Since the Main Report Parameters and Sub-report parameters have the same name, you just need to map the sub-report parameters with the respective Main report parameters values. For e.g. for first parameter @param1
Right Click the Sub-Report -> Click Sub-Report Properties -> Click Parameters -> Click Add -> Put param1 in the Name column and put [@param1] (I guess) in the Value column.
Same needs to be done for the rest of the parameters. For more details, here is the link to BOL, where the key part of having the same parameter names is already done by you.
answered Jul 09 '12 at 11:33 AM