Methods and apparatus for transmitting uplink control information (UCI) in carrier aggregated spectrums are disclosed. UCI may include, but is not limited to, Precoding Matrix Indicator (PMI), Rank Indication (RI), Channel Quality Indicator (CQI), Acknowledge/Not Acknowledge (ACK/NACK) and Scheduling Request (SR). For symmetric carrier aggregation, uplink (UL) and downlink (DL) component carriers may be paired and use physical uplink control channel (PUCCH) in each UL component carrier to send UCI for the corresponding DL component carrier. For asymmetric carrier aggregation, methods are provided for UCI transmission and resource allocation depending on component carrier configuration or assignment. Methods are provided for multiple and single component carrier configurations that may further provide backward compatibility.