基于协作中继的认知无线电网络性能优化

PERFORMANCE IMPROVEMENT WITH COOPERATIVE RELAYING IN THE COGNITIVE RADIO NETWORKS

认知无线电被认为是一种在允许主从网络共存的情况下,完成高效频谱利用的智能无线通信系统。其中有一个基本挑战,是在最大化认知无线电用户的传输速率的情况下保证主网链接的服务质量(QoS)。研究了在次要网络中基于协作的频谱存取方式。在严格的QoS要求下,认知无线电被允许传输的功率很低,因此传输速率受到限制。如果认知无线电用户可以获得来自周围认知无线电用户的协作,这将有利于提高传输速率。能够提供最大传输速率的最佳中继被用来进行协作。对峰值干扰受限和平均干扰受限的传输速率性能进行研究。仿真结果表明,通过协作,认知无线电链路的传输速率可以提高,尤其是当直接链路的功率受限时。在平均干扰约束下,由于传输端和中继的功率适应性,传输速率优于峰值干扰限制下的情况。传输速率要优于直接传输。并且随着潜在中继数量的增长,将获得更高的增益。

The cognitive radio has been considered as an intelligent wireless communication system to achieve efficient spectrum usage by allowing the coexistence of the primary and secondary networks.One fundamental challenge is to ensure the quality of service （QoS） of the primary link while maximizing the transmission rate of the cognitive radio user.We investigate the cooperation based spectrum access at the secondary networks.If the QoS requirement is stringent,low power is allowed at the cognitive radio transmitter and hence the transmission rate is limited.It is beneficial that the cognitive radio user can obtain cooperation from the surrounding cognitive radio users to increase the transmission rate.The best relay which can provide the maximal transmission rate is selected for cooperation.The transmission rate performance is investigated under the peak and average interference constraints.The simulation results show that the transmission rate of cognitive radio link rate can be improved by cooperation,especially when the power of the direct link is limited.Under the average interference constraint,the transmission rate is better than that under the peak interference constraint,due to the power adaptation between the transmitter and relay.Finally,the higher gain can be obtained as the number of potential relays increases.