基于蚁群算法的无线通信频率最优指配策略

针对试验场无线通信频率指配问题,修改了电磁兼容定量值的计算方法,增加了天线增益算子和功率衰减因子,改进了频率指配问题的干扰限制条件。将场区无线通信频率指配问题建模为数学优化问题,并针对不同的应用需求,给出试验场最少载频数量和最小频谱跨度两类频率指配最优目标,最后对改进模型进行了仿真验证。仿真结果表明改进模型可减少频率指配过程中频谱资源的消耗代价,有效地提高频谱资源利用率。     

三维频率复用环境中的信道偏移指配方法

一种新的信道指配法－信道偏移指配方法正受到越来越多的重视，这种方法能在现有的频率资源条件下，较大地提高移动通信系统的容量。本文主要讨论了三维频率复用环境中的信道偏移指配方法，详细地分析了同频复用和相邻信道使用距离，定量地计量了信道偏移系统的频谱节约效率。本文最后还通过几个实例验证了所提算法的实用性。     

局域增强系统台站最小保护间隔的计算

针对局域增强系统( LAAS)的频率指配问题,提出了一种基于频率保护服务区的频率指配方法。根据LAAS频率保护服务区的定义,在机载接收机信号干扰比要求的基础上,结合无线电传播模型和空间几何关系,详细描述了计算LAAS台站间最小保护间隔的方法。计算结果与美国联邦航空局( FAA)的规范吻合,为LAAS设备的频率指配提供了简单有效的计算方法。该方法可有效提高导航频率资源利用率,解决频率资源短缺的问题。     

澳大利亚频率执照拍卖的回顾

澳大利亚频率主管部门是通信信息技术和艺术部下设的澳大利亚电信管理局(ACA).为了加强频谱管理和提高频谱的利用率,ACA采取了一系列方针政策,其中频率执照的拍卖就是重要措施之一.根据澳大利亚1992年无线电法,从1994年ACA就开始进行电台设备执照和频率执照拍卖,已取得了很大的进展.以拍卖方式指配频率有很多优点,例如可以增加政策的透明度,做到公开、公平,合理,促进经济有效的利用频谱,是一种客观的频率指配机制,提高程序效率,并且增加政府财政收入作为使用频谱资源的回报.同时能给新的电信运营商提供参加竞争的机会.最后达到加强无线电频谱管理,提高频谱利用率和促进无线电通信发展的目的.     

指配频率电磁兼容，分析先行

根据山东青岛地区的地理地貌及超短波通信系统特点,以频率台站数据库为基础,研究讨论了适应于青岛地区的电波传播模型、频率指配中的电磁兼容分析技术和管理策略,建立了用于预指配频率的EMC计算模型,给出了管理信息系统设计和实现的原理与方法。     

基于模拟退火算法的频率指配算法优化

模拟退火算法是最早应用于频率指配的智能算法之一,具有设计简单、频率指配合理等优点。但在某些具体频率指配环境中,模拟退火算法存在运算时间较长的缺点。通过分析频率指配影响算法的条件,深入剖析模拟退火算法在频率指配中的运行机制,缩小邻域选择范围、引进贪婪原则改进新解产生方式、增加升温过程和初始解重新设置等方式,对模拟退火算法在频率指配中的应用进行了优化,在保证符合频率指配约束条件的情况下,提升了模拟退火算法的运算效率。     

基于最大色度着色的频率指配方法

本文主要介绍了基于最大色度着色的频率指配方法,并给出相关算法和程序流程图,最后将其应用到了实际的频率指配问题中.     

基于用频需求匹配度的频率指配算法

针对大量异构用频装备同时同区域部署运用带来的频率资源紧张、指配效率低等问题，构建用频需求及频率资源表征模型，分析了频率资源指配流程，提出了基于用频需求匹配度的频率指配算法。该算法通过提高频率资源与用频需求带宽的匹配度，充分利用可用频率资源，实现资源集约使用。同时，为避免用频规律性被敌方识别、利用，引入频率间隔因子，提高了用频的灵活性、随机性。仿真结果验证了算法的有效性，相对于其他算法，可以显著提高装备用频需求满足度。     

基于软件无线电的广域自适应频谱技术

O．引言 本文介绍的自适应频谱接入技术是在软件无线电的基础之上发展起来的一种新型的频率指配和使用系统。该系统相对于传统的频率指配和使用具有更高的利用率和灵活性。由于政策的制定相比于技术的发展具有一定的滞后性，所以对于该系统，可能现行的频谱政策并不能够支持。但是我们在文中主要是从技术的方面来考虑。     

利用信号特征分析测量频谱占用度

0引言频谱的有效利用是无线电频谱管理中需要考虑的最重要的因素之一。频谱占用度统计用于测量信道和频段的使用情况,评估信道利用率和频率指配的有效性是频谱监测的主要任务。按国际电联(ITU)编写的《频谱监测手册》定义,频谱的使用数据或信道占用度反映了某特定频率     

OFDMA分布式无线接入网络中基于共享标准的资源分布研究

Distributed radio access network (DRAN) is a novel wireless access architecture and can solve the problem of the available spectrum scarcity in wireless communications. In this paper, we investigate resource allocation for the downlink of OFDMA DRAN. Unlike previous exclusive criterion based algorithms that allocate each subcarrier to only one user in the system, the proposed algorithms are based on shared criterion that allow each subcarrier to be allocated to multiple users through different antennas and to only one user through same antenna. First, an adaptive resource allocation algorithm based on shared criterion is proposed to maximize total system rate under each user’s minimal rate and each antenna’s maximal power constraints. Then we improve the above algorithm by considering the influence of the resource allocation scheme on single user. The simulation results show that the shared criterion based algorithm provide much higher total system rate than that of the exclusive criterion based algorithm at the expense of the outage performance and the fairness, while the improved algorithm based on shared criterion can achieve a good tradeoff performance.     

认知Ad hoc网络中基于市场的三级频谱分配方案

分簇是Ad hoc网络规模较大时采用的主要结构,而频谱分配是Ad hoc网络的关键技术之一。该文针对认知无线电环境的分簇Ad hoc网络,提出了一种新的基于市场的频谱分配方案,该方案中簇首节点依据业务比例从频谱管理中心购买频谱,簇内采用基于供需市场理论的频谱分配算法。分析了簇内频谱市场的两种迭代定价算法额外需求迭代算法和连续松弛迭代算法以及簇首需求订购的过程。该方案能实现各簇收益的最大化,簇首基于需求的频谱购买相对于等量购买进一步提高了频谱效用。仿真结果表明这种频谱分配方案能有效提高系统频谱效用,额外需求迭代算法和连续松弛迭代算法均表现出良好的收敛性能。     

组播OFDM系统中基于子载波成对调整的功率分配算法

 研究了在总功率的约束下,组播OFDM系统中最大化组播速率的功率分配问题. 首先引入贪婪算法求解该问题以降低复杂度,但贪婪算法只执行预设的固定次数分配后即停止,其截止条件与功率分配过程中的状态无关,无法有效地提高系统性能;进而提出了两种基于子载波成对调整的功率分配算法,在初始功率分配的基础上选择子载波对交换功率,将功率重新分配给能够使组播速率提高得最多的子载波,并只在无法进一步提高组播速率时才停止调整. 研究和仿真结果表明,所提出的两种调整算法能够有效地提高组播速率,性能接近根据凸函数优化方法求得的最优解,且显著降低了算法的复杂度.     

A dynamic channel allocation technique based on Hopfield neuralnetworks

The interest in global spectrum allocation techniques is growing with the always increasing spectrum demand for (cellular) mobile communications. However, the best algorithms suffer from high computational times that reduce the possibility of a practical implementation. This paper deals with a dynamic channel allocation (DCA) technique based on an energy function whose minimization gives the optimal allocation. Due to the particular formulation of such an energy function, the minimization can be performed by a Hopfield neural network for which a fast hardware implementation has been recently proposed in the literature. The performance of the proposed DCA technique is derived by computer simulations. Comparisons with a classical fixed allocation technique (FCA) and a different DCA technique are shown to highlight the better performance of the proposed DCA technique     

Adaptive subcarrier-distribution algorithm for routing and spectrum allocation in OFDM-based elastic optical networks

In this paper, we have proposed the adaptive subcarriers-distribution routing and spectrum allocation (ASD-RSA) algorithm, which is the first elastic optical network routing and spectrum allocation algorithm based on distributed subcarriers. It allocates lightpaths to request adaptively and proved to achieve much lower bandwidth blocking probability than traditional routing and spectrum allocation algorithms based on centralized subcarriers with integer linear programming and dynamic simulation methods. Additionally, the ASD-RSA algorithm performs the best with three alternate routing paths; this character will decrease the calculating amount of both alternate routing path searching and spectrum allocation immensely in large networks.     

Resource allocation in orthogonal frequency division multiple access‐based cognitive radio systems with minimum rate constraints

In this paper, resource allocation problem in orthogonal frequency division multiple access‐based cognitive radio (CR) systems to maintain minimum transmission rate constraints of CR users (CRUs) with the specified interference thresholds is investigated. Firstly, a single primary user (PU) CR system is considered, and a suboptimal resource allocation algorithm to maximize the sum transmission rate of all CRUs is proposed. Secondly, the single‐PU scenario is extended to multiple‐PU case, and an asymptotically optimal resource allocation algorithm is proposed using dual methods subject to constraints on both interference thresholds of PUs and total transmit power of all CRUs. Analysis and numerical results show that, in contrast to classical resource allocation algorithms, the proposed algorithm can achieve higher transmission rate and guarantee each CRU's minimum transmission rate in both scenarios. Copyright © 2012 John Wiley & Sons, Ltd.     

Utility‐based resource allocation in uplink of OFDMA‐based cognitive radio networks

Cognitive radio makes it possible for an unlicensed user to access a spectrum opportunistically on the basis of non‐interfering to licensed users. This paper addresses the problem of resource allocation for multiaccess channel (MAC) of OFDMA‐based cognitive radio networks. The objective is to maximize the system utility, which is used as an approach to balance the efficiency and fairness of wireless resource allocation. First, a theoretical framework is provided, where necessary and sufficient conditions for utility‐based optimal subcarrier assignment and power allocation are presented under certain constraints. Second, based on the theoretical framework, effective algorithms are devised for more practical conditions, including ellipsoid method for Lagrangian multipliers iteration and Frank–Wolfe method for marginal utilities iteration. Third, it is shown that the proposed scheme does not have to track the instantaneous channel state via an outage‐probability‐based solution. In the end, numerical results have confirmed that the utility‐based resource allocation can achieve the optimal system performance and guarantee fairness. Copyright © 2009 John Wiley & Sons, Ltd.     

Stackelberg game for backhaul resource allocation in the two-tier LTE femtocell networks

As one promising technology for indoor coverage and service offloading from the conventional cellular networks, femtocells have attracted considerable attention in recent years. However, most of previous work are focused on resource allocation during the access period, and the backhaul involved resource allocation is seriously ignored. The authors studied the backhaul resource allocation in the wireless backhaul based two-tier heterogeneous networks （HetNets）, in which cross-tier interference control during access period is jointly considered. Assuming that the macrocell base station （MBS） protects itself from interference by pricing the backhaul spectrum allocated to femtocells, a Stackelberg game is formulated to work on the joint utility maximization of the macrocell and femtocells subject to a maximum interference tolerance at the MBS. The closed-form expressions of the optimal strategies are obtained to characterize the Stackelberg equilibriums for the proposed games, and a backhaul spectrum payment selection algorithm with guaranteed convergence is proposed to implement the backhaul resource allocation for femtocell base stations （FBSs）. Simulations are presented to demonstrate the Stackelberg equilibrium （SE） is obtained by the proposed algorithm and the proposed scheme is effective in backhaul resource allocation and macrocell protection in the spectrum-sharing HetNets.     

改进粒子群算法在频谱功率分配中的应用

在认知无线电中,由于次用户干扰门限要求的存在,传统频谱功率分配方式获得的次用户有效信道容量较低。针对这一问题,提出了一种基于粒子群算法的频谱功率分配算法。首先建立基于干扰距离的认知网络干扰模型,将频谱功率分配问题转化为函数优化问题,并借助混合随机变异思想的粒子群算法进行求解;针对寻优过程中的约束问题,提出了一种基于投入产出比的外点法,保证粒子群在可行域中寻优,最终获得频谱功率分配。仿真结果表明,与传统算法相比,所提算法能够获得较高的次用户有效信道容量。     

Adaptive Power and Bit Allocation in Multicarrier Systems

We present two adaptive power and bit allocation algorithms for multicarrier systems in a frequency selective fading environment. One algorithm allocstes bit based on maximizing the channel capacity, another allocates bit based on minimizing the bit-error-rate （BER）. Two algorithms allocate power based on minimizing the BER. Results show that the proposed algorithms are more effective than Fischer＇s algorithm at low average signal-to-noise ration （SNR）. This indicates that our algorithms can achieve high spectral efficiency and high communication reliability during bad channel state. Results also denote the bit and power allocation of each algorithm and effects of the number of subcarriers on the BER performance.