Abstract
The currently deployed terrestrial wireless networks experience difficulties while coping with the massive connectivity demands of coexisting users and devices. The addition of satellite segments has been proposed as a viable way of providing improved coverage and capacity, leading to the formation of integrated satellite-terrestrial networks. In such topologies, non-orthogonal multiple access (NOMA) can further enhance the efficient use of wireless resources by simultaneously serving multiple users. In this paper, an integrated satellite-terrestrial NOMA network is studied where cooperation between ground users is allowed, following the device-to-device (D2D) paradigm. More specifically, the proposed satellite NOMA cooperative (SANOCO) D2D scheme optimally selects pairs of users, by considering the channel conditions of the satellite and the terrestrial D2D links. In SANOCO-D2D users are served through NOMA in the satellite link, and then, if the weak user fails to decode its signal, terrestrial D2D communication is activated to maintain the total sum rate of the system. Comparisons with conventional orthogonal multiple access (OMA) and an alternative NOMA optimal user pairing scheme show that significant sum rate and spectral efficiency gains can be harvested through SANOCO-D2D under varying channel conditions and terrestrial D2D bandwidth.
Highlights
Future wireless networks will be characterized by dense topologies and diverse services, ranging from high-throughput multimedia applications to ultra-reliable Internet of Things (IoT) communication.The coexistence of both users and devices results in unprecedented hurdles for the currently deployed terrestrial infrastructure
We aim at improving the performance of integrated satellite-terrestrial non-orthogonal multiple access (NOMA)
The main goal of this study is to identify the pairs of users that can benefit from the terrestrial cooperation combined with NOMA in satellite segment, thereby maximizing the total sum rate of the system compared to standalone NOMA
Summary
Future wireless networks will be characterized by dense topologies and diverse services, ranging from high-throughput multimedia applications to ultra-reliable Internet of Things (IoT) communication. It has been observed that user cooperation in integrated satellite-terrestrial networks, following the D2D paradigm, improves the diversity of the transmission and the performance of spectral-efficient communication techniques, such as NOMA [11]. We aim at improving the performance of integrated satellite-terrestrial NOMA networks comprising multiple ground users by enabling cooperative D2D communication among them For this purpose, a pairing scheme for ground users is presented, considering each user’s satellite channel, and the terrestrial channels between the users. The main goal of this study is to identify the pairs of users that can benefit from the terrestrial cooperation combined with NOMA in satellite segment, thereby maximizing the total sum rate of the system compared to standalone NOMA Towards this end, user pairing is modeled as a maximum weighted perfect matching problem in graph theory, considering the achievable rates in the terrestrial and satellite segments.
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