基于OFDMA的认知无线电网络联合资源分配算法研究

发布时间：2018-01-03 04:07

本文关键词：基于OFDMA的认知无线电网络联合资源分配算法研究　出处：《吉林大学》2016年硕士论文　论文类型：学位论文

更多相关文章： 认知无线电 资源分配 OFDM 鲁棒性

【摘要】：无线电资源日益紧张,但据调查显示,传统资源分配算法的频谱利用率很低。为解决无线电资源紧缺的问题,认知无线电这项技术应运而生。认知无线电(Cognitive Radio,CR)网络通过感知频谱空穴,未授权用户(次用户,Second User,SU)利用授权用户(主用户,Primary User,PU)占用的频谱资源来传输信息,在次用户传输信息的过程中需要根据传输环境来自适应调整一些传输参数,如传输速率、传输功率和带宽等。在这一过程中,次用户对主用户产生的干扰是影响认知无线电网络传输质量的主要因素。正交频分复用系统(Orthogonal Frequency Division Multiplexing,OFDM)能够灵活地动态分配子载波给多个用户,并且相邻子载波间的干扰较低。因此,它在认知无线电网络中得到了广泛的使用。在实际的OFDM系统中,由于传输信号不完全正交,使得主用户和次用户间存在相互干扰。而传统的资源分配算法可能会对主用户产生过高的干扰。在传统的认知无线电网络中,通常以填充或衬底的方式为次用户分配频谱。填充式即认知无线电网络感知频谱空穴,次用户利用没有被主用户占用的频谱进行传输,并在一定的总功率和干扰上限的约束下最大化传输速率。而认知网络以衬底方式分配资源时,只要次用户对主用户的干扰在一定阈值内,网络就允许次用户与主用户一起共享该频谱。由于单独的填充式或衬底式的资源分配算法不能够充分利用频谱资源,因此有些学者提出了填充和衬底联合的频谱接入方式。在以往的联合资源分配算法中,只考虑填充这种方式的子载波所产生的干扰,未考虑以衬底方式分配子载波所产生的干扰,且在次用户网络中,没有考虑感知错误对网络通信质量的影响。子载波分配是资源分配的第一步,一些子载波分配算法只是根据次用户发射机到次用户接收机的信道增益来为次用户分配子载波,还有一些算法即考虑信道增益又考虑传输速率。但在这些子载波分配算法中,都忽略了次用户的初始功率分配对子载波分配的影响。目前,针对联合资源分配算法的研究都假设信道增益已知,但在实际的通信场景中,信道不确定性会对认知无线电网络通信质量产生影响。本文中以填充和衬底联合的形式为多个次用户分配资源,首先提出一子载波分配算法,在子载波分配过程中,采用子载波分配度量因子。此度量因子与信道情况、子载波干扰、子载波功率有关。根据计算度量因子的数值,将信道情况好,且对其它子载波产生干扰小的子载波优先分配给次用户,这种分配方式更加公平,可使每个次用户传输速率基本一致。在最优功率分配过程中,利用了拉格朗日乘子和KKT条件来计算功率,最大化传输速率,并控制总干扰和总功率在一定阈值内,同时考虑了感知错误对认知无线电网络的影响。最后,我们基于Worst-case方法,对次用户和主用户间的信道不确定性进行鲁棒性分析,并利用拉格朗日对偶法来求解最优功率值。仿真结果表明,在相同条件下,文中提出的资源分配最优算法和次优算法都要优于单独的填充式或衬底式资源分配算法。子载波分配算法能够保证每个次用户的利益。通过对次用户和主用户间的信道不确定性进行鲁棒分析可以使认知无线电网络通信性能更稳定。
[Abstract]:The radio resources are increasingly strained, but according to the survey, the traditional resource allocation algorithm of the spectrum utilization rate is very low. In order to solve the problem of shortage of radio resource, cognitive radio emerged. The technology of cognitive radio (Cognitive Radio CR) network through spectrum sensing hole, unauthorized users (secondary users, Second User, SU) by authorization users (primary users, Primary User, PU) the occupied spectrum resource to transmit information, in the process of transmission of information to users according to the transmission environment to adaptively adjust some transmission parameters such as transmission rate, transmission power and bandwidth. In this process, the interference of secondary users to primary users is generated the main factors of the cognitive radio network transmission quality. Orthogonal frequency division multiplexing system (Orthogonal Frequency Division Multiplexing, OFDM) can dynamically allocate the subcarriers to multiple users, and The interference between neighboring subcarriers is low. Therefore, it has been widely used in cognitive radio networks. In the practical OFDM system, because the transmission signals are not completely orthogonal to the interference between the users and the winner between secondary users. The traditional resource allocation algorithm may produce excessive interference to primary users. In the cognitive radio network in the traditional, usually to fill or substrate for secondary users of spectrum allocation in cognitive radio networks. The filling type sensing spectrum holes of secondary users are not using the spectrum of the primary user occupied for transmission, and the total power in a certain limit and interference under the restriction of the maximum transmission rate and cognitive. The network distribution of resources by way of time as long as the substrate, interference to the primary user in a certain threshold, the network allows secondary users and primary users share the spectrum. The separate filling or lining At the end of the resource allocation algorithm can not make full use of spectrum resources, so some scholars put forward the way of filling joint and the substrate spectrum access. In the joint resource allocation algorithm in the past, only considering the carrier interference generated by filling this way, without considering the interference to the substrate produced by the way subcarrier allocation, and in the secondary users in the network, without considering the influence of perceived errors on the quality of network communication. The subcarrier allocation is the first step in the allocation of resources, some subcarrier allocation algorithm is based on the secondary user transmitter to the user receiver channel to gain user subcarrier allocation algorithm, and some consider the channel gain and consider the transmission rate. But in the subcarrier allocation algorithm, have ignored the impact of the user's initial power allocation of subcarrier allocation. At present, the research on joint resource allocation algorithm Assume that the channel gain is known, but in the actual communication scenario, the channel uncertainty will affect the quality of communication in cognitive radio networks. In the form of filling and the substrate in this paper combined into a plurality of user resource allocation, first proposed a subcarrier allocation algorithm, the subcarrier allocation, using subcarrier allocation measure factor. This measure factor and channel condition, sub carrier interference, the sub carrier power. According to the numerical calculation of measurement factors, the situation of the channel, and the interference of small sub carrier allocation of priority to the secondary users other sub carriers, this allocation more equitable, can make each time the user transmission rate is basically the same. The optimal power allocation process, using the Lagrange multipliers and the KKT condition to calculate power, the maximum transmission rate, and control the total interference and the total power in a certain threshold, while taking into account the sense Know the effect of error on the cognitive radio network. Finally, we based on the Worst-case method, the channel time between the user and the primary user uncertainty robustness analysis, and using Lagrange dual method to solve the optimal power value. The simulation results show that under the same conditions, the proposed algorithm and the optimal resource allocation algorithm is superior to the filling type resource allocation algorithm or substrate alone. The subcarrier allocation algorithm can guarantee that each time the interests of users. Robust analysis can make cognitive radio network communication performance is more stable through the channel between the user and the primary user time uncertainty.

【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN925

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