Hi Osman
background checks are done in two parts :
1. Checking of all your documents that you sent to your visa office. This happens when your ecase shows in process. This may include verifying with your employers and so on. If all your documents are perfect , you get your medicals , if not then they probe further n further till they are completely satisfied.
2. Security checks : this is done after your medicals . This is to ensure that you are not a threat to Canada and they will conduct a detailed checkup regarding any criminal issues and offenses you have been accounted for. If you have travelled to many countries , then they would look into all that . Nevertheless, if everything is good you would get passport requests. They usually say wait 4 months after medicals to expect passport requests. But it can be done earlier as well.
So this group members are all awaiting for their security checks o be done ASAP
Cheers!!!