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  • LTE MAC Layer Interview Questions And Answers 21-30


    21.       What is HARQ RTT Timer?
    Ans:It is HARQ Round Trip Timer means  a timer which is a min amount of subframe duration from the time new transmission is received and before the UE can except a re transmission of the same packet.

    22.       What is msg3 buffer?
    Ans: At the time of sending msg3 which is nothing but a RRC connection request at the time of initial attach than the msg3 need to stored in a HARQ buffer which is called as a msg3 buffer.
    Here msg3 always stored in a HARQ buffer.

    23.       What is PRACH Resource Index?
    Ans: Its a common channel and used for just a resource index with the help of it we will able be determine and identify in freq domain which resource ue can use for PRACH transmission.
    PRACH-in-lte


    PRACH RESOURCE INDEX TABLE

    24.       What is ra-PRACH-MaskIndex?
    Ans: PRACH mask index identifies which PRACH resources the UE is allowed to use for its access attempt as shown in below table. More specifically, the mask defines that in which PRACH within a frame, UE can transmit a Random Access Preamble.
    ra-PRACH-MaskIndex
    PRACH MASK INDEX TABLE

    25.       What are the Logical Channels carried through HARQ?
    Ans: CCCH, DCCH and DTCH logical channels.
       
    26.       What are the Logical Channels NOT carried through HARQ?
    Ans: PCCH And BCCH logical channels

    27.       What are the Physical Channels Terminate at MAC/Physical boundary and are irrelevant to the upper layers?
    Ans: All the pure physical channels are terminate like PSS, SSS, PCFICH,PHICH,RS,PBCH etc.

    28.       What are the Logical channels through which PBCH is carried through?
    Ans : Through BCCH channel.

    29.       What are the Logical Channels Carried by UL-SCH and DL-SCH?
    Ans: DLSCH- BCCH,CCCH,DCCH and DTCH.
             ULSCH-CCCH,DCCH and DTCH.

    30.       What Logical channels are carried by PDCCH and PUCCH Physical Channels?
    Ans. Logically there is no Direct connectivity of these channel to logical Channels. But they carry information of PDSCH (which carry DLSCH info) and PUSCH(carry ULSCH info).

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