A coordinated non-orthogonal multiple access strategy for integrated terrestrial-satellite networks

Abstract

In this paper, we investigate the outage probability and ergodic sum capacity of the downlink of the integrated satellite-terrestrial networks (ISTN) with a cooperative non-orthogonal multiple access (CNOMA) scheme, in which a user with better channel condition acts as a relay node and forwards information to the other users. In this paper, a pilot-based channel estimation method is considered which can verify the performance of this scheme with the imperfect channel state information. In this model, all these users are equipped with multi-antennas, and all of them are both in the coverage of a same beam of the satellite. Specifically, the exact analytical expression for the outage probability and ergodic sum capacity of the system is derived. The result shows that this coordinated non-orthogonal multiple access (CNOMA) scheme performs better than that of OMA (TDMA) in this model. Finally, the future research directions are given to further enhance the system capacity.

Non-Terrestrial Networks Based on Non-Orthogonal Multiple Access Towards 6G

“…Then the beam gain 𝐺 𝑖 (𝜑 𝑖 ) of User 𝑖 can be given as where 𝐺 𝑠 is the maximum antenna gain at satellite, J (.) is the Bessel function and 𝑢 𝑖 is defined as 𝑢 𝑖 = 2.07123 sin 𝜑 𝑖 sin𝜑 𝑖 3𝑑𝐵 (25) with 𝜑 𝑖 3𝑑𝐵 being the 3-dB angle [117].…”

“…The key ideas in NOMA are to use the power domain at the transmitter to superpose multiple signals and the successive interference cancellation (SIC) technique at the receiver for signal detection. NOMA has been identified as a potential candidate technology to provide low latency, high reliability, massive connectivity, improved fairness, and high throughput for the B5G and the future 6G technology to support the NTN system [18], [25][26][27]. The connection density of the 6G networks will approach 10 8 devices per square kilometer, which is 100 times larger than that in 5G.…”

“…Satellites are categorized into three groups based on their altitude: geostationary equatorial orbit (GEO), medium earth orbit (MEO), and low earth orbit (LEO) satellites, as shown in Figure 2 [20], [25], [26], [31]. For worldwide coverage, OneWeb, Starlink, and Telesat are some examples of satellite constellation projects that are currently in the works [3], [32].…”