Resource Allocation for OFDM Based Cognitive Radio System
Resource Allocation for OFDM Based Cognitive Radio System
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发表时间：
2015
期刊：
影响因子：
2.1
通讯作者：
Kartik Chaudhary;Bharatkumar D. Prajapati
中科院分区：
文献类型：
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作者：
Kartik Chaudhary;Bharatkumar D. Prajapati
认知无线电是一种提高无线电频谱利用率的新概念。它是一种软件控制的无线电，可以随时从广阔但拥挤的无线电频谱中感知未使用的频谱。这保证了稀缺的无线电资源的有效利用。正交频分复用（OFDM）是认知无线电系统中一种可靠的传输方案，它为动态环境下的无线资源分配提供了灵活性。它还保证了相邻的CR无线信道之间没有相互干扰，使其成为CR系统中使用的最佳方案之一。无线资源分配是认知无线电系统面临的主要挑战。在动态环境中，必须考虑影响系统总数据速率的许多参数和情况。次要用户（CRU/SU）可以在保守的基础上或在更积极的基础上与主要用户（PU）共存，只要对PU的感应干扰低于可接受的水平，就允许次要传输。在本文中，我们考虑了具有一个PU的上行链路认知无线电系统与M个SU共存，以及具有一个基站（BS）服务一个PU和K个SU的多用户正交频分复用CR系统的下行链路。本文重点研究了认知OFDM系统在非理想CSI下的子载波和功率分配方案的设计与分析。提出了一种两步比特率算法，用于获得（1）次用户的子载波分配和（2）子载波上的比特功率分配。该算法试图最大化的CR系统（次要用户）的总吞吐量的CR系统的总功率约束和可容忍的干扰和许可频带（主要用户）。
Cognitive Radio (CR) is a novel concept for improving the utilization of the radio spectrum. It is a software controlled radio that senses the unused frequency spectrum at any time from the wide but congested wireless radio spectrum. This promises the efficient use of scarce radio resources. Orthogonal Frequency Division Multiplexing (OFDM) is a reliable transmission scheme for Cognitive Radio Systems which provides flexibility in allocating the radio resources in dynamic environment. It also assures no mutual interference among the CR radio channels which are just adjacent to each other, making it one of the best schemes to be used in CR systems. Allocation of radio resources is a major challenge in cognitive radio systems. In a dynamic environment, many parameters and situations have to be considered which affect the total data rate of the system. A Secondary users (CRUs/SUs) may coexist with the Primary user (PU) either on Conservative basis or on a more aggressive basis which allows secondary transmissions as long as the induced interference to the PU is below acceptable level. In this we have considered Uplink cognitive radio system heaving one PU coexists with M SUs and A Downlink of an Multi User Orthogonal Frequency Division Multiplexing CR system with one base station (BS) serving one PU and K SUs. We focused on the design on the design and analysis of subcarrier and power allocation scheme under imperfect CSI for cognitive OFDM systems. A two – step Algorithm for bit rate is proposed to obtain the (1) subcarrier allocation to secondary users and (2) bits, power allocation on subcarriers. The algorithms attempt to maximize the total throughput of the CR system (secondary users) subject to the total power constraint of the CR system and tolerable interference from and to the licensed band (primary users).