You can go by this.
Check if equipped SDCCH capacity is sufficient to cater the BBH SDCCH Traffic.If YES,
A)Check for H/W issues
B)High HR Traffic
D)No. of SDCCH configured/TRX
E)Change the LAC boundary if SDCCH usage due to LU is very high.
F)Go for Carrier Augmentation if Cell Utilisation is High
A)Add SDCCH and check.
B)Enable Dynamic SDCCH,if disabled.