NeTS-WN: COGNET: Cognitive Radio Networks based on OFDM

认知无线电网络使得能够与授权用户共享无线频谱，但是由于频谱的波动性质以及不同的服务质量（QoS）要求而带来挑战。为了解决这些挑战，提出了一种基于正交频分复用（OFDM）的频谱感知认知无线电网络（COGNET），主要研究了五个方向：（1）首先，开发一种对非线性具有鲁棒性的频率捷变、宽带模拟/RF前端技术（RF/模拟IC设计）。(2)为了检测授权用户的存在，利用多用户网络固有的空间分集特性，提出了一种快速检测方案（频谱感知）。（3）为了选择最佳信道，提出了一种新的综合考虑信道信息、授权用户活动和应用需求的判决方法（频谱判决）。(4)提出了一种双模式频谱共享框架，该框架能够接入现有网络以及认知无线电用户之间的协调（频谱共享）。(5)提出了一种频谱移动性管理框架，以实现有效的操作，认知用户之间的信道切换时，检测到一个授权用户（频谱移动性）。虽然COGNET最初被提议用于基础设施和ad hoc网络，但由于预算削减，ad hoc网络的研究主题（“COGNET ad hoc接入的合作频谱感知”和“COGNET ad hoc接入的频谱自适应路由恢复”）将不会被研究。

Cognitive radio networks enable the sharing of the wireless spectrum with licensed users, but impose challenges due to the fluctuating nature of the spectrum as well as the diverse quality-of-service (QoS) requirements. To address these challenges, a spectrum-aware COGnitive radio NETwork (COGNET) based on orthogonal frequency division multiplexing (OFDM) is proposed.In COGNET, five major research directions are investigated: (1) First, a frequency agile, wideband analog/RF front-end technology is developed, which is robust to non-linearity (RF/analog IC design). (2) To detect the presence of licensed users, a fast detection scheme is developed by exploiting the spatial diversity inherent to multi-user networks (spectrum sensing), (3) To select the best channel, novel decision methods are proposed that consider channel information, licensed user activities, and application requirements (spectrum decision). (4) A dual-mode spectrum sharing framework is proposed, which enables access to existing networks as well as coordination between cognitive radio users (spectrum sharing). (5) A spectrum mobility management framework is proposed to achieve efficient operations as cognitive users switch between the channels when a licensed user is detected (spectrum mobility). Based on these research topics, a testbed is developed to demonstrate the protocols developed on cognitive radio transceivers.Although COGNET was originally proposed for both infrastructure and ad hoc networks, due to the budget cut, research topics on ad hoc networks ("cooperative spectrum sensing for COGNET ad-hoc access" and "spectrum-adaptive route recovery for COGNET ad hoc access") will not be investigated.