Ditech Networks' Solutions
Experience Intelligence™ for VoIP Networks
The deployment of Voice-over-IP (VoIP) technology in voice networks has introduced a number of new voice quality issues. IP problems such as packet loss, packet delay, and packet jitter reduce voice quality and increase the annoyance of traditional network impairments, such as hybrid echo, acoustic echo, differing voice levels, and background noise. The aggregation of these quality impairments can be significant enough to affect customer satisfaction and retention rates. To exacerbate the issue, carriers have not had a view into the complete set of voice quality impairments within the VoIP network, until now.
| Speech Quality Measurements | Ditech Platform | |
EXi measures and reports the following
|
Ditech’s Experience Intelligence™ (EXi) solution for VoIP is available on the Packet Voice Processor: |
A Comprehensive View of Network Impairments
Ditech’s EXi solution is a powerful tool that measures and reports a comprehensive set of voice quality statistics generated from live calls in a VoIP network. Unlike competing voice quality monitoring solutions that require intrusive test tools, Ditech’s EXi non-intrusively monitors every call that passes through a Packet Voice Processor. Other solutions only report on test calls or packet impairments, while EXi offers a full suite of quality information including speech and noise levels, echo delay, return loss, MOS scores, and R values, as well as packet impairment data for actual customer calls.
The extended visibility offered by EXi allows VoIP service providers to proactively identify and address network quality issues in great detail to improve the customer experience. In addition, the ability to retrieve and analyze records of call quality statistics allows customer issues to be addressed easily through simple queries and analysis. This view of customer experience – looking at the total voice quality within a VoIP call – gives service providers the knowledge and intelligence to improve customer satisfaction and reduce customer churn.
Voice Quality Impairments in a VoIP Network
The EXi Architecture
Ditech’s EXi solution has three parts: the EXi-Agent, which resides on the Packet Voice Processor, and the EXi-Collector and EXi-Reporter, which reside on the Element Management System (EMS). The EXi-Agent is responsible for collecting individual call data, calculating R Factors, and correlating MOS values. The EXi-Collector is responsible for gathering the EXi data from all Packet Voice Processor nodes and storing to a database. The EXi-Reporter analyses the data and provides a graphical display of networkwide voice quality statistics.
EXi-Agent – Live Call Measurement
The EXi-Agent leverages Ditech’s expertise in echo cancellation and voice enhancement by utilizing voice processing DSP resources to continuously and non-intrusively measure and record voice quality impairments that are traditionally ignored by passive VoIP test tools. This level of quality analysis provides an unparalleled approach to understanding true voice quality, as it happens, within live calls.
Noise and Speech Levels
An increasing number of calls originate from
noisy urban environments where call quality
can be negatively affected by background
noise. Ditech’s EXi-Agent measures per-call
speech level, noise level, and signal-to-noise
ratio (SNR) in both directions to identify and
report unwanted noise in a call.
Echo and Delay
Transporting voice over IP networks usually results in greater and more
variable latency than TDM. The majority of legacy hybrid echo cancellers are unable to handle this added delay,
leaving callers unprotected from annoying hybrid echo.
In addition, the proliferation of user choices in terminal equipment (handsets, headsets, PC-based softphones, and speakerphones) continues to expand rapidly without necessarily providing adequate acoustic isolation, exposing more users to acoustic echo.
The EXi-Agent monitors from 0 to 400 ms in both directions, ensuring complete and accurate measurement of echo.
Transmission Rating Factors and Mean Opinion Scores
Per-call listening and conversational R Factor
and MOS values are computed continuously
and non-intrusively based on the measured
voice quality impairments (speech, noise,
and echo) as well as codec type. EXi’s objective
scores follow the ITU-T G.107 E-Model
standard and use a unique DSP-based
approach to analyze live voice streams.
The EXi-Agent determines R Factors for
the following:
- Listening Quality (LQ) – This score includes speech quality, noise, and voice level. It does not include impairments that affect conversation, such as delay.
- Conversational Quality (CQ) – This score includes the impairments measured for the LQ score and adds echo and delay, which affect conversational quality.
These R values are then correlated to subjective MOS values from Absolute Category Rating (ACR) MOS listening tests.
EXi-Agent – Packet Measurements
In VoIP networks, packet characteristics can have a significant impact on the quality of a call. Ditech’s EXi-Agent non-intrusively measures and collects these statistics on an ongoing, per-call basis to quickly identify the source of IP issues that are affecting voice quality.
Packet Jitter
The variation of inter-arrival time between
packets adds to delay because the jitter
buffer adjusts to establish a constant input
for decoding voice packets. EXi-Agent provides
a packet jitter profile for each call.
Packet Delay
Congestion, queuing, packet processing,
and routing all affect the amount of delay
a packet experiences when crossing an IP
network. The packet delay affects the overall
delay of the call and the amount of noticeable
echo within a call. EXi-Agent provides
packet delay information on a per-call basis.
Packet Counts
Per-call packet count measurements help
determine whether speech quality issues
are related to the packet network or are a
result of other issues. Ditech’s packet count
statistics include:
- Total Packets – The total packets received per call.
- Discarded Packets – The number of discarded packets received per call.
- Packet Loss – The number of packets lost per call.
EXi-Collector and EXi-Reporter – Networkwide Analysis
Ditech’s EXi-Collector gathers voice quality statistics from Ditech network elements and, based on chosen thresholds and filters, the EXi-Reporter analyzes and summarizes networkwide statistics, including:
- Summary views of voice quality measurement results
- Detailed views of specific voice quality impairments, based on voice quality thresholds and filters
- Historical data for trend analysis
When combined with Ditech’s industry-leading Voice Quality Assurance (VQA™) and Packet Quality Assurance™ (PQA™) solutions, Ditech’s EXi solution becomes a powerful tool to measure, monitor, and improve voice quality issues in a VoIP network.
For more information on Ditech Networks’ solutions and feature availability, please contact us.