CIF: Small: Cognitive Spectrum Access: Fundamental Limits, Protocols, and Performance Analysis

通过未经许可的频谱进行无线接入是未来宽带计划的主要组成部分。不幸的是，未经许可的频段拥塞，现有技术不能为具有不同接入优先级和需求的用户提供质量保证。缺乏服务质量保证是提供多媒体内容和促进宽带通信的关键障碍。迫切需要通过动态频谱感知、学习和频谱机会的认知共享来提供无许可频谱的分布式分层接入的技术。这项研究为多类别用户共享的无线频谱认知接入发展了数学理论和实用方法。本研究的技术方法是基于某些载波监听策略的结构最优性。这些策略的最优性和简单性导致了不同优先级用户之间认知频谱共享的新的实用但最优的解决方案。总体目标有两个。首先，它的目的是对分层网络中认知频谱接入的限制有一个基础性的了解。特别是，它通过利用认知感知和接入的最优策略的结构来表征不同优先级的用户的最大吞吐量和有效带宽区域。其次，提出了共享频谱分散认知接入的工程实用解决方案。特别是，新的多用户监听和接入协议被开发和测试用于实际应用。此外，还研究了衰落、干扰和其他实现问题的影响。这项研究包括一个重要的教育组成部分，旨在将前沿研究与本科生和研究生课程相结合。

Wireless access through unlicensed spectrum is a major component for future broadband initiatives. Unfortunately, unlicensed frequency bands are congested, and existing technologies do not provide quality assurance for users with different access priorities and needs. The lack of quality of service guarantee is a key roadblock to providing multimedia content and facilitating broadband communications. There is a cogent need for technologies that provide distributed hierarchical access of unlicensed spectrum through dynamic spectrum sensing, learning, and cognitive sharing of spectrum opportunities. This research develops mathematical theory and practical methodologies for the cognitive access of wireless spectrum shared by multiple classes of users. The technical approaches of this research are based on the structural optimality of certain carrier sensing policies. The optimality and simplicity of these policies result in new practical yet optimal solutions to cognitive spectrum sharing among users from different priority classes. The overall objective is twofold. First, it aims at gaining a foundational understanding of the limits of cognitive spectrum access in hierarchical networks. In particular, it characterizes the maximum throughput and effective bandwidth regions for users for different priority classes by exploiting structures of optimal policies for cognitive sensing and access. Second, this research develops engineering practical solutions for decentralized cognitive access of shared spectrum. In particular, new multiuser sensing and access protocols are developed and tested for practical applications. Effects of fading, interference and other implementation issues are also examined. This research includes a significant education component aimed at integrating frontier research with undergraduate and graduate curricula.