⚡ electrical engineering

One-hot Coding-based URA with RFFI-Enabled Message Authentication

This paper proposes a one-hot coding-based unsourced random access framework that leverages radio-frequency fingerprint identification to authenticate IoT messages without additional payloads, thereby securing transmissions against spoofing while maintaining reliable communication performance.

Original authors: Wenbo Fan, Zeping Sui, Yuhei Takahashi, Jun Cheng, Zilong Liu, Pingzhi Fan

Published 2026-05-19

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CC BY 4.0

Original authors: Wenbo Fan, Zeping Sui, Yuhei Takahashi, Jun Cheng, Zilong Liu, Pingzhi Fan

Original paper licensed under CC BY 4.0 (http://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

The Big Problem: The "Anonymous Party"

Imagine a massive, chaotic party where thousands of people (IoT devices) want to shout a short secret message to the host (the Base Station). To keep things organized, everyone agrees on a rule: nobody introduces themselves. They just shout their message.

This is called Unsourced Random Access (URA). It's great for efficiency because you don't waste time saying "Hi, I'm Bob." However, it has a huge security flaw: The host doesn't know who is shouting.

If a bad guy (an illegitimate device) learns the secret codebook the group is using, they can walk in, shout a fake message, and the host will think, "Oh, that's a valid message from a guest!" The host has no way to tell the difference between a real guest and an imposter.

The Solution: The "Unique Voice Print"

The authors propose a clever trick to solve this without breaking the "no introductions" rule. They combine two ideas: One-Hot Coding and Radio-Frequency Fingerprints (RFFI).

1. The "One-Hot" Trick (The Empty Room)

Usually, when people shout messages, they might all talk at once, causing a mess. The authors suggest a different way:

Imagine a room with thousands of tiny, separate booths (channels).
Each person has a specific message (like a number).
The Rule: If you want to say "Message #5," you must go into Booth #5 and shout. All other booths remain silent.
Because everyone picks a different booth for their specific message, their voices don't overlap (collide) unless two people accidentally pick the exact same message.

This creates a very clean signal. The host only needs to listen to the specific booth where a sound is coming from.

2. The "Voice Print" (The Hardware Flaw)

Here is the magic part. Even if two people are shouting the exact same word in the exact same booth, their voices sound slightly different. Why? Because no two human vocal cords are identical.

In the world of electronics, every device has tiny, unavoidable manufacturing flaws (like a slightly crooked microphone or a slightly wobbly amplifier). These flaws create a unique Radio-Frequency (RF) Fingerprint.

Legitimate devices have fingerprints the host already knows (like a guest list).
Bad guys have unknown fingerprints.

How It Works Together

The system works like a bouncer at a club who checks two things:

Did you shout the right word in the right booth? (Decoding the message).
Does your voice sound like someone on the guest list? (Checking the RF fingerprint).

If a bad guy tries to shout a fake message:

They might get the booth right.
They might get the message right.
But their "voice" (hardware fingerprint) won't match the guest list.
The host says, "This message is fake," and rejects it.

Why This Is Special

Usually, to prove you are who you say you are, you have to carry a heavy ID card (extra data). This slows you down.

Old way: You shout your message plus a long password.
This paper's way: You just shout your message. The system checks your "voice" automatically. It adds zero extra weight to your message, which is perfect for tiny devices that only have a few bits of data to send.

The Results

The authors did the math and ran simulations to prove this works:

Security: It successfully stops bad guys from fooling the system (spoofing).
Efficiency: It doesn't require more power or bandwidth than the standard method. In fact, because the signals are so clean (no overlapping voices), the system actually works better and requires less energy to hear the messages clearly.
Real-world test: They even tested it with "imperfect" hardware (simulating real-world flaws) and found it still works well, though the "voice check" needs to be very precise.

Summary

This paper invents a way for thousands of anonymous devices to talk to a central hub securely. Instead of asking "Who are you?" (which wastes space), the hub listens to "How do you sound?" (which is free). By using a special "one message per booth" rule and listening for unique hardware "voice prints," the system can spot and reject fake messages without slowing anything down.

Technical Summary: One-hot Coding-based URA with RFFI-Enabled Message Authentication

Problem Statement
Unsourced Random Access (URA) is a promising paradigm for massive connectivity in Internet-of-Things (IoT) networks, particularly for scenarios involving ultra-short payloads (e.g., 10–20 bits) where devices transmit without identifiers. While existing URA schemes (such as T-fold ALOHA, segmentation coding, and two-phase coding) have narrowed the performance gap to theoretical achievability bounds, they inherently introduce security vulnerabilities. Because the receiver decodes messages in an unordered manner without associating them with specific device identities, the system is susceptible to spoofing attacks. If an illegitimate device compromises the common codebook, it can inject forged messages that the base station (BS) may decode as legitimate. While cryptographic authentication methods exist, they often introduce prohibitive computational complexity or require additional payload overhead, which is unsuitable for ultra-short-payload IoT scenarios. Furthermore, existing physical-layer authentication schemes typically assume collision-free transmissions, a condition not guaranteed in massive random access.

Methodology
The paper proposes a One-Hot Coding (OHC)-based URA framework that integrates Radio-Frequency Fingerprint Identification (RFFI) to enable message authentication without violating the unsourced transmission principle or adding authentication payloads.

System Model: The system considers a network with a large number of devices sharing a common codebook. A subset of devices ( $D_L$ ) is legitimate (registered), while others ( $D_I$ ) are illegitimate.
Transmission Scheme:
- One-Hot Coding (OHC): Distinct $B$ -bit messages are mapped onto orthogonal channel uses via a common codebook effectively represented as an identity matrix. A message $w$ with decimal index $q$ is mapped to a codeword $x$ where only the $q$ -th element is 1, and all others are 0.
- Modulation: The system employs On-Off Keying (OOK). Consequently, for a given message, only one of the $N = 2^B$ channel uses is occupied, while the remaining $N-1$ remain idle. This concentrates the total energy of the $B$ -bit message into a single OOK symbol.
- RF Impairments: The scheme exploits device-specific hardware impairments (e.g., power amplifier nonlinearity) inherent in the RF front ends. These impairments, modeled by a device-specific mapping function $\psi_k(\cdot)$ , create unique "fingerprints" for each device.
Receiver Processing:
- The BS performs decoding and authentication on a per-channel-use basis.
- Demodulation: Coherent OOK demodulation is used. If a signal is detected in a channel use, the index is converted back to the message.
- Authentication: The BS extracts RF features from the received signal and performs open-set RFFI. The decoded message is accepted only if the extracted features match a registered reference in the access list within a specific similarity threshold. If signal collisions occur (multiple devices transmitting on the same channel use), authentication is assumed to fail.

Key Contributions

Secure URA Framework: The paper introduces a URA scheme that enables physical-layer message authentication without modifying the core unsourced principle or adding extra payload bits.
Orthogonal Channel Structure: By utilizing OHC and OOK, the scheme ensures that distinct messages occupy orthogonal channel uses. This structure not only prevents interference between different messages but also facilitates the isolation of signals for RFFI analysis.
Theoretical Analysis: The authors derive analytical expressions for:
- The Per-User Probability of Error (PUPE) for legitimate devices.
- The Probability of Successful Spoofing ( $P_I$ ) for illegitimate devices.
- The analysis accounts for code rate, $E_b/N_0$ , the number of active devices, and RFFI error probabilities (miss-detection and false-alarm rates).
Performance Evaluation: The study provides numerical results comparing the proposed scheme against a baseline URA scheme (from [2]) and analyzes the impact of imperfect RFFI modules and RF impairments (specifically power amplifier nonlinearity).

Results

Efficiency: Analytical results indicate that the proposed OHC-based scheme requires a lower $E_b/N_0$ compared to the baseline scheme from [2] for a target PUPE of 0.05. This gain is attributed to the orthogonal transmission structure, which enhances symbol-level SNR and avoids the inter-message interference present in schemes where signals are spread across all channel uses.
Security: The scheme effectively mitigates spoofing attacks. Numerical results demonstrate that the probability of successful spoofing ( $P_I$ ) is significantly reduced when RFFI is employed.
Robustness: Simulations incorporating power amplifier nonlinearity show that while RF impairments slightly degrade OOK demodulation performance (causing a minor discrepancy between analytical and simulation results), the overall framework remains effective. Imperfect RFFI modules (with non-zero miss-detection and false-alarm probabilities) reduce the number of supportable active devices and slightly degrade the minimum required $E_b/N_0$ , but the system maintains secure transmission capabilities.

Significance
The paper claims that the proposed scheme offers a viable solution for securing ultra-short-payload IoT transmissions in massive access scenarios. By leveraging the inherent hardware imperfections of devices, it achieves message authentication without the overhead of cryptographic keys or additional payload bits. The authors note that while the current design is tailored for ultra-short payloads, the authentication stage can potentially be combined with segmentation-based or two-phase URA schemes to accommodate higher payload sizes in future implementations. The work addresses a critical gap in physical-layer security for URA, where traditional collision-free assumptions do not hold.