Resource-Aware Federated Mixture-of-Experts with Adaptive Pruning for Onboard Learning in LEO Satellite Constellations
Authors: Mohamed Shaaban, Mohamed Elmahallawy, Marius Bernahrndt, Tobias Hecking
Organizations: School of Engineering and Applied Science, Washington State University, Richland, WA 99354, USA · Institute for Software Technology, German Aerospace Center (DLR), Porz, 51147 Cologne, Germany
Low-Earth-orbit (LEO) satellites are increasingly expected to perform onboard learning for applications such as disaster response and environmental monitoring. However, conventional federated learning (FL) is ill-suited to onboard satellite learning, as it assumes computational, memory, and communication resources beyond the capabilities of resource-constrained LEO platforms, often necessitating the transmission of raw imagery to ground stations. We present COSMIC-FL, a resource-aware FL framework for efficient onboard learning in LEO satellite constellations. COSMIC-FL introduces two complementary Mixture-of-Experts (MoE) architectures: a Sliced design that shares backbone representations while activating task-specific channel subsets, and a Modular design that employs lightweight gating to route inputs to physically separated expert networks. A semantic class-to-expert mapping enables each satellite to train, update, and communicate only the expert paths relevant to its local data. To further improve efficiency, COSMIC-FL integrates staged optimization with three structured pruning strategies: server-side pruning, client-side fixed-ratio pruning with mean-vote aggregation, and adaptive client-side per-layer pruning based on aggregated importance and a MAD-based gap criterion. Combined with semantic expert routing, these techniques jointly adapt computation and model sparsity to both data semantics and layer importance, yielding a favourable accuracy--efficiency trade-off for heterogeneous space platforms. Experiments on six image classification benchmarks under highly non-i.i.d. settings show that COSMIC-FL maintains competitive accuracy while reducing communication, computation, and energy consumption by up to 80% over SOTA FL methods. We further validate COSMIC-FL on an NVIDIA Jetson AGX Orin, confirming its efficiency gains under realistic embedded deployment constraints.
Figures & tables
Figure 1: Overview of the four stages of the COSMIC-FL framework.
Method (# Satellites)
CIFAR-10
AID
EuroSAT
RESISC45
UC Merced
FedAvg (10)
88.50
79.39
97.41
83.73
83.81
FedAvg (50)
82.03
62.88
94.48
72.78
56.51
FedAvg (100)
75.46
53.24
91.07
60.40
49.21
FedProx (10)
86.99
78.80
97.30
83.02
83.17
FedProx (50)
81.55
64.80
94.56
73.67
55.87
FedProx (100)
74.61
53.43
90.22
62.82
48.89
Table 1: Accuracy (%) under IID settings with different numbers of satellites.
Method
α=0.1
α=0.3
α=1.0
α=10.0
FedAvg
81.33
90.89
93.74
94.41
FedProx
83.00
90.63
93.37
94.48
CentMoE
86.89
94.07
95.07
95.26
PM-MoE
11.11
92.70
95.22
95.26
FedDropout ( r=0.75 )
64.72
75.13
79.19
79.94
HeteroFL ( r=0.75 )
74.98
81.70
86.17
89.54
Table 2: Impact of data heterogeneity (Dirichlet- α ) on test accuracy (EuroSAT, 50 clients). Lower α = more non-i.i.d (see Supplementary Material F for more results).
Figure 2: Inference cost (GFLOPs per sample) by method and dataset (AID, EuroSAT, RESISC45). Methods: CentMoE, COSMIC-FL (Modular), COSMIC-FL (Sliced), and their server-, client-, and adaptive-pruning variants.
Model
Prune
Server
Client
Adaptive
P
Acc
P
Acc
P
Acc
COSMIC-FL (Sliced)
0
12.4
87.56
12.4
87.56
12.4
87.56
10
11.5
83.74
11.5
82.07
11.5
83.15
30
8.2
81.15
8.2
81.04
8.4
81.93
50
5.6
80.67
5.6
82.04
5.8
82.22
70
3.5
80.59
3.5
79.67
4.0
80.89
Table 3: Pruning strategy and ratio analysis for COSMIC-FL (Sliced and Modular) on EuroSAT with 50 satellites. Results report retained parameters (P, millions) and accuracy (%). Additional results are provided in Supplementary Material F.
EuroSAT
RESISC45
Method
Acc
Lat.
Mem
Pow
Acc
Lat.
Mem
Pow
FedAvg
94.3
3.66
38.2
4.90
72.1
3.66
38.3
4.96
FedProx
94.6
3.65
38.2
4.99
72.1
3.66
38.3
5.04
FedDropout
79.7
4.52
39.1
4.34
42.8
4.53
40.0
4.59
HeteroFL
89.2
4.54
26.9
4.12
58.4
4.54
26.9
4.12
PM-MoE
96.0
22.9
190.3
4.47
68.6
22.9
193.8
4.47
Table 4: Jetson AGX Orin inference performance on EuroSAT and RESISC45. Reported metrics include classification accuracy (%), latency (ms), peak allocated GPU memory (MB), and average board power (W).
Appendix figures & tables13 assets
Supplementary material from the paper’s appendix.
Appendix
Dataset
Impl.
Target
z=1
z=2
z=3
z=10
z=20
EuroSAT
Modular
30%
20.44 / 78.30
20.44 / 78.30
20.44 / 78.30
20.44 / 78.30
16.14 / 77.63
EuroSAT
Modular
50%
35.42 / 79.11
35.42 / 79.11
35.42 / 79.11
35.42 / 79.11
24.54 / 77.78
EuroSAT
Modular
70%
49.97 / 78.93
49.97 / 78.93
49.97 / 78.93
47.01 / 79.00
33.54 / 78.33
EuroSAT
Sliced
30%
34.52 / 80.19
34.52 / 80.19
34.52 / 80.19
29.79 / 82.22
18.00 / 79.81
EuroSAT
Sliced
50%
53.30 / 79.52
53.30 / 79.52
53.30 / 79.52
46.47 / 81.63
29.94 / 77.37
EuroSAT
Sliced
70%
65.05 / 76.93
65.05 / 76.93
65.05 / 76.93
56.29 / 79.56
39.15 / 79.96
Appendix
Table 5: MAD-threshold sensitivity of adaptive pruning for the reported threshold sweep. Each cell reports achieved parameter pruning and test accuracy.
Num. Experts
EuroSAT
RESISC45
Modular
Sliced
Modular
Sliced
Params (M)
Acc. (%)
Params (M)
Acc. (%)
Params (M)
Acc. (%)
Params (M)
Acc. (%)
3
19.8
88.19
7.4
87.96
19.9
65.82
7.4
63.67
5
33.0
73.56
9.0
73.85
33.2
55.56
9.0
40.27
7
46.3
67.74
10.6
73.44
46.5
49.07
10.7
37.98
Best
19.8
88.19
7.4
87.96
19.9
65.82
7.4
63.67
Appendix
Table 6: Impact of the number of experts on COSMIC-FL modular and sliced variants evaluated on EuroSAT and RESISC45 with 50 clients. Results report parameter counts (M) and classification accuracy (%).
Modular
Sliced
Num. Experts
Params (M)
Acc. short (%)
Acc. long (%)
Params (M)
Acc. short (%)
Acc. long (%)
3
17.6
21.00
29.05
7.6
22.30
29.15
5
29.3
18.37
25.21
9.2
15.46
19.31
7
41.0
15.52
21.59
10.9
10.22
13.20
10
58.6
14.03
19.96
13.4
9.13
12.72
Appendix
Table 7: Impact of the number of experts on COSMIC-FL modular and sliced variants evaluated on CIFAR-100 (100 classes) under a short and a long training budget. Results report parameter counts (M) and classification accuracy (%).
α=0.1
α=0.3
α=1.0
α=10
Stage
Acc.
δ
Acc.
δ
Acc.
δ
Acc.
δ
Gate pretraining (init.)
8.07
–
8.22
–
8.52
–
8.48
–
+ Expert specialization
53.15
+45.08
73.48
+65.26
75.85
+67.33
76.37
+67.89
+ Gate fine-tuning
57.04
+3.89
76.52
+3.04
80.19
+4.34
80.07
+3.70
+ Head fine-tuning
67.67
+10.63
83.26
+6.74
86.52
+6.33
87.78
+7.71
Appendix
Table 8: Test accuracy (%) after each training stage of COSMIC-FL (Sliced) on EuroSAT with 50 clients under varying Dirichlet heterogeneity. δ = gain over the preceding stage.
Figure 3: Test accuracy during the expert-specialization phase with 50 rounds and 50 clients on EuroSAT, AID, and RESISC45. Curves compare FedAvg, FedProx, CentMoE, PM-MoE, and the COSMIC-FL variants.
Modular
Sliced
Metric
Sparse
Normal
Sparse
Normal
10 clients
Val. accuracy (%)
76.22
75.78
80.41
78.85
Expert participation rate (%)
60.0
100
56.7
100
Experts trained / client / round
1.80
3.00
1.70
3.00
Params transferred / client / round (M)
11.89
19.81
4.19
7.39
Appendix
Table 9: Sparse expert participation vs. full (normal) expert training for COSMIC-FL (EuroSAT, Dirichlet α=0.1 , 3 experts, 15 rotation rounds) across 10, 50, and 100 clients. With sparse participation, a client only trains experts for which it holds sufficient local samples, so it does not have to train the whole expert set each round. As the constellation scales, each client holds fewer samples, so fewer experts pass the ownership threshold: the communication saving grows (40% → 89% for Modular, 43% → 88% for Sliced) while validation accuracy is maintained or improved.
Method
EuroSAT
RESISC45
α=0.1
α=0.3
α=1.0
α=10.0
α=0.1
α=0.3
α=1.0
α=10.0
FedAvg
81.33
90.89
93.74
94.41
57.69
66.64
69.24
72.2
FedProx
83.00
90.63
93.37
94.48
62.27
68.42
70.98
73.27
CentMoE
86.89
94.07
95.07
95.26
61.49
66.60
66.96
67.36
PM-MoE
11.11
92.70
95.22
95.26
29.91
45.44
65.91
71.56
FedDropout ( r=0.75 )
64.72
75.13
79.19
79.94
33.28
36.84
41.09
43.73
Appendix
Table 10: Impact of data heterogeneity (Dirichlet- α ) on test accuracy (EuroSAT & RESISC45, 50 clients). Lower α = more non-i.i.d.
Figure 4: Per-client parameters trained and uploaded per round (millions) on EuroSAT, AID, and RESISC45. Each phase communicates only the parameters being optimized. CentMoE and PM-MoE train full models, while COSMIC-FL (Sliced/Modular) separates expert, gating, and head components.
Payload / client / round (M)
Total uplink (G)
Method
Rotation
Gate
Head
50 clients
100 clients
FedAvg (full model)
5.82
–
–
14.5
29.1
FedProx (full model)
5.82
–
–
14.5
29.1
CentMoE
7.40
–
–
18.5
37.0
PM-MoE †
5.02
–
–
58.0
195.4
FedDropout ( r=0.75 )
3.27
–
–
8.2
16.4
Appendix
Table 11: Total uplink communication across all training phases on EuroSAT, computed from measured per-client per-round payloads under the reference schedule ( TE=50 , TG=20 , TH=20 ). Sparse-expert variants scale rotation communication by the measured expert-participation rate ρ (Table 9 ). “–” denotes methods without separate gate or head phases. † PM-MoE communication is derived from the implementation, where Phase 2 aggregates the full model including body, heads, and gate, causing client-dependent scaling.
Method (# Satellites)
CIFAR-10
AID
EuroSAT
RESISC45
UC Merced
FedDropout ( r=0.25 , 10)
31.53
14.33
33.72
12.42
5.08
FedDropout ( r=0.25 , 50)
21.75
6.30
19.59
6.62
7.62
FedDropout ( r=0.25 , 100)
14.41
5.56
18.24
4.47
4.76
FedDropout ( r=0.5 , 10)
65.01
37.44
66.33
35.04
13.65
FedDropout ( r=0.5 , 50)
43.92
13.46
59.98
16.42
9.52
FedDropout ( r=0.5 , 100)
38.71
6.90
47.13
9.41
8.57
Appendix
Table 12: Full capacity-fraction sweep for FedDropout and HeteroFL: accuracy (%) under IID settings with different numbers of satellites.
Model
Pruning
EuroSAT
RESISC45
Server
Client
Adaptive
Server
Client
Adaptive
P
Acc
P
Acc
P
Acc
P
Acc
P
Acc
P
Acc
COSMIC-FL (Sliced)
0
12.4
87.56
12.4
87.56
12.4
87.56
12.5
64.07
12.5
64.07
12.5
64.07
10
11.5
83.74
11.5
82.07
11.5
83.15
11.5
46.62
11.5
46.58
11.5
46.40
30
8.2
81.15
8.2
81.04
8.4
81.93
8.3
44.91
8.3
44.31
8.5
46.96
50
5.6
80.67
5.6
82.04
5.8
82.22
5.7
44.09
5.7
45.33
6.3
43.27
Appendix
Table 13: Impact of pruning ratio and strategy (server-side, client-side, adaptive) on COSMIC-FL (Sliced and Modular) on EuroSAT and RESISC45 with 50 satellites. Results report parameters (P, millions) and test accuracy (%).
Dataset
Impl.
Variant
Acc. (%)
Ach. pruning (%)
Latency (ms)
Throughput (img/s)
Peak memory (MB)
EuroSAT
Modular
Dense
86.22
0.00
10.59
94.43
83.45
EuroSAT
Modular
Adaptive
79.11
35.42
11.21
89.17
61.52
EuroSAT
Sliced
Dense
86.26
0.00
23.23
43.05
105.05
EuroSAT
Sliced
Adaptive
79.52
53.30
21.37
46.80
42.28
RESISC45
Modular
Dense
63.60
0.00
10.70
93.50
84.78
RESISC45
Modular
Adaptive
58.87
39.81
11.23
89.07
55.01
Appendix
Table 14: Dense and adaptively pruned proposed models on the Jetson AGX Orin. Values are averaged over two independent runs.
Dataset
Impl.
Memory
Latency
Throughput
Power
EuroSAT
Modular
−26.28%
+5.90%
−5.57%
−3.96%
EuroSAT
Sliced
−59.75%
−7.98%
+8.70%
−10.75%
RESISC45
Modular
−35.11%
+4.96%
−4.73%
−6.20%
RESISC45
Sliced
−57.74%
−7.36%
+7.94%
−11.11%
Appendix
Table 15: Relative hardware effect of adaptive pruning with respect to the corresponding dense implementation.
School of Information Engineering, Gannan University of Science and Technology, Ganzhou 341000, China · Department of Computer Science and Technology, Tsinghua University, Beijing 100084, China · Department of Electrical and Computer Engineering, Queen University, Kingston, ON K7L 3N6, Canada +2