How UE gets the value of BI in lte?

Question

How ever ENB will send either BI or RAPID in RAR, then if ENB sends only RAPID then how ue gets BI to apply for rach failure ?

Answer 1

Backoff Indicator' is a special form of MAC header/subheader. Its made up of 4 bits & it can carry the value from 0~15.
As per 36.321, Backoff Parameter values are presented in Table 7.2-1.

Comments

Hi, thank you. But my question was if ENB sends only rapid then how UE will get to know these BI vales?

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I think,ENB can choose a random BI value in this case .
like- If PRACH resources are more in reserved ,then BI time can be less.

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BI is applied y UE, If ENB selects random then how UE will get to know this ?

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enb will send BI in RAR ,then ue will assigns corresponding value according to table given above