這是LTE Signaling - Troubleshouting and Optimization提到的。抱歉我沒說清楚，一開始粘貼的是1.10.7.1的內(nèi)容。
4.4.1.5 Paging Failures
The analysis of paging failures requires a distinct workflow rather than just a simple KPI. Due to the
tracking area concept of the E-UTRAN, the last known location of a handset that does not respond
to paging messages sent by the MME can be more tightly encircled. In a network with one cell
representing a single tracking area the UE will be paged in a few cells only, whereas in 2G and 3G
RAN paging messages are typically sent to all cells of a particular Location Area Code (LAC) – a few
hundred cells compared to a few dozen in the E-UTRAN. However, a paging failure ratio KPI on cell
aggregation level will always have a questionable value due to the fact that a UE can only camp in a
single cell and, hence, from most cells to where the paging was sent there will be no paging response.
It therefore makes sense to store the subscriber ID of UEs that have not answered the paging and
investigate what may have happened to them before the paging failure and where they may have gone
to. The most likely reasons for paging failures are as follows:
• The UE is defective and went out of order without being able to detach from the network.
• The UE while in IDLE mode performed a new cell (re)selection and is camping now on a 3G or
2G cell without informing the network properly about the new location that is geographically the
same as before, but covered by a different RAT.
Possible root causes of paging failures to be investigated according to these symptoms are:
• defective handsets;
• insufficient coverage;
• wrong settings for broadcast cell (re)selection parameters like S0 criteria.
252 LTE Signaling, Troubleshooting and Optimization
Considering the interworking between 3G and 4G radio access, it must be highlighted that it
will become very important to monitor both radio access networks to get rapid updates of UEs
toggling between the different RATs. This requirement is driven by the fact that the handsets in
UTRA CELL_PCH and URA_PCH are allowed to perform cell reselection to the E-UTRA without
further notice (see Section 1.10.7.1). While this will rather lead to paging failures in the 3G part
of the network, continuous toggling of radio access will also lead to performance degradation and
accessibility failures that impact both radio access technologies.