Abstract
Non-orthogonal multiple access (NOMA) has the potential to provide higher throughput than conventional orthogonal multiple access (OMA), which has been considered as a key technology for 5G. NOMA in satellite communication system can provide anytime, anywhere access with improved spectral efficiency and system capacity because of its ubiquitous coverage. However, the characteristics of the satellite channels are different from that of the terrestrial network, i.e., huge time delay and Doppler shift. In this paper, different from the existing works, which mainly focus on the performance of NOMA in static terrestrial base stations and Geostationary orbit (GEO) scenarios, we investigate the performance analysis of downlink NOMA in dynamic low earth orbit (LEO) satellite communication system with Doppler shift considered. We combine NOMA and orthogonal frequency division multiplexing (OFDM) for better spectral efficiency. Our channel model includes both small scale model and large scale model. For simplify, we only consider two users in one spot beam. Besides, we express the performance analysis of downlink NOMA in LEO satellite communication system, like ergodic capacity, outage probability (OP) and mutual information. However, in traditional NOMA scheme, the proceeding error decision of the high power user will cause the deterioration of the subsequent detection performance. Therefore, a symmetrical coding (SC) scheme for different modulation mode is proposed for low power users to get better performance. Finally, simulation results validate the performance of the NOMA scheme is better than that of the OMA scheme. The proposed SC scheme can achieve a prominent increase performance contrasted to the traditional NOMA scheme.
Highlights
With the development of the wireless communication, the multiple access (MA) scheme has been the key technology to distinguish different wireless systems from the first generation (1G) to 4G [1]
We find that when the orbital altitude h increases, the average ergodic capacity decreases, but the Non-orthogonal multiple access (NOMA) schemes are still superior to the orthogonal multiple access (OMA) schemes
What’s more, we can see that the bit error rate performance (BER) performance of the near user (NU) in the proposed symmetrical coding (SC) scheme has quite improved on the tradition NOMA scheme
Summary
With the development of the wireless communication, the multiple access (MA) scheme has been the key technology to distinguish different wireless systems from the first generation (1G) to 4G [1]. In traditional SIC, the proceeding error decision of the high power user will cause the deterioration of the subsequent detection performance To solve this problem, a symmetric superposition coding (SSC) and symmetric SIC (SSIC) decoding scheme are proposed to overcome the error propagation (EP) problem for downlink NOMA-based VLC network [21]. We propose a SC scheme for different modulation mode for downlink NOMA in LEO communication system. In order to overcome the influence of error propagation on the performance of low power users, we propose a SC scheme for different modulation mode for practical.
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