docsIf31CmtsDsOfdmChanCyclicPrefix
DOCS-IF31-MIB ·
.1.3.6.1.4.1.4491.2.1.28.1.19.1.14
Object
column
number of samples DsOfdmCyclicPrefix
Cyclic prefix enables the receiver to overcome the effects of inter-symbol-interference and intercarrier-interference caused by micro-reflections in the channel. There are five possible values for the length of the CP and the choice depends on the delay spread of the channel - a longer delay spread requires a longer cyclic prefix. The cyclic prefix (in usec) are converted into samples using the sample rate of 204.8 Msamples/s and is an integer multiple of: 1/64 * 20 us.
Context
- MIB
- DOCS-IF31-MIB
- OID
.1.3.6.1.4.1.4491.2.1.28.1.19.1.14- Type
- column
- Access
- readonly
- Status
- current
- Units
- number of samples
- Parent
- docsIf31CmtsDsOfdmChanEntry
- Table
- docsIf31CmtsDsOfdmChanTable
- Siblings
- 19
Syntax
number of samples DsOfdmCyclicPrefix
- Source
- DsOfdmCyclicPrefix
- Base type
Unsigned32
Values & Constraints
Type Constraints
range: 192
range: 256
range: 512
range: 768
range: 1024
Related Objects
Sibling Objects
| Object | Type | Syntax | OID |
|---|---|---|---|
| docsIf31CmtsDsOfdmChanChannelId The Cable Modem Termination System identification of the
OFDM downstream channel within this particular MAC interface.
if the interface is down, the object returns the most
curren… | column | Integer32 | .1.3.6.1.4.1.4491.2.1.28.1.19.1.1 |
| docsIf31CmtsDsOfdmChanNumActiveSubcarriers This attribute represents the number of active data
subcarriers within the OFDM downstream channel (i.e. this
exclude subcarriers for continuous pilots and the PLC).
For 4K FFT mo… | column | SNMPv2-SMIUnsigned32 | .1.3.6.1.4.1.4491.2.1.28.1.19.1.10 |
| docsIf31CmtsDsOfdmChanSubcarrierSpacing This attribute defines the subcarrier spacing associated with
a particular FFT mode configured on the OFDM downstream
channel. If it is 4K mode, then the subcarrier spacing is
50k… | column | kHz SubcarrierSpacingType | .1.3.6.1.4.1.4491.2.1.28.1.19.1.11 |
| docsIf31CmtsDsOfdmChanLowerGuardbandWidth This attribute is the width in Hertz of the lower guard
band of the OFDM channel. The valid range is 0 or
1MHz to 1.77GHz. | column | SNMPv2-SMIUnsigned32 | .1.3.6.1.4.1.4491.2.1.28.1.19.1.12 |
| docsIf31CmtsDsOfdmChanUpperGuardbandWidth This attribute is the width in Hertz of the upper guard
band of the OFDM channel. The valid range is 0 or
1MHz to 1.77GHz | column | SNMPv2-SMIUnsigned32 | .1.3.6.1.4.1.4491.2.1.28.1.19.1.13 |
| docsIf31CmtsDsOfdmChanRollOffPeriod Roll off period maximizes channel capacity by sharpening the
edges of the spectrum of the OFDM signal. For windowing
purposes another segment at the start of the IDFT output is
ap… | column | number of samples DsOfdmRollOffPeriod | .1.3.6.1.4.1.4491.2.1.28.1.19.1.15 |
| docsIf31CmtsDsOfdmChanTimeInterleaverDepth This attribute represents the number of samples for the
OFDM Downstream channel. This is limited to 16 samples for
and 32 samples for 50 kHz and 25 kHz Subcarrier Spacing,
respect… | column | symbols TimeInterleaverDepth | .1.3.6.1.4.1.4491.2.1.28.1.19.1.16 |
| docsIf31CmtsDsOfdmChanNumPilots This attribute is the number of continuous pilots
for the OFDM downstream channel. | column | SNMPv2-SMIUnsigned32 | .1.3.6.1.4.1.4491.2.1.28.1.19.1.17 |
| docsIf31CmtsDsOfdmChanPilotScaleFactor This attribute represents the scale factor for calculating
the number of continuous pilots. | column | SNMPv2-SMIUnsigned32 | .1.3.6.1.4.1.4491.2.1.28.1.19.1.18 |
| docsIf31CmtsDsOfdmChanNcpModulation This attribute represents the modulation of all subcarriers in
the NCP channel. Valid values are qpsk, qam16 and qam64. | column | DsOfdmModulationType | .1.3.6.1.4.1.4491.2.1.28.1.19.1.19 |
| docsIf31CmtsDsOfdmChanLowerBdryFreq This attribute represents either the lower boundary frequency
of the lower guardband or (if no guardband is defined) the
lower boundary frequency of the lowest active subcarrier o… | column | Hz SNMPv2-SMIUnsigned32 | .1.3.6.1.4.1.4491.2.1.28.1.19.1.2 |
| docsIf31CmtsDsOfdmChanUtilization The utilization for this OFDM downstream channel, accurate as
of the most recent docsIfCmtsChannelUtilizationInterval.
See Reference for specific details on this at… | column | percent Unsigned32 | .1.3.6.1.4.1.4491.2.1.28.1.19.1.20 |
| docsIf31CmtsDsOfdmChanUpperBdryFreq This attribute represents either the upper boundary frequency
of the upper guardband or (if no guardband is defined) the
upper boundary frequency of the highest active subcarrier … | column | Hz SNMPv2-SMIUnsigned32 | .1.3.6.1.4.1.4491.2.1.28.1.19.1.3 |
| docsIf31CmtsDsOfdmChanLowerBdryEncompSpectrum This attribute represents the lower boundary frequency
of the encompassed spectrum. | column | Hz SNMPv2-SMIUnsigned32 | .1.3.6.1.4.1.4491.2.1.28.1.19.1.4 |
| docsIf31CmtsDsOfdmChanUpperBdryEncompSpectrum This attribute represents the upper boundary frequency
of the encompassed spectrum. | column | Hz SNMPv2-SMIUnsigned32 | .1.3.6.1.4.1.4491.2.1.28.1.19.1.5 |
| docsIf31CmtsDsOfdmChanPlcFreq This is the PHY Link Channel (PLC) frequency. It is the center
frequency of the lowest frequency subcarrier of the PLC. The
aim of the PLC is for the CMTS to convey to the CM the
… | column | Hz SNMPv2-SMIUnsigned32 | .1.3.6.1.4.1.4491.2.1.28.1.19.1.6 |
| docsIf31CmtsDsOfdmChanSubcarrierZeroFreq This attribute specifies the center frequency of the
subcarrier 0 of the OFDM transmission. Note that since
subcarrier 0 is always excluded, it will actually be below the
allowed … | column | Hz SNMPv2-SMIUnsigned32 | .1.3.6.1.4.1.4491.2.1.28.1.19.1.7 |
| docsIf31CmtsDsOfdmChanFirstActiveSubcarrierNum This attribute corresponds to the number of the first
non-excluded subcarrier. The valid range is 148 to 7895. | column | SNMPv2-SMIUnsigned32 | .1.3.6.1.4.1.4491.2.1.28.1.19.1.8 |
| docsIf31CmtsDsOfdmChanLastActiveSubcarrierNum This attribute corresponds to the number of the last
non-excluded subcarrier. The valid range is 148 to 7895 | column | SNMPv2-SMIUnsigned32 | .1.3.6.1.4.1.4491.2.1.28.1.19.1.9 |