info

Provide dimensioning information for OFDM demodulator

Syntax

S = info(obj)

Description

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

example

Examples

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Create and Modify OFDM Demodulator

Open Live Script

Create an OFDM demodulator System object™ with default properties. Modify some of the properties. Inspect the object configuration by using the info object function.

ofdmDemod = comm.OFDMDemodulator

ofdmDemod = 
  comm.OFDMDemodulator with properties:

               FFTLength: 64
    NumGuardBandCarriers: [2×1 double]
         RemoveDCCarrier: false
         PilotOutputPort: false
      CyclicPrefixLength: 16
      OversamplingFactor: 1
              NumSymbols: 1
      NumReceiveAntennas: 1

info(ofdmDemod)

ans = struct with fields:
         InputSize: [80 1]
    DataOutputSize: [53 1]

Modify the number of subcarriers, symbols, and receive streams. Also enable the pilot output.

ofdmDemod.FFTLength = 128;
ofdmDemod.PilotOutputPort = 1;
ofdmDemod.NumSymbols = 2;
ofdmDemod.NumReceiveAntennas = 2;

Verify that the number of subcarriers and the number of symbols changed. Reinspect the input and output signal dimensions by using the info object function. Notice the addition of the pilot output dimensions to the information structure. Because the number of receive streams is greater than 1, the data and pilot output dimensions are 3D arrays rather than matrices.

ofdmDemod

ofdmDemod = 
  comm.OFDMDemodulator with properties:

               FFTLength: 128
    NumGuardBandCarriers: [2×1 double]
         RemoveDCCarrier: false
         PilotOutputPort: true
     PilotCarrierIndices: [4×1 double]
      CyclicPrefixLength: 16
      OversamplingFactor: 1
              NumSymbols: 2
      NumReceiveAntennas: 2

info(ofdmDemod)

ans = struct with fields:
          InputSize: [288 2]
     DataOutputSize: [113 2 2]
    PilotOutputSize: [4 2 2]

Input Arguments

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`obj` — System object to return dimensional information for
`comm.OFDMDemodulator`

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

Data Types: object

Output Arguments

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`S` — Dimensions for OFDM demodulator signals
structure

Dimensions for OFDM demodulator signals, returned as a structure with fields that identify the dimensions of the input and output signals for the OFDM demodulator object, obj.

`InputSize` — Demodulator input data dimensions
column vector

Demodulator input signal dimensions, specified as a column vector. The element values are computed as [N_In,N_Streams], based on the configuration of the input obj.

For variable definitions, see List of Variables.

Data Types: double

`OutputDataSize` — Dimensions of output data signal
column vector

Dimensions of output data signal, specified as a column vector. The element values are computed as [N_DataSC,N_Sym,N_Streams], based on the configuration of the input obj.

For variable definitions, see List of Variables.

Data Types: double

`OutputPilotSize` — Dimensions of pilot output signal
column vector

Dimensions of the pilot output signal, specified as a column vector. The element values are computed as [N_Pilot,N_Sym,N_Streams], based on the configuration of the input obj.

For variable definitions, see List of Variables.

Data Types: double

More About

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List of Variables

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

Variable	Description
N_DataSC	Number of data subcarriers, such that N_DataSC = N_FFT − N_leftG − N_rightG − N_DCNull − N_Pilot − N_CustNull.
N_FFT	Number of subcarriers, `obj.FFTLength`.
N_leftG and N_rightG	Left and right guard bands specified by `obj.NumGuardBandCarriers`.
N_DCNull	Number of DC null subcarriers specified as either `0` or `1`, `obj.InsertDCNull`.
N_Pilot	Number of pilot subcarriers. When you set `obj.PilotOutputPort` to `1`, N_Pilot = `size(obj.PilotCarrierIndices,1)`. When you set `obj.PilotOutputPort` to `0`, N_Pilot = `0` for the calculation of N_DataSC. .
N_CustNull	Number of subcarriers used for custom nulls. This variable applies only when the `obj.PilotCarrierIndices` is a 3D array.
N_Sym	Number of symbols, `obj.NumSymbols`.
N_Streams	Number of receive streams, `obj.NumReceiveAntennnas`.
N_CP	Cyclic prefix length for each symbol. When `obj.CyclicPrefixLength` is a scalar, N_CP = `obj.CyclicPrefixLength`.
N_CPTotal	Total cyclic prefix length over all the symbols. When `obj.CyclicPrefixLength` is a row vector, N_CPTotal = `sum(obj.CyclicPrefixLength)`.
N_In	When `obj.CyclicPrefixLength` is a scalar, N_In = N_Sym × (N_FFT + N_CP). When `obj.CyclicPrefixLength` is a row vector, N_In = (N_Sym × N_FFT) + N_CPTotal.

Version History

Introduced in R2014a

info

Syntax

Description

Examples

Create and Modify OFDM Demodulator

Input Arguments

`obj` — System object to return dimensional information for
`comm.OFDMDemodulator`

Output Arguments

`S` — Dimensions for OFDM demodulator signals
structure

`InputSize` — Demodulator input data dimensions
column vector

`OutputDataSize` — Dimensions of output data signal
column vector

`OutputPilotSize` — Dimensions of pilot output signal
column vector

More About

List of Variables

Version History

See Also

Objects

Functions

info

Syntax

Description

Examples

Create and Modify OFDM Demodulator

Input Arguments

obj — System object to return dimensional information for comm.OFDMDemodulator

Output Arguments

S — Dimensions for OFDM demodulator signals structure

InputSize — Demodulator input data dimensions column vector

OutputDataSize — Dimensions of output data signal column vector

OutputPilotSize — Dimensions of pilot output signal column vector

More About

List of Variables

Version History

See Also

Objects

Functions

`obj` — System object to return dimensional information for
`comm.OFDMDemodulator`

`S` — Dimensions for OFDM demodulator signals
structure

`InputSize` — Demodulator input data dimensions
column vector

`OutputDataSize` — Dimensions of output data signal
column vector

`OutputPilotSize` — Dimensions of pilot output signal
column vector