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1.
In cellular communications, one of the main research issues is how to achieve optimum system capacity with limited frequency
spectrum. For many years, researchers have proposed and studied many dynamic channel assignment (DCA) schemes to increase
the capacity of cellular systems. Another proposed technique, Reuse Partitioning (RP), is used to achieve higher capacity
by reducing the overall reuse distance. In convention, when RP is exploited in network-based DCA, a portion of channels will
be assigned permanently to each partitioned region. However, the number of channels assigned to each region may not be~optimum
due to factors like the uneven and time-varying traffics. In this paper, a new network-based DCA scheme is proposed with the
flexible use of RP technique, named as flexible dynamic reuse partitioning with interference information (FDRP-WI). In this
scheme, channels are open to all incoming calls and no channel pre-allocation for each region is required. As long as the
channel assignment satisfies the co-channel interference constraints, any user from any region can use any channel. The scheme
aims to minimize the effect of assigned channels on the availability of channels for use in the interfering cells and to reduce
overall reuse distance. Both FDRP-WI with stationary users and mobile users are investigated. Simulation results have confirmed
the effectiveness of FDRP-WI scheme. In the case with stationary users, FDRP-WI exhibits outstanding performance in improving
the system capacity under both uniform and non-uniform traffic distributions. Under the uniform traffic case, the scheme can
provide over 100% capacity improvement as compared to conventional fixed channel assignment scheme with 70 system channels
at 1% blocking probability. In the case with mobile users, the impact of mobility on the new call probability, P
b, and the call dropping probability, P
d, is evaluated. The effect on system capacity of reserving some channels for handoff calls is first studied. Then, we propose
a new handoff scheme, called “Reverse Overflow” (RO), to improve the utilization of channels with smaller reuse distances
under mobile environment. Simulation results show that, with RO handoff, the system capacity of FDRP-WI is effectively improved
at the expense of higher handoff rates in the cellular system. 相似文献
2.
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. 相似文献
3.
个人通信网和个人通信服务 总被引:1,自引:0,他引:1
作为第三代移动通信的创新概念“个人通信”被提出以来,个人通信网和个人通信服务从定义、理论、技术、设备等各方面得到不断发展和明显进步,得到全世界通信学界的极大重视,本文依据个人通信网的定义和现实发展,对个人通信网的研究发展方向,技术重点,实现个人通信服务所需求的功能和应用前景等进行讨论。 相似文献
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Research on the Handover of a Novel Cellular Architecture in Wireless Personal Communication Systems
ZHANG Zu-fan~ 《中国邮电高校学报(英文版)》2003,10(4)
1 IntroductionHandoverbetweencellsisplayinganimportantroleincellularcommunicationsystems[1~ 1 2 ] .Thehandoverprocedureanditseffectivenessareseriouslylimitedbythecellulararchitectureasaresultofmar ketplanning .Basedonthehexagonalcellulararchi tecture,manyhandoverprocedureshavebeendis cussedandevaluated ,andmostoftheimprovementproposedonthemleadstotheintroductionofsector ingcellularorlayeredcellularmodel.Otherwise ,abetterhandoverprocedureisessentialinmaintainingacallinprogressbutitreflectshi… 相似文献
6.
蜂窝移动通信中一种分级紧致的动态信道分配方案 总被引:2,自引:0,他引:2
本文提出一种分级紧致的动态信道分配(CCDCA)方案。文中首先根据信道使用情况与业务量的关系,将小区分成“冷态”和“热态”,并给出了相应的阈值,然后在对“热态”的处理过程中利用“冷态”的先验信息,对不同状态的小区给出了不同的紧致措施。该方案还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。文中还根据冷、热态的特点构造了一个二维马尔科夫链模型,计算出了模型的主要参数;其思想可用于分析多种信道分配问题。仿真结果证明CCDCA方案有较小的呼阻率和较高的频谱利用率。 相似文献
7.
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. 相似文献
8.
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. 相似文献
9.
高效频谱调制方式在蜂窝移动通信系统中的性能分析 总被引:5,自引:0,他引:5
本文研究高效频谱调制方式MPSK及MQAM在蜂窝移动通信中的应用及其性能。在综合考虑共道干扰,Rayleigh衰落以及高斯噪声等影响因素的基础上,结合分集接收技术,我们给出了MPSK及MQAM应用于蜂窝移动通信时误码率计算的通用近似公式。蒙特-卡洛仿真表明文中给出的误码率近似公式能很好地吻合实际系统的仿真结果。 相似文献
10.
A mathematical model that predicts the dynamic flows in cellular mobile networks that allocate channels using the Borrowing Channel Assignment (BCA) scheme is described in this paper. Two types of handoff procedures – the prioritized and non-prioritized schemes – will be considered in the model. Discrete event simulations were performed and the results were found to be comparable to the results obtained using the mathematical model. Application to comparative study of the dynamic behaviours of the BCA and the Fixed Channel Assignment (FCA) schemes is also presented. 相似文献
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在蜂窝通信系统中,为了减小由于频率复用造成的共信道干扰,必须对用户的发送功率进行控制。针对已有文献存在的问题,如控制步长和迭代需要全局信息,迭代步数对于信道环境敏感,迭代约束条件苛刻等,本文提出了一种新型的分布式功控算法。研究结果表明,与其它算法相比,本算法性能和迭代速度得到明显提高。 相似文献
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With the rapid development of wireless communications systems, different system standards are being merged. Operators take stringent measures to reduce Operational Expenditure (OPEX) and Capital Expenditure (CAPEX); and as a result,soft base stations supporting multiple standards become the evolutionary tend of wireless base stations. This paper introduces the background of soft base stations and analyzes their architecture design, system modules. The key technologies in system implementation and future directions are also presented. 相似文献
15.
This paper proposes and evaluates a set of physical level assisted cross-layer channel assignment schemes. These schemes allocate an incoming call the available channel that experienced the best channel quality conditions during previous transmissions. To estimate such conditions, three different link quality metrics have been considered. The performance of the proposed schemes has been compared to that of the commonly employed random allocation mechanism. The obtained results show that the proposed schemes improve the system performance of an adaptive packet-switched mobile radio system while also exhibiting the long-term channel uniform use characteristic of the random allocation mechanism. The higher performance attained with the proposed schemes is due to their short-term channel use pattern that results in an implicit cooperation among co-channel interfering cells during the channel allocation process. With the proposed schemes, interfering cells avoid assigning the same channels to simultaneous incoming calls, therefore reducing the experienced interference and increasing the system performance.
Javier Gozalvez received an electronics engineering degree from ENSEIRB (Bordeaux, France), a DEA in Electronics from Université de Bordeaux I and a PhD in Mobile Communications from the University of Strathclyde (Glasgow, UK). During his PhD, he received a Best Student Paper Award at the Fourth International Symposium on Wireless Personal Multimedia Communications (WPMC) in 2001. Since October 2002, he is a lecturer at the Signal Theory and Communications Division of the University Miguel Hernández (Elche, Spain). Dr. Javier Gozalvez currently serves as Mobile Radio Senior Editor of the IEEE Vehicular Technology Society News publication and as Associate Editor of the IEEE Communication Letters journal. He has also served in the organizing and/or technical committees of various international conferences including IEEE Vehicular Technology Conferences and International Symposiums on Wireless Communications Systems (ISWCS), and as member of the IASTED Technical Committee on Telecommunications. Over the last years, he has researched on various aspects of adaptive radio resource management techniques. His current research interests include: radio resource management, heterogeneous systems, application of wireless communications to the vehicular environment and wireless sensor networking.
Juan-Jesús González-Delicado received a BEng in Telecommunications Engineering from the University Miguel Hernández (Elche, Spain), obtaining an award for the best academic records. At the moment, Mr Gonzalez-Delicado is pursuing the final year of the MEng in Telecommunications Engineering at the University Miguel Hernández, conducting research in cross-layer radio resource management and heterogeneous wireless systems. 相似文献
16.
I. Panoutsopoulos S. Kotsopoulos K. Ioannou S. Louvros 《Wireless Personal Communications》2004,31(3-4):149-159
This paper analyses an alternative traffic queuing model for the quality of service (QoS) optimization in mobile communications systems. According to the proposed model, the queue of handover attempts is separated to each of the used transceivers of a base transceiver station that covers a particular area. Fixed channel assignment and TDMA are considered, while the proposed technique is compared to the classic queuing model. The comparison results show that the QoS of the proposed model is fully optimized, especially if large queue sizes are chosen. 相似文献
17.
Chong Peter H. J. Leung Cyril 《International Journal of Wireless Information Networks》2001,8(3):155-165
Network-based dynamic channel assignment (DCA) schemes can be used to increase the capacity of TDMA cellular systems. In this paper, a new distributed network-based DCA scheme, known as DCA with interference information, DCA-WI, is proposed and its performance is studied. In this scheme, a base station (BS) assigns a channel in such a way as to minimize the effect on the availability of channels for use in its interfering cells. To accomplish this, each BS maintains an interference information table which contains information about the local cell and its interfering cells. DCA-WI does not require system-wide information. Channel reassignment for new and completed calls are used to further reduce the call blocking probability. Simulation results show that DCA-WI provides a lower call blocking probability compared to other existing schemes in both uniform and nonuniform traffic distributions. 相似文献
18.
Recent demand for mobile telephone service has been growing rapidly while the electro-magnetic spectrum of frequencies allocated for this purpose remains limited. Any solution to the channel assignment problem is subject to this limitation, as well as the interference constraint between adjacent channels in the spectrum. Channel allocation schemes provide a flexible and efficient access to bandwidth in wireless and mobile communication systems. In this paper, we present an efficient distributed algorithm for dynamic channel allocation based upon mutual exclusion model, where the channels are grouped by the number of cells in a cluster and each group of channels cannot be shared concurrently within the cluster. We discuss the algorithm and prove its correctness. We also show that the algorithm requires at most (worst case) O(N
gN
n logN
n) messages, where N
g is the number of groups and N
n is the number of neighbors. This is compared to Choy's algorithm which requires O(N
g
2N
n), where N
g is the number of groups and N
n is the number of neighboring cells in the system. We report our algorithm's performance with several channel systems using different types of call arrival patterns. Our results indicate that significant low denial rate, low message complexity and low acquisition time can be obtained using our algorithm. 相似文献
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本文研究了最优化方法在蜂窝通信系统信道复用,信道配置中的应用,通过研究共信道干扰总概率Pt与系统各参数间的关系,应用最优化方法求出使pt最小的各参数值,从而达到信道最佳复用,通过系统呼叫失败概率pt与信道配置参数间的关系,应用最优化方法求出使pt最小的信道配置参数,从而达到信道的最佳配置,文中还给出了设计实例。 相似文献