| Adaptive Multi-Rate
(AMR) |
| |
| Moesarc Technology has released a tester for AMR,
based on our GSM test platform, the MT-200X- series. Another recent
product release is a tester for TFO- Tandem Free Operation. Both testers
are software modules that are installed as options on the MT-200X platform. |
| |
| Key features of the AMR package
for MT-200X |
| The AMR package for MT200X is available for
both ordinary TRAU systems and TFO capable TRAU systems |
| MT-200X supports analyses of all codec modes,
from 4.75 kbit/s to 12.2 kbit/s for AMR full rate speech, and lower
codec mode, 6.70 kbit/s, and 7.40 kbit/s modes for AMR half rate
speech |
| MT-200X provides simulation possiblities for
all AMR codec modes, including: -TRAU frame control parameters -No-speech
frames -PCM A-law/u-law audio samples from file can be directly encoded
according to AMR codec and transmitted in TRAU frames. -AMR TFO configuration
parameters |
| MT-200X provides test statistics of test results |
| Speech can be sent to PC sound card |
| |
| About AMR |
The GSM speech quality has improved as a result
of the introduction of EFR- the Enhanced Full-Rate. Now, the introduction
of the AMR - Adaptive Multi- Rate Codec represents a significant
step forward.
Today's GSM speech codecs operate at fixed coding rates. The AMR, on the
other hand, selects in real-time the type of channel, and for each channel
type, one of several codec bit-rates. This allows the optimum combination
of speech coding and channel coding bit-rate to be selected to meet the
instantaneous radio channel conditions and local capacity requirements.
It is anticipated that the AMR will be installed in all GSM systems world
wide during first Quarter 2001, and all GSM systems suppliers are getting
ready.
Moesarc has started shipping their AMR Protocol Tester, which is configured
on their well known platform - the MT-200X series protocol analysers/simulators |
| |
| Major benifits of AMR |
| Codec rates are selected dynamically depending
on radio conditions and local capacity requirements |
| Codec bit rate selected by an adaptation algorithm
specific to the system application e.g. GSM and UMTS |
| Generic speech codec application to many mobile
systems |
| Source codec rates are changeable between 4
kbit/s and 14.4 kbit/s |
| Operation in both GSM full rate (22.8 kbps)
and half rate (11.4 kbps) channels |
| Increased robustness against channel errors |
| Enhanced quality in the half-rate channel |
| provides a user friendly way of analyzing the
protocol decode |
| High AMR performance targets and the flexibility
obtained by the switchable codec bit-rate have made it an interesting
candidate for UMTS and IMT2000 |
| Ability to adapt the bit-rates within a wide
range may also be of interest for VoIP applications |
| Codec simulation for Half-Rate and EFR speech
are also supported |
