Cooperative Wideband Spectrum Detection Based on Maximum Likelihood Ratio for CR Enhanced VANET
Cooperative Wideband Spectrum Detection Based on Maximum Likelihood Ratio for CR Enhanced VANET
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DOI：
10.12720/jcm.8.12.814-821
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
Xiaorong Xu;J. Bao;Yi Luo;Huaxia Wang
中科院分区：
文献类型：
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作者：
Xiaorong Xu;J. Bao;Yi Luo;Huaxia Wang
认知无线电增强型车载自组织网络（CR-VANET）是一种特殊的车载自组织网络，每辆车都可以通过动态接入频谱空洞来探索本地频谱间隙，减少干扰，从而减少数据拥塞。CR-VANET最重要的挑战之一是识别特定时间和特定地理位置宽带频谱上主要用户（PU）的存在。本文提出了最大似然比（MLR）检测作为基于正交频分复用（OFDM）的覆盖CR-VANET中宽带频谱检测的有效方案。在路边采用平方律选择的OR融合规则，结合各车辆的局部检测结果进行全局检测决策。因此，在动态拓扑CRVANET中实现协作宽带频谱检测，以提高频谱检测的可靠性。具体而言，鲁棒的协作感知技术的研究与感知信道的信噪比，报告信道衰落，以及用户间的错误率的考虑，在多车辆的协作感知场景中利用多样性的目的。针对空时分组码（STBC）和时分多址（TDMA）协议中的MLR检测，提出了合作宽带频谱感知的局限性。仿真结果证实了我们的理论推导。结果表明，与传统的能量检测（艾德）相比，基于MLR的合作宽带频谱检测具有自适应的检测门限。此外，鲁棒的合作感知路边SLS或规则及其局限性也进行了接收机的操作特性（ROC）。实验结果表明，MLR检测在动态门限变化的协作感知中是有效的，可用于CR-VANET的实际应用。
Cognitive radio (CR) enhanced vehicular ad hoc network (CR-VANET) is a special VANET that each vehicle could explore local spectrum gap and reduce data congestion by mitigating interference by dynamically accessing spectrum holes. One of the most important challenges for CR-VANET is to identify the presence of primary users (PU) over wideband spectrum at a particular time and specific geographic location. In this paper, maximum likelihood ratio (MLR) detection is proposed as an effective scheme for wideband spectrum detection in orthogonal frequency division multiplexing (OFDM) based overlay CR-VANET. OR fusion rule with square-law selection (SLS) is implemented at roadside to make global detection decision by means of the combination of each vehicle’s local sensing results. Hence, cooperative wideband spectrum detection is implemented in dynamic topology CRVANET to enhance the reliability of spectrum detection. Specifically, robust cooperative sensing technique is investigated with the consideration of sensing channel SNR, reporting channel fading, as well as inter-user error rate, with the purpose of exploiting diversity in multi-vehicle cooperative sensing scenario. Limitations of cooperative wideband spectrum sensing are presented with MLR detection in space-time block code (STBC) and time division multiple access (TDMA) protocols for practical consideration. Simulation results are presented to confirm our theoretical derivations. It is revealed that, compared with conventional energy detection (ED), cooperative wideband spectrum detection with MLR has adaptive detection thresholds. Moreover, robust cooperative sensing by roadside SLS OR rule and its limitations are also performed with receiver operation characteristics (ROC). It is proven that, MLR detection is available in robust cooperative sensing with dynamic threshold variations for CR-VANET practical applications.