Massive Multiple Access Techniques in Wireless Communications

Massive multiple access encompasses a suite of protocols designed to enable exceptionally large numbers of wireless devices to share limited spectral resources without central coordination. As the Internet of Things and machine-type communications proliferate, traditional grant-based schemes struggle to accommodate sporadic, low-latency transmissions from vast device populations. Emerging approaches favour grant-free and unsourced paradigms, where end devices transmit autonomously and base stations recover payloads without explicit device identifiers. Key techniques include coded compressed sensing, which exploits signal sparsity to reconstruct many concurrent transmissions; irregular repetition slotted ALOHA, which distributes replicas of each packet across time slots to facilitate iterative decoding; and index modulation, which embeds information in the choice of active resources. Together with successive interference cancellation, these methods push the limits of spectral efficiency and energy conservation, supporting applications from environmental sensing to industrial automation in forthcoming 6G networks.

Research from Nature Portfolio

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Research from all publishers

Recent work has advanced random access frameworks for next-generation networks. An asymptotic analysis of grant-free slotted schemes operating over the Gaussian multiple access channel introduced irregular repetition slotted ALOHA (IRSA) codes combined with density-evolution techniques. This approach delineates energy–spectral trade-offs, deriving load thresholds and minimum signal-to-noise ratio requirements to guarantee specified packet-loss probabilities under high user loads. A second line of inquiry explores coded compressed sensing with patterned Reed–Muller sequences to support unsourced random access. By partitioning binary vector spaces into subspaces for slot-controlled sequence assignment and employing projective decoding, the scheme achieves enhanced energy efficiency and supports greater numbers of active users compared with conventional approaches. Additionally, joint intra- and inter-slot code designs for unsourced multiple access in 6G Internet of Things environments have been proposed. These methods leverage interleave-division multiple access and low-complexity successive interference cancellation decoders to balance coding gains across and within time slots, optimising signal-to-noise ratio requirements while maintaining manageable implementation complexity.

Massive Multiple Access Techniques in Wireless Communications publication trend

The graph below shows the total number of articles in massive multiple access techniques in wireless communications across all publications each year (not limited to Nature Index journals).

Technical terms

Massive multiple access: Protocols that support simultaneous transmission from a very large number of devices over shared spectrum.

Unsourced random access: A grant-free paradigm in which received messages are decoded without identifying individual transmitters.

Compressed sensing: A signal-processing technique that reconstructs sparse signals from a limited set of measurements.

Irregular repetition slotted ALOHA (IRSA): A random access protocol combining time-slot partitioning with irregular repetition of transmissions to facilitate iterative decoding.

Successive interference cancellation (SIC): An iterative method to separate and decode overlapping signals by cancelling strong components sequentially.

Index modulation: A scheme that conveys information via the selection of active subcarriers, antennas or time slots, alongside conventional data symbols.

References

1. Patterned Reed–Muller Sequences with Outer A-Channel Codes and Projective Decoding for Slot-Controlled Unsourced Random Access. Sensors (2023).
2. Joint Intra/Inter-Slot Code Design for Unsourced Multiple Access in 6G Internet of Things. Sensors (2022).
3. Index Modulation–Aided Mixed Massive Random Access. Frontiers in Communications and Networks (2021).
4. IRSA-Based Random Access Over the Gaussian Channel. IEEE Transactions on Information Theory (2024).