###### Abstract  
Low earth orbit (LEO) satellite networks can provide Internet service to users in areas where cellular networks are difficult to deploy. One critical function of satellites is to transfer data from satellite networks to ground core network through earth stations (ESs). The Ka-band multiple-input multiple-output (MIMO) can be used to establish feeder links with larger bandwidth between satellites and ESs. However, propagation at the Ka band is subjected to rain attenuation and various atmospheric fading mechanisms, which severely reduce the maximum link capacity. As a result, the insufficient capacity of feed link becomes the throughput bottleneck of satellite networks. In order to increase network throughput, it is important to fully use feeder link resources. In this paper, we propose a cooperation scheme to route packets to ESs through a well-resourced feeder link, such that the bandwidth of the feeder links can be fully utilized and the throughput of data downloading at the ESs is maximized. Firstly, we model the satellite network system and the feeder link based on MIMO technology. Then, a Maximum-Flow-Minimum-Cost (MCMF) routing algorithm consisting of two Linear Programs (LPs) is presented to compute maximum-flow routings for data download. Eventually, a variety of simulations are conducted to assess the proposed scheme, which shows that the cooperative routing scheme outperforms the existing SiRRS method in terms of throughput and delay. LEO satellite systems; network flow; satellite data downloading; routing algorithm +
Footnote †: This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ([[https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/)]([https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/))). Footnote †: This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ([[https://creativecommons.org/licenses/by/4.0/0](https://creativecommons.org/licenses/by/4.0/0)]([https://creativecommons.org/licenses/by/4.0/0](https://creativecommons.org/licenses/by/4.0/0))). Footnote †: This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ([[https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/)]([https://creativecommons.org/licenses/by/4.0/](https://creativecommons.org/licenses/by/4.0/))). Footnote †: This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons. Compared with the traditional SISO(single-input single-output), MIMO communication technology has the advantages of higher transmission rate, spectrum utilization, and power efficiency [2]. Recently, many researchers have proposed to use MIMO technology at Ka-band to build a high-speed feeder link between satellite and ES [3]. Nevertheless, radio propagation at ka-band suffers from atmospheric attenuation mechanisms in the troposphere, such as rain absorption and scattering. Rain attenuation is a phenomenon relative to the rate and frequency of rainfall that can lead to increased path losses, decreasing coverage areas and thus deteriorating system performance. Consequently, the capacity of feeder links in different channel environments will be different. This will lead to inadequate utilization of feeder link bandwidth. For instance, some feeder links may be severely affected by regional rain attenuation and have their capacity reduced, while the the adjacent satellite feeder links still have spare/available bandwidth. In this paper, we first analyze the capacity of feeder links at Ka-band. Then, we propose the Cooperative Data Downloading (CDD) scheme, in which the traffic converges to the satellites with feeder link through the ISLs.