WSO2 Carbon 4.1.0 is tested and documented only against Eclipse Equinox and that is the recommended OSGi container. Felix has not been tested for Carbon since version 2.0. Though theoretically it should be possible to use Felix instead of Equinox it is not documented and tested for Carbon so you want be able to find any documentation on how it can be configured in WSO2 Carbon docs. would recommend you to use Equinox if possible. hope this will help you.
Regards