一种新的优化动态信道分配策略及建模分析

本文提出一种新的动态信道分配策略,称之为分级紧致的动态信道分配(CCDCA),所谓分级就是基于引入的"冷态"和"热态"的概念,将小区所处的状态分为冷态与热态;所谓紧致就是对处于不同状态的小区给出不同的紧致模型.该策略在对"热态"的处理过程中利用了"冷态"的先验信息,有机地结合了局部信息与整体信息,同时能保证小区间有较小的服务偏差,提高了整个系统的服务质量.文中还从理论上给出了冷、热态阈值的分析模型,计算出了模型的主要参数,该模型也可以用来分析系统性能.仿真结果证明该方案有较小的呼阻率和较高的频谱利用率,所提出的模型比较接近实际系统.     

蜂窝移动通信系统中的一种新的优化信道分配模型

本文提出了一种新的蜂窝移动通信系统最优信道分配模型.首先根据信道分配的特点构造了一种信道分配方程模型;进而建立了信道分配最优模型,利用Pontryain最小值原理获得了模型的最优解;给出的仿真结果验证了分析结论的正确性.该模型可以用来有效地研究信道分配问题的宏观性能,并提供了一种高效、快速的算法.     

蜂窝移动通信系统中一种热点业务分配算法

基于提出的最优组合业务量预测模型,对下一时刻的业务量进行预测,从而确定蜂窝系统中业务分布情况,据此将蜂窝小区分成冷点区域和热点区域,并提出一种优化的混合信道分配(OHCA)方案,分析并给出了该方案中动静信道比的定量关系。仿真结果证实了该最优组合预测模型较单一预测方法降低了预测误差、提高了预测精度,同时该优化分配算法较固定信道分配(FCA)和动态信道分配(DCA)方案,有较小的呼阻率和较高的频谱利用率,该策略可用来有效处理热点业务问题,有较好的应用前景。     

一种半速率蜂窝移动通信信道指配策略

本文提出了一种新的蜂窝移动通信系统信道指配策略——基于紧凑模式的半速率信道借用指配策略(SRCPCB).这种策略将半速率信道的思想引入到新近提出的CPCB策略中,以短时间降低部分呼叫的话音质量为代价,来降低系统的呼叫阻塞.通过各种业务模型的仿真,获得了系统的初始呼叫阻塞率、强制中断率和话音质量下降率等性能指标.结果表明:SRCPCB的系统综合性能优于FCA、DCA、BCO、BDCL、CPDCA和CPCB等策略.这对于缓解系统频谱资源紧缺、改善系统性能等具有十分重要的意义.     

蜂窝移动通信系统中信道指配的新方法

详细介绍了蜂窝移动通信系统中现存的主要信道指配方法,并在此基础上提出了一种新的动态信道指配方法——全局最优动态信道指配方法。计算机模拟结果表明:这种方法比目前通常使用的动态信道指配方法具有更优越的性能。它克服了常规动态信道指配方法的一些弱点,在通信系统话务量较大时仍能保持较低的阻塞率。     

微蜂窝移动通信信道特性

由于分区半径小和传播环境复杂,微蜂窝信道具有不同于其它移动通信信道的典型特性。本文从视距传播和非视距传播两个方面对微蜂窝电波传播路径损失、信道的慢衰落和快衰落等特性进行了分析,重点讨论了几种常用微蜂窝信道模型。     

移动通信系统中信道分配的方案及其算法

移动通信正在迅速发展和普及，用户数增长与无线频率资源紧张这一矛盾日益突出，如何更有效地提高频度利用率成为大家所关注的焦点。本文主要是针对小区制蜂窝系统中，在信道共用情况下，为进一步提高信道的利用率，将目前所提出的各种信道分配方案进行分析比较和论证，阐明共各自的特点和适用范围，并用一些实际的结果加以验证。     

一种蜂窝系统信道频率配置新方案

在蜂窝移动通信系统中,为处理不同的话务量寻求一种好的信道频率配置方案,已做了大量的研究工作。但要使配置的信道频率既要实现频谱利用率高,又要没有干扰,还比较困难.本文提出一种频谱利用率高且基本上没有干扰的信道频率配置新方案,该方案将实现没有同信道干扰、小区内无邻信道干扰和不出现双信号三阶互调干扰.提出的新方案与现有的蜂窝系统信道颍率配置方案.其主要差别是计算话务量负荷时不考虑干扰。在设计新方案中是假设蜂窝系统所有小区的话务量是均匀的以及各小区的信道数是相同的.     

TDD/CDMA移动通信系统的一种信道分配方案

未来的TD/CDMA移动通信系统中存活话音及上下行业务量不等、优先级不同的数据业务，为适应新业务的特点，充分发挥TDD/CDMA移动通信系统自身的优势，本文提出了TDD/CDMA移动通信的一种新的信道分配方案。仿真结果表明，该方案可大大降低低优先级业务的掉线概率，充分利用有限的信道资源。     

微蜂窝移动通信信道特性

由于分区半径小和传播环境复杂,微蜂窝信道具有不同于其它移动通信信道的典型特性。本文从视距传播和非视距传播两个方面对微蜂窝电波传播路径损失、信道的慢衰落和快衰落等特性进行了分析,重点讨论了几种常用微蜂窝信道模型。     

A compact dynamic channel assignment scheme based on Hopfield networks for cellular radio systems

In this paper, a new channel assignment strategy named compact dynamic channel assignment (CDCA) is proposed. The CDCA differs from other strategies by consistently keeping the system in the utmost optimal state, and thus the scheme allows to determine a call succeeding or failing by local information instead of that of the whole network. It employs Hopfield neural networks for optimization which avoids the complicated assessment of channel compactness and guarantees optimum solutions for every assignment. A scheme based on Hopfield neural network is considered before; however, unlike others, in this algorithm an energy function is derived in such a way that for a neuron, the more a channel is currently being allocated in other cells, the more excitation the neuron will acquire, so as to guarantee each cluster using channels as few as possible. Performance measures in terms of the blocking probability, convergence rate and convergence time are obtained to assess the viability of the proposed scheme. Results presented show that the approach significantly reduces stringent requirements of searching space and convergence time. The algorithm is simple and straightforward, hence the efficient algorithm makes the real‐time implementation of channel assignment based on neural network feasibility. Copyright © 2008 John Wiley & Sons, Ltd.     

Performance analysis of dynamic channel assignment algorithms in cellular mobile systems with hand‐off

In this paper, the traffic performance of dynamic channel assignment (DCA) in cellular mobile system with hand‐off is investigated. A traffic model for cellular system incorporating hand‐off is established first. Under the framework of the model, a hand‐off priority scheme is developed to reduce the forced termination of calls in progress. This paper analyses and derives the traffic performance bound for DCA strategies with hand‐off by extending the maximum packing (MP) scheme to include the hand‐off procedure. For practical implementation, a distributed DCA algorithm (DDCA) is also proposed. A non‐priority scheme and the proposed priority scheme can be combined with either MP or DDCA. It is shown that the simulation results of DDCA scheme are comparable with the analytical bounds given by MP for both the non‐prioritized case and prioritized case. A reasonable trade‐off between the new call blocking probability and forced termination probability can be achieved by using the proposed prioritized scheme in DCA. Copyright © 2002 John Wiley & Sons, Ltd.     

A dynamic channel assignment scheme for clustered multihop cellular networks

Whereas cellular systems have traditionally adopted single‐hop transmissions between the mobile station (MS) and the base station (BS), researchers expect multihop transmission to be utilised in the future. Cellular systems present several challenges, such as channel assignment, which are exacerbated by multimedia service traffic and an increasing number of subscribers. Recently, a clustered multihop cellular network (cMCN) architecture that complements traditional cellular systems has been proposed and studied using fixed channel assignment (FCA). However, the performance of FCA is limited when the traffic pattern varies in a service area. This paper proposes the use of dedicated information ports (DIPs) as clusterheads in cMCN, followed by a multihop dynamic channel assignment (mDCA) scheme. The mDCA works by assigning channels based on information about interference in surrounding cells. Two different channel searching strategies are developed and evaluated. Through computer simulation, we show that the proposed mDCA is able to achieve a significantly improved capacity which is maintained when the number of system channels is increased. Finally, issues regarding the implementation of the mDCA and future work on this topic are discussed. Copyright © 2007 John Wiley & Sons, Ltd.     

A channel state‐driven ACM algorithm for mobile satellite communications

The last decade has been characterized by an increasing demand of higher throughput and more reliable communication links for supporting multimedia applications. To this aim, the focus has been toward both broadband and broadcast solutions providing multimedia services to mobile users. In order to exploit such advanced services, ubiquitous and efficient mobile connections are required: satellite communications (SatCom), able to cover low density populated areas and to fill terrestrial coverage gaps, are a viable solution, as long as capacity is properly optimized. Waveform adaptation can be considered as one of the reference approaches for increasing the throughput and the reliability in wireless communication links. However, the large round trip time and user mobility in SatCom scenarios represent a serious challenge that limits the effectiveness of transmission parameters adaptation. In this paper, we focus on a novel state‐driven adaptive coding and modulation approach aiming to predict the most suitable modulation and coding scheme for each communication state, based on channel state estimation and a Markov propagation model. The paper introduces the concept of state estimation decision reliability and transmission reliability. Different from other approaches, the state‐driven algorithm allows to increase the system reliability by lowering the outage probability in the selected scenarios. The effectiveness of the proposed approach has been validated by resorting to numerical results after a careful parameter optimization. Copyright © 2015 John Wiley & Sons, Ltd.     

阴影衰落信道下多波束卫星移动通信系统的动态信道分配策略

针对已有动态信道分配策略在阴影衰落环境中性能损失较大的问题,对卫星移动通信系统的阴影衰落信道模型进行分析,提出了一种动态信道分配策略。该策略结合用户的运动状态,通过在用户的预测运动轨迹上选取抽样点,将这些抽样点的平均干扰作为信道分配的指标,并采用链路质量约束避免了流量较大时的性能恶化。仿真结果表明提出的动态信道策略可在不增大阻塞率的前提下,在中低流量时将用户平均信噪比提高约0.5 dB。该策略可以应用于阴影衰落信道下的地面移动卫星通信系统,以提高用户的平均链路性能。     

Optimal channel assignment in cellular networks

In this paper, we consider the problem of assigning frequencies to mobile terminals in a cellular network. We show that an optimal solution can be obtained by solving a sequence of alternating linear and quadratic maximization programming problems. We address co-channel constraints and adopt as an objective function the maximization of potentially established calls. Our algorithm is fairly general, and does not depend on any special network structure. This study indicates that mathematical programming can be used as an efficient technique for solving the aforementioned problem.     

多波束天线下多层蜂窝小区切换性能分析

分析了一种基于多波束天线在垂直面发射形成的多层蜂窝移动通信小区结构的切换性能.在切换算法中引入了以移动台所接收有用信号功率与干扰信号功率之和作为切换发起的判断规则之一,讨论了在阴影衰落无线传播环境下,该多层小区的3种切换发起规则,并给出了相应的切换发起概率表示式.最后计算机模拟结果比较了不同切换发起规则下切换发起概率与小区区群数和基站天线俯仰角间的关系.     

On the development of fully adaptive channel allocation strategies for usage in high‐capacity cellular mobile radio systems

An alternative mathematical expression for the co‐channel interference probability is used, in order to calculate the cellular mobile radio system capacity and to construct a set of compatibility constraints needed for the development of fully adaptive channel allocation (FACA) strategies. The development of such channel allocation techniques becomes a main thrust for the system engineers in order to design an efficient system to manage traffic demands over the service area of a third generation cellular system. Three proposed FACA strategies are analysed and a simulation model is developed, in order to examine the performance of these strategies. Copyright © 2001 John Wiley & Sons, Ltd.