This object indicates the type of bearers.
gbr - Guaranteed Bit Rate(GBR).
GBR bearer has a minimum amount of bandwidth that
is reserved by the network, and these resources are
always consumed in a radio base station regardless
of whether it is used or not.
nonGbr - non-Guaranteed Bit Rate(Non-GBR).
Non-GBR bearers are for best-effort services and do
not consume any network
resources.
unknown - the type of bearers is unknown.