In underlay spectrum sharing, the interference constraint limits transmissions by the secondary transmitter, which concurrently accesses the spectrum, to protect the primary user from excessive interference. Transmit antenna selection enables a secondary user to overcome the limitations imposed by the interference constraint using low-complexity hardware. We develop an optimal and novel joint antenna selection and power adaptation rule that minimizes the average symbol error probability (SEP) of a secondary user that is subject to two practically well-motivated constraints. The first is the less-studied but general interference-outage constraint, which limits the probability that the interference power at the primary receiver exceeds a threshold. The second constraint limits the peak transmit power of the secondary transmitter. We show that the optimal rule for the interference-outage constraint has a novel structure that is markedly different from the rules considered in the literature. We then present an insightful geometric interpretation of its structure. Using this, we also propose a practically amenable and near-optimal variant of the optimal rule called the linear rule, and analyze its performance. Our numerical results show that the optimal rule reduces the average SEP by one to two orders of magnitude compared to the rules in the literature.

中文翻译：

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利用发射天线选择进行功率自适应以实现干扰中断受限的底层频谱共享

在底层频谱共享中，干扰约束限制了同时访问频谱的次要发射机的传输，以保护主要用户免受过度干扰。发射天线选择使次要用户能够使用低复杂度硬件克服干扰约束所施加的限制。我们开发了一种最优且新颖的联合天线选择和功率自适应规则，该规则可最大限度地减少受两个实际动机良好的约束的次级用户的平均符号错误概率 (SEP)。第一个是研究较少但普遍的干扰中断约束，它限制了主接收器上的干扰功率超过阈值的可能性。第二个约束限制了次要发射机的峰值发射功率。我们表明，干扰中断约束的最佳规则具有与文献中考虑的规则明显不同的新颖结构。然后，我们对其结构进行了深入的几何解释。使用这一点，我们还提出了一种称为线性规则的最优规则的实际可行且接近最优的变体，并分析了其性能。我们的数值结果表明，与文献中的规则相比，最优规则将平均 SEP 降低了一到两个数量级。我们还提出了一种称为线性规则的最优规则的实际可行且接近最优的变体，并分析了其性能。我们的数值结果表明，与文献中的规则相比，最优规则将平均 SEP 降低了一到两个数量级。我们还提出了一种称为线性规则的最优规则的实际可行且接近最优的变体，并分析了其性能。我们的数值结果表明，与文献中的规则相比，最优规则将平均 SEP 降低了一到两个数量级。