共查询到20条相似文献,搜索用时 93 毫秒
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为提高频谱使用率并增加异构无线网络收益,用微观经济学的无限期轮流出价讨价还价博弈模型进行了异构网络间动态频谱管理的研究,提出了基于讨价还价理论的动态频谱管理(BDSM)方案。根据相关博弈理论,引入讨价还价耐心因子后BDSM存在唯一的均衡点。基于此,提出了实现BDSM方案的简化流程。仿真结果显示,BDSM能有效地提高频谱使用率、扩大单个运营商的利润并提高用户满意度。 相似文献
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针对宏微协同组网下小区间无线资源管理问题,文章提出一种大规模多入多出系统下基于微小区分簇的联合传输和动态频谱分配策略,该策略分两步执行以优化网络加权和速率.首先,所提算法根据各用户当前的信道状态执行微小区分簇,以尽可能地降低小区间干扰,提升系统容量.接着,宏基站和各微小区簇根据所服务用户当前的业务请求信息分别为其动态分配子载波,以最大化网络加权和速率,并提升资源利用率.仿真结果显示,该文提出的微小区分簇和动态频谱分配策略能在尽可能降低宏微协同组网中用户间干扰的同时,有效地提升系统吞吐量. 相似文献
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WiMax与3G LTE网络互联与融合技术研究 总被引:1,自引:0,他引:1
本文先分析WiMax与3GPP长期演进项目(LTE)两种无线接入技术融合的可能性.基于通用链路层(GLL)和协同无线资源管理(CRRM)机制的引入.提出了两种不同的协作程度的百联融合技术的网络架构.引入GLL的目的是为不同的无线接入机制提供统-的链路层数据处理.同时带来两个新的研究子课题:异构发送分集与异构多跳技术.CRRM完成网络间无线资源的协调管理,以达到最优化无线资源利用率和最大化系统容量的目的.几种关键的协同无线资源管理机制包括:接人选择、负载均衡、动态频谱控制技术在文中进行了详细分析及讨论. 相似文献
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基于传统正交频分复用技术的OFDMA多址接入技术仍然存在循环前缀-正交频分复用(CP-OFDM)技术的固有缺陷,即循环前缀的添加降低了系统频谱利用率,多普勒频移对传统OFDMA系统产生较强的子载波间干扰,且对相邻频带的其他无线传输系统引入较强的相邻信道干扰。该文主要讨论基于扩展高斯函数的正交频分复用系统自适应波形设计,通过信道散射函数选择合适的扩展因子参数,获取更高的频谱利用率和抑制符号间干扰和子载波间干扰。最后该文将自适应波形设计的思想扩展至基于扩展高斯函数的多址接入系统,使每个用户能够根据信道条件选择合适的成形滤波器函数,进而使多址接入系统达到全局最优化。仿真结果验证了该文方法的有效性。 相似文献
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一种基于频谱复用的新型频谱管理方法 总被引:1,自引:0,他引:1
为了解决不完善的频谱管理方法使频谱接入能力所受到的限制而导致频谱资源得不到充分利用的问题,文中提出了一种新颖的谱管理方法.该方法通过动态频谱管理系统和相应帧格式来实现频谱复用,从而增加了系统容量,提高了频谱利用率. 相似文献
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Recent studies have been conducted to indicate the ineffective usage of licensed bands due to static spectrum allocation. In order to improve spectrum utilization, cognitive radio (CR) is therefore suggested to dynamically exploit the opportunistic primary frequency spectrums. How to provide efficient spectrum handoff has been considered a crucial issue in the CR networks. Existing spectrum handoff algorithms assume that all the channels can be correctly sensed by the CR users in order to perform appropriate spectrum handoff process. However, this assumption is impractical since excessive time will be required for the CR user to sense the entire spectrum space. In this paper, the partially observable Markov decision process (POMDP) is applied to estimate the network information by partially sensing the frequency spectrums. A POMDP-based spectrum handoff (POSH) scheme is proposed to determine the optimal target channel for spectrum handoff according to the partially observable channel state information. Moreover, a POMDP-based multi-user spectrum handoff (M-POSH) protocol is proposed to exploit the POMDP policy into multi-user CR networks by distributing CR users to frequency spectrum bins opportunistically. By adopting the policies resulted from the POSH and M-POSH algorithms for target channel selection, minimal waiting time at each occurrence of spectrum handoff can be achieved which will be feasible for multimedia applications. Numerical results illustrate that the proposed spectrum handoff protocols can effectively minimize the required waiting time for spectrum handoff in the CR networks. 相似文献
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Mohamed A. Kalil Hassan Al-Mahdi Andreas Mitschele-Thiel 《Wireless Personal Communications》2013,72(4):2251-2262
Radio spectrum is a limited natural resource and with the increasing number of wireless devices, an efficient spectrum management concept to make a better utilization of this resource is essential. Opportunistic spectrum access (OSA) concept is a solution to increase the spectrum capacity and thus reducing the data collision for wireless ad hoc networks. Cognitive radio (CR) technology is developed to realize OSA. Based on CR, the secondary users access opportunistically the spectrum owned by primary users. However, the consequence appearance of primary users affects greatly the performance of secondary users within OSA. Thus, a new spectrum management scheme is a must to reduce such effect. In this paper, a new spectrum management scheme over a heterogeneous spectrum environment is proposed. The proposed scheme is based on using channels from both licensed and unlicensed bands as spectrum environment for ad hoc networks. An analytical model based on Markov chains is developed to evaluate the proposed scheme. 相似文献
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Code-division multiple-access (CDMA) implemented with direct-sequence spread spectrum (DS/SS) signaling is a promising multiplexing technique for cellular telecommunications services. The efficiency of a direct-sequence spread-spectrum code-division multiple-access (DS-CDMA) system depends heavily on the shape of the spectrum of the spread signal. Maximum efficiency is obtained with an ideal brick-wall bandpass spectrum. There are two approaches toward achieving such a spectrum. One is to use a simple spreader that produces a broad spectrum and then follow it with a precise, high order filter to band limit the spectrum. A second approach, which is the approach taken in this paper, is to use a spreader that produces a spectrum close to the ideal spectrum and then employ a simple filter to control the out-of-band power. The proposed spreader/despreader is based on a simple hybrid function and can be easily implemented. An analysis provides a compact expression for the signal-to-noise ratio (SNR) of a RAKE receiver. The expression includes the effects of baseband, intermediate frequency (IF) and RF filtering as well as the effects of the spectral densities of the spreading/despreading functions. The analysis shows that the proposed spreader/despreader yields superior performance over a conventional pseudo noise (PN) spreading/despreading mechanism 相似文献
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在认知无线电(CR)背景下,动态频谱接入已成为提高无线网络频谱利用率的重要途径。基于全球移动通信系统-铁路(GSM-R)系统中采集的细粒度频谱监测数据,提出一种数据驱动的深度学习方法,建模频谱模式,并建立一套动态频谱接入访问框架。采用一种深度频谱生成模型指导频谱分配;设计一种综合递归序列表征与场景特征嵌入的深度网络,建模和预测短时频谱占用情况,并由此提出一种动态信道接入策略。进一步,利用软件无线电(SDR)平台实现一套跳频系统,并将其与动态频谱接入策略进行集成。使用真实的历史频谱数据评估该系统的数据吞吐能力,测试结果表明,所提方法及构建的跳频系统能有效提高机会通信能力,高效利用频谱资源。该频谱接入框架及SDR系统实现具有较强的通用性,易于集成到不同场景和频段的系统中。 相似文献
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The identification of rice seeds is crucial for agriculture production. An inverse Fourier transform (IFT) method based on laser-induced breakdown spectroscopy (LIBS) is proposed to identify five kinds of rice seeds. The LIBS data of the samples were preprocessed by inverse fast Fourier transform (IFFT), and the time-domain signals of rice seeds were obtained. The back propagation (BP) neural network was used to establish full spectrum, segmented spectrum, time-domain full spectrum and time-domain segmented spectrum discrimination models. Compared with the original spectrum, the time-domain spectrum can significantly improve the identification accuracy. The time-domain full-spectrum identification accuracy reached 95.28%, and the time-domain segmented spectrum identification accuracy reached 94.36%, whose identification time was only a few seconds. The results demonstrate that LIBS detection technology combined IFFT and BP neural network is fast and accurate, which provides a new idea for batch detection of rice seeds. 相似文献
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The secondary usage of spectrum has been investigated in Cognitive Radio (CR) network to resolving the spectrum scarcity issue
in wireless communication. When Primary Users (PU) who own the spectrum appear, spectrum handoff is needed to maintain the
communications of Secondary Users. But the decision making of spectrum handoff is a challenge issue for CR network, because
the input of decision making, which obtain through spectrum sensing, is heterogeneous and inexact. In this paper we will use
fuzzy logic control theory to solve this issue and make use of new information for handoff operation: the probability of PU’s
occupancy at a certain channel. Our new algorithm can make more intelligent decision compared to simple traditional spectrum
handoff decision making and reduce the probability of spectrum handoff, also the performance of SU’s communication can be
enhanced. 相似文献
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Usama Mir Leila Merghem-Boulahia Moez Esseghir Dominique Gaïti 《Wireless Personal Communications》2014,79(3):1765-1786
In recent wireless network domains static spectrum access is a major concern. Generally, this access leads to spectrum scarcity problem by creating empty holes or white spaces. However, the scarcity is temporary and can be alleviated if spectrum access is performed dynamically and efficiently. One important step towards dynamic spectrum access is the development of cognitive radio (CR) technology, which senses nearby spectrum portions (or bands) and tries to use them either opportunistically or by negotiating with the neighboring users. Nonetheless, dynamic spectrum access raises several challenges which need to be addressed in detail. These challenges include efficient allocation of spectrum for users in order to maximize spectrum utilization and to avoid user level conflicts both under licensed and unlicensed bands. In this paper, considering the relative rarity of solutions for unlicensed spectrum access and their inadequacy, we propose a scheme, where the CR devices (equipped with agents) interact with their neighbors to form several coalitions over the unlicensed bands. These types of coalitions can provide a less-conflicted access as the agents mutually agree for spectrum sharing and they allow other CR users to enter in their vicinity of acquired spectrum via bilateral message exchanges. Further, we present continuous time Markov chains to model the spectrum access process in continuous time and derive important performance metric as the blocking probability for without and with queuing systems. Amongst others, the important comparisons we made between analytical and simulation results in terms of blocking probability verify that our proposed model is correct. In essence, our proposed solution aims to increase dynamic spectrum usage by enabling cooperation between the users. 相似文献
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YIN Liang YIN Si-xing WANG Shuai ZHANG Er-qing HONG Wei-jun LIShu-fang 《中国邮电高校学报(英文版)》2012,19(3):122-128
Due to the usable frequency becomes more and more crowed,dynamic spectrum access (DSA) is a new hope to solve this problem.However,DSA in China requires a quantitative analysis of the current spectrum ... 相似文献