OFDM系统中D2D通信资源分配算法的研究

发布时间：2018-12-10 13:40

【摘要】：在传统蜂窝系统中引入Device-to-Device(D2D)通信技术能够降低终端的发射功率,减轻基站的负担,提高系统的频谱利用率,在一定程度上解决无线通信系统频谱资源匮乏这一难题。然而该技术的引入也带来了蜂窝系统与D2D系统之间的干扰问题,如何协调好系统资源进行合理地信道和功率分配,成为当前的一个重要课题。本文分析了D2D和蜂窝混合系统的频谱共享方式和上下行干扰模型,研究了功率控制技术对系统性能的影响与信道分配,具体内容如下：(1)研究了D2D系统中资源集中优化分配算法,该算法中D2D用户可使用多个子载波,对蜂窝用户和D2D用户的发射功率同时进行优化,由于蜂窝用户和D2D用户的资源分配方式都受基站控制,因此基站需要搜集所有用户的信道信息。为了减轻基站的负担,可以采用次优的分布式资源分配方法,各个用户自行搜集信道信息,蜂窝用户以固定功率发射,优化D2D用户的发射功率。为了便于实现D2D用户通常只用一个子载波进行通信,在这种场景下,对蜂窝和D2D用户的发射功率同时进行优化,该算法的复杂度较低,但性能也会有所下降。仿真比较了三种分配算法下D2D用户的吞吐量性能。(2)在确保蜂窝用户通信质量的前提下,提出一种D2D用户的资源分配算法,该算法以最大化D2D用户的系统容量为目标构建优化问题,并分两步求解。首先,以最小化对蜂窝用户造成的干扰和最大化D2D用户的系统容量为准则,为D2D用户分配子载波；其次,采用次梯度法求解功率。仿真结果表明,该算法对D2D用户的系统容量和系统总容量都有所提高。(3)提出了一种基于图论和博弈论的资源分配算法,为D2D用户分配子载波和发射功率。首先利用图论着色理论为D2D用户分配可用的子载波,为确保蜂窝用户的通信QoS对D2D用户的颜色集合进行调整,然后构建D2D用户之间的有向权重干扰图,再次调整各用户的颜色集合；接着引入博弈论理论对D2D用户在各可用子载波上的发射功率进行分配,理论推导和仿真都验证了纳什均衡点的存在性和唯一性。仿真结果表明该算法在保证蜂窝用户QoS条件下,提高了D2D用户的吞吐量和频谱利用率。
[Abstract]:The introduction of Device-to-Device (D2D) communication technology in traditional cellular system can reduce the transmission power of the terminal, lighten the burden of the base station, and improve the spectrum efficiency of the system. To a certain extent, the problem of spectrum scarcity in wireless communication systems is solved. However, the introduction of this technology also brings the interference between the cellular system and the D2D system. How to coordinate the system resources for a reasonable channel and power allocation has become an important issue at present. In this paper, the spectrum sharing mode and upstream / downstream interference model of D2D and cellular hybrid systems are analyzed, and the influence of power control technology on system performance and channel allocation are studied. The main contents are as follows: (1) the optimal resource allocation algorithm in D2D system is studied. In this algorithm, the transmit power of both cellular and D2D users can be optimized simultaneously by using multiple subcarriers. Because the resource allocation of both cellular and D2D users is controlled by the base station, the base station needs to collect the channel information of all users. In order to lighten the burden of the base station, the sub-optimal distributed resource allocation method can be adopted. The channel information can be collected by each user, and the transmission power of the D2D user can be optimized by the cellular user transmitting with the fixed power. In order to realize D2D user communication with only one subcarrier, in this scenario, the transmission power of both cellular and D2D users is optimized simultaneously, the complexity of the algorithm is lower, but the performance will also be degraded. The throughput performance of D2D users under three allocation algorithms is compared. (2) under the premise of ensuring the communication quality of cellular users, a D2D user resource allocation algorithm is proposed. The algorithm aims at maximizing the system capacity of D2D users and solving the optimization problem in two steps. Firstly, subcarriers are assigned to D2D users based on the criteria of minimizing interference to cellular users and maximizing the system capacity of D2D users. Secondly, subgradient method is used to solve the power problem. Simulation results show that the proposed algorithm improves both the system capacity and the total system capacity of D2D users. (3) A resource allocation algorithm based on graph theory and game theory is proposed to allocate subcarriers and transmit power to D2D users. In order to ensure the communication QoS of cellular users, the color set of D2D users is adjusted by using graph theory coloring theory to allocate available subcarriers to D2D users, and then the directed weight interference graph between D2D users is constructed. Adjust the color set of each user again; Then the game theory is introduced to allocate the transmit power of D2D users on each available subcarrier. The theoretical derivation and simulation verify the existence and uniqueness of Nash equilibrium point. The simulation results show that the proposed algorithm can improve the throughput and spectrum efficiency of D2D users under the condition of guaranteed cellular user QoS.
【学位授予单位】：南京邮电大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN929.53

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