摘要：随着无线通讯设备的增长以及无线通信的需求增加，无线频率这种不可再生资源日益紧张，成为稀缺资源。现行的频率资源分配策略中，频率被划分成不同频段，不同的频段承载不同的无线业务，这些业务独立使用各自的频段，互不干扰。这种分配策略管理简单，但频谱使用效率却较为低下。实际上，频率资源并非真正的消耗殆尽，现有的研究结果表明当前无线频谱的使用效率极为低下。

如今，频谱预测主要研究信道状态的预测方法。本文提出一种基于感知门限的频谱预测一感知机制，按照预测结果按信道空闲概率从大到小的顺序进行频谱感知，使SU高效地利用频谱资源，从而提高SU的频谱利用率并减少频谱感知次数，以节省感知时间和能量。同时，本文根据实际情况，假设在一个时隙内，SU能够感知一定数量的信道来发现可用信道，从而得到感知门限(一个时隙内SU能够最大感知信道的数目)对SU频谱利用率和感知时间的影响。

关键词：无线电，频谱预测，感知门限

Abstract：With the growth of wireless communication equipment and the increasing demand for wireless communication, the non renewable resources of radio frequency become increasingly scarce and become scarce resources. In the current allocation strategy of frequency resources, frequency is pided into different frequency bands. Different frequency bands carry different wireless services. These services use their respective frequency bands independently, and they do not disturb each other. This allocation strategy is simple in management but inefficient in spectrum usage. In the traditional spectrum allocation strategy, the spectrum resource is pided into different frequency bands. Each frequency band carries different communication services. This allocation strategy is easy to manage, but the utilization rate of the spectrum is low, so it can not meet the increasing demand of wireless communication service. In fact, the frequency resources are not really depleted. The existing research results show that the efficiency of the current wireless spectrum is extremely low.

Nowadays, spectrum prediction is mainly concerned with the prediction method of channel state. In this paper, a perceptual threshold based spectrum prediction mechanism is proposed. According to the prediction results, the spectrum sensing is carried out in a large or small order in order to make the SU use the spectrum resource efficiently, so as to improve the frequency spectrum utilization of SU and reduce the frequency of spectrum sensing, so as to save time and energy. At the same time, this paper, according to the actual situation, assumes that in a time slot, SU can perceive a certain number of channels to find the available channels, thus obtaining the effect of the perceptual threshold (the number of the maximum perceptive channels of the SU in a slot) on the SU spectrum utilization and the perception time.

Keyword: wireless，Spectrum prediction，Perceptual threshold

前言

随着信息时代的到来,无线频谱已成为现代社会不可或缺的宝贵资源。它目前主要由国家统一分配授权使用,一个频段一般只能供一个无线通信系统独 立使用,这种静态的无线频谱管理方式,简单而有效的避免了不同无线通信系统间的相互干扰。随着无线通信业务的迅猛发展，联邦电信委员会(Federal Communications Commission, FCC)所提出的固定频谱分配策略己不能满足人们对无线频谱的需求。大量的文献证明了现有的频谱资源并没有得到充分的利用，频谱资源存在着严重的浪费。认知无线电的提出就是为了解决当前频谱资源需求紧张而相对而言浪费严重的问题。

但是在这些已分配的授权频段与非授权频段中存在着频谱资源利用的不平衡性:一方面,授权频段占用了整个频谱资源的很大一部分,但 其中不少频段处于空闲状态;另一方面,开放使用的非授权频段占整个频谱资 源的很少一部分,但在该频段上的用户很多,业务量也很大,无线电频段已基 本趋于饱和。于是在无线和移动通信迅速发展的今天,频谱资源贫乏的问题也 显得日益严重。因此,寻求一种更有效的频谱管理方式,充分利用各地区、各 时间段的空闲频段,缓解不断增长的频谱的需求矛盾,成为人们关注的问题。