共查询到20条相似文献,搜索用时 62 毫秒
1.
第三代移动通信系统可支持全IP的体系结构来灵活部署IP技术,同时提供实时和非实时服务.为了减少切换过程中的分组丢失和时延,提出了一种新的切换方案.同时提出了一种根据网络状况为呼叫请求分配资源的自适应资源分配方案.这一方案可以尽量降低切换呼叫的掉话率和始发呼叫的阻塞率,以便更充分利用系统资源. 相似文献
2.
第三代移动通信系统可支持全IP的体系结构来灵活部署IP技术,同时提供实时和非实时服务。为了减少切换过程中的分组丢失和时延,提出了一种新的切换方案。同时提出了一种根据网络状况为呼叫请求分配资源的自适应资源分配方案。这一方面可以尽量降低切换呼叫的掉话率和始发呼叫的阻塞率,以便更充分利用系统资源。 相似文献
3.
4.
5.
本文提出了一种分层小区结构系统中的呼叫接入控制策略,系统根据当前本小区和周围小区的干扰情况实时地对呼叫请求作相应控制,考虑了实时语音和非实时数据两种典型业务,为切换呼叫设置了高于新呼叫的优先级,并对暂时得不到资源的切换呼叫(包括语音和数据业务)进行排队处理,有效地降低了系统的切换掉话率。 相似文献
6.
7.
8.
9.
无线局域网采用移动IP实现移动性管理.移动IP切换存在切换时延大,数据包易丢失的问题.切换时延由移动检测时延和注册时延组成,而移动检测时延在其中占主要部分.文章提出了一种移动检测优化方案,采用了自适应绑定的算法,同时充分考虑了域内小范围高频度切换的情况,使移动节点在无线局域网环境中进行快速有效的切换. 相似文献
10.
11.
The Guard Channel Scheme (GCS) and Handoff Queueing Scheme (HQS) are the popular and practical strategies to prioritize handoff
calls in wireless cellular networks. A key issue of giving handoff calls the higher priority is how to achieve a tradeoff
among the handoff call blocking probability, new call blocking probability and handoff delay. This paper extends GCS and HQS
and presents an efficient handoff scheme that dynamically manages the channels reserved for handoff calls depending on the
current status of the handoff queue. A three-dimensional Markov model is developed to analyze the performance of this scheme
and investigate the desirable performance tradeoff. The Poisson process and Markov-Modulated-Poisson-Process (MMPP) are used
to model the arrival processes of new and handoff calls, respectively. The accuracy of this model is evaluated through the
extensive comparison of the analytical results to those obtained from discrete-event simulation experiments. Performance measures
in terms of the mean number of calls in the system, aggregate response time, aggregate call blocking probability, handoff
call blocking probability, new call blocking probability and handoff delay are evaluated. The analytical model is used to
investigate the effects of the number of channels originally reserved for handoff calls, the number of dynamic channels, and
the ratio of the rate of handover calls to the aggregate arrival rate on the system performance. 相似文献
12.
Chang C. Chung-Ju Chang Kuen-Rong Lo 《Vehicular Technology, IEEE Transactions on》1999,48(4):1080-1091
We analyze a hierarchical cellular system with finite queues for new and handoff calls. Both the effect of the reneging of waiting new calls because of the callers' impatience and the effect of the dropping of queued handoff calls as the callers move out of the handoff area are considered, besides the effect of the guard channel scheme. We successfully solve the system by adopting the multidimensional Markovian chain and using the transition-probability matrix and the signal-flow graph to obtain the average new-call blocking probability, the forced termination probability, and the average waiting time of queued new and handoff calls. We further investigate how the design parameters of the buffer sizes and guard channel numbers in macrocell and microcells affect the performance of the hierarchical cellular system. The results show that provision of a buffering scheme and guard channel scheme can effectively reduce the new call blocking probability and the forced termination probability in the hierarchical cellular system, and the effectiveness is more significant in the macrocell than in the microcells 相似文献
13.
Hassan Al-Mahdi Hamed Nassar Yasser Fouad Mohamed Ali 《Wireless Personal Communications》2013,69(2):579-599
In this paper, a channel assignment scheme is proposed for use in CDMA/TDMA mobile networks carrying voice and data traffic. In each cell, three types of calls are assumed to compete for access to the limited number of available channels by the cell: new voice calls, handoff voice calls, and data calls. The scheme uses the movable boundary concept in both the code and time domains in order to guarantee the quality of service (QoS) requirements of each type. A traditional Markov analysis method is employed to evaluate the performance of the proposed scheme. Measures, namely, the new call blocking probability, the handoff call forced termination probability, the data call loss probability, the expected number of handoff and the handoff link maintenance probability are obtained from the analysis. The numerical results, which are validated by simulation, indicate that the scheme helps meet the QoS requirements of the different call types. 相似文献
14.
In future personal communications networks (PCNs) supporting network-wide handoffs, new and handoff requests will compete for connection resources in both the mobile and backbone networks. Forced call terminations due to handoff call blocking are generally more objectionable than new call blocking. The previously proposed guard channel scheme for radio channel allocation in cellular networks reduces handoff call blocking probability substantially at the expense of slight increases in new call blocking probability by giving resource access priority to handoff calls over new calls in call admission control. While the effectiveness of a fixed number of guard channels has been demonstrated under stationary traffic conditions, with nonstationary call arrival rates in a practical system, the achieved handoff call blocking probability may deviate significantly from the desired objective. We propose a novel dynamic guard channel scheme which adapts the number of guard channels in each cell according to the current estimate of the handoff call arrival rate derived from the current number of ongoing calls in neighboring cells and the mobility pattern, so as to keep the handoff call blocking probability close to the targeted objective while constraining the new call blocking probability to be below a given level. The proposed scheme is applicable to channel allocation over cellular mobile networks, and is extended to bandwidth allocation over the backbone network to enable a unified approach to prioritized call admission control over the ATM-based PCN 相似文献
15.
A traffic management scheme is proposed in a multicode code-division multiple-access system supporting soft handoff that uses guard channels and a queue for real-time traffic. Preemptive queue control gives priority to queued handoff calls. Handoff traffic is derived as a function of the new call arrival rate, the size of the soft handoff region, mobile speed, the new call blocking probability, and the handoff failure probability. System performance with K types of calls is analyzed by introducing a concept of effective channel. The effects of the number of guard channels, the number of effective channels, system capacity, and other factors are numerically investigated. The effectiveness of the proposed queue control scheme is also observed in terms of handoff processing delay 相似文献
16.
为了降低多媒体业务在移动环境中的呼叫中断率,提高无线信道的利用率,该文提出了一种动态预留带宽分配机制(DRBA),该机制对到达的越区切换呼叫按业务类型区别处理,对于高优先级的实时业务,通过在邻近小区内预留带宽的方法降低呼叫中断率;对于非实时业务,当小区内的信道带宽不足以支持新到达的越区切换呼叫时,通过动态地借用实时业务过度预留的带宽,改善非实时业务的呼叫中断率,进一步达到提高无线信道利用率,为不同的业务类型提供公平的服务质量(QoS)的目标。 相似文献
17.
Sachiko Yamanaka Katsunori Shimohara 《International Journal of Communication Systems》2006,19(3):317-333
This paper presents the analysis of CDMA cellular networks with channel sub‐rating. From users' point of view, our considered scheme gives higher priority to handoff calls over new calls by sub‐rating the existing connections when handoff calls find no idle channels upon their arrivals. Therefore, it is considered that the disadvantage of the soft handoff which needs more channels than the hard handoff is made up for. Handoff calls can also wait in a queue while they are in handoff areas if all channels are sub‐rated in the cell of interest. We mathematically model this scheme by applying queueing theory. Then, we analyse its performance to derive the blocking probabilities of the new and handoff calls, the probability that handoff calls leave the handoff area without getting new channels, the degradation ratio of the voice quality by sub‐rating, mean and coefficient of variation of the waiting time of handoff calls. In numerical results, the analytical results are compared with the simulation ones to validate our analytical approach. Moreover, we compare the sub‐rating scheme with full‐rating one with respect to some characteristic values to show the effect of sub‐rating. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
18.
Young Chon Kim Dong Eun Lee Bong Ju Lee Young Sun Kim Mukherjee B. 《Communications Magazine, IEEE》1999,37(11):47-51
We present a dynamic channel reservation scheme to improve the utilization of wireless network resources while guaranteeing the required QoS of handoff calls. The wireless channels are dynamically reserved by using the request probability determined by the mobility characteristics and channel occupancy to guarantee acceptable quality of handoff calls and keep the new call blocking probability as low as possible 相似文献
19.
Wei Kuang Lai Yu-Jyr Jin Hsin Wei Chen Chieh Ying Pan 《Vehicular Technology, IEEE Transactions on》2003,52(4):876-890
The paper focuses on how to assign channels for initial and handoff calls. Previous schemes give priority to handoff calls by queuing handoff calls, reserving some channels for handoff calls, or subrating existing calls for handoff calls. We queue both initial and handoff calls. We take this idea from derivations of the optimal value for an approximation to the call-completion probability. Our goal is to have higher call-completion probability and still keep forced-termination probability low. We propose four schemes: SFTT (single-queue, FIFO, timeout, average timeout), SPTT (single-queue, priority, timeout, average timeout), DFTS (dual-queues, FIFO, timeout, statistical TDM), and DPTS (dual-queues, priority, timeout, statistical TDM). The four schemes, along with the NPS and FIFO schemes, were simulated and compared. For the SFTT scheme, we also simulated different average timeouts for initial calls. All four proposed schemes have better call-completion probabilities than the NPS and FIFO schemes. Call-completion probabilities can be improved by implementing a priority scheme which serves the waiting call with the least remaining time first. The implementation of statistical multiplexing also has the effect of increasing call-completion probability when the average new-call arrival rates are high. However, both the priority scheme and statistical multiplexing may increase forced-termination probability. 相似文献
20.
A MAC protocol for new and handoff calls with a finite populationof users, rather than with an infinite user population as indynamic channel reservation scheme (DCRS), is considered. Similarto DCRS, we divide the wireless channels into shared channels andreserved channels. The handoff calls access any available channelwith probability of one, while the new calls access a sharedchannel with probability of one and access a reserved channel witha request probability. We propose three simpler formulae than thatused in the existing DCRS in setting the request probability. Inaddition, the handoff calls in our proposed protocol are allowedto queue in a finite buffer. To evaluate the system performance, amathematical model based on queuing theory, rather than asimulation method used in DCRS, is developed. It is a generalmodel that can be adopted for any types of request probabilitiesincluding DCRS. Suggestions of how to get the optimum values ofthe design parameters are also given. 相似文献