SDCCH Blocking

SD blocking means that you are not getting SD resource for the call origination. When MS connects with NW then RACH and AGCH are provided. After AGCH,SDCCH is provided but if SDCCH is not provided at this time due some problems or due to unavailable of SD by BSC ,it’s called as SD Blocking. There are no of reasons for that.If such a case arises the customer will not be able to originate any call.

Reasons for SD Blocking:

Some of them are-

LAC boundary.
HW Prob.

Solutions for removal of SD Blocking:

Here are some steps by which we can reduce SD Blocking-

1. Check the No. of SDCCH channel Available, if less then increase SD channel taking care that there is no TCH Blocking.

2. Check LAC boundary, If location update is more then change theLAC of that site and set C2 and HYS.

3. Use of Dynamic SDCCH (It is a BSC parameter and will be applied on whole BTS).

4. Hardware check / shift SD to new time slot.

5. Some times BMA and HYS parameters are useful to remove SDBlocking.

Usefull Reports For SD Blocking:

Use 182 to analyses SD Blocking reasons.

130 for SD congestion.

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