volume ctrol disabled and disabled, transparent double talk performance Uplink and downlink sensitivities in recommended range MOS-LQO values sufficiently high transparent device, high speech quality w/o sending AT+= Noise reducti: enabled Echo canceller: enabled Device: 2-WB Volume ctrol disabled and disabled, transparent double talk performance Uplink and downlink sensitivities in recommended range MOS-LQO values sufficiently high transparent device, high speech quality w/o sending AT+= Noise reducti: enabled Echo canceller: enabled - 1 -

18 Test Report: Performance Assessment of Mobile Phes as Gateways to Car Hands-free Systems - / -1 / 1 AT+ = * Informative result - / -1 / 1 ms -1/1-1/1-1 / 1 1 ms 2 ms AT+ = * Informative result - / -1 / 1 ms -1/1-1/1-1 / 1 - / 1 ms 2 ms AT+ = * Informative result ms -1/1-1/1 - / 1 ms 2 ms -1 / 1 - / DT * DT * DT * Device: -WB Volume ctrol disabled and disabled, transparent double talk performance Uplink and downlink sensitivities in recommended range MOS-LQO values sufficiently high transparent device, high speech quality w/o sending AT+= Noise reducti: enabled Echo canceller: enabled Device: -WB Volume ctrol disabled and disabled, transparent double talk performance Uplink and downlink sensitivities in recommended range MOS-LQO values sufficiently high transparent device, high speech quality w/o sending AT+= Noise reducti: enabled Echo canceller: enabled Device: 5-WB Volume ctrol disabled and disabled, transparent double talk performance Uplink and downlink sensitivities in recommended range MOS-LQO values sufficiently high transparent device, high speech quality w/o sending AT+= Noise reducti: enabled Echo canceller: enabled

19 Test Report: Performance Assessment of Mobile Phes as Gateways to Car Hands-free Systems 5.5 Cross-Cnecti Tests (Informative results) The sending and receiving sensitivities and possible level ctrasts are analyzed in crosscnecti scenarios, cascading a Bluetooth cnecti in wideband mode (BT WB) with wideband and narrowband network cnectis. These tests can ly be carried out for wideband Bluetooth capable phes. It can be assumed that head units in vehicles today are wideband Bluetooth capable and cnect in wideband mode to the mobile phe. The following figures compare the wideband sensitivities in sending () and receiving directi () to the narrowband network cnecti and the measured JLR values: the curves are measured and compared for the wideband cnecti (wideband Bluetooth and wideband network, black curve) and the cross cnecti (wideband Bluetooth and narrowband network, green curve) in the left hand figures. Correspdingly the curves are compared in the right hand figures (wideband Bluetooth and wideband network, black curve; wideband Bluetooth and narrowband network, red curve). All devices show a more or less cstant sensitivity in the narrowband transmissi range. The sensitivity differences are all below 1 db, no noticeable level set between the narrowband network cnecti and the wideband network cnecti can be observed. Neither the driver (receiving directi) nor the far end subscriber (sending directi) will notice any level ctrast, if the network cnecti switches from wideband to narrowband. rd Octave FFT Size:28 Overlap:67,% L/dB 2 15 rd Octave FFT Size:28 Overlap:67,% L/dB db JLRcross (SND): -.6 db 1-WB -5-5 : -.1 db f/hz f/hz JLRcross (RCV): -.8 db rd Octave FFT Size:28 Overlap:67,% L/dB 2 15 rd Octave FFT Size:28 Overlap:67,% L/dB db JLRcross (SND): -.6 db 2-WB -5-5 :. db f/hz f/hz JLRcross (RCV): -.8 db rd Octave FFT Size:28 Overlap:67,% L/dB 2 15 rd Octave FFT Size:28 Overlap:67,% L/dB db JLRcross (SND): -.6 db -WB -5-5 : -.1 db f/hz f/hz JLRcross (RCV): -.8 db

20 Test Report: Performance Assessment of Mobile Phes as Gateways to Car Hands-free Systems rd Octave FFT Size:28 Overlap:67,% L/dB 2 15 rd Octave FFT Size:28 Overlap:67,% L/dB db JLRcross (SND): -.6 db -WB -5-5 : -.1 db f/hz f/hz JLRcross (RCV): -.7 db

21 Test Report: Performance Assessment of Mobile Phes as Gateways to Car Hands-free Systems 6. References [1] Recommendati ITU-T P.11; Narrowband hands-free communicati in motor vehicles, [2] Recommendati ITU-T P.111; Wideband hands-free communicati in motor vehicles, [] Recommendati ITU-T P.11; Narrowband hands-free communicati in motor vehicles, -217 [] Recommendati ITU-T P.111; Wideband hands-free communicati in motor vehicles, -217 [5] Performance assessment of vehicle-mounted mobile phes in cjuncti with Hands-free Terminals according to Recommendatis ITU-T P.11 and ITU-T P Final Versi; [6] 2 nd ITU Test Event: Performance of Mobile Phes as Gateways to Car Hands-free Systems, Geneva 2-25 May 216; [7] Bluetooth Telephy Working Group: Hands-free Profile 1.7, Bluetooth Profile Specificati, Revisi V1.7., September 18, 21 [8] Compatibility of mobile phes and vehicle hands-free terminals, [9] Recommendati ITU-T P.51; Test signals for use in telephometry, -217 [1] Recommendati ITU-T P.86; Perceptual objective listening quality assessment, 9-21 [11] Recommendati ITU-T P.55; One-view visualizati of speech quality measurement results,