Techniques for encoding a phase adjustment for a feedback signal in a closed-loop transmit diversity system. In an aspect, codewords for the phase adjustments are chosen according to a variable-length prefix code. The prefix code aspect allows the codewords to be transmitted in sequence on the feedback channel without being separated by “commas” or demarcation symbols. The variable-length aspect provides a variety of coarse and fine phase adjustment quantization step sizes to accommodate multiple different channel scenarios. In an aspect, the length of the codewords may be further optimized according to the Huffman encoding algorithm.