In LTE, Uplink L1/L2 control signaling consists of one (or more) of the following pieces of information:
Hybrid-ARQ acknowledgements related to reception of DL-SCH transport blocks.
CQI (Channel-Quality Indicator) indicating the instantaneous downlink channel quality perceived by the terminal. CQI reports can be used by the network for downlink channel-dependent scheduling and rate control. LTE CQI reports indicate the channel quality in both the time and frequency domain.
Scheduling requests (SR) used by the UE to request UL-SCH resources in case it does not have a valid scheduling grant.
MIMO Related Information: MIMO related information such as Precoding Matrix Indicator (PMI) and Rank Indicator (RI), etc. are also transmitted in the uplink