Aspects of the disclosure provide for methods and systems for Sub-codebook based Trellis Coded Quantization for CSI Feedback. An aspect of the disclosure provides method executed by a receiver. The method includes receiving a signal from a transmitter, via a communication channel between the receiver and the transmitter. The method further includes estimating parameters associated with the channel based on the received signal. The method further includes obtaining phase information from the estimated parameters. The method further includes applying a trellis coded quantization (TCQ) scheme to the obtained phase information by mapping each sub-codebook index of a set of sub-codebook indices to output bits of each trellis branch making the distance between sub-codebooks maximally equal. The method further includes transmitting a channel state information (CSI) measurement feedback to the transmitter, the CSI measurement feedback based on the TCQ scheme and comprising one or more of: a beginning state, input bits to the TCQ scheme, and a sub-codebook index.