2G
Handover Optimization
Classification
by Reason
Timing advance (TA) Emergency HO
Triggering condition
_ The actual TA > TA HO Thrsh.
Object cell selection
_ The cell must be of the highest
priority in the candidate cell sequence and
meet the following restrictions.
Restriction
_ The service cell cannot be the
object cell.
_ HO is not allowed when TA Thresh.
of the neighboring cell with the same
BTS
is smaller than that of the service cell.
Bad
Quality HO
Triggering condition
_ UL receiving quality >=UL
receiving quality thrsh. of the service cell.
_ OR DL receiving quality >=DL
receiving quality thrsh. of the service
cell.
Object cell selection
_ The cells must be of the highest
priority in the candidate cell
sequence and meet the following restrictions.
Restriction
_ Handover to the neighboring cell with
the highest priority. If there is no
neighboring cell, handover to the service cell, and the channel at
different TRX is preference.
_ Rx Level (n) > Rx Level (s) +
Inter Cell HO Hysteresis + BQ HO Margin
Signal
Level Rapid Drop HO
Triggering condition
_ Due to downlink signal level drop
_ Triggered upon detecting rapid
level drop during MS busy mode
_ Object cell selection
_ The neighboring cell with the
highest priority and whose priority is higher
than that of the service cell in the candidate cell group.
_ Restriction
_ The service cell cannot be the
object cell.
Interference
HO
Triggering condition
_ UL receiving quality>=Service
cell UL receiving quality Thrsh. AND
UL receiving level>=Service cell UL receiving level Thrsh.
_ OR DL receiving
quality>=Service cell DL receiving quality Thrsh.
AND DL receiving level>=Service cell DL receiving level Thrsh.
Object cell selection
_ The cells must be of the highest
priority in the candidate cell
sequence and meet the following restrictions.
Restriction
_ The service cell that is not in
the penalty time for intra-cell handover.
_ The neighboring cell with the
receiving level higher than the inter
layer
HO Thrsh.
Load
HO
Triggering condition
_ The load HO switch of the service
cell is enabled.
_ The system signaling flow is not
larger than the Load HO system flow Thrsh.
_ The service cell traffic is
larger than the Load HO Thrsh.
_ The DL receiving level is in the
load HO zones.
Object cell selection
_ The service cell cannot be the
object cell.
_ The traffic of the neighboring
cell must be lower than its load HO receiving
thrsh.
_ The neighboring cell with the
receiving level higher than the inter layer HO
Thrsh.
Restriction
_ It is not available with SDCCH.
_ Load HO just occur within the
same BSC.
Edge
HO
Triggering condition
_ The DL receiving level < Edge
HO DL RX_LEV Thrsh.
_ OR The UL receiving level <
Edge HO UL RX_LEV Thrsh.
_ Satisfying P/N rule.
Object cell selection
_ The service cell cannot be the
object cell.
_ The neighboring cell with the
highest priority and whose priority is
higher
than that of the service cell.
Layer
HO
Triggering condition
_ The layer of the object cell is
lower than that of the service cell.
_ The DL level of the object cell
is higher than the inter layer HO thrsh.
_ Satisfying P/N rule.
Object cell selection
_ The service cell cannot be the
object cell.
_ The neighboring cell with the
highest priority and whose priority is
higher
than that of the service cell
PBGT
HO
Triggering condition
_ The layer and level of the object
cell are the same as those of the
service cell.
_ The DL level must be the result
of the following formula.
Object cell selection
_ The service cell cannot be the
object cell.
_ The neighboring cell with the
highest priority and whose priority is
higher than that of the service cell.
Restriction
_ It is not available with SDCCH.
Fast-Moving HO
Triggering condition
_ In Fast Moving Watch Time, the
mobile phone moves through P cells
of N.
_ The layer of N cells must be less
than four (none Umbrella cell).
Object cell selection
_ The neighboring cell with the
highest priority and meet the following
condition.
_ The layer of the object cell must
be no less than four, that is, the
Umbrella cell.
_ The receiving level of the object
cell >= the inter layer HO thrsh. +
inter
layer HO hysterisis.