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AIF2 usage in implementing CPRI Interface between REC and RE

Vivek Khanna
Prodigy 70 points


 

I am finding difficuilty in programming  AIF2 in one of aspects.

As we know, there are C&M data  and AXC data(IQ samples Data) to be sent over CPRI Interface.

Approach I am following to configure AIF2, is to use different C&M Data generator SW and AXC data Generator SW. Since C&M data is demand based,so it would not be sent regularly. AXC Data would be sent regularly. I would use MCN(PKTDMA) functionality to transfer both types of Data to AIF2 FIFO . Now both type of data are in buffer (FIFO).

How would I make sure that which portion of data in FIFO is AXC data or C&M data ? We need to differentiate both type of data as both are put into different positions of CPRI Basic frame. If we cannot differentiate type of data , then how would both these data go into correct positions of CPRI frame ?

Please provide rsolution to this problem.

 

  • 0
    TI__Prodigy 230 points

    Hi Vivek,

    There are a few things we need to consider when transferring control words for C&M mixed with AxC data:

    The CPRI control word allocation within CPRI hyperframes can be established through the CPRI Control Word LUT. The LUT (per link) specifies which basic frames of the CPRI hyperframe to activate as control words on the specified link. This LUT exists for both the protocol encoder and decoder, and will allow you to specify how the control words are interleaved with the antenna carrier data on a given link. You will also need to program the Pack module for assigning specific DMA channels to the control words. This programming will need to be done for both the protocol encoder and decoder.

    Also keep in mind that out of the 128 possible streams available per link, four of these streams are dedicated to control word traffic (124-127). This means the protocol encoder and decoder can have up to four dedicated channels for processing control words. It also means that we can have dedicated DB FIFOs to process these control words, or have them process a mix of AxC data and control words. Your application must make sure to appropriate program certain channels to be reserved for control word processing.

    Let me know if anything is unclear. The MCSDK should provide AIF2 examples that setup the control word allocation similar to your purpose.

    Regards,
    Sahil Hingorani

  • 0 in reply to Sahil Hingorani
    Prodigy 70 points

    Hi sahil

    I understand that there are different channels dedicated for the control words. I still have a query and I would ask it with help of example.

    Lets take one link out of 6 links. Control words are dedicated 124-127 channels of DB by correct register settings in  pack module of PD/PE.

    Few of remaining channels are used for AXC data.

    There are two types of SW: one generates AXc data(IQ samples; continuous stream) and other generate CM data(demand based). Also, AIF2 register bit PM_CTL  (Egress Data Buffer Configuration Register) is set indicating using same DB FIFO buffer for both AXc data and control data.  Both SW would copy data to same DB FIFO using PKTDMA. Now both type of data are present inside the same DB FIFO.

    Since SW has configured dedicated DB Channels in pack module of PE and PD,so how data mixed inside the DB FIFO will move to different DB channels?

    I hope you understand my query.

    Please respond to query.