user equipment reports single - cell or multi - cell channel state information to a base station on a physical uplink control channel format 3 resource . the pf 3 resource selected depends on whether ack / nack needs to be reported simultaneously . different coding and / or scrambling and / or interleaving schemes are used depending on whether ack / nack bits are present , as well as the number of ack / nack and / or csi bits . resource compatibility is maintained independently of the details of coding , interleaving , or scrambling — that is , all formats can be orthogonally multiplexed onto the same time - frequency resources . the format used for csi only is pf 3c whereas the format used for csi and ack / nack is pf 3b . pucch formats 3b and 3c may be further differentiated depending on whether a csi from a single or multiple cells are reported , or from which cells an ack / nack is reported .