I am trying to figure out the channel capacity of OFDM with index modulation (OFDM-IM). One of the article reports that the conditional channel capacity of OFDM-IM is $\mathcal{C}_{\mathrm{OFDM-IM}}(\gamma) = \frac{1}{L}\left[I(\boldsymbol{x}_s;\boldsymbol{y}\vert \boldsymbol{x}_c)+I(\boldsymbol{x}_c;\boldsymbol{y})\right]$, where $\gamma$ is the SNR, $L$ is the number of subcarriers available for modulation in one group, $I(\boldsymbol{x}_s;\boldsymbol{y}\vert \boldsymbol{x}_c)$ provides constellation domain information, $I(\boldsymbol{x}_c;\boldsymbol{y})$ is the index domain information and $\boldsymbol{y}$ is the vector of received symbol. I was wondering whether this relation is only valid when we expect a complex-valued signal after IFFT? Secondly, how would this relation change if we need a real-valued signal after IFFT, i.e., when Hermitian symmetry is enforced in the frequency domain prior to IFFT?


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.