业务非均匀分布CDMA系统中一种基于公平性保证的贪婪呼叫接纳控制策略

呼叫接纳控制(Call Admission Control,CAC)是移动通信系统资源管理的主要内容之一。它通过接纳或者拒绝一种用户服务请求,来保持系统的正常运行,是平衡用户服务满意度与系统资源最大化利用矛盾的主要手段。该文主要研究小区间业务非均匀分布时基于公平性保证的动态CAC策略,提出了一种新的CAC策略,可适用于多业务且有变速率(Variable BitRate,VBR)业务的情况。该策略采用贪婪算法,用户请求接入以全系统的预期信干比作为判决条件,从而实现了不同到达率小区之间阻塞率的均衡,保证了用户接入的公平性,对于实际系统的应用具有重要的意义。     

异步相干扩时光码分多址系统的干扰性能分析

从码字的非周期互相关函数出发,分析异步相干扩时光码分多址(OCDMA)系统的多址干扰(MAI)和差拍噪声(BN).干扰用户不同的传输时延,非周期互相关强度均值随之变化,差拍噪声和多址干扰也随之变化.给出了差拍噪声和多址干扰与非周期互相关强度均值的关系,讨论了异步相干扩时OCDMA系统的误码率(BER)与非周期互相关强度均值的关系.最后,以码长511的Gold码为例,针对干扰用户之间不同的传输时延,得到了异步相干扩时OCDMA系统的误码率上界与平均误码率性能.在平均误码率情况下,OCDMA系统能支持12个干扰用户,而在最差情况下(误码率上界),系统容纳的干扰用户数不超过4个.     

Interference and Queuing Delay Based Uplink Packet Access Control in Wideband Code-Division Multiple-Access Systems

In this letter, we propose a packet access control algorithm for non-real-time, interactive packet services via dedicated channels in the uplink of wideband code-division multiple-access (WCDMA) systems. We first derive an analytical expression of packet throughput as a function of packet queuing delay and the required signal-to-interference-plus-noise-density ratio. Based on such a relationship, we then propose a packet access control algorithm that not only maximizes the packet throughput per cell, but also provides quality of service (QoS) assurance. Practical aspects of a CDMA system such as the effects of power control inaccuracy and other cell interference are considered in the analysis.     

A Novel Effective Bandwidth Based Call Admission Control for Multimedia CDMA Systems

A novel Call Admission Control(CAC)scheme is proposed for multimedia CDMA systems.The effectivebandwidth of real time calls is reserved in the CAC with the consideration of active factors.The admission of non-real timecalls is controlled by the system according to the residual effective bandwidth left from real time calls.Simulation resultshave shown that the novel CAC has greatly enlarged the admission region for real time calls and make the transmission de-lay of non-real time calls under an acceptable level.     

一种CDMA网络多业务的呼叫允许控制算法

现今无线网络中的多媒体业务具有很大需求。该文对多业务CDMA通信系统容量进行分析,引入有效带宽概念,提出一种呼叫允许控制资源分配优化算法(CAC-RA)。此算法将多媒体业务分为实时业务和非实时业务,通过对自适应实时业务采用马尔科夫模型,对非实时业务采用排队模型,将两模型合并生成的的利益函数采用非线性规划,使呼叫允许控制、切换策略和资源分配问题同时得到解决。实验数据显示CAC-RA算法实现了合理的资源利用和最大的利益值,能较好地适应多业务CDMA网络。     

LEO卫星通信系统的呼叫接入性能分析

在均匀业务模型的基础上,根据LEO卫星通信系统自身特点,提出了一种简单有效的呼叫接入控制策略,这种策略能在非均匀业务下较好地工作,此时系统新呼叫阻塞率和切换呼叫失败率能达到更好的平衡。在分析随机接入（RANDOM）算法和预留保护信道（GC）算法的基础上,进行了计算机仿真,并给出了相应的仿真结果。     

基于缓存的语音/数据呼叫无线接入控制算法

该文提出了一种新的无线网络中语音/ 数据的呼叫接入控制算法(DTQ-VBR算法),设置资源预留的双重门限及呼叫缓存,兼顾数据业务的VBR特性,动态改变其服务带宽,并利用三维马氏链对其进行性能分析。大量的仿真实验表明,与DTR-Q、 DTBR算法相比,该文算法的平均信道利用率、呼叫强拆率及阻塞率等性能具有明显的提高。     

Soft QoS in Call Admission Control for Wireless Personal Communications

In wireless multimedia communication systems, call admission control (CAC) is critical for simultaneously achieving a high resource utilization efficiency and maintaining quality-of-service (QoS) to mobile users. User mobility, heterogeneous nature of multimedia traffic, and limited radio spectrum pose significant challenges to CAC. QoS provisioning to both new calls and handoff calls comes with a cost of low resource utilization. This paper proposes a CAC policy for a wireless communication system supporting integrated voice and dataservices. In particular, soft QoS (or relaxed target QoS) is incorporated in the CAC policy to make compromises among different objectives.Numerical results are presented to demonstrate that (a) in dealing with the dilemma between QoS satisfaction and high resource utilization, how the resource utilization efficiency can be increased by introducing soft QoS; and (b) in accommodating different types of traffic, how the QoS of low priority traffic can be improved by specifying soft QoS to high priority traffic.     

一种新的CDMA系统多业务接入控制算法

文中提出一种新的CDMA系统中多业务接入控制算法。为了提高系统容量,在传统容量干扰受限的CDMA系统接入控制算法的基础上,考虑各种业务的激活因子,计算出系统接入呼叫用户后各个业务的中断概率,根据其中断概率是否满足QoS要求判断业务是否接入。仿真结果表明：所提算法的各种业务的阻塞概率明显低于传统算法,并且系统获得的性能改善随着桌些业务呼叫强度的增加而下降,从而证明了所提算法在系统容量上的优势。     

On Schemes for Multriate Support in DS-CDMA Systems

Different modulation schemes supporting multiple data rates in a Direct Sequence Code Division Multiple Access (DS-CDMA) system are studied. Both AWGN and multipath Rayleigh fading channels are considered. It is shown that the multi processing-gain scheme and the multi-channel scheme have almost the same performance. However, the multi-channel scheme may have some advantages due to easier code design and multiuser receiver construction. The drawback though, is the need for linear amplifiers also in mobile terminals. A multi-modulation scheme is also possible, but the performance for the users with the high data rates are significantly worse than for the other schemes. Furthermore multi chip-rate, parallel combinatory spread spectrum (PC/SS), pulse position modulation (PPM) and variable duty cycle schemes are discussed briefly.     

不平衡业务下CDMA蜂窝系统的呼叫接入控制方案

针对 CDMA蜂窝系统区间业务不平衡的情况 ,文中提出了一种呼叫接入控制方案 ,在重负荷小区为邻区即将到来的呼叫预留部分资源 ,预留的大小随呼叫阻塞情况自适应地调整。仿真结果显示 :该方案能很好地解决区间业务不平衡的问题 ,而且与基于固定资源预留的呼叫接入控制方案相比 ,还能获得低的系统呼叫阻塞率     

Capacity Analysis for Connection Admission Control in Indoor Multimedia CDMA Wireless Communications

In this paper, the capacity analysis for connection admission control is presented for the reverse-link transmission of a packetized indoor multimedia wireless communication system using direct sequence code division multiple access (DS/CDMA). Since CDMA is interference limited, the signal-to-interference-plus-noise ratio criterion is used to check if there is enough system resources (i.e., the CDMA channels and received signal power) for each new connection request. Taking into account the stochastical nature of multimedia traffic, the effective bit rate is used to characterize the resources required by each mobile user and a linear approximation is then used to find the total resources required by all the mobile users already admitted to the system and the new connection request. Transmission errors due to both base station buffer overflow and wireless channel impairments are considered. The capacity of multimedia traffic is determined in such a way that the utilization of the system resources is maximized and, at the same time, the required transmission bit error rate and transmission delay of all users admitted to the system are guaranteed. Computer simulation results are given to demonstrate the performance of the proposed method for capacity analysis.     

3G动态预留呼叫接纳控制算法研究

第三代移动通信技术支持不同服务质量(QoS)的多媒体业务,而呼叫接纳控制(CAC)技术是移动通信中的关键技术之一.本文提出一种动态预留呼叫接纳控制算法,该算法根据小区中各业务的话务量预测各业务所需信道教,从而为切换业务和新业务预留一定的信道.通过比较动态预留算法与新呼叫受限算法和中断优先级算法的性能,得出动态预留算法在降低语音和数据业务的呼叫阻塞率、中断率方面有明显的改善,是一种比较理想的呼叫接纳控制算法.     

Scalable Schemes for Call Admission and Handover in Cellular Networks with Multiple Services

The introduction of new service categories withdifferent bandwidth requirements, e.g., data and multimedia, to cellularmobile radio networks makes many of the traditional mechanisms for controlingtraffic unusable orless efficient. The call admission and the handover handling are of the mostsensitive issues in this extension to new services. The performance of allservices includingthe traditional voice and the new services can be dramatically affected ifappropriate schemes are not used. In this paper, we propose call admission andhandover handling schemes for a cellular mobile network that offers twoservice types: voice and data. The data connections are assumed to transmitatdifferent transmission rates that are integer multiples to that of one radiochannel. In the case of congestion, the base station asks the active dataconnections to reduce their transmission rate in order to provide freechannels for the newly arrived request of both service types. This isbasically intended for incoming handover requests. The request will berejected if the transmission rate of the active connections reaches a givenminimum rate. Similar mechanism can also be used for new call arrivals, butsome priority can be given to handovers by setting a higher transmission ratethreshold for the new call rejection. As an extension to the proposedscalability, aqueuing of new calls is also proposed and analyzed. Analytical models werebuilt for the two proposed schemes together with the traditional channelreservation scheme. The effect of different traffic and configurationparameters on the performance measures like the grade of service, blockingprobabilities, and utilization, are studied using the proposed technique.Results show that the proposed schemes provide very good performance and morefairness among the different service types.     

WCDMA系统中高速下行分组接入的接纳控制策略

高速下行分组接入(HSDPA)技术是WCDMA对于下行链路分组数据的增强,其分组数据的调度由基站(NodeB)中的MAC hs实体完成。在HSDPA的接纳控制中,数据业务的接纳控制由无线网络控制器(RNC)完成,其判决依据是当前资源的使用状况,这样就需要Node B能通过Iub接口向RNC提供详细的资源使用状况。通过针对HSDPA中流类业务、交互/后台类业务接纳控制的特点,分别从资源的分配、判别门限的设定等方面进行了分析和阐述,并给出了HSDPA中接纳控制的基本流程示意图。     

话音/数据综合的多时隙预约多址协议及其性能分析

本文提出了一种综合话音和数据的多时隙预约多址协议.该协议在保证话音终端的优先权的情况下,允许数据终端在报文的传输期间在连续多个帧中预约多个信息时隙.文中对协议进行了理论分析,并推导出了协议的重要性能指标(如话音分组丢失率、数据报文平均接入时延、系统平均吞吐率等)的解析表达式.研究表明,该协议可以支持比IPRMA、NC-IPRMA更高的等效数据终端速率,而且系统平均吞吐率在很大的负载范围内接近最大值.     

On Admission Control and Scheduling of Multimedia Burst Data for CDMA Systems

In order to support transmissions of multimedia data (high data rate and burst) with performance guarantees in a wideband CDMA system, it is crucial to design a judicious algorithm for burst data admission control and scheduling. However, in the current literature there are only simple techniques (such as first-come-first-served and equal sharing) suggested for tackling the problem. Indeed, these existing schemes are not designed for optimizing the precious bandwidth resources while providing performance guarantees (e.g., a user admitted with a certain data rate can enjoy the assigned rate without interruption). In this paper, we first present our novel integer programming formulation of the burst data admission control and scheduling problem. The objective of the optimization can be maximizing the utilization of the bandwidth resources or minimizing the delays of the user transmissions. Taking into account all the important factors such as mobility, power control, and soft handoff, our formulation induces an algorithm for generating an optimal admission control solution which consists of: (1) the burst data rate (in terms of the number of channels); (2) the burst duration; and (3) the burst start time. For practical implementation, we also suggest a near-optimal version of the algorithm, which is evaluated via static and dynamic simulations, and comparisons with two existing schemes.     

An OCDMA Scheme to Reduce Multiple Access Interference and Enhance Performance for Optical Subscriber Access Networks

We propose a new optical code division multiple access (OCDMA) scheme for reducing multiple access interference (MAI) and enhancing performance for optical subscriber access networks using modified pseudorandom noise (PN)‐coded fiber Bragg gratings with bipolar OCDMA decoders. Through the bipolar OCDMA decoder and the modified PN codes, MAI among users is effectively depressed. As the data are encoded either by a unipolar signature sequence of the modified PN code or its complement according to whether the data bit is 1 or 0, the bit error ratio (BER) can be more improved with the same signal to interference plus noise ratio over the conventional on‐off shift keying‐based OCDMA system. We prove by numerical analysis that the BER of the proposed bipolar OCDMA system is better than the conventional unipolar OCDMA system. We also analyze the spectral power distortion effects of the broadband light source.     

QoS Performance Bounds and Efficient Connection Admission Control for Heterogeneous Services in Wireless Cellular Networks

Quality-of-Service (QoS) performance and connection admission control (CAC) for heterogeneous services in wireless multiple access networks are investigated. The heterogeneous services include constant bit rate (CBR), variable bit rate (VBR) and available bit rate (ABR) services. Multiple access control is handled by a polling-based scheme with non-preemptive priority. Tight delay variation (jitter) bounds for CBR connections and delay bounds for VBR connections are derived. A CAC scheme based on the derived bounds is developed. The CAC makes use of user mobility information to reserve an appropriate amount of system resources for potential handoff connections to achieve low handoff connection dropping rate (HCDR). Simulation results show that the proposed CAC scheme can achieve both low HCDR and high resource utilization.     

时分双工环境下的分组预约多址(PRMA/TDD)协议及其性能

在分析标准分组预约多址（PRMA／FDD）协议的基础上,提出了时分双工环境下的分组预约多址（PRMA／TDD）协议,理论分析和计算机仿真均表明,PRMA／TDD与PRMA／FDD的性能相近,可以较大幅度地提高系统的容量。