Techniques for aggregating heterogeneous carriers in a wireless communication system are disclosed. A mobile device may receive a configuration for aggregating a plurality of component carriers including one or more cellular carriers and a wireless local area network (WLAN) carrier. The one or more cellular carriers may include LTE carriers, and aggregation may be performed at a sub-IP protocol layer of operation. In one aspect, protocol entities may be modified to perform quality of service determinations, carrier selection, traffic mapping, or the like, in view of the different capabilities and characteristics of the heterogeneous carriers in the carrier aggregation configuration.