Systems and methods for providing opportunistic carrier aggregation to short range or low power extension carriers are generally disclosed herein. One embodiment includes data traffic offload techniques to offload data communicated in a Wireless Wide Area Network (WWAN) from a primary cell to a secondary cell. For example, the primary cell may be provided by a LTE/LTE-A base station operating in licensed spectrum, and the secondary cell may be provided by a low-power extension carrier operating in unlicensed spectrum using a LTE/LTE-A standard. The low-power extension carrier may be activated as needed to offload data transfers from the primary cell, in download-only, upload-only, and time-division LTE (TD-LTE) modes. Configurations involving multimode base stations, multi mode user equipment (UE), relay extension carriers, and remote radio equipment are also described herein, in conjunction with deployment of opportunistic carrier aggregation using extension carriers.