06.613GPPSubstitution and muting of lost frames for encanced full rate speech traffic channelsTS
For the purposes of the present document, the following term and definition applies:
5-point median operation: consists of sorting the 5 elements belonging to the set for which the median operation is to be performed in an ascending order according to their values, and selecting the third largest value of the sorted set as the median value.
Further definitions of terms used in the present document can be found in GSM 06.60 , GSM 06.81 , GSM 05.03  and GSM 08.60 .
For the purposes of the present document, the following abbreviations apply:
BFI Bad Frame Indication from Radio Sub System
BSI_Abis Bad Sub-block Indication obtained from A-bis CRC checks
CCU Channel Coding Unit
CRC Cyclic Redundancy Check
DTX Discontinuous transmission
median5 5-point median operation
PrevBFI Bad Frame Indication of Previous frame
RSS Radio Sub System
SID SIlence Descriptor frame
TRAU Transcoding Rate Adaptation Unit