Fu Yuanhua, Yang Fan, He Zhiming
School of Information and Communication Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China.
Institute of Electronic and Information Engineering of University of Electronic Science and Technology of China in Guangdong, Dongguan 523808, China.
Sensors (Basel). 2018 Feb 6;18(2):473. doi: 10.3390/s18020473.
Spectrum sensing remains a challenge in the context of cognitive radio networks (CRNs). Compared with traditional single-user sensing, cooperative spectrum sensing (CSS) exploits multiuser diversity to overcome channel fading, shadowing, and hidden terminal problems, which can effectively enhance the sensing performance and protect licensed users from harmful interference. However, for a large number of sensing nodes that need high bandwidth of the control channel for data transmitting, CSS increases cooperative overhead. To address this problem, we investigated the soft decision fusion strategy under a limited bandwidth of the control channel and proposed a simple quantization-based multibit data soft fusion rule for CSS for its simple structure and easily implementation. Under the quantization-based sensing strategy, each cooperative secondary user (SU) adopts an energy detector for local spectrum sensing. Each SU transmits quantized multibit data that sends local sensing information, instead of forwarding local one-bit hard decision results or original observation statistics, to the fusion center (FC). Furthermore, the closed-form expressions of the quantization levels and the quantization thresholds are analytically derived. Simulation results indicate that the detection performance of the proposed method approaches that of the conventional soft fusion rule with less cooperative overhead and outperforms the hard decision rules. Extensive simulations also show that multibit quantization fusion achieves a desirable tradeoff between the sensing performance and the control channel overhead for CSS.
在认知无线电网络（CRN）的背景下，频谱感知仍然是一项挑战。与传统的单用户感知相比，协作频谱感知（CSS）利用多用户分集来克服信道衰落、阴影和隐藏终端问题，这可以有效提高感知性能并保护授权用户免受有害干扰。然而，对于大量需要高带宽控制信道进行数据传输的感知节点，CSS会增加协作开销。为了解决这个问题，我们研究了控制信道带宽有限情况下的软判决融合策略，并针对CSS提出了一种基于简单量化的多比特数据软融合规则，因其结构简单且易于实现。在基于量化的感知策略下，每个协作次用户（SU）采用能量检测器进行本地频谱感知。每个SU传输量化的多比特数据来发送本地感知信息，而不是将本地的单比特硬判决结果或原始观测统计量转发到融合中心（FC）。此外，还通过解析推导得出了量化级别和量化阈值的闭式表达式。仿真结果表明，所提方法的检测性能接近传统软融合规则，但协作开销更小，且优于硬判决规则。大量仿真还表明，多比特量化融合在CSS的感知性能和控制信道开销之间实现了理想的权衡。
