Mobile communications is on the brink of a quantum leap in voice quality: This is made possible by AMR Wideband (AMR, Adaptive Multi-Rate), a voice coding technology that will, in the future, enable HiFi quality mobile phone calls. T-Mobile and Ericsson have put the potential of AMR Wideband to the test. During a field trial in Cologne and Hamburg, the large majority of the participating T-Mobile customers were impressed by a significant hike in voice quality. The field trial was the first AMR Wideband trial in the world to be conducted in a commercial mobile radio network.

“AMR Wideband technology delivers voice quality that was hitherto unknown. The technology therefore gives T-Mobile an excellent chance to further improve quality from a customer standpoint, and to boost customer satisfaction for the long term,” says Klaus-Jürgen Krath, Vice President RAN Engineering at T Mobile International. “The field trial has produced key findings from which we stand to benefit when we deploy the technology in our network in the future.”

The four-week AMR Wideband field trial was held in summer this year. Participating were 150 T-Mobile customers who make frequent mobile calls. Over 70 percent of participants stated that the voice quality of their mobile phone calls had improved to a major degree. This result tallies with information gleaned in previous Ericsson studies. Additionally, these surveys had shown that mobile customer satisfaction increased hand in hand with voice quality. An important aspect from a mobile carrier standpoint was that satisfied customers are prepared to make longer mobile phone calls - with minutes of use volume (MoU) increasing.

Ericsson’s AMR Wideband is a new, standardized voice codec (coder/decoder) for GSM and UMTS networks. The objective in development was to improve the quality and clarity of voice transmission in mobile radio networks to a level above that currently achieved in fixed networks. With AMR Wideband, call partners are still easily understood even if they speak in a whisper or phone from locations with major background noise. AMR Wideband also offers improved support for services such as conference calls with several parties and the provision of sound logos.

The technology is based on a state-of-the-art algorithm for voice compression. The bandwidth for voice transmission is doubled without increasing requirements for transport performance in the mobile radio networks themselves. The result is an audible improvement in voice and sound quality.