In this paper, we propose an enhanced Huffman coded orthogonal frequency-division multiplexing with index modulation (EHC-OFDM-IM) scheme. The proposed scheme is capable of utilizing all legitimate subcarrier activation patterns (SAPs) and adapting the bijective mapping relation between SAPs and leaves on a given Huffman tree according to channel state information (CSI). As a result, a dynamic codebook update mechanism is obtained, which can provide more reliable transmissions.We take the average block error rate (BLER) as the performance evaluation metric and approximate it in closed form when the transmit power allocated to each subcarrier is independent of channel states.Also, we propose two CSI-based power allocation schemes with different requirements for computational complexity to further improve the error performance. Subsequently, we carry out numerical simulations to corroborate the error performance analysis and the proposed dynamic power allocation schemes. By studying the numerical results, we find that the depth of the Huffman tree has a significant impact on the error performance when the SAP-to-leaf mapping relation is optimized based on CSI. Meanwhile, through numerical results, we also discuss the trade-off between error performance and data transmission rate and investigate the impacts of imperfect CSI on the error performance of EHC-OFDM-IM.Orthogonal frequency-division multiplexing with index modulation (OFDM-IM), Huffman coding, dynamic codebook design, power allocation, channel state information (CSI).both provide good thoughts on how the Huffman tree architecture could be adapted to provide a higher capacity and transmission rate when utilizing all legitimate SAPs. In [25], Huffman coding was applied to OFDM-IM with the help of channel state information (CSI). However, the Huffman coded OFDM-IM scheme proposed in [25] did not fully exploit all legitimate SAPs, and thereby only shows limited improvements. The latest research results with respect to the optimization of the achievable rate of binary-tree coded OFDM-IM (a generic version of Huffman coded OFDM-IM) were presented in [26]. In this work, the achievable rate is optimized by dynamically varying the SAP probability distribution and transmit power allocated to active subcarriers. January 7, 2020 DRAFT