Dear community friends, today I would like to share with you some content about OFDM.
If you do not know what OFDM is, you can click on this link for more information: The OFDM.
So what I'm going to share today is how OFDM signals are generated.
OFDM Signal Generation Process
The process of generating uplink and downlink signals involves many steps at the physical layer. The following figure shows the typical processing of the downlink physical layer.
What do codeword, layer, and antenna port stand for?
Codeword
Generally, during LTE physical layer processing, one codeword corresponds to one transport block TB (transport block).
Layer
Rank corresponds to the maximum number of independent paths over the air interface. Different layers correspond to different paths.
Antenna port
An antenna port is a logical port and can be mapped to a physical antenna port.
What is scrambling?
Scrambling is a pseudo-random process, which can effectively randomize noises to reduce interference to useful signals.
What is modulation mapping?
What is layer mapping?
The layer mapping entity effectively maps modulation symbols in plural form onto one or more transport layers, dividing the data into multiple layers. Different layer mapping manners may be used according to different transmission manners.
What is precoding?
Spatial multiplexing involves two scenarios: CDD (cyclic delay diversity) and non-CDD.
CDD is a diversity solution for OFDM-based telecommunications systems. lt converts spatial diversity Into frequency diversity to avoid intersymbol interference.
What is RE Mapping?
The precoding step is followed by resource element RE mapping. The RE mapping entity maps plural forms of symbols onto allocated resources.
The last step of physical layer processing is to generate an OFDM signal, that is, to generate a time-domain signal on each antenna. This step is a pure numerical calculation process.
Dear community friends, this is the generation process of the OFDM signal that I shared.
You are welcome to read and leave a message.
