Research map / Time series / Long-term forecasting
Unlocking the Power of LSTM for Long Term Time Series Forecasting
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Proposes P-sLSTM, an sLSTM-based long-term time series forecaster that adds patching and channel independence to counter sLSTM's short-memory behavior, reporting competitive or SOTA results on five multivariate datasets.
Problem
LSTM and sLSTM struggle to capture long-term dependencies in multivariate long-term time series forecasting; the paper argues sLSTM's exponential gating does not guarantee long memory.
Approach
Builds on sLSTM by applying patching to each univariate channel (channel independence with a shared backbone), so the recurrent model processes shorter patch sequences, and provides a Markov-chain / geometric-ergodicity analysis of sLSTM memory.
Key results
- P-sLSTM ranks first in 23 and second in 10 of 40 settings across five datasets (Weather, Electricity, Solar, ETTm1, PEMS03).
- On Weather with horizon 96, P-sLSTM achieves MSE 0.149 / MAE 0.208 versus sLSTM 0.172 / 0.261 and LSTM 0.236 / 0.304.
- Channel-independent P-sLSTM shows higher training error but lower validation and test error than the channel-mixing variant on Weather, supporting overfitting reduction; P-sLSTM trains faster than iTransformer (52.54 s vs 79.12 s on Weather).
Measured effects reported in the paper
| What was changed | Where | Measured | Effect |
|---|---|---|---|
| add patching and channel independence to sLSTM | sLSTM · Weather, horizon 96 | MSE: 0.172 -> 0.149 | Helped |
| add patching and channel independence to sLSTM | sLSTM · Electricity, horizon 96 | MSE: 0.281 -> 0.130 | Helped |
| add patching and channel independence to sLSTM | sLSTM · PEMS03, horizon 12 | MSE: 0.103 -> 0.077 | Hurt |
| remove memory mixing (ablation) | P-sLSTM · Weather, horizon 96, look-back 336 | MSE: 0.149 -> 0.151 | Hurt |
| remove memory mixing (ablation) | P-sLSTM · Weather, horizon 96, look-back 336 | MAE: 0.208 -> 0.209 | Hurt |
| remove memory mixing (ablation) | P-sLSTM · Weather, horizon 192, look-back 336 | MSE: 0.197 -> 0.201 | Hurt |
| remove memory mixing (ablation) | P-sLSTM · Weather, horizon 336, look-back 336 | MAE: 0.297 -> 0.306 | Hurt |
| remove memory mixing (ablation) | P-sLSTM · Weather, horizon 720, look-back 336 | MSE: 0.320 -> 0.320 | No clear effect |
| replace channel independence with channel mixing (ablation) | P-sLSTM · Weather, horizons 96, 192, 336, 720 | test MSE: 0.167 -> 0.227; 0.180 -> 0.234; 0.190 -> 0.265; 0.196 -> 0.260 | Hurt |
| increase patch size (ablation) | P-sLSTM · Weather | MSE | Mixed |
| increase look-back window using patching (ablation) | P-sLSTM · Weather, horizon 720 | MSE | Helped |
Surprising findings
- Channel independence lowers test error despite higher training error, which the authors attribute to reduced overfitting.
- P-sLSTM does not perform well on PEMS03, which the authors attribute to noise without a denoising mechanism.
Limitations
- Performance is not uniformly best; P-sLSTM underperforms on PEMS03 and is weaker than iTransformer in some settings.
- Optimal patch size varies by dataset and must be found by trial and error.
- Theoretical analysis relies on assumptions (e.g., no external input, bounded forget gate) that may not hold in practice; the paper notes gradient clipping implicitly bounds the forget gate.
Experimental setup
Datasets: Weather Electricity Solar ETTm1 PEMS03
Benchmarks: Weather Electricity Solar ETTm1 PEMS03
Metrics: MSE MAE
Baselines: sLSTM LSTM iTransformer FEDformer Crossformer RLinear DLinear TimesNet Mamba
Builds on: xLSTM sLSTM PatchTST LSTM
Closest papers by meaning
- xLSTM: Extended Long Short-Term Memory (NeurIPS 2024 · similarity 0.86)
- Time-LLM: Time Series Forecasting by Reprogramming Large Language Models (ICLR 2024 · similarity 0.86)
- PGN: The RNN's New Successor is Effective for Long-Range Time Series Forecasting (NeurIPS 2024 · similarity 0.86)
- xLSTM-Mixer: Multivariate Time Series Forecasting by Mixing via Scalar Memories (NeurIPS 2025 · similarity 0.86)
- Sequence Complementor: Complementing Transformers for Time Series Forecasting with Learnable Sequences (AAAI 2025 · similarity 0.85)
- Unlocking the Power of Patch: Patch-Based MLP for Long-Term Time Series Forecasting (AAAI 2025 · similarity 0.85)
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