comm.gpu.ConvolutionalInterleaver

Permute input symbols using shift registers with GPU

To use this object, you must install Parallel Computing Toolbox™ and have access to a supported GPU. If the host computer has a GPU configured, processing uses the GPU. Otherwise, processing uses the CPU. For more information about GPUs, see GPU Computing (Parallel Computing Toolbox).

Description

The comm.gpu.ConvolutionalInterleaver System object™ permutes the symbols in the input sequence with a graphics processing unit (GPU).

To permute the symbols in the input sequence:

1. Create the comm.gpu.ConvolutionalInterleaver object and set its properties.

2. Call the object with arguments, as if it were a function.

To learn more about how System objects work, see What Are System Objects?

Creation

Syntax

intrlvr = comm.gpu.ConvolutionalInterleaver

intrlvr = comm.gpu.ConvolutionalInterleaver(Name=Value)

intrlvr = comm.gpu.ConvolutionalInterleaver(m,b,ic)

Description

intrlvr = comm.gpu.ConvolutionalInterleaver creates a GPU-based convolutional interleaver System object.

intrlvr = comm.gpu.ConvolutionalInterleaver(Name=Value) sets properties using one or more name-value arguments. For example, NumRegisters=10 specifies the number of internal shift registers.

intrlvr = comm.gpu.ConvolutionalInterleaver(m,b,ic) sets the NumRegisters property to m, the RegisterLengthStep property to b, and the InitialConditions property to ic.

Properties

Unless otherwise indicated, properties are nontunable, which means you cannot change their values after calling the object. Objects lock when you call them, and the release function unlocks them.

If a property is tunable, you can change its value at any time.

For more information on changing property values, see System Design in MATLAB Using System Objects.

NumRegisters — Number of internal shift registers

6 (default) | positive integer

Number of internal shift registers, specified as a positive integer.

Data Types: double

RegisterLengthStep — Number of additional symbols that fit in each successive shift register

2 (default) | positive integer

Number of additional symbols that fit in each successive shift register, specified as a positive integer. The first register holds zero symbols.

Data Types: double

InitialConditions — Initial conditions of shift registers

0 (default) | numeric scalar | column vector

Initial conditions of the shift registers, specified as one of these values.

• Scalar — All shift registers, except the first one, store the same specified value.

• Column vector — If the length of the column vector equals the value of the NumRegisters property, then the kth shift register stores the kth element of the specified vector.

You do not need to specify a value for the first shift register, which has zero delay. Because the first shift register has zero delay, the object ignores the first element of this property.

Data Types: double

Usage

Syntax

intrlvseq = intrlvr(inputseq)

Description

intrlvseq = intrlvr(inputseq) permutes the input sequence of symbols inputseq by using a set of shift registers. If the host computer has a GPU configured, processing uses the GPU. Otherwise, processing uses the CPU. The output is the interleaved sequence.

For information about delays, see Delays of Convolutional Interleaving and Deinterleaving.

Input Arguments

inputseq — Sequence of symbols

column vector

Sequence of symbols, specified as a column vector.

Data Types: double | single | uint32 | int32 | logical

Output Arguments

intrlvseq — Interleaved sequence of symbols

column vector

Interleaved sequence of symbols, returned as a column vector with the same data type and size as the inputseq input.

Data Types: double | single | uint32 | int32 | logical

Object Functions

To use an object function, specify the System object as the first input argument. For example, to release system resources of a System object named obj, use this syntax:

release(obj)

Common to All System Objects

step	Run System object algorithm
release	Release resources and allow changes to System object property values and input characteristics
reset	Reset internal states of System object

Examples

GPU-Based Convolutionally Interleave and Deinterleave Sequence

Create GPU-based convolutional interleaver and deinterleaver System objects.

intrlvr = comm.gpu.ConvolutionalInterleaver('NumRegisters',2, ...
    'RegisterLengthStep',3);
deintrlvr = comm.gpu.ConvolutionalDeinterleaver('NumRegisters',2, ...
    'RegisterLengthStep',3);

Generate a random data sequence. Pass the data sequence through the interleaver and then the deinterleaver.

data = (0:20)';
intrlvData = intrlvr(data);
deintrlvData = deintrlvr(intrlvData);

Display the original sequence, interleaved sequence, and restored sequence.

[data intrlvData deintrlvData]

ans = 21×3

     0     0     0
     1     0     0
     2     2     0
     3     0     0
     4     4     0
     5     0     0
     6     6     0
     7     1     1
     8     8     2
     9     3     3
      ⋮

The delay through the interleaver and deinterleaver pair is equal to the product of the NumRegisters and RegisterLengthStep properties.

intrlvDelay = intrlvr.NumRegisters * intrlvr.RegisterLengthStep

intrlvDelay = 6

After accounting for this delay, verify that the original and deinterleaved data are identical.

numSymErrors = symerr(data(1:end-intrlvDelay), ...
    deintrlvData(1+intrlvDelay:end))

numSymErrors = 0

More About

Delays of Convolutional Interleaving and Deinterleaving

The total delay due to a convolutional interleaver and deinterleaver pair is N × slope × (N – 1).

• N is the number of registers and equals the value of the NumRegisters property

• slope is the register length step and equals the value of the RegisterLengthStep property

This diagram shows the structure of a general convolutional interleaver comprised of a set of shift registers, each having a specified delay shown as D(1), D(2),..., D(N), and a commutator to switch input and output symbols through registers. The kth shift register holds D(k) symbols, where k = 1, 2, 3, … N. The kth shift register has a delay value of ((k–1) × slope). With each new input symbol, the commutator switches to a new register and shifts in the new symbol while shifting out the oldest symbol in that register. When the commutator reaches the Nth register, upon the next new input, the commutator returns to the first register.

Array Processing with GPU-based System Objects

A GPU-based System object accepts typical MATLAB^® arrays or gpuArray (Parallel Computing Toolbox) objects. The output signal data type matches the input signal data type.

• When the input signal to the GPU-based System object is a gpuArray object, calculations take place entirely on the GPU, the data remains on the GPU, and the output signal is a gpuArray object. Passing gpuArray arguments minimizes data transfer latency by limiting the number of data transfers between the CPU and the GPU when your simulation runs. For more information, see Establish Arrays on a GPU (Parallel Computing Toolbox).

• When the input signal is a MATLAB array, the GPU-based System object transfers the data between the CPU and the GPU for each object call. The output signal is a MATLAB array and data transfer latency occurs.

Extended Capabilities

GPU Arrays

Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.

This System object runs on a GPU, and also supports GPU array inputs. For more information, see Accelerate Simulation Using GPUs.

Version History

Introduced in R2012a