Lorincz Josip, Ramljak Ivana, Begušić Dinko
Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture (FESB), University of Split, 21000 Split, Croatia.
Elektroprenos-Elektroprijenos BiH" a.d. Banja Luka, 88000 Mostar, Bosnia and Herzegovina.
Sensors (Basel). 2021 Nov 18;21(22):7678. doi: 10.3390/s21227678.
Cognitive radio (CR) technology has the potential to detect and share the unutilized spectrum by enabling dynamic spectrum access. To detect the primary users' (PUs) activity, energy detection (ED) is widely exploited due to its applicability when it comes to sensing a large range of PU signals, low computation complexity, and implementation costs. As orthogonal frequency-division multiplexing (OFDM) transmission has been proven to have a high resistance to interference, the ED of OFDM signals has become an important local spectrum-sensing (SS) concept in cognitive radio networks (CRNs). In combination with multiple-input multiple-output (MIMO) transmissions, MIMO-OFDM-based transmissions have started to become a widely accepted air interface, which ensures a significant improvement in spectral efficiency. Taking into account the future massive implementation of MIMO-OFDM systems in the fifth and sixth generation of mobile networks, this work introduces a mathematical formulation of expressions that enable the analysis of ED performance based on the square-law combining (SLC) method in MIMO-OFDM systems. The analysis of the ED performance was done through simulations performed using the developed algorithms that enable the performance analysis of the ED process based on the SLC in the MIMO-OFDM systems having a different number of transmit (Tx) and receive (Rx) communication branches. The impact of the distinct factors including the PU Tx power, the false alarm probability, the number of Tx and Rx MIMO branches, the number of samples in the ED process, and the different modulation techniques on the ED performance in environments with different levels of signal-to-noise ratios are presented. A comprehensive analysis of the obtained results indicated how the appropriate selection of the analyzed factors can be used to enhance the ED performance of MIMO-OFDM-based CRNs.
认知无线电（CR）技术通过实现动态频谱接入，具有检测和共享未使用频谱的潜力。为了检测主用户（PU）的活动，能量检测（ED）因其在感知大范围PU信号时的适用性、低计算复杂度和实现成本而被广泛采用。由于正交频分复用（OFDM）传输已被证明具有高抗干扰性，OFDM信号的能量检测已成为认知无线电网络（CRN）中一个重要的本地频谱感知（SS）概念。结合多输入多输出（MIMO）传输，基于MIMO - OFDM的传输已开始成为一种被广泛接受的空中接口，可确保频谱效率得到显著提高。考虑到MIMO - OFDM系统在第五代和第六代移动网络中的未来大规模应用，这项工作引入了一些表达式的数学公式，这些表达式能够基于MIMO - OFDM系统中的平方律合并（SLC）方法对能量检测性能进行分析。能量检测性能分析是通过使用所开发的算法进行仿真来完成的，这些算法能够基于SLC对具有不同数量发射（Tx）和接收（Rx）通信分支的MIMO - OFDM系统中的能量检测过程进行性能分析。文中呈现了包括PU发射功率、虚警概率、Tx和Rx MIMO分支数量、能量检测过程中的采样数量以及不同调制技术等不同因素对不同信噪比环境下能量检测性能的影响。对所得结果的全面分析表明，如何通过对分析因素的适当选择来提高基于MIMO - OFDM的CRN的能量检测性能。
