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LTE: Why does PHICH info present on MIB ?

+6 votes
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LTE: Why does PHICH info present on MIB ?
posted Nov 5, 2013 by Vikram Singh

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4 Answers

+3 votes

PHICH Info consist of phich-Duration & phich-Resource which comes in MIB.

  1. This is the down link physical channel which is used to send the ACK/NACK for the uplink data coming from UE..
  2. When UE sends any data then ENODEB uses this PHICH resource to send acknowledgement for the uplink data.
  3. As MIB is most frequently transferred so it is part of this as far as i guess.
answer Nov 5, 2013 by Sachidananda Sahu
+3 votes

Do decode PDCCH, exact number of OFDM symbols are being used in the system required. So the number of OFDM symbols are figure out by PCFICH and PHICH. PCFICH and PHICH both are placed at first OFDM symbol for each downlink frame.

answer Nov 5, 2013 by Vimal Kumar Mishra
+2 votes

After decoding MIB UE has to has to decode PDCCH for other SIBs. Location of PCFICH can be identified from physical layer cell id which can be deduced from PSS and SSS. So before reading PDCCH, UE has to know about RE occupied by PHICH and hence PHICH information is included into MIB.

answer Nov 7, 2013 by anonymous
+1 vote

MIB holds the information whether the PHICH is Normal or Extended Duration.

Normal Duration --> 1st OFDMA symbols belonging to a subframe
Extended Duration --> 1st 3 OFDMA symbols to a subframe

PHICH is used to signal Ack or Nack for UL data transferred on PUSCH

0 +ve Ack
1-ve Ack [Nack]
answer Dec 14, 2013 by anonymous
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