LTE switching and TAU issues

If there are two LTE base station a B (same-frequency network) AB TAC different and add a two-way neighbor relationship now the terminal is re-elected to a and then move to the B direction is the first switch? Or the Advanced Tau update

This has no effect, and tau does not need to be idle. As I understand it is certain to switch to the new cell through the rrcreconfiguration, when UE found into a new Tai, and then launched the TAU process.

for the process of switching, the UE is not fully into the new community before. The child tau process is the UE completely after the new community, parsing system messages, found Tai different before the launch of Tau. So from the point of time, 2 of the process must be carried out, the switching process should be before the tau!

If Lower layers indicate a tai change, and the current Tai are not on the Tai list, the ESM procedure shall be Abor Ted and Re-initiated after successfully performing a tracking area updating procedure .

If Lower layers indicate a tai change, but the current Tai was still part of the Tai list, it's up to the UE imple mentation How the ESM procedure is re-initiated .  

If lower layers indicate the TAI have not changed, it's up to the UE implementation how the ESM procedure is re-initiated .  

NOTE 1:the ESM procedure can typically be re-initiated using a retransmission mechanism of the uplink Messa GE (the one, have previously failed to is transmitted) with new sequence number

One of the tau purposes: MME load Balancing

TAU---Tracking area updating procedure

TA is a tracking area, similar to the routing area in 2G and 3G. Tau is a tracking area update, which is a signaling notification method after the change tracking area. In LTE, a cell can belong to a plurality of TA, each E-node B will be at the same time and a plurality of Mme and S-GW/P-GW connected, the UE in the end to choose which Mme and the business side of the S-GW/P-GW is determined by the E-node B, one of the factors that determine the load balance. This signaling process can be used to change the tracking area that the UE belongs to when eNodeB discovers that the load on an area is too large.

When the Mme Load is too high, it will trigger the Mme Overload Start and the Mme Configuration update updates its weight factor, in the meantime, the Mme will re-assign the user to the other Mme ...
The process is as follows: Notify ecm-connected user via S1 Release (Cause:tau loadbalancing), reconnect to other Mme, paging for idle user, and then S1 after recovery Release (Cause:tau loadbalancing) notifies the user to reconnect to the other Mme.

The tau process includes the boot TA process, the TAC change trigger process, and the periodic TA update process. The TAC changes the triggering tau, which is related to TA's planning. The results of the tau process may lead to load balancing, but there is no causal relationship.

S1-flex load Balancing is ENB to select the appropriate S-GW/PGW according to the load situation, but SGW/PGW is not related to the division of the TAC, the TAC is subordinate to the Mme, and the different Mme can have the same TAC (though it is not actually used), ENB is not related to the TAC when choosing SGW.

LTE switching and TAU issues