Ditech Networks' Solutions
Voice Quality Assurance for VoIP Networks
The migration from circuit to Voice-over-IP (VoIP) technology introduces new voice quality issues into communications networks. These problems include packet loss, packet delay, and packet jitter. Additionally, legacy problems such as echo, voice level variation, and background noise, which are also present in the circuit-based network, are compounded in the VoIP network. The combination of new VoIP voice quality problems and legacy voice quality problems presents a significant challenge for VoIP service providers.
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Ditech’s VQA technology for VoIP is available on the Packet Voice Processor:
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Ditech’s Packet Voice Processor™ platform with Voice Quality Assurance (VQA™) technology enables VoIP carriers to significantly improve the total end-to-end voice quality of VoIP networks. VQA features improve voice clarity on every call by providing noise reduction, enhanced voice intelligibility, voice level control, acoustic echo control, and hybrid echo cancellation.
Ditech’s Packet Quality Assurance™ (PQA™) features address additional voice issues specific to IP, such as packet loss, delay, and jitter to dramatically improve overall VoIP call quality and clarity.
By deploying Ditech’s VQA solution suite at the IP network border or peering point, service providers can centralize high-performance media processing to enable universal, high-quality voice. With the Packet Voice Processor, service providers benefit from purpose-built equipment that eliminates the need for end-point devices with limited processing capabilities. This ensures a ubiquitous voice quality experience for all customers, consumer and enterprise.
Ditech’s VQA Solution in a VoIP Network
Acoustic Echo Control (AEC)
Acoustic Echo Control (AEC) solves echo problems that are common in VoIP networks due to poor acoustic isolation between the speaker and microphone of a user’s device (e.g., handset, speakerphone, IP softphone). Acoustic echo becomes more problematic with VoIP-induced packet delay, making the echo more noticeable. Ditech’s AEC feature suppresses a wide range of echo variances using algorithms based on talker energy levels and Weighted Acoustic Echo Path Loss (WAEPL) to effectively suppress acoustic echo and significantly improve voice quality.
Adaptive Noise Cancellation (ANC)
Ditech’s Adaptive Noise Cancellation (ANC) technology includes a high-precision noise reduction algorithm that removes the noise components of a call without reducing talker volume. This feature effectively suppresses background noise (such as road noise, restaurant babble, and jet noise) by up to 21 dB to improve the quality of a call, resulting in greater customer satisfaction and enhanced call clarity.
Automatic Level Control (ALC)
When voice calls are connected between two different VoIP endpoint devices, the volume levels are often unbalanced with one side of the call higher or lower than the other. Ditech’s Automatic Level Control (ALC) technology dynamically detects level imbalances and automatically adds up to 15 dB or attenuates as much as needed to bring both sides of the call to a specified volume.
Enhanced Voice Intelligibility (EVI)
Encoding and decoding voice calls using compressed VoIP codecs reduces the sharpness of speech and can lead to poor voice intelligibility. With an increasing number of IP borders and multiple transcoding points across a network, providers must compensate for this loss in fidelity. Ditech’s Enhanced Voice Intelligibility (EVI) feature improves the quality of speech by boosting the critical speech formants to allow users to more easily understand the voice on the call. EVI improves the intelligibility of speech without distorting or amplifying the signal.
Intelligent Packet Restoration (IPR)
IPR is an advanced feature that reconstructs missing packets within a VoIP packet stream. With the capability to analyze and process the received voice packets, the IPR feature uses a predictive speech model to reconstruct a missing packet’s voice payload and rebuild it upon packet play out. This offers an enhanced ability to support high-quality voice over IP, even in congested IP networks with substantial packet delay and loss.
Hybrid Echo Cancellation (HEC)
Hybrid echo occurs at the 4-wire to 2-wire conversion point in a PSTN network. Hybrid echo is an electrical signal reflection that becomes more noticeable when packet delay is added from the IP network. Although media gateways may include hybrid echo cancellation, their echo tail capability is often too small and does not fully protect callers from echo. Ditech’s industry-leading Hybrid Echo Cancellation (HEC) feature completely eliminates hybrid echo from end-to-end VoIP calls that traverse a PSTN hybrid.
Conclusion
Delivering quality voice calls is a critical consideration in making an investment in VoIP. Although the revenue generating opportunities enabled by deploying VoIP are great, service providers must address the technical challenges associated with the transition to VoIP to ensure that customers experience voice quality that is equal to or better than conventional network infrastructures. Ditech’s Packet Voice Processor platform, integrated with our VQA technology, reduces quality issues associated with TDM-to-VoIP transitions and dramatically improves the voice quality and sound clarity of end-to-end VoIP calls.