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C6670 AIF2 CPRI radio hardware delay synchronization

Ricardo Martinez
Intellectual 290 points

Dear all,

We are trying to connect a C6670 to a radio through CPRI. Radio is CPRI slave.

We have Dowlink transmission up and running..

But we are facing synchronization issues with the Uplink.

In LTE, uplink radio frame and downlink radio frame are time aligned in the air.

As there are delays in both TX chain and RX chain of the radio, from the DSP point of view, DL and UL are going to be desyncrhonized: UL frame is going to be delayed with respect to DL frame by TX chain delay plus RX chain delay.

We have found in AIF2 User's Guide that AIF2 peripheral, more precisely the AT module, has a few registers to configure UL radT and DL radT timers, for example defining DL and UL symbol offsets. We wonder if this would be the proper way to solve this problem.

Please, could you give any advice or description about what values should be programmend into those registers to adjust UL and DL offsets? Because AIF2 User's Guide does not provide any descriptions.

Could you please give us any advice about how can we face this problem?

Thanks in advance.

Regards

 

  • 0
    TI__Expert 4740 points

    Hi,

    AIF2 UG already has some information about UL and DL Rad timer and how it is related with normal RAD timer.

    we have separate timers for UL and DL and only difference among normal, UL, DL RAD timers are init offset(frame, symbol, clock count). if user set different init offset for each of those three timers, user can get max three different timing. DL for downlink application, UL for uplink application and normal RADT for general application.

    AIF2 LLD example also shows how to use UL or DL timer and AIF2 UG timing chapter (chapter 4.5) shows how user calculates offset for DL or UL case.  

    Regards,

    Albert