Cognitive Coexistence of Non-cooperative Heterogeneous Wireless Systems

频谱共享最近被视为提高现有无线系统性能、满足日益增长的频谱接入需求以及实现新应用的重要组成部分。例如，蜂窝系统可以通过毫微微小区提供更好的覆盖和容量，其中主网络使用的频谱在由低功率基站覆盖的本地区域共享。此外，频谱共享作为一种解决频谱稀缺悖论的方法正受到越来越多的关注，因为存在着大量低效利用许可频谱的情况。在这种情况下，在频谱的主用户和次用户之间以及在多个并置的次系统之间出现共存问题。通常，媒体访问控制和物理层标准不支持网间通信，协作共享策略非常有限。因此，不同的无线系统将需要共存，同时独立运行，而不需要合作。

Spectrum sharing has been recently seen as a vital ingredient in enhancing the performance of existing wireless systems, satisfying the growing demand for spectrum access, and enabling new applications. For example, cellular systems can provide improved coverage and capacity via femto cells, in which the spectrum used by the main network is shared over a local area covered by a low power base station. Furthermore, spectrum sharing is receiving increasing attention as a solution to the paradox of spectrum scarcity amid the existence of broad expanses of inefficiently utilized licensed spectrum. In such scenarios, coexistence problems arise between the primary and secondary users of the spectrum, as well as between multiple collocated secondary systems. Usually, the medium access control and physical layer standards do not support inter-network communications, and cooperative sharing strategies are very limited. Hence, heterogeneous wireless systems will need to coexist while operating independently without cooperation.