Achievable Rate and Coding Principle for MIMO Multicarrier Systems With Cross-Domain MAMP Receiver Over Doubly Selective Channels

2026-01-07

IEEE Transactions on Wireless Communications

AI Summary

This work addresses the lack of achievable rate theory and low-complexity receivers for MIMO multicarrier systems—such as OFDM, OTFS, and AFDM—operating over doubly selective channels. It establishes, for the first time, the fundamental limits on achievable rates for coded systems under such channel conditions and derives the corresponding optimal coding principles. To approach these limits with practical complexity, the paper proposes a multi-slot cross-domain memory approximate message passing (MS-CD-MAMP) receiver that jointly exploits temporal channel sparsity and symbol-domain constellation constraints. Combined with a simplified SISO variational state evolution analysis and optimized LDPC code design, the proposed framework achieves performance within 0.5–1.8 dB of the theoretical limit at finite blocklengths, outperforming conventional LDPC codes by 0.8–4.4 dB, while enabling all three multicarrier schemes to attain the same maximum achievable rate.

Technology Category

• Multiagent Systems: Multiagent Learning
• Cognitive Modeling & Cognitive Systems: Neural Spike Coding
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization
• Security and Privacy: Large-scale security measurements
• Search and Retrieval-Augmented AI: Vertical and domain-specific search

Abstract

The integration of multicarrier modulation and multiple-input-multiple-output (MIMO) is critical for reliable transmission of wireless signals in complex environments, which significantly improve spectrum efficiency. Existing studies have shown that popular orthogonal time frequency space (OTFS) and affine frequency division multiplexing (AFDM) offer significant advantages over orthogonal frequency division multiplexing (OFDM) in uncoded doubly selective channels. However, it remains uncertain whether these benefits extend to coded systems. Meanwhile, the information-theoretic limit analysis of coded MIMO multicarrier systems and the corresponding low-complexity receiver design remain unclear. To overcome these challenges, this paper proposes a multi-slot cross-domain memory approximate message passing (MS-CD-MAMP) receiver as well as develops its information-theoretic (i.e., achievable rate) limit and optimal coding principle for MIMO-multicarrier modulation (e.g., OFDM, OTFS, and AFDM) systems. The proposed MS-CD-MAMP receiver can exploit not only the time domain channel sparsity for low complexity but also the corresponding symbol domain constellation constraints for performance enhancement. Meanwhile, limited by the high-dimensional complex state evolution (SE), a simplified single-input single-output variational SE is proposed to derive the achievable rate of MS-CD-MAMP and the optimal coding principle with the goal of maximizing the achievable rate. Numerical results show that coded MIMO-OFDM/OTFS/AFDM with MS-CD-MAMP achieve the same maximum achievable rate in doubly selective channels, whose finite-length performance with practical optimized low-density parity-check (LDPC) codes is only $0.5\sim 1.8$ dB away from the associated theoretical limit, and has $0.8\sim 4.4$ dB gain over the well-designed point-to-point LDPC codes.

Problem

• MIMO multicarrier systems
• doubly selective channels
• achievable rate
• coded systems
• low-complexity receiver

Innovation

• MIMO multicarrier systems
• cross-domain MAMP receiver
• achievable rate
• doubly selective channels
• optimal coding principle