# Load-Balancing Routing for LEO Satellite Network with Distributed Hops-Based Back-Pressure Strategy
## 7 Conclusions  
With the properties of wide coverage and high communication capacity, the LSN will be a vital supplement to terrestrial networks and a significant part of SAGIN. Nevertheless, the bursty property and uneven geographical distribution of network traffic result in the load imbalance of the LEO satellite network. To address these issues, we propose distributed hops-based back-pressure routing (DHBP). Firstly, a method for estimating the minimum end-to-end hops count between satellites in inclined constellations is deduced theoretically. On this basis, DHBP takes the queue length of the intermediate satellite  
Figure 11: Simulation results under bursty traffic.  
Figure 12: Average performance under Poisson traffic and bursty traffic.  
and remaining hops count between the intermediate satellite and destination satellites as the backlog metric of back-pressure routing. By dynamically selecting the shortest path to achieve low congestion, the traffic overhead of the satellite network can be balanced. Considering the link redundancy resulting from the property of the Manhattan network, this paper restricts the permitted propagation region to a rectangular area determined by the source and destination nodes, so as to control the transmission cost. Taking an inclined orbit constellation consisting of 648 satellites as an example, the proposed scheme is verified by network simulation. The simulation results demonstrate that, compared with DBPR, DHBP improves performance under CBR traffic in terms of delay, transmission cost, throughput, and data delivery ratio by 12.42%, 13.13%, 10.47%, and 11.59%, respectively. Meanwhile, DHBP has more significant advantages under bursty traffic. Therefore, it is demonstrated that DHBP improves throughput and optimizes the transmission cost, especially under bursty traffic environments.  
In our future work, we will further explore more scenarios with a link break and different traffic patterns. In particular, the performance of the LEO satellite network under different link break patterns will be analyzed.  
Conceptualization, C.H.; methodology, C.H.; software, R.Y.; validation, W.X.; formal analysis, C.H.; investigation, W.X.; resources, W.X.; data curation, C.H.; writing--original draft preparation, C.H.; writing--review and editing, C.H.; visualization, C.H.; supervision, W.X.; project administration, W.X. and R.Y.; funding acquisition, W.X. and R.Y. All authors have read and agreed to the published version of the manuscript.  
This research was funded by Space Engineering University grant number 614201003022207.  
Not applicable.  
The relevant data of this paper can be accessed by contacting [EMAIL_ADDRESS].  
The authors declare no conflict of interest.  
The following abbreviations are used in this manuscript:  
\begin{tabular}{l l} LEO & Low Earth Orbit \\ GEO & Geostationary Earth Orbit \\ MEO & Medium Earth Orbit \\ DHBP & Distributed hops-based back-pressure routing \\ SAGIN & Space-air-ground integrated network \\ DHD & Destination-hops-delay \\ ISL & Inter-satellite links \\ OSPF & Open Shortest Path First \\ LSN & LEO satellite network \\ DDR & Data delivery ratio \\ \end{tabular}