认知无线电网络的MAC层关键技术

认知无线电作为一种智能的频谱共享技术，已成为无线通信领域的研究热点。为达到在不干扰授权用户的条件下有效地实现机会式频谱利用，认知无线电网络的媒体接入控制（MAC）层不仅需要提供传统的服务，还要求能支持一套全新的功能。频谱检测管理通过对检测模式的选取、检测周期及检测时长的设置、检测信道的选取和检测静默期的设置等实现检测策略和参数的选取及优化。接入控制主要采用与授权用户协调接入和透明接入两种方式避免与授权用户的接入产生碰撞。动态频谱分配针对二进制干扰模型和累积干扰模型进行不确定频谱资源的优化分配。安全机制通过增加MAC帧的认证和保密以防御MAC层的安全攻击。跨层设计结合物理层和网络层、传输层等上层信息设计和实现全局优化的MAC层技术。

MAC Layer Key Technologies of Cognitive Radio Network

As a smart spectrum sharing technology, cognitive radio is becoming a hot topic in the field of wireless telecommunications. Besides providing traditional services, the cognitive radio network Media Access Control （MAC） layer is required to perform an entirely new set of functions for effective reusing spectrum opportunity, without causing any harmful interference to incumbents. Spectrum sensing management selects and optimizes sensing strategies and parameters by the selection of sensing mode, sensing period, sensing time, sensing channel, and sensing quiet period. Access control avoids collision with primary users mainly by cooperation access and transparent access. Dynamic spectrum allocation optimizes the allocation of uncertain spectrum for binary interference model and accumulative interference model. Security mechanism adds authentication and encryption mechanisms to MAC frame to defense MAC layer security attacks. Cross-layer design combines MAC layer information with physical layer or higher layers information, such as network layer, transmission layer, to achieve global optimization.