Now that mobile networks have transitioned to fully IP-based architectures, there is a need for voice quality enhancement algorithms that can be performed in the IP-domain. Voice traffic has traditionally passed through an IMS-MGW or TDM to IP gateway, where echo cancellation was performed. With the migration to IP, the need for packet-based Voice Quality Enhancement (VQE) has emerged.
The most common algorithms used in mobile environments are Acoustic Echo Cancellation (AEC) and Adaptive Noise Reduction (ANR).
While these algorithms are already being delivered today in traditional gateways, some vendors are developing systems that deliver high-density VQE “in-line” on AMR packets.
Acoustic Echo Cancellation
AEC is used to reduce or eliminate the echo that is created by the mobile handset. Coupling between the speaker and microphone causes echo that is perceptible, this is due to the long round trip times caused by VoIP networks. While most high-end mobile devices offer some amount of AEC, applying sophisticated AEC algorithms in the gateway ensures maximal quality to subscribers, regardless of the quality of the mobile device.
Adaptive Noise Reduction
ANR is key to improving intelligibility in mobile environments. ANR attenuates or removes environmental noise, increasing the signal to noise ratio, and allowing the speech to be more clearly understood.
As mobile and enterprise voice networks adopt wideband audio, all VQE algorithms must be upgraded to benefit from this richer experience.
Octasic has developed many different algorithms to adjust the levels on both legs of a call. Basic techniques such as Automatic Gain Control (AGC) can be used to bring the signal level to a pre-determined target.
More advanced routines such as Natural Listener Enhancement (NLE) adjust the level sent to a user, based on his or her ambient noise. This prevents the user from constantly having to increase or decrease the volume on their handset as they transition between noisy and quiet environments.
Octasic delivers these Voice Quality Enhancements in the highest channel density solution for packet-based networks. Low-latency processing ensures that these algorithms can be performed without incurring much more than a packet size of delay.
Go to Carrier Class MGW, Octasic Media Processing Application.