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arXiv 1402.6243cs.NIcs.ITmath.IT
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密集认知无线电网络中的全局最优协作

Globally Optimal Cooperation in Dense Cognitive Radio Networks

Ahmed M. Alaa, Omar A. Nasr

摘要:

在基于硬判决的协作频谱感知中,局部判决门限和全局判决门限的计算是一个数学难题。以前的工作依赖于简单的次优计数规则的决策融合,以避免获得最佳阈值所需的穷举数值搜索。然而,这些简单的规则不是全局最优的,因为它们没有通过联合选择局部和全局阈值来最大化整体全局检测概率。相反,它们最大化特定全局阈值的检测概率。本文基于Neyman-Pearson(NP)准则,推导了一种主用户信号检测的全局最优判决融合规则。该算法是基于一种新的表示的全球性能指标的正则化不完全β函数。基于这种数学表示,它表明,全球最优的NP硬决策融合测试可以把一个传统的一维凸优化问题的形式。可以应用全局阈值的二分搜索,产生O(log 2(N))的复杂度,其中N表示协作用户的数量。对数复杂度是值得赞赏的,因为我们关注的是密集网络,因此N预计会很大。所提出的最优方案优于传统的计数规则,如OR,AND和MAJORITY规则。仿真结果表明,虽然在协作用户数较少的情况下,最优规则趋向于简单的OR规则,但在协作用户数较多的密集认知无线电网络中,最优规则能显著提高信噪比。

英文摘要:

The problem of calculating the local and global decision thresholds in hard decisions based cooperative spectrum sensing is well known for its mathematical intractability. Previous work relied on simple suboptimal counting rules for decision fusion in order to avoid the exhaustive numerical search required for obtaining the optimal thresholds. However, these simple rules are not globally optimal as they do not maximize the overall global detection probability by jointly selecting local and global thresholds. Instead, they maximize the detection probability for a specific global threshold. In this paper, a globally optimal decision fusion rule for Primary User signal detection based on the Neyman- Pearson (NP) criterion is derived. The algorithm is based on a novel representation for the global performance metrics in terms of the regularized incomplete beta function. Based on this mathematical representation, it is shown that the globally optimal NP hard decision fusion test can be put in the form of a conventional one dimensional convex optimization problem. A binary search for the global threshold can be applied yielding a complexity of O(log2(N)), where N represents the number of cooperating users. The logarithmic complexity is appreciated because we are concerned with dense networks, and thus N is expected to be large. The proposed optimal scheme outperforms conventional counting rules, such as the OR, AND, and MAJORITY rules. It is shown via simulations that, although the optimal rule tends to the simple OR rule when the number of cooperating secondary users is small, it offers significant SNR gain in dense cognitive radio networks with large number of cooperating users.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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