In this paper, we propose a feedback-efficient hybrid precoding framework for wideband millimeter-wave (mmWave) multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) systems. To reduce the hardware cost of radio-frequency (RF) chains and the feedback burden associated with frequency-selective digital precoding, frequency-flat analog precoders and combiners are first constructed from the dominant angle-of-arrival (AoA) and angle-of-departure (AoD) directions associated with the strongest propagation paths. For digital precoding, a shared quantized codebook is designed using the Lloyd algorithm, and a binary-search-based hierarchical interpolation method is developed to identify codeword switching locations between adjacent pilot subcarriers. By avoiding exhaustive codeword comparisons over all intermediate subcarriers, the proposed method reduces online search complexity and enables compact digital-precoder feedback. For the considered system configuration, the proposed method achieves a worst-case feedback reduction of approximately 98.34% relative to full-grid per-subcarrier feedback. Simulation results further demonstrate competitive spectral efficiency and bit error rate (BER) performance, low computational cost, and robustness under imperfect effective channel state information (CSI).

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