Please explain below doubts with respect to FAPI Msgs ?

Question

1 . once Dl_config recived by L2 , after how many subframes corresponding TX_Request Received from L1 (is it fixed or any other factors effect this) ??

1. As like above what about in case of UL_config and ULSCH_indication ?

Answer 1

Hi,

TX-request is not received from L1, L2 will send Tx-request to L1. If L2 schedules some DL-Config then corresponding tx-request will be sent in same subframe .

For UL, L2 will send Ul-config to receive UL_SCH data , but UL_SCH data will come form L1 at any subframe.

Comments

Hi, if UL_SCH data receives from L1 at any subframe how eNodeB identifies it to the corresponding UE ?

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Hi,
Enb will include RNTI in UL-SCH PDU , so L2 will come to know which UE data it is.

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Can you please make it clear, UL-config is given by enodeB which tells in which SFN-SF and with process id UE have to send data ... That should be decided by enb and enb convey that to UE through ul-config .... is it right or not ?? if yes, for the data coming in UL direction  how enb include RNTI ???

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Hi,
Enb will not send Ul-config message to UE, UL-config is to ENB PHY layer, MAC will send UL-config to ENB phy saying that when to receive data, once ENB PHY received data from UE, ENB PHY will include the received data RNTI, then ENB PHY will forward that data to ENB MAC.

UE will come to know when to send data through DCI which is received in PDCCH

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Hi, Thanks ... through which FAPI message enb-phy  asks to eNodeB-mac about grant asked by UE. And through which FAPI message enb-mac  provides grant to eNodeB-PHY which it shd convey to UE.

And howmany subframes before to ul-config this should be done ?

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ENB-PHY wont ask any grant, UE will send BSR as part of PUSCH data, then ENB MAC will decide how much grant to give, then ENB MAC will send HI-DCI0 message to L1,L1 convert this HI-DCI0 to  DCI message and sends in PDCCH to UE ,after 3 SF ENB MAC has to give UL-CONFIG to phy to receive the data from UE(because we gave grant to UE in HI-DCI0) , then L1 will receive data from UE,after this it will forward data to L2.

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very well explained, Thanks alot ... please clear below doubts ..

1. Lets suppose UE sends BSR in 850-0 , in which subframe eNB-MAC sends HI-DCI0 to eNB-PHY?
2. In Fapi document about HI-DCI0 it stated as "The SFN/SF in this message should be the same as the corresponding DL_CONFIG.request message." ... what the meaning of this ... please explain? (DL_CONFIG is for downlink assignment and DCI0 is for uplink grant .. so its confusing me )

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Nothing to do with that statement, If you are sending HI-DCI0 or tx-req then SFN/SF should be same as corresponding DL-config message SFN/SF(in the same SF you might send DL-config, so whatever SF your are including in DL-CONFIG should match with DCI0 and TX).

If UE sending BSR at 850-0 then ENB can give at any SF grant to UE, say ENB gives HI-DCI0 at 850-5 to L1, then UE will send data at 850-9(because UE will receive grant in 850-5 then +4SF). ENB L2 has to give Ul-config message at 850-8 to L1 so that L1 will receive data at 850-9.

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Hi, for sending HI_DCI0 also enb-mac should send DL_Config which includes no of HI PDUs and DCI PDUs ??? Is it correct ?

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No, DL-Config doesn't includes information about HI-DCI0. But Dl-Config message is mandatory and If you dont have any Dl-transmission then you can leave that message as empty message and include only SFN/SF in dl-config message then send to PHY.
Then if the same Sub frame you are sending HI-DCIO then include same SFN/SF which included in above DL-CONFIG