Subband division for Gaussian relay channel

This work considers the achievable rate region of full-duplex Gaussian relay channel. Under Gaussian signaling, it was found that neither Decode-Forward (DF) nor Compress-Forward (CF) can achieve better performance than the other for all channel gains. Recently, it was verified that superposing CF on DF in one band has a better performance than both DF and CF for Gaussian signaling. In this work, we consider another combining structure of CF and DF by making use of Subband Division (SD). It will show that our new developed strategy will achieve a larger rate for Gaussian signaling by comparing with DF lower bound, CF lower bound and the result of superposing CF on DF. In addition, a closed form solution of the achievable rate is found, in which the subband division factors are also given. Numerical results confirm our developed theoretical results.