The performance analysis of NOMA in LEO satellite rain attenuation and fading hybrid channel

In the fifth-generation (5G) and future sixth-generation (6G) networks, improving spectral efficiency and system capacity is still the main concern. Adding LEO satellite to the construction of 5G and 6G can make the network structure three-dimensional, which lets the network construction get rid of the limitation of ground space propagation distance and makes the wider area enjoy the convenience of 5G and 6G. However, due to the large link distance between space and the ground, the communication of LEO satellite in Ka band is greatly affected by rain attenuation and shadow fading. In order to improve the ergodic capacity of LEO satellite downlink, this paper attempts to apply nonorthogonal multiple access (NOMA) to hybrid channels with rainfall fading and shadow fading. In the simulation results, the ergodic capacity of orthogonal frequency division multiple access (OFDMA) and NOMA is compared, and it is found that the system capacity of hybrid channel can be improved by increasing the power allocation factor of NOMA. The experiments have studied the influence of LEO satellite's orbital height, fading degree, and transmission power in the communication link on the performance of LEO satellite system in this paper. The experimental results show that the lower the orbit height is, the better system performance will become under the same fading degree. Moreover, the energy consumed gradually decreases with the transmission power becoming small.