认知无线电中的敏捷增益分析

Analysis on Agility Gain in Cognitive Radio

改进原有模型中的问题,利用新的数字模型研究了在中继用户有功率约束条件下,路径损耗指数之比、主用户与认知用户直线间的夹角、发射功率对敏捷增益的影响;并且通过分析论证和大量的仿真运算证明了新数字模型更具有可行性.结果表明:认知用户的传输衰减比主用户传输衰减慢时,感测性能能够得到明显改善;敏捷增益随角度的增加而减小;认知用户的传输功率远小于主用户传输功率时,认知用户无法获得敏捷增益.

The original model has been improved,impacts of some important parameters on agility gain are discussed by using a new numerical model for the cooperative scheme based on cooperative relay,when there is transmission power constraint for the relay user.The parameters that are taken into account are as follows： the ratio of path loss exponent α2/α1,the angle  between the straight line from the primary to cognitive user and the straight line from cognitive to cognitive user,and transmission power.The feasibility of our model is well explained and supported by extensive simulations. The results indicate that when cognitive user＇ s transmission attenuate more slowly than the primary transmissions do, the improvement in sensing performance reduces remarkably ; also, the agility gain decreases with the increasing of angle qo ; finally, while the transmission power of cognitive user is much smaller than that of primary user, it is hard to achieve agility gain for cognitive user.