What is KSIasme and Why MME is sending to UE instead of KASME during authentication procedure?

Question

Is it the wish of HSS or MME or UE ?

Answer 1

The MME stores the AVs received from the HSS, and selects one of them to use in LTE authentication of the UE. In Figure 3, the MME selected ith AV (AVi). KASME is a base key of MME and serves as a top-level key in the access network. It stays within EPC only and is not delivered to the UE through E-UTRAN, which is not secure. The MME allocates KSIASME, an index for KASME, and delivers it instead of KASME to the UE so that the UE and the MME can use it as a substitute for KASME
Source:http://www.netmanias.com/en/post/techdocs/5902/lte-security/lte-security-i-concept-and-authentication