Capacity Region of Asynchronous Multiple Access Channels With FTN

This letter derives the capacity region of asynchronous multiple access channel (MAC) with faster-than-Nyquist (FTN) signaling. We first express the capacity region in the frequency domain. Next, we prove that the capacity definition for finite memory MAC can be generalized to infinite memory MAC. The achievable rate region utilizing the finite memory definition in fact achieves the same region calculated in the frequency domain. Our analysis shows that power optimization is necessary to achieve the capacity region for asynchronous MAC and FTN.