Fundamental limits of spectrum-sharing in fading environments
Fundamental limits of spectrum-sharing in fading environments
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DOI：
10.1109/twc.2007.05447
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发表时间：
2007-02-01
影响因子：
10.4
通讯作者：
Sousa, Elvino S.
中科院分区：
文献类型：
--
作者：
Ghasemi, Amir;Sousa, Elvino S.
传统上，频谱由政府机构以严格的方式许可给用户，其中被许可人拥有访问所分配频段的专有权。因此，被许可人始终受到保护，免受任何干扰。然而，从实际角度来看，未经许可的（次要）用户可以与其许可（主要）所有者共享频带，只要被许可人认为其产生的干扰不有害。在衰落环境中，当许可接收器接收到的其信号严重衰落时，次要用户可以通过机会性地以高功率进行发射来利用这一事实。在本文中，我们研究了当信道因衰落而变化时，这种动态频谱共享方法所提供的容量增益。特别是，我们量化了辅助信道容量和对主用户造成的干扰之间的关系。我们进一步评估和比较不同衰落分布下的容量。有趣的是，我们的结果表明，与确定性情况相比，衰落环境中的频谱访问有了显着的增益。
Traditionally, the frequency spectrum is licensed to users by government agencies in a rigid manner where the licensee has the exclusive right to access the allocated band. Therefore, licensees are protected from any interference all the time. From a practical standpoint, however, an unlicensed (secondary) user may share a frequency band with its licensed (primary) owner as long as the interference it incurs is not deemed harmful by the licensee. In a fading environment, a secondary user may take advantage of this fact by opportunistically transmitting with high power when its signal, as received by the licensed receiver, is deeply faded. In this paper we investigate the capacity gains offered by this dynamic spectrum sharing approach when channels vary due to fading. In particular, we quantify the relation between the secondary channel capacity and the interference inflicted on the primary user. We further evaluate and compare the capacity under different fading distributions. Interestingly, our results indicate a significant gain in spectrum access in fading environments compared to the deterministic case.