D-CAT: An Efficient Algorithm for Distributed Channel Allocation in Cellular Mobile Networks

We propose a distributed channel allocation algorithm based on a threshold scheme, called D-CAT, for cellular mobile networks. The algorithm employs two thresholds: (i) a heavy threshold for determining whether a cell is heavy, or overloaded, and for triggering the channel allocation algorithm; and (ii) a target threshold for indicating the target number of free channels that a heavy cell intends to acquire. Based on the two-threshold scheme, the D-CAT algorithm can determine the optimal number of free channels as well as the cell(s) from where a heavy cell should import channels in order to satisfy the required channel demand. Simulation experiments and analyses show that the proposed algorithm incurs lower overhead for channel allocation and is more efficient in terms of channel utilization than other distributed channel allocation algorithms. It also outperforms other centralized and distributed algorithms in terms of call blocking probability.     

A Mutual Exclusion Algorithm for Ad Hoc Mobile Networks

A fault-tolerant distributed mutual exclusion algorithm that adjusts to node mobility is presented, along with proof of correctness and simulation results. The algorithm requires nodes to communicate with only their current neighbors, making it well-suited to the ad hoc environment. Experimental results indicate that adaptation to mobility can improve performance over that of similar non-adaptive algorithms when nodes are mobile.     

Predictive Dynamic Channel Allocation Scheme for Improving Power Saving and Mobility in BWA Networks

The radio spectrum of IEEE 802.16 medium access control (MAC) protocol ranges from 2–66 GHz, which is one of potential solutions for broadband wireless access (BWA) or beyond third generation (B3G)/4G networks. The maximum transmission range can reach about 48 km. However, with the property of radio propagation, the maximum transmission distance is proportioned inversely to the frequency the mobile subscriber station (MSS) carries. According to this property, the channel allocation can be based on how far the distance between the MSS and the base station (BS) in a macrocell. Therefore, this paper first proposes a new concept of channel allocation model for BWA system and investigates the relations between the signal propagation and the distance as well as propose a signal-aware dynamic channel allocation (SDCA) scheme for dynamic channel allocation (DCA) in BWA networks (BWANs). The SDCA enables the BS to allocate appropriate channels to MSSs according to the received signal-to-noise ratio (SNR) value from the MSSs. Besides, according to the frequency, the SDCA can estimate a minimum power for MSS to communicate. The SDCA not only increases the capacity of the system but saves the overall power consumption of the system well. We also present a new out-of-service prevention scheme for supporting mobility in the system. Simulation results show that the proposed SDCA can achieve the channel utilization (throughput) by up to 94.4% when the spectrum ranges from 2–11 GHz.

An Adaptive and Fault-Tolerant Channel Set Allocation Algorithm for Microcell/Macrocell Cellular Networks

Microcell/macrocell architectures are generally deployed in current cellular networks, and involve allocating each cell to a preliminary channel set to support the communications of mobile subscribers. However, cellular networks suffer risks of base transceiver station (BTS) service failure and traffic load variation among BTSs. Both of these conditions impact traffic-carrying capacity and mobile subscriber satisfaction. This investigation presents a dynamic channel set allocation algorithm for ensuring continuous optimization of overall traffic-carrying capacity. This algorithm can tolerate BTSs failure and also resolve the traffic-adaptive problem. Additionally, analytical and simulation results are presented to demonstrate the efficiency of the algorithm.Chyi-Ren Dow was born in 1962. He received the B.S. and M.S. degrees in information engineering from National Chiao Tung University, Taiwan, in 1984 and 1988, respectively, and the M.S. and Ph.D. degrees in computer science from the University of Pittsburgh, U.S.A., in 1992 and 1994, respectively. Currently, he is a Professor in the Department of Information Engineering, Feng Chia University, Taiwan. His research interests include mobile ad-hoc networks, network agents, learning technologies, and embedded systems.Jong-Shin Chen was born in 1972. He received the B.Sc. and Ph.D. degrees in engineering from Feng Chia University, Taiwan, in 1996 and 2003, respectively. His research interests include mobile computing, wireless communications, capacity planning, and systems.Yi-Hsung Li was born in 1979. He received his B.S. degree and M.S. degree in information engineering from Feng Chia University, Taiwan, in 2001 and 2003. He is currently a graduate student for the Ph.D. degree in the Department of Information Engineering and Computer, Feng Chia University, Taiwan. His research interests include personal communications, mobile computing, learning technologies, and network agents.     

一种基于GSM／GPRS的动态信道分配策略

针对GSM／GPRS网络中某些小区因频繁切换导致掉话率高的问题,提出了一种新的动态信道分配策略。该方案将信道划分为数据业务专用信道和语音／数据业务共享信道,并在共享信道中为切换型语音呼叫预留保护信道以降低其呼叫失败率。对于数据业务采用FIFO排队机制。最后利用一种近似计算方法求取该策略的呼叫阻塞率等指标。实验结果表明该方案能有效降低语音呼叫掉话率。     

基于改进遗传算法的分布式资源动态调度技术

在网络中心战条件下,为了解决分布式作战资源的动态最优部署问题,提出了一种分布式资源的动态调度算法。首先针对资源动态调度问题建立了数学模型,接着,借鉴粒子群算法的思想,使用遗传算法解决了资源调度任务指派的快速寻优问题。仿真验证表明资源调度算法是有效的,并且该算法可使分布式系统的任务处理能力和处理资源利用率大幅度提高。     

TD-SCDMA系统多业务动态信道分配算法研究

在基于的第三代移动通信中,由于业务的多样性,使得原有的只考虑到语音业务的信道分配无法满足TD-SCDMA系统需要,在信道资源分配上需要使用动态信道分配。为了适应多业务资源管理,该文在已有的DCA研究成果基础上,对DCA各个执行阶段进行了分析和阐述,并对移动边界策略和双门限带宽预留的多业务算法做了介绍和分析,分析结果表明这些策略能更好的适应于语音和数据的业务系统。     

TD-SCDMA系统的一种慢速动态信道分配算法

动态信道分配是TD-SCDMA的关键技术之一,根据网络负载和干扰的变化自适应地调整信道资源,使之达到合理配置。文中针对TD-SCDMA系统的帧结构,分析了双小区模型,并提出了一种采用双小区相同上下行时隙进行信道分配的方法,仿真结果表明:与传统的固定信道分配算法相比,推荐的算法大大提高了频谱利用率及系统容量。     

Integrating Distributed Channel Allocation and Adaptive Handoff Management for QoS-Sensitive Cellular Networks

Next generation high-speed cellular networks are expected to support multimedia applications, which require QoS provisions. Since frequency spectrum is the most expensive resource in wireless networks, it is a challenge to support QoS using limited frequency spectrum. In the literature, two orthogonal approaches are used to address the bandwidth utilization issue and the QoS provision issue; that is, channel allocation schemes have been proposed to improve bandwidth efficiency, whereas handoff management schemes, based on bandwidth reservation, have been proposed to guarantee a low connection dropping rate. However, little effort has been taken to address both issues together. In this paper, we integrate distributed channel allocation and adaptive handoff management to provide QoS guarantees and efficiently utilize the bandwidth. First, we present a complete distributed distributed channel allocation algorithm and propose techniques to reduce its message complexity and intra-handoff overhead. Second, we integrate the proposed distributed channel allocation algorithm with an adaptive handoff management scheme to provide QoS guarantees and efficiently utilize the bandwidth. Detailed simulation experiments are carried out to evaluate the proposed methodology. Compared to previous schemes, our scheme can significantly reduce the message complexity and intra-handoff overhead. Moreover, the proposed scheme can improve the bandwidth utilization while providing QoS guarantees.     

Dynamic Base Station Selection for Personal Communication Systems with Distributed Control Schemes

Distributed control schemes allow base stations in personal communication systems to be placed at locations corresponding to high expected traffic. This flexible base station placement creates significant overlapping coverage areas that can be utilized to improve system performance [1]. A new technique for dynamic base station selection in systems with overlapping cells is considered and its effect on traffic performance is characterized. The technique realizes robust performance for personal communication systems in fluctuating and heavily tapered traffic. A mathematical analysis based on a state transition model is used to evaluate performance of a system that employs the proposed technique. The results indicate that improved blocking probability and carried traffic performance are obtainable. Computer simulations were undertaken confirm the analytical results.     

分布式协作通信网络中的MAC层协议

分布式协作网络通过节点间的相互合作来达到网络资源的共享,然而如何设计高效的媒体访问控制（MAC）层协议是分布式协作通信网络中的核心问题之一。文章基于MAC层协作的动机,探讨了分布式协作网络中MAC层协议设计所面临的问题和挑战,基于近年来涌现的典型协作MAC协议和协议性能的分析,得出结论：只有全面考虑分布式网络的特点和需求,合理地设计协议的各个环节,才能使协同通信技术在分布式网络中得到更好应用。     

A New Dynamic Channel Allocation Scheme for Microcellular Systems

1IntroductionThetremendousgrowthofthemobileuserpopulahonrequiresefficientreuseofscarceradiospectrUmallocatedtomobilecommunications.InmobilenetWorks,co-channelinterferencecausedbyfrequencyreuseisthemostrestrainingfactorontheoverallsystemcapacity.Inthecurrentcellularsystems,themainideabehindchannelallocationistomakeuseofradiopropagationpathlosscharacteristicsinordertondnindzethecaacer-tointerferenceratio(CIR)andhencetoincreasetheradiospecmimreuseefficiency.MicrocellularsystemshaveshowngreatPO…     

智能天线系统中动态信道分配算法性能研究

在讨论了智能天线技术对动态信道分配算法性能影响的基础上,通过对智能天线系统下的动态信道分配算法进行仿真研究,与没有利用智能天线技术时的动态信道分配算法比较,两种情况在接收端误比特率的分析,说明采用智能天线技术时,能够在很大程度上改善系统在接收端的误比特率指标。     

一种基于多小区OFDMA系统用户公平性约束的分布式资源分配算法

针对多小区OFDMA系统下行链路,研究了用户公平性约束下的资源分配问题,提出了一种多基站协作的迭代优化的分布式资源分配算法。每个小区根据干扰状况及用户公平性,迭代地进行子载波和功率的资源优化;而每次迭代中,根据用户公平性准则分配子载波,并将非凸的小区功率优化问题转化为其下界的凸问题,通过一个分布式算法来求解。通过仿真验证了算法的有效性;仿真结果表明,与传统网络的固定功率分配的情形相比,所提算法保证了用户之间的公平性并显著提高了系统吞吐量。     

多用户OFDM系统中改进的动态子载波与功率分配算法

提出了一种对于多用户OFDM（Orthogonal Frequency Division Multiple）系统改进的动态子载波和功率分配算法.算法采用分步的思想对系统资源进行动态分配,在已知系统总功率和用户最小速率请求的条件下,使系统总的比特速率最大,资源得到了有效利用.此算法简单易于理解,复杂度较低,仿真结果表明,其性能接近于联合的分配算法.     

一种基于移动Agent的分布式Skyline查询算法

针对分布式计算环境,利用移动Agent技术提出了一种基于移动Agent的分布式Skyline查询算法,并进行了深入的分析。通过分析可知,该算法可以实现在分布式环境下求解全局Skyline点。     

有线电视网络多频道动态分配机制的改进

在有线电视网络标准中,DOCSIS提出了优先权的思想和许多保障机制,利用给与不同Cable Modem(CM)不同的优先权,保证那些等级较高的使用者可以得到较高的传输效能.这里探讨了DOCSIS1.1对QoS的支持,提出了一个在CM频道配置过程中加入优先权机制的方法,利用两个机制来确保有线电视网络的所有CM能得到一个最佳的分布,首先利用一个更改后的频道分配机制来确保CM能得到最佳的分布,而当频道的状况由于CM数量或流量的改变而产生变化时,便利用另一个频道平衡机制,来平衡各频道的流量和各频道中CM的数量.     

一种结合信道性能的频谱分配算法

在认知无线电网络中,由于授权信道的时变性,各可用信道的性能相差较大。为避免过多使用忙闲交替频繁的信道,首先用ON—OFF模型建模授权信道的使用情况,并推导了认知用户切换概率,提出了一种用信道状态变化率衡量信道性能的方法。在此基础上提出了一种结合信道性能的频谱分配算法,在网络吞吐量相同或相近情况下优先分配性能较好的信道。仿真分析表明,这种结合信道性能的频谱分配算法在降低切换概率的同时提高了实际总效益。     

A Channel Sharing Scheme for Cellular Mobile Communications

This paper presents a channel sharing scheme, Neighbor Cell Channel Sharing (NCCS) , based on region partitioning of cell coverage for wireless cellular networks. Each cell is divided into an inner-cell region and an outer-cell region. Cochannel interference is suppressed by limiting the usage of sharing channels in the inner-cell region. The channel sharing scheme achieves a traffic-adaptive channel assignment and does not require any channel locking. Performance analysis shows that using the NCCS scheme leads to a lower call blocking probability and a better channel utilization as compared with other previously proposed channel assignment schemes.