In Downlink, how to check previous transmission of present re-transmission?

Question

Lets suppose, At present SFN=744, SF=1 re-transmission happen for perticular UE. So how to check when its previous transmission happens(because DL is Asynchronous)?

Answer 1

Hi sripathi,

Irrespective of synchronous or asynchronous HARQ, If current transmission is RE-tX then you check previous transmission of same HARQ process that will be your new transmission. If you are meaning time difference between last and current means then it is implementation specific we cant say one timing, basic implementation is 8ms.

Comments

Hi jaganathan,
time difference is fixed in UL, but cant be fixed in DL Asynchronous HARQ. Why because eNodeB will be busy with processing another UEs.

As you said checking with same HARQ PID that works for debugging, But here my problem is something like in DL At present re-transmission i have to obtain previous transmission of that PID, How its possible?

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It is same as what you have it for re transmission.
HARQ retx will happen at same PID which is used for new transmission.