Spectrum shortage is a fundamental problem in wireless networks, and this problem becomes increasingly acute with the rapid proliferation of wireless devices. To address this issue, spectrum sharing in the context of cognitive radio networks (CRNs) has been regarded as a promising solution. Although there is a large body of work on spectrum sharing in the literature, most existing work is limited to theoretical exploration and the progress in practical solution design remains scarce. In this paper, we propose a practical scheme to enable transparent spectrum sharing for a small CRN by leveraging recent advances in multiple-input multiple-output (MIMO) technology. The key components of our scheme are two MIMO-based interference management techniques: blind beamforming (BBF) and blind interference cancellation (BIC). These two techniques enable secondary users to mitigate cross-network interference in the absence of inter-network coordination, fine-grained synchronization, and mutual knowledge. We have built a prototype of our scheme on a wireless testbed and demonstrated its compatibility with commercial Wi-Fi devices (primary users). Experimental results show that, for a secondary device with two/three antennas, BBF and BIC achieve an average of 25 dB and 33 dB interference cancellation capabilities in real-world wireless environments, respectively.

中文翻译：

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认知无线电网络的实用频谱共享方案：设计和实验

频谱短缺是无线网络中的一个基本问题，并且随着无线设备的迅速普及，这个问题变得越来越严重。为了解决这个问题，在认知无线电网络（CRN）中共享频谱已被认为是一个有前途的解决方案。尽管文献中有关频谱共享的工作量很大，但大多数现有工作仅限于理论探索，而实际解决方案设计的进展仍然很少。在本文中，我们提出了一种实用的方案，以利用多输入多输出（MIMO）技术的最新进展来实现小型CRN的透明频谱共享。我们方案的关键组件是两种基于MIMO的干扰管理技术：盲波束成形（BBF）和盲干扰消除（BIC）。这两种技术使次级用户可以在没有网络间协调，细粒度同步和相互知识的情况下减轻跨网络干扰。我们已经在无线测试平台上构建了该方案的原型，并展示了其与商用Wi-Fi设备（主要用户）的兼容性。实验结果表明，对于带有两个/三个天线的辅助设备，BBF和BIC在实际无线环境中分别实现了平均25 dB和33 dB的干扰消除能力。