Research On Resource Allocation And Power Control Strategies For D2D Communication In Cellular Networks

With the rapid development of mobile communication technology,the number of mobile devices in the world is increasing exponentially.Mobile intelligent terminals need spectrum resources to access communication networks,but spectrum resources are limited.The surge in the number of smart devices makes the available spectrum resources less and less,scarce spectrum resources restrict the further improvement of the mobile communication rate.While scholars in the communication field were troubled by the lack of spectrum resources,D2D(Device-to-Device)communication technology emerged as the times require.In cellular networks,D2D communication technology allows two D2D users with similar geographical locations to reuse the spectrum of cellular users to communicate with each other,this technology can save spectrum resources and improve frequency band utilization,it is one of key technologies in 5G communication applications.The introduction of D2D users into the traditional cellular system will bring about the problem of co-frequency interference while improving the frequency band utilization.Usually,the D2D communication-related algorithms aim to reduce the total system interference and improve the total system throughput.This paper focuses on the early application of D2D technology and the adaptability of it to 5G related applications.The main research is divided into following two parts:(1)Chapter 3 proposes a resource allocation algorithm based on greedy strategy in the priority scenario.The algorithm considers both user priority and service priority,and proposes the concept of comprehensive priority,then it converts the interference difference between D2D users and cellular users into the priority gradient of cellular user.D2D users with less link interference are preferentially allocated to cellular users with higher priority.This method establishes a reasonable user priority mechanism based on the difference of cellular link interference,which fully guarantees the satisfaction of cellular users and improves it of whole users in the system.Therefore,this scheme is suitable for the communication systems in transition period of turning pure cellular into cellular-D2D.The simulation results show that the algorithm in this chapter can effectively improve the communication quality satisfaction of each priority cellular user in the system,and it can better guarantee the communication experience of cellular users than other general D2D communication algorithms.(2)Chapter 4 proposes an algorithm named Fast Joint Power Control Algorithm Based on Hungarian Algorithm.The power control part of the algorithm is based on the Joint Power Control Algorithm.By flexibly setting the power adjustment step in the closed-loop control link to let it be positively correlated with the SINR difference,the method reduces the iteration times of user power’s adjustment and improves the speed of this process,it reduces the communication delay by reducing the time for users’SINR from initial state to be stable.Therefore,the algorithm is more suitable for 5G communication system that has stricter requirements on communication delay than 4G.The resource allocation part of the algorithm has the ability to reduce the total interference in the system by introducing the Hungarian algorithm.When interference of the system is reduced,the power of transmitters to reach the target SINR range of users will also decrease accordingly,then the power consumed by whole system will decrease.This optimization is conducive to the development of low-carbon and environmental protection businesses.The simulation results show that the algorithm proposed in this chapter can effectively reduce the iterations of user’s transmit power,so the time delay caused by power adjustment in communication can be decreased.Total transmit power of the system can be reduced as well.