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info

Provide dimensioning information for OFDM modulator

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Syntax

S = info(obj)

Description

S = info(obj) returns a structure with fields that identify the input and output signal dimensions for the comm.OFDMModulator System object™, obj.

example

Examples

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Open Live Script

Get the OFDM modulator data dimensions by using the info object function.

Create an OFDM modulator object with pilot indices, a DC null, and two transmit antennas. 

ofdmMod = comm.OFDMModulator( ...
    NumGuardBandCarriers=[4; 3], ...
    PilotInputPort=true, ...
    PilotCarrierIndices=cat(3,[12; 26; 40; 54],[11; 25; 39; 53]), ...
    InsertDCNull=true, ...
    NumTransmitAntennas=2);

Use the info object function to get the modulator input data, pilot input data, and output data sizes.

info(ofdmMod)
ans = struct with fields:
     DataInputSize: [48 1 2]
    PilotInputSize: [4 1 2]
        OutputSize: [80 2]

Input Arguments

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System object to return dimensional information for, specified as a comm.OFDMModulator System object.

Output Arguments

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Dimensions for OFDM modulator signals, returned as a structure with fields that identify the input and output signal dimensions for the comm.OFDMModulator System object, obj.

Dimensions of input data signal, returned as a column vector. The element values are computed as [NData,NSym,NT], based on the configuration of the input obj.

For variable definitions, see List of Variables.

Data Types: double

Dimensions of the pilot input signal, returned as a column vector. The element values are computed as [NPilot,NSym,NT], based on the configuration of the input obj.

For variable definitions, see List of Variables.

Data Types: double

Modulator output signal matrix dimensions, returned as a column vector. The element values are computed as [(NCPTotal + (NFFT×NSym)),NT], based on the configuration of the input obj.

For variable definitions, see List of Variables.

Data Types: double

Data Types: struct

More About

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List of Variables

These variables describe the dimensions of the input and output signals for the comm.OFDMModulator System object.

VariableDescription

NData

Number of data subcarriers, such that NData = NFFT − NleftG − NrightG − NDCNull − NPilot − NCustNull.

NFFT

Number of subcarriers, obj.FFTLength.

NleftG and NrightG

Left and right guard bands specified by obj.NumGuardBandCarriers.

NDCNull

Number of DC null subcarriers specified as either 0 or 1, obj.InsertDCNull.

NPilot

Number of pilot subcarriers.

  • When you set obj.PilotOutputPort to 1, NPilot = size(obj.PilotCarrierIndices,1).

  • When you set obj.PilotOutputPort to 0,

    NPilot = 0 for the calculation of NData.

.

NCustNull

Number of subcarriers used for custom nulls. This variable applies only when the obj.PilotCarrierIndices is a 3D array.

NSym

Number of symbols, obj.NumSymbols.

NT

Number of transmit antennas, obj.NumTransmitAntennnas.

NCPTotal

Cyclic prefix length over all the symbols.

  • NCP represents the cyclic prefix length as determined by obj.CyclicPrefixLength.

  • When obj.CyclicPrefixLength is a scalar, NCPTotal = NCP × NSym.

  • When obj.CyclicPrefixLength is a row vector, NCPTotal = ∑ NCP.

Version History

Introduced in R2014a

See Also

Objects

Functions