OFDM Frame Equalizer

Performs equalization in one or two dimensions on a tagged OFDM frame.

This does two things:

First, it removes the coarse carrier offset. If a tag is found on the first item with the key 'ofdm_sync_carr_offset', this is interpreted as the coarse frequency offset in number of carriers.

Next, it performs equalization in one or two dimensions on a tagged OFDM frame. The actual equalization is done by a ofdm_frame_equalizer object, outside of the block.

Note that the tag with the coarse carrier offset is not removed. Blocks downstream from this block must not attempt to also correct this offset.

Input

a tagged series of OFDM symbols.

Output

The same as the input, but equalized and frequency-corrected.

Parameters

FFT length

Used to set the input and output vector sizes

CP length

Length of the cyclic prefix in samples (required to correct the frequency offset)

Equalizer

The equalizer object that will do the actual work

Length Tag Key

TSB key

Propagate Channel State

If true, the channel state after the last symbol will be added to the first symbol as a tag

Fixed frame length

Set if the frame length is fixed. When this value is given, the Length tag key can be left empty, but it is useful even when using tagged streams at the input.

Example Flowgraph

Insert description of flowgraph here, then show a screenshot of the flowgraph and the output if there is an interesting GUI. Currently we have no standard method of uploading the actual flowgraph to the wiki or git repo, unfortunately. The plan is to have an example flowgraph showing how the block might be used, for every block, and the flowgraphs will live in the git repo.

Source Files

C++ files

[1]

Header files

[2]

Public header files

[3]

Block definition

[4]