The RFSoC DFE PRACH core can perform statically or dynamically scheduled PRACH extraction and down-conversion for up to 16 PRACH channels. The PRACH channels can be flexibly allocated across up to three independent bands, each of which supports up to 16 component carriers and up to eight antennas. The PRACH channels are extracted from the antennas in parallel, with the number of extractions dependent on the number of antennas configured in the source band.
An overview of the core functional structure is shown in the following figure.
There are three standard AXI4-Stream data input interfaces, one is mandatory and the others are enabled depending upon the number of bands configured in the core instance. A standard AXI4-Stream interface is used for data output. The core internally processes data using a 16-bit sample width but can also accept 18-bit data, in which case the samples are rounded before PRACH processing is performed. Each sample comprises I and Q components, for a total of 32 or 36 bits per sample. The sample width selected is applied across all active bands.
Samples from multiple component carriers and antennas are interleaved on each input data bus according to a dynamically programmable multiplexing sequence. The component carriers and the antenna interleave pattern can be uniquely defined for each band.
Each AXI4-Stream interface has associated
TUSER and TLAST signals
for user-defined framing/timing control purposes.
CORDIC-based NCOs are used to perform PRACH extraction. Data for the individual PRACH channels are then passed to a multi-channel down-converter (DDC) which performs a sample rate change from the sample rate of the component carrier to the desired sample rate of the PRACH signal, using a configurable chain of symmetric half-band decimation filters (with the option of a final 3x decimation stage).
Input component carrier sample rates of up to 245.76 MSPS are supported. Overall decimation factors ranging from 2x up to 96x are possible. The decimation filter banks have fixed pre-optimized coefficients. The stopband attenuation is at least 60 dB in all operating modes, with ±0.25 dB passband ripple.