Main factors causing high SDCCH Drop rate are as follows:
(I) Inappropriate parameter configuration (system information)
(II) Inadequate system capacity
(1) Parameter modification (threshold of random access error, RACH access threshold),maximum times for retransmission, the number of TS in transmission expansion.
(2) Attention to parameter configuration for partition of location area and location renewal update (configuration for 1800MHz dual band network, CRO, cell reselection hysteresis parameters, time for periodic location etc.,)
(3) In Dual band networks, an exceedingly high rate of excessive location renewal update may be caused by an exceedingly high rate of excessive handover between mobile switch offices centers. Modification shall be made to handover parameters of the 1800MHz dual network, CRO, etc
(4) Apart from factors mentioned above, there might be capacity problems. SDCCH configuration number shall be increased or dynamic SDCCH assignment function and TCH carrier shall be engaged.