Use of NH and NCC:
NH: Its the 256bit key which is derived at MME and UE in exactly in the same way as KeNB is generated. This value send to eNB during HO procedure then its called as NH whereas send during attach procedure is called as KeNB.
Q) Why NH is not termed as KeNB?
Ans) During key derivation in HO / Reestablishment etc procedure used/unused NH pair is being used. So NH may be kept in context as unused/used while KeNB would be the key under current use.
NCC: This value has significance at UE. As there is no security key exhange in LTE. So based on the NCC value UE can derive the corresponding NH value which were derived in network.
X2 based HO: KeNB* is generated and send to the target eNB.
S1 based HO: MME generates the NH and send to Target eNB.