由于终端资源受限,蜂窝上行链路传输的安全性难以保证.考虑到D2D (device-to-device)蜂窝系统中同频干扰能够带来安全增益,提出一种机会D2D接入的安全传输方案.该方案分别利用无线信道的方向性和增益刻画复用资源的D2D用户对蜂窝用户和其他D2D用户的干扰大小,为保证两者通信的可靠性,首先,选择满足干扰受限条件的D2D用户接入网络进行通信,而接入网络的D2D用户可看作蜂窝用户的友好干扰者为其带来安全增益.其次,采用泊松点过程(PPP,Poisson point process)对系统中的各节点进行建模,分别利用安全中断概率(SOP,secrecy outage probability)和连通中断概率(COP,connection outage probability)表征蜂窝用户通信的安全性和D2D用户通信的可靠性,并分析了干扰门限对两者通信性能的影响.然后,在保证蜂窝用户SOP性能需求的前提下,提出一种在满足蜂窝用户安全性的条件下,最小化D2D用户COP的优化模型,并利用联合搜索方法得到最佳干扰门限值.最后,仿真证明了所提方案的有效性.%The mutual interference between cellular links and D2D links can bring the secrecy gain to cellular users in D2D-enable cellular networks.To make full use of them,a cooperative secrecy transmission scheme was proposed based on wireless channels.The channel direction information and gains depict the interference from D2D links to cellular links and other D2D links in the proposed scheme.Firstly,only the D2D users which meet the limited interference conditions were accessed to cellular networks to ensure their reliable communications.It was assumed that legitimate users and eavesdroppers were independent two-dimensional homogeneous Poisson point processes (PPP) distribution.Then the security outage probability (SOP) was derived for cellular users and the connection outage probability (COP) for D2D users,and the impacts of interference thresholds were discussed on their performances.Next,an optimization model was given to minimize D2D users' COP while ensuring the secrecy performance requirements of cellular users,thus achieving the optimal performance.Finally,simulation results verify the validity of the proposed scheme.
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