Table 1 Comparative study of the existing surveys with our study survey.

Jahid et al¹.

✔

⨯

✔

✔

⨯

Proposes blockchain integration into 6G networks and IoT to tackle 5G data challenges, emphasizing decentralization and security crucial for IoT and Industry 4.0.

Identifies challenges like infrastructure sharing and latency in blockchain, 6G, and IoT convergence, exploring mitigation techniques for improved integration.

Pajooh et al².

✔

⨯

✔

✔

⨯

Surveying the potential of integrating 6G IoT with blockchain for improved security and decentralized access control.

Examining IoT security, centralization limitations, and challenges in integrating 6G IoT with blockchain.

Xu et al¹⁹.

✔

⨯

⨯

✔

⨯

Exploring blockchain’s potential for efficient resource management and sharing in 6G networks to meet emerging service requirements.

Address spectrum scarcity and optimize resource use in IoT, D2D communication, network slicing, and blockchain ecosystems.

Al-Dulaimi et al²⁰.

⨯

✔

✔

⨯

⨯

Offers insights into cognitive radio’s role in addressing spectrum scarcity, focusing on IoT contexts and dynamic spectrum access strategies.

The study proposes cognitive radio as a solution for spectrum scarcity, and explores advanced spectrum sensing, including machine learning, to boost spectrum efficiency in IoT.

Khasawneh et al²¹.

⨯

✔

✔

⨯

⨯

Emphasizes CRN-IoT integration benefits and presents a state-of-the-art systems overview.

The study focuses on addressing wireless communication and IoT application demands through CRN-IoT integration.

Zainuddin et al²².

✔

⨯

✔

✔

⨯

Highlight blockchain’s enhancement of IoT network security and traceability, showcasing its applicability in supply chains, healthcare, and smart cities.

The study addresses challenges including scalability, energy consumption, interoperability, and privacy concerns associated with blockchain integration into IoT networks.

Bhaskar et al²³.

✔

✔

✔

⨯

⨯

Discusses cognitive radio’s potential for IoT communication, addressing wireless access issues like collision and contention.

The study focuses on optimizing spectrum use and efficient management through cognitive radio technology in wireless access networks.

Mathew²⁴

✔

⨯

✔

✔

⨯

examines the convergence of edge computing and blockchain in 6G, with a focus on addressing security challenges and obstacles.

The study highlights security and privacy challenges in integrating edge computing and blockchain into 6G networks

Rachakonda et al²⁵.

✔

✔

✔

⨯

⨯

The research explores spectrum-sharing solutions to optimize IoT connectivity amidst limited resources.

Highlighting security concerns, the study evaluates spectrum-sharing technology for IoT.

This Survey

✔

✔

✔

✔

✔

The study discusses advancements in blockchain-enabled security for spectrum access in 6G cognitive radio IoT networks, highlighting its potential to enhance security and reviewing recent research.

It addresses security challenges in Cognitive Radio 6G IoT Networks, showcasing blockchain’s potential in managing spectrum, interference, and authentication.