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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
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在对信道分配问题分析的基础上,给出数学模型,将此问题转化为带约束的优化问题,并通过设计遗传算法的个体编码方式,适应度函数、遗传算子实现了移动通信中的信道分配问题的优化。 相似文献
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TD-SCDMA是由中国提出并被ITU所接受的第三代移动通信标准,是第三代移动通信系统(UMTS)和IMT2000国际电信标准大家庭中的重要成员。 一、 TD-SCDMA的特点TD-SCDMA的移动无线系统是针对所有无线环境下对称和非对称的3G业务所设计的,它运行在不成对的射频频谱上,适用于TDD模式下的TDMA操作系统。TD-SCDMA的先进设计支持每射频载波上灵活的时域上/下行链路的转换,从而更加能够适应于不同3G业务中不同的上/下链路关系。传输方向的时域自适应资源分配可取得独立于对称业务负载关系的频谱分配的最佳利用率,因此,… 相似文献
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TD-SCDMA是由中国提出并被ITU所接受的第三代无线通信标准,并已成为第三代无线通信系统UMTS和IMT2000国际电信标准大家庭中的重要成员. 相似文献
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首先讨论了信道分配中电磁兼容限制因素、分类及性能评价,具体分析了各种动态信道分配方案,最后对“有序信道借用OCS”方案进行了模拟,得出了不同条件下的DCA的性能曲线,并与FCA进行了比较。 相似文献
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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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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
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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
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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
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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. 相似文献
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The conventional approach of hybrid channel assignment strategy in cellular networks is rather inefficient due to the fact that it does not take advantage of the FCA scheme to the extreme. In this paper, we divide a cell into two parts: inner cell region and outer cell region, and apply the dynamic channel assignment and the fixed channel assignment schemes to the inner region and out region, respectively, in an attempt to fully utilize the strengths of the channel assignment schemes. In the performance evaluation, we demonstrate that the channel reuse efficiency has been improved compared to the FCA and DCA schemes. We also calculate the probability of an intracell handoff due to the use of the space partitioning. The proposed scheme can be adapted to a multi-tier structure with high/low speed mobile users, and hot spots. 相似文献