Cognitive radio networks enabling techniques

认知无线电网络支持技术

• 批准号: 3917-2011
• 负责人: Yongacoglu, Abbas
• 金额: $ 2.33万
• 依托单位: University of Ottawa
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2011
• 资助国家: 加拿大
• 起止时间: 2011-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=473768
• 关键词: Cognitive; radio; networks; enabling; techniques

It appears that with the introduction of each new service at highly desirable frequency bands (e.g. 1 to 3 GHz), bandwidth scarcity becomes more acute. For decades, most of the demand for efficient utilization of spectrum has been addressed by improvements in modulation, coding and multiple access techniques. Further efficiency improvements by these conventional approaches seem to be limited. More importantly, it has been determined that often there is no real scarcity of spectrum to meet the increased demand. Scarcity is due to static and permanent assignment of the bands only to license holders. Considering space-time distribution of spectrum, the desirable frequency bands are severely underutilized at many locations for most of the time. Once the conventional model is modified to allow unlicensed users to share the spectrum, the scarcity can disappear. Hence the critical issue is to find ways to dynamically utilize the available bandwidth. Cognitive Radio (CR) allows unlicensed secondary users to share the spectrum that is licensed to primary users. This sharing may take place if secondary users transmit when primary user is not active, or by transmitting at a level not harmful to the license holder.

看来，随着每项新服务在非常理想的频段（例如 1 至 3 GHz）的推出，带宽稀缺问题变得更加严重。几十年来，高效利用频谱的大部分需求已通过调制、编码和多址技术的改进得到满足。这些传统方法的进一步效率提高似乎受到限制。更重要的是，已经确定通常并不存在真正的频谱短缺来满足不断增长的需求。稀缺性是由于频段仅静态且永久地分配给许可证持有者。考虑到频谱的时空分布，在大多数时间，许多地点所需的频段都严重未得到充分利用。一旦传统模式被修改为允许未经许可的用户共享频谱，稀缺性就会消失。因此，关键问题是找到动态利用可用带宽的方法。认知无线电 (CR) 允许未经许可的次要用户共享许可给主要用户的频谱。如果次要用户在主要用户不活跃时进行传输，或者以对许可证持有者无害的级别进行传输，则可以发生这种共享。