Convert sample stream to frame-based data
Wireless HDL Toolbox / I/O Interfaces
The Samples To Frame block reconstructs frame-based data from a stream of samples and its corresponding control signals. It removes any idle or nonvalid samples from the data. See Streaming Sample Interface for details of the streaming format.
Use this block to process output from a subsystem targeted for HDL code generation. This block does not support HDL code generation.
sample— Stream of samples
Stream of samples, specified as a scalar or vector. Vector input
values represent a single sample, such as turbo-encoded samples
represented by one systematic value and two parity values. The stream
can include idle cycles between samples and between frames. Idle samples
are supported for simulation but not for HDL code generation.
ctrl— Control signals accompanying sample stream
Control signals accompanying the sample stream, specified as a
samplecontrol bus. The bus includes the
valid control signals, which indicate the
boundaries of the frame and the validity of the samples.
start — Indicates the start of the input frame
end — Indicates the end of the input frame
valid — Indicates that the data on the input
data port is valid
frame— Frame of output samples
Frame of output samples, returned as a column vector. Each frame is the same size. If the input frame is smaller than Output size, the block pads the frame with zeroes. If the output frame is larger than the Output size, the block forms the frame by using the first Output size samples. You can optionally output the number of valid samples in each frame on the len port.
valid— Validity of output frame
Validity of output frame, returned as a
scalar. This port returns
when the values on the frame and
len (optional) ports, are valid.
len— Number of valid samples in output frame
Number of valid samples in output frame, returned as an integer. The input sample stream can have frames of different sizes. The block returns a constant size vector on the frame port, padded with zeroes when the input frame is smaller than Output size. The len port indicates how many valid samples are in the output frame. If the output frame is larger than the Output size, the block forms the frame by using the first Output size samples.
Input size— Number of values representing each sample
Number of values representing each sample, specified as a positive integer
scalar. The block accepts a vector of Input size
values. Each vector has one corresponding set of control signals. For
example, you can use this parameter for turbo-encoded samples. In the LTE
standard, the turbo code rate is 1/3, so each sample is represented by one
systematic value and two parity values: S_n,
P1_n, and P2_n. In this case, set
Input size to
Frame search window— Number of input cycles to buffer
Number of input cycles to buffer before attempting to form an output frame, specified as an integer. The block simulates faster when this parameter is larger. However, the block returns at most one frame from each search window. If more than one frame fits in this window, the block returns the first one it finds and drops the later frames. The default setting, 1 cycle, never drops frames, but results in slower simulation. Therefore, it is a best practice to set this parameter to the minimum number of cycles per frame, including idle cycles.
For example, calculate the valid cycles and idle cycles representing each frame. Each cycle may include more than one sample, depending on your Input size (samplesize) setting.
% Exact setting: includes idle cycles totalframesize = ((framesamples/samplesize)*... (idlecyclesbetweensamples+1))+idlecyclesbetweenframes;
% Conservative setting: number of valid output cycles, without idles encoderrate = 3; numtailbits = 12; framesize = (framesamples+numtailbits)/encoderrate;
Output size— Maximum samples per frame
Maximum number of samples per frame, specified as an integer. The input sample stream can have frames of different sizes. The block returns a constant size vector, padded with zeroes if the frame is smaller than Output size. If the block receives a frame larger than Output size, it truncates the frame.
Compose output from interleaved input samples— Order of output samples relative to input order
Order of output samples relative to input order, when more than one value
represents each sample. For example, 1/3 turbo-encoded samples are
[S_1 P1_1 P2_1] and
P2_2]. The default output order is
[S_1 P1_1 P2_1 S_2
P1_2 P2_2]. To reorder the samples so that systematic and
parity values are grouped together, select Compose output from
interleaved input samples. The output order is then
[S_1 S_2 P1_1 P1_2 P2_1 P2_2].
Enable frame length output port— Output number of valid samples
Enable frame length output port. Select this option to return the number of valid samples in each output frame. The length is returned on the len port and is qualified by the valid signal. Use this option when the sample stream has variable size frames or when a downstream block requires the frame size as input, such as LTE Turbo Decoder.
This block supports C/C++ code generation for Simulink® accelerator and rapid accelerator modes and for DPI component generation.