| In order to cope with the predicament of spectrum scarce in communication networks and meet the rapid growth of data traffic in cellular communications brought by multimedia and social network applications,Device-to-Device communications(D2D)is introduced into 5G communication network.Moreover,D2 D communication underlying cellular network can not only improve the overall system data rate and the performance of cell edge users,but also reduce the communication transmission delay and the traffic load of central BS.However,because D2 D users reuse the spectrum resources of cellular users,there will occur interference between users which sharing the same spectrum.In order to effectively avoid interference and improve the performance of D2 D communication systems,it is necessary to reasonably and effectively allocate communication resources to users.In view of this,this paper mainly focuses on the resource allocation problems in D2 D communications underlying cellular networks which mainly studies the resource management problem of D2 D unicast and multicast communication mode to improve their system performance.For the different the research contents about the different communication modes of D2 D communications,we designed different mathematical models and further proposed different resource management schemes.Besides,the performance of the proposed algorithm is verified by simulations.Specifically,our works mainly conclude into the following two aspects:(1)We studied the joint uplink and downlink resource allocation problem for D2 D unicast communications underlying cellular networks which maximizes the overall data rate of the system.Specifically,unlike the previous communication scenario in which the D2 D pair can only reuse the uplink or downlink subcarriers of the cellular network,this paper allows the D2 D pairs to jointly reuse the uplink and downlink subcarrier resources,and maximizes the overall system data rate under the all user's basic data rate requirements.In order to solve the Mixed Integer Non-leaner programming(MINLP),we proposed subcarrier allocation and power control algorithm.First,for each potential pairing of cellular and D2 D users,a geometric programming algorithm is used to derive the user's optimal power control solutions.Then,the Hungarian algorithm is used to achieve optimal matching between subcarrier resources and D2 D users.Finally,the proposed resource allocation algorithm is verified by reasonable simulation experiments.The experimental results show that the joint reusing of uplink and downlink subcarrier resources is performs better than the traditional resource allocation scheme.It is shown that not only the overall system data rate can be enhanced,but also the access rate of D2 D users can be further improved.(2)We studied the resource allocation problem for D2 D multicast communications underlying cellular network under the “many-to-many” subcarrier sharing model which aims to maximize the multicast data rate from the perspective of overall system resource management.Specifically,it is studied to maximize the data rate of D2 D multicast groups based on meeting the basic data rate requirements of cellular users.The problem is mathematically modeled and the nature of the problem is analyzed as MINLP problem,so the problem is decomposed into two sub-problems.For the subcarrier assignment subproblem,a heuristic subcarrier allocation algorithm is proposed.Based on this,for the power allocation problem,the D.C.programming is first used to convert the non-convex function into a convex function form.The non-smooth objective function is then processed to further reveal the hidden convex optimization programming.Finally,the proposed algorithm is analyzed through detailed simulation experiments.The simulation results show that the "many-to-many" subcarrier sharing scenario and joint subcarrier assignment and power control from the perspective of overall resource management can greatly improve the sum of data rates of D2 D multicast groups. |
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