Cognitive Radio Networks and Non-Orthogonal Multiple Access Techniques
Summary
Cognitive radio networks (CRNs) and non-orthogonal multiple access (NOMA) have emerged as complementary solutions to address spectrum scarcity and the ever-growing demand for wireless connectivity. CRNs dynamically monitor and adapt spectrum use, allowing secondary users to exploit underutilised bands without causing harmful interference to primary users. NOMA departs from traditional orthogonal schemes by superimposing multiple users in the power or code domain, thereby enhancing spectral efficiency and supporting massive connectivity for applications such as 5G, beyond-5G and Internet of Things (IoT). When combined, CR-NOMA systems leverage intelligent spectrum sensing, dynamic power allocation and advanced interference cancellation to achieve significant throughput gains and energy-efficient transmission. Key enabling technologies include multiple-input multiple-output (MIMO) antennas, cooperative relaying protocols and energy harvesting. These systems must contend with imperfect channel state information, hardware impairments and successive interference cancellation errors. Advances in signal processing, resource allocation and network architecture continue to drive CR-NOMA towards practical deployment, offering global impact across urban dense networks, vehicular communications and rural broadband access.
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Cognitive Radio Networks and Non-Orthogonal Multiple Access Techniques publication trend
The graph below shows the total number of articles in cognitive radio networks and non-orthogonal multiple access techniques across all publications each year (not limited to Nature Index journals).
Technical terms
Cognitive Radio Network: A wireless system that senses spectrum usage and dynamically adjusts transmission parameters to exploit unused frequency bands while protecting licensed users.
Non-Orthogonal Multiple Access (NOMA): A multiple access scheme that superimposes user signals in power or code domain, enabling simultaneous transmission to multiple users over the same resource block.
Spectrum Sensing: The process by which a cognitive radio monitors frequency bands to detect the presence or absence of primary transmissions.
Successive Interference Cancellation (SIC): A receiver technique that sequentially decodes superimposed signals by subtracting the strongest decoded signal from the composite waveform.
Underlay Spectrum Sharing: A CR paradigm in which secondary users transmit concurrently with primary users under a strict interference power constraint.
Cooperative Relaying: A method in which intermediate nodes assist transmission by forwarding or amplifying signals to improve coverage and reliability.
References
- Blockchain-enabled cooperative spectrum sensing in 5G and B5G cognitive radio via massive multiple-input multiple-output nonorthogonal multiple access. Results in Engineering (2024).
- NOMA in Cooperative Underlay Cognitive Radio Networks Under Imperfect SIC. IEEE Access (2020).
- Performance Evaluation of Relay-Aided CR-NOMA for Beyond 5G Communications. IEEE Access (2020).
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