Generalized mutual information (GMI) is used to compute achievable rates for fading channels with various types of channel state information at the transmitter (CSIT) and receiver (CSIR). The GMI is based on variations of auxiliary channels with additive white Gaussian noise (AWGN). One variation is for receivers unaware of the CSIT where adaptive codewords, or Shannon strategies, achieve capacity. The GMI is then based on auxiliary channels with inputs that are linear functions of the adaptive codewords' symbols. For scalar channels, the input that maximizes the GMI is shown to give a conventional codebook but where the amplitude and phase of each symbol is modified based on the CSIT. A second variation partitions the channel output alphabet and has a different auxiliary channel for each subset of the partition. The partitioning helps to determine the capacity scaling at high signal to noise ratios. A class of power control policies is described for partial CSIR, including a truncated minimum mean square error policy for full CSIT and quadratic waterfilling if the CSIT is known at the receiver. Several examples for fading channels with AWGN illustrate the theory, with a focus on on-off fading and Rayleigh fading. The capacity results are generalized to block fading channels with in-block feedback, including capacity expressions based on mutual information and directed information.

翻译：广义互信息（GMI）用于计算在发射机（CSIT）和接收机（CSIR）具有不同类型信道状态信息时衰落信道的可达速率。GMI基于含加性高斯白噪声（AWGN）的辅助信道的变体：一种变体适用于不知道CSIT的接收机，其中自适应码字（或香农策略）实现信道容量。此时GMI基于其输入为自适应码字符号线性函数的辅助信道。对于标量信道，使GMI最大化的输入对应于常规码本，但每个符号的幅度和相位根据CSIT进行调整。第二种变体对信道输出字母表进行划分，并为每个划分子集定义不同的辅助信道。该划分有助于确定高信噪比下的容量标度。针对部分CSIR情况，描述了一类功率控制策略，包括完全CSIT下的截断最小均方误差策略，以及当CSIT在接收机已知时的二次注水策略。若干含AWGN的衰落信道（重点研究通断衰落和瑞利衰落）实例验证了该理论。容量结果被推广至具有块内反馈的块衰落信道，包括基于互信息和有向信息的容量表达式。