Enhanced Full Rate
Encyclopedia
Enhanced Full Rate or EFR or GSM-EFR or GSM 06.60 is a speech coding
standard that was developed in order to improve the quite poor quality of GSM-Full Rate
(FR) codec. Working at 12.2 kbit/s the EFR provides wirelike quality in any noise free and background noise conditions. The EFR 12.2 kbit/s speech coding standard is compatible with the highest AMR
mode (both are ACELP). Although the Enhanced Full Rate helps to improve call quality, this codec have higher computational complexity, which in a mobile device can potentially result in increase of energy consumption as high as 5% compared to 'old' FR codec.
Enhanced Full Rate was developed by Nokia
and the University of Sherbrooke (Canada). In 1995, ETSI has selected the Enhanced Full Rate voice codec as the industry standard codec for GSM/DCS.
The Enhanced Full Rate (GSM 06.60) technical specification describes the detailed mapping between input blocks of 160 speech samples in 13-bit uniform PCM format to encoded blocks of 244 bits and from encoded blocks of 244 bits to output blocks of 160 reconstructed speech samples. It also specifies the conversion between A-law or μ-law (PCS 1900) 8-bit PCM and 13-bit uniform PCM. This part of specification also describes the codec down to the bit level, thus enabling the verification of compliance to the part to a high degree of confidence by use of a set of digital test sequences. These test sequences are described in GSM 06.54 and are available on disks.
This standard is defined in ETSI ETS 300 726 (GSM 06.60). The packing is specified in ETSI Technical Specification TS 101 318.
ETSI has selected the Enhanced Full Rate voice codec as the industry standard codec for GSM/DCS in 1995. Enhanced Full Rate was also chosen as the industry standard in US market for PCS 1900 GSM frequency band.
Enhanced Full Rate was developed by Nokia and the University of Sherbrooke (Canada).
Speech encoding
Speech coding is the application of data compression of digital audio signals containing speech. Speech coding uses speech-specific parameter estimation using audio signal processing techniques to model the speech signal, combined with generic data compression algorithms to represent the resulting...
standard that was developed in order to improve the quite poor quality of GSM-Full Rate
Full Rate
Full Rate or FR or GSM-FR or GSM 06.10 was the first digital speech coding standard used in the GSM digital mobile phone system. The bit rate of the codec is 13 kbit/s, or 1.625 bits/audio sample...
(FR) codec. Working at 12.2 kbit/s the EFR provides wirelike quality in any noise free and background noise conditions. The EFR 12.2 kbit/s speech coding standard is compatible with the highest AMR
Adaptive Multi-Rate
The Adaptive Multi-Rate audio codec is a patented audio data compression scheme optimized for speech coding. AMR was adopted as the standard speech codec by 3GPP in October 1999 and is now widely used in GSM and UMTS...
mode (both are ACELP). Although the Enhanced Full Rate helps to improve call quality, this codec have higher computational complexity, which in a mobile device can potentially result in increase of energy consumption as high as 5% compared to 'old' FR codec.
Enhanced Full Rate was developed by Nokia
Nokia
Nokia Corporation is a Finnish multinational communications corporation that is headquartered in Keilaniemi, Espoo, a city neighbouring Finland's capital Helsinki...
and the University of Sherbrooke (Canada). In 1995, ETSI has selected the Enhanced Full Rate voice codec as the industry standard codec for GSM/DCS.
Technology
The sampling rate is 8000 sample/s leading to a bit rate for the encoded bit stream of 12.2 kbit/s. The coding scheme is the so-called Algebraic Code Excited Linear Prediction Coder (ACELP). The encoder is fed with data consisting of samples with a resolution of 13 bits left justified in a 16-bit word. The three least significant bits are set to 0. The decoder outputs data in the same format.The Enhanced Full Rate (GSM 06.60) technical specification describes the detailed mapping between input blocks of 160 speech samples in 13-bit uniform PCM format to encoded blocks of 244 bits and from encoded blocks of 244 bits to output blocks of 160 reconstructed speech samples. It also specifies the conversion between A-law or μ-law (PCS 1900) 8-bit PCM and 13-bit uniform PCM. This part of specification also describes the codec down to the bit level, thus enabling the verification of compliance to the part to a high degree of confidence by use of a set of digital test sequences. These test sequences are described in GSM 06.54 and are available on disks.
This standard is defined in ETSI ETS 300 726 (GSM 06.60). The packing is specified in ETSI Technical Specification TS 101 318.
ETSI has selected the Enhanced Full Rate voice codec as the industry standard codec for GSM/DCS in 1995. Enhanced Full Rate was also chosen as the industry standard in US market for PCS 1900 GSM frequency band.
Licensing and patent issues
The Enhanced Full Rate incorporate several patents. It uses the patented ACELP technology, which is licensed by the VoiceAge Corporation.Enhanced Full Rate was developed by Nokia and the University of Sherbrooke (Canada).
See also
- Half RateHalf RateHalf Rate is a speech coding system for GSM, developed in the early 1990s.Since the codec, operating at 5.6 kbit/s, requires half the bandwidth of the Full Rate codec, network capacity for voice traffic is doubled, at the expense of audio quality. It is recommended to use this codec when the...
- Full RateFull RateFull Rate or FR or GSM-FR or GSM 06.10 was the first digital speech coding standard used in the GSM digital mobile phone system. The bit rate of the codec is 13 kbit/s, or 1.625 bits/audio sample...
- Adaptive Multi-RateAdaptive Multi-RateThe Adaptive Multi-Rate audio codec is a patented audio data compression scheme optimized for speech coding. AMR was adopted as the standard speech codec by 3GPP in October 1999 and is now widely used in GSM and UMTS...
(AMR) - Adaptive Multi-Rate Wideband (AMR-WB)
- Extended Adaptive Multi-Rate - Wideband (AMR-WB+)
- Comparison of audio codecsComparison of audio codecsThe following tables compare general and technical information for a variety of audio formats and audio compression formats. For listening tests comparing the perceived audio quality of audio formats and codecs, see the article Codec listening test....
External links
- RFC 3551 - GSM-EFR (GSM 06.60)
- ETS 300 726 (GSM 06.60)
- Summary of GSM Codecs