Research On Key Technologies Of Cognitive Vehicle Ad Hoc Network Based On Radar Detection

In the scenario of cognitive vehicular ad-hoc network(VANET),the secondary user accesses the spectrum of the primary users for data transmission opportunistically in order to improve the utilization of spectrum resources.However,due to the strong mobility of the VANET and the randomness of the communication process,the traditional spectrum sensing technologies are prone to cause serious interference to the primary users and they are unable to detect the driving conditions of surrounding vehicles autonomously.Forthermore,the performance of spectrum sensing is also unstable.In view of the above problems,this thesis studies the cognitive VANET technology based on radar detection.The main contributions are as follows.1.Considering the limitation of the space of vehicles and the integration trend of on-board radar and communication unit,this thesis studies the cognitive VANET technology based on radar detection for the purpose of achieving maximum communication efficiency for the secondary user from the perspective of time allocation.And then the radar sensing-throughput trade-off problem is proved.The feasibility of radar detection technology is verified by simulation analysis.It is also proved that there exists the optimal time allocation scheme under the condition of sufficient protection of the primary users,and the throughput of the secondary user is maximized.For the three target types of Swerling 0,2,and 4,when the frame duration is 10ms,the average SNR of the radar signal is 10dB,the optimal radar sensing time achieving the maximum throughput are 0.05ms,0.14ms and 0.09ms,respectively.2.Since the intelligent vehicles are passive during driving,this thesis studies the cognitive VANET technology based on radar detection from the perspectives of time allocation and energy control.Through simulation and analysis of the radar sensing-throughput trade-off problem,it is proved that under the condition of the primary users being protected sufficiently,there exists the optimal energy allocation scheme and the joint allocation scheme to maximize the throughput of the secondary user.For the three target types of Swerling 0,2,and 4,when the frame duration is 10ms,the total energy of each frame is 10mJ,the optimal radar sensing time and radar system energy achieving the maximum throughput are 0.02ms and 0.3mJ,0.03ms and 0.8mJ,0.02ms and 0.4mJ,respectively.