Capacity of Uplink Partial Overlapping Non-Orthogonal Multiple Access for Underwater Acoustic Networks

The unique characteristic of bandwidth-distance relationship in underwater acoustic (UWA) channels makes standard uplink non-orthogonal multiple access (NOMA) scheme not be applicable in general underwater acoustic networks (UWANs). In this article, we propose an uplink partial overlapping non-orthogonal multiple access (PONOMA) scheme for UWANs, and investigate capacity region of uplink PONOMA in UWANs. By formulating the problem of the optimal energy distribution for uplink PONOMA based on UWA channel modeling, the closed-form solutions for optimal power spectral density (p.s.d.) and capacity region are derived. Furthermore, we modify the channel modeling by building in parameter uncertainty induced by the empirical nature of UWA channel modeling using box sets, and derived robust capacity region under parameter uncertainty. Numerical results are provided to demonstrate the performance of our proposed scheme.