How can cognitive radio networks improve spectrum efficiency and avoid interference?

1 Spectrum Sensing

Spectrum sensing is the process of detecting the presence or absence of licensed users in a frequency band. It is essential for CRNs to avoid interfering with the primary users and to identify the spectrum opportunities. Spectrum sensing can be performed by individual nodes (local sensing) or by a group of nodes (cooperative sensing) that share their observations. Spectrum sensing techniques can be classified into three categories: energy detection, feature detection, and matched filter detection.

2 Spectrum Management

Spectrum management is the process of allocating and utilizing the spectrum resources among the CRN nodes. It involves four functions: spectrum analysis, spectrum decision, spectrum sharing, and spectrum mobility. Spectrum analysis is the process of estimating the spectrum availability and quality based on the sensing results. Spectrum decision is the process of selecting the best frequency band for transmission based on the spectrum analysis and the application requirements. Spectrum sharing is the process of coordinating the access and interference among the CRN nodes and the primary users. Spectrum mobility is the process of switching to a different frequency band when the current one becomes unavailable or unsuitable.

3 Spectrum Efficiency

Spectrum efficiency is the measure of how well the spectrum resources are utilized by the CRN nodes. It depends on several factors, such as the spectrum sensing accuracy, the spectrum management strategy, the modulation and coding scheme, the channel conditions, and the network topology. Spectrum efficiency can be improved by using adaptive and intelligent techniques that can optimize the spectrum access and utilization based on the spectrum environment and the application needs. For example, CRNs can use cognitive beamforming, cognitive relaying, cognitive routing, and cognitive medium access control to enhance the spectrum efficiency.

4 Interference Avoidance

Interference avoidance is the goal of minimizing the negative impact of the CRN nodes on the primary users and vice versa. Interference avoidance can be achieved by using various techniques, such as interference alignment, interference cancellation, interference mitigation, and interference coordination. Interference alignment is the technique of aligning the signals of multiple CRN nodes in a subspace that does not interfere with the primary users. Interference cancellation is the technique of subtracting the interference signals from the received signals by using advanced signal processing methods. Interference mitigation is the technique of reducing the interference power by using power control, directional antennas, or spatial diversity. Interference coordination is the technique of managing the interference among the CRN nodes and the primary users by using game theory, auction theory, or cooperative communication.

6 Here’s what else to consider

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