Saturday, June 9, 2012

Master Information Block (MIB) in LTE


The very first step for UE to gain initial access to the network after completing initial cell synchronization is to read the Master information block (MIB) on BCCH (Logical channel), BCH (Transport channel) and PBCH (Physical channel). Resource elements used by MIB are the first 4 OFDMA symbols of second slot of first subframe of a radio frame. On frequency domain it occupies 72 subcarriers. MIB carries very little but most important information for UE initial access. The content of MIB includes

·         Downlink channel bandwidth in term of resource blocks (RBs)
·         PHICH configuration (PHICH duration and PHICH resource)
·         System Frame Number

New MIB is broadcasted every radio frame for which SFN mod 4 = 0 (40ms repetition) while its copies are broadcasted in the middle 10ms radio frames as shown in the figure below




5 comments:

  1. This comment has been removed by the author.

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  2. No not the copies are broadcasting in the middle 10ms.. extracting all the data in 40ms at this position i.e SFN mod 4 = 0,1,2 and 3 forms complete 1920 bits MIB block..

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  3. Each of the repeated transmission is self decodable to make one complete MIB provided the radio conditions are very good. Otherwise in bad SIR, soft combination over four radio frames is used to improve decoding performance

    See page 191,192 "LTE - The UMTS Long Term Evolution: From Theory to Practice"

    Please share your source of information

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  4. Can a UE read the MIB information in the camped but non-attached state?

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    Replies
    1. If you mean ECM idle (EMM Registered) then yes it can ..

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