Research On D2D Power Control And Safety Rate Technology In Cellular Networks

The introduction of D2 D communication technology in cellular networks allows communication between neighboring users to be transmitted without relaying through a base station(BS),thus improving the whole resource utilization.However,the introduction of D2 D communication will cause the D2 D signal to become a new source of interference,causing the cellular link to be interfered by the D2 D transmission,which will not only be interfered with by other D2 D users,but also be interfered by the cellular link.Therefore,to ensure the successful co-existence of cellular subscribers and D2 D links,interference management is essential.Power control is an effective way to mitigate interference in wireless networks,and is widely used in today's wireless systems.In this paper,we first analyze the application of D2 D communication technology in cellular networks.When there is interference between D2 D users and cellular systems after the introduction of D2 D communication in cellular networks,a power control algorithm based on interference alignment(IA)is proposed.The algorithm provides the opportunity for all D2 D Links to share the available subcarriers simultaneously using IA technique.Besides,it controls the power budget of each D2 D pair in order to maximize the sum-rate of the system without inducing excessive interference to cellular user(CU).The simulation results show that compared with the fractional power control algorithm in conventional frequency division multiple access(FDMA)system,the power control algorithm achieves a total rate of 6bit / s / Hz for the D2 D user when the interference threshold is 10 dBm.Then,an improved power control algorithm based on IA is proposed to overcome the shortcomings of high computational complexity of power control algorithms based on IA.The algorithm uses IA technique to make all D2 D users occupy the available sub-carriers at the same time,it controls the power budget of each D2 D pair with water-filling in order to maximize the sum-rate of the system without inducing excessive interference to CU.The simulation results show that compared with the fractional power control algorithm in conventional FDMA system,the total power of the D2 D user is increased by about 5bit / s / Hz when the interference threshold is 10 dBm and also significantly reduces the computational complexity.The new application scenario exposes the unique security threats of D2 Dcommunication services.Then in this paper,an optimization of D2 D security rate algorithm based on power control is provided to enhance the physical layer security underlaying D2 D communication and guarantee the data rate requirement of the CU at the same time.First,a scenario model is set up,in which an eavesdropper is considered to wiretap the information of D2 D transmitters.Then,a secure region of D2 D communication is proposed,when D2 D residing outside the secure region,the spectrum of CU's is not allowed to share with the D2 D so as to avoid eavesdropper tapping useful information of D2 D.When D2 D residing inside the secure region,the security rate of D2 D is maximized by optimization the transmitting power of D2 D and CU.The simulation results show that the achieved D2 D security rate of the proposed algorithm increases 2.8bps / Hz when signal to interference plus noise power ratio(SINR)is 15 dB,compared with that when using random access algorithm.