(Optional) Setting DSP Parameters
Context
The digital signal processing (DSP) collects, converts, filters, measures, enhances, compresses, or identifies signals and coverts the signal from an analog to a digital form.
The DSP module converts analog voice signals into digital signals and stores a certain number of digital signals into packets for transmission. To improve the voice communication quality, the DSP needs to process voice signals.
- Enabling Echo Cancellation on a DSP Channel
- Enabling PLC on a DSP Channel
- Enabling Silence Compression on a DSP Channel
- Setting Fax Parameters
- Setting Jitter Buffer Parameters
- Setting the Payload Type Value
- Setting RTCP Parameters
- Setting DSP Resource Parameters
- Configuring a DSP Channel
- Verifying the DSP Configuration
Enabling Echo Cancellation on a DSP Channel
Enabling PLC on a DSP Channel
Context
PLC is a technique that masks the effects of packet loss in VoIP communications. PLC is effective only when the packet loss ratio is low. During communication, the average packet loss ratio may be low, but a high burst packet loss ratio results in severe voice quality deterioration. PLC can insert a static frame in the place where a packet is lost, regenerate a packet received prior to the lost one, or generate an analog voice packet. If packets are lost during communication and PLC is not used, the voice communication is interrupted. You can use a proper PLC algorithm to minimize effects of packet losses.
Enabling Silence Compression on a DSP Channel
Context
To save network bandwidth, enable silence compression on a DSP channel. When no voice is detected, the encoder generates short silence codes, but does not generate voice compression codes. In addition, the encoder notifies the receiver of silence start until the voice is restored. The silence compression function reduces the number of sent voice packets.
Setting Fax Parameters
Procedure
- Run:
system-viewThe system view is displayed.
- Run:
voiceThe voice view is displayed.
- Run:
dsp-attributeThe DSP view is displayed.
- Set fax parameters.
Run:
fax redundancy-t4 redundancy-t4–value
The T.4 redundancy parameter value of the T.38 fax is set.
Run:
fax redundancy-t30 redundancy-t30–value
The T.30 redundancy parameter value of the T.38 fax is set.
Run:
fax training-mode { e2e | local }
The fax training mode is set.
Run:
fax training-rate { v17 | v29 | v27 }
The maximum fax training rate is set.
Run:
fax v8negotiate enableV8 negotiation is enabled.
Setting Jitter Buffer Parameters
Context
Delay variations in voice packet arrival time can occur because of network congestion or route changes. To reduce sound distortion caused by the delay jitter and packet loss, a jitter buffer is used. You can set proper jitter buffer parameters to minimize delay variations so that packets can be processed in a timely manner and smooth voice communication can be provided as much as possible.
Procedure
- Run:
system-viewThe system view is displayed.
- Run:
voiceThe voice view is displayed.
- Run:
dsp-attributeThe DSP view is displayed.
- Set parameters for the Jitter Buffer.
Run:
jitter-buffer adapt-jb-threshold adapt-jb-threshold
The alarm threshold of the dynamic jitter buffer is set.
Run:
jitter-buffer init-adapt-jb init-adapt-jb-value
The initial value of the dynamic jitter buffer is set.
Run:
jitter-buffer init-fixed-jb normal-fixed-jb-value
The initial value of the static jitter buffer is set.
Run:
jitter-buffer max-adapt-jb max-adapt-jb-value
The maximum value of the dynamic jitter buffer is set.
Run:
jitter-buffer min-adapt-jb min-adapt-jb-value
The minimum value of the dynamic jitter buffer is set.
Run:
jitter-buffer max-fixed-jb max-fixed-jb-value
The maximum value of the static jitter buffer is set.
Run:
jitter-buffer min-fixed-jb min-fixed-jb-value
The minimum value of the static jitter buffer is set.
Setting the Payload Type Value
Procedure
- Run:
system-viewThe system view is displayed.
- Run:
voiceThe voice view is displayed.
- Run:
dsp-attributeThe DSP view is displayed.
- Set Payload Type parameters.
The following payload type values must be different.
Run:
payload-type clear-mode clearmode-value
The RTP payload type value of a DSP channel is set.
Run:
payload-type g726-16k g726-16k-value
The G.726-16k payload type value of a DSP channel is set.
Run:
payload-type g726-24k g726-24k-value
The G.726-24k payload type value of a DSP channel is set.
Run:
payload-type g726-32k g726-32k-value
The G.726-32k payload type value of a DSP channel is set.
Run:
payload-type g726-40k g726-40k-value
The G.726-40k payload type value of a DSP channel is set.
Run:
payload-type nte nte-value
The NTE payload type value of a DSP channel is set.
Run:
payload-type redundancy redundancy-value
The redundancy payload type value of a DSP channel is set.
Run:
payload-type vbd vbd-value
The VBD payload type value of a DSP channel is set.
Setting RTCP Parameters
Context
RTCP monitors the quality of service and conveys information about participants in an on-going session. RTCP periodically sends packets to all the participants in the session to monitor the quality of service and obtain identity information about the participants. This section describes how to set RTP control protocol (RTCP) parameters.
Procedure
- Run:
system-viewThe system view is displayed.
- Run:
voiceThe voice view is displayed.
- Run:
dsp-attributeThe DSP view is displayed.
- Run the following commands as required.
Run:
rtcp rtcp-interval rtcp-interval
The interval at which a DSP channel sends RTCP packets is set.
Run:
rtcp rtcpxr enableThe RTP Control Protocol Extended Reports (RTCP XR) function is enabled.
Run:
rtcp sev-degradethreshold sev-degradethresholdval
The threshold for the number of severe degrade seconds is set.
Run:
rtcp vqm enableThe Voice Quality Monitor (VQM) function is enabled.
Setting DSP Resource Parameters
Context
DSP resources are limited and users have different requirements for DSP resources. To control and allocate DSP resources properly, set the DSP resource control mode and the resource threshold in hierarchical control mode.
Procedure
- Run:
system-viewThe system view is displayed.
- Run:
voiceThe voice view is displayed.
- Run:
dsp-attributeThe DSP view is displayed.
- Run the following commands as required.
Run:
resource-threshold mode { priority | normal }
The DSP resource control mode is configured.
Run:
resource-threshold { threshold1 threshold1 | threshold2 threshold2 | threshold3 threshold3 }
The resource threshold in hierarchical control mode is set.
The resource threshold in hierarchical control mode can be set only when the DSP resource control mode is priority.
Configuring a DSP Channel
Context
You can enable a digital signal processor (DSP) channel to work in loopback mode, and set the loopback mode (PCM-side loopback test and IP-side loopback test). When the DSP channel between the calling party and called party cannot transmit signals or can transmit signals only in one direction, run the loop-back command to locate the fault. If the calling party hears the echo in a PCM-side loopback test, the speech channel between the calling phone and the calling DSP channel is functioning properly. If the called party hears the echo in an IP-side loopback test, the speech channel between the called phone and the calling DSP channel is functioning properly.
To control resources of DSP channels, prohibit the DSP channels. The prohibited DSP channels cannot participate in resource allocation.
Procedure
- Run:
system-viewThe system view is displayed.
- Run:
voiceThe voice view is displayed.
- Run:
dsp slot/dsp-index
The DSP resource management view is displayed.
- Run the following commands as required.
Run:
loop-back loopback-type channel
The loopback function is configured on a DSP channel.
Run:
prohibit channel [ count ]
DSP channels are prohibited.
Verifying the DSP Configuration
- Enabling Echo Cancellation on a DSP Channel
- Enabling PLC on a DSP Channel
- Enabling Silence Compression on a DSP Channel
- Setting Fax Parameters
- Setting Jitter Buffer Parameters
- Setting the Payload Type Value
- Setting RTCP Parameters
- Setting DSP Resource Parameters
- Configuring a DSP Channel
- Verifying the DSP Configuration