TECHNICAL PROBLEMS FOUND

Key findings of the ITU test event in Geneva 12-16 May 2014:

1. 35 different mobile phones from 12 different vendors were selected from the participating companies. A total of 46 tests were conducted in narrowband and wideband mode.
2. The tests were based on the chapter 12 Tests of Recommendations ITU-T P.1100 and P.1110. The tests’ requirements were adapted and applied to real-world scenarios. The methodology and results of the tests event will feed into an ongoing process to refine the standards under the leadership of ITU-T Study Group 12 (Performance, QoS and QoE).
3. All tested mobile phones in narrowband and wideband mode respond with “ok” to the “AT+NREC=0” command, indicating that the internal signal processing (noise reduction, echo cancellation) is disabled.
4. Approximately 30% of the tested phones violate the adapted round-trip delay requirement of ≤ 210 ms. The maximum round delay was determined to be nearly 500 ms for one phone in narrowband mode.
5. Approximately 30% of the devices tested in narrowband mode do not disable noise reduction and echo cancellation, despite their responding with “ok” to the AT command. Customer complaints can be expected for these devices.
6. Other influences on the transmitted signals were detected during the tests, such as active volume control on the Bluetooth® link, signal amplification of up to 12 dB in the sending direction (highest measured amplification) or active equalizers.
7. Only approximately 40% of the tested mobile phones can be regarded as fully transparent, as required.
8. With the exception of one phone, all phones tested in wideband mode disable noise reduction and echo cancellation. However, other signal influences were detected, such as signal amplification of up to 17 dB in the sending direction (highest measured amplification in wideband mode, which would definitely lead to signal saturation and distorted voice) or active equalizers.
9. Cross-connection tests in narrowband Bluetooth® connection in combination with wideband network access (or vice versa) indicate unexpected inband level contrasts in both transmission directions.
10. Additional tests without sending the “AT+NREC=0” command to the mobile phones (relevant for Bluetooth®headsets also communicating with mobile phones via the Hands-Free Profile) found that approximately 25% of the mobile phones disabled internal signal processing even without being requested to do so. This is an important issue for Bluetooth® headsets without their own implemented signal processing. In this case, the mobile phone should keep the algorithms active.