Traffic Aided Uplink Opportunistic Scheduling with QoS Support in Multiservice CDMA Networks

In this letter, we address the problem of resource allocation with efficiency and quality of service (QoS) support in uplink for a wireless CDMA network supporting real‐time (RT) and non‐realtime (NRT) communication services. For RT and NRT users, there are different QoS requirements. We introduce and describe a new scheme, namely, traffic aided uplink opportunistic scheduling (TAUOS). While guaranteeing the different QoS requirements, TAUOS exploits the channel condition to improve system throughput. In TAUOS, the cross‐layer information, file size information, is used to improve fairness for NRT users. Extensive simulation results show that our scheme can achieve high system throughput in uplink wireless CDMA systems, while guaranteeing QoS requirements.     

Analysis of Traffic Distribution and Blocking Probability in Future Wireless Networks

Future wireless networks are envisioned to provide good quality multimedia services to mobile users anywhere at anytime. Traditional analysis of teletraffic in such networks assumes that call arrivals follow a Poisson process, as each cell is being modeled as an M/G/c/c queueing system. This does not reflect the real situation since handoff traffic arrivals are not generally Poissonian. In this paper, we propose to model each cell in future wireless networks as a G/G/c/c queueing system. As such a model has not been explicitly addressed in the literature, our main contribution is to propose a solution which enables to evaluate both traffic distribution and blocking probability within each cell of the service area. Result analysis reveals that coefficient of variation of call arrivals has more impact on the network performance than coefficient of variation of channel holding time.     

On Blocking Probability of Multi-Beam CDMA Systems Using SBF Array Antennas

In wireless cellular systems, a code division multiple access (CDMA) technology with array antennas can significantly reduce interferences by taking advantage of the combination of spreading spectrum and spatial filtering. We investigate blocking probabilities of multi-beam CDMA systems using switched beamforming (SBF) array antennas considering non-homogeneous traffic loading over a cell which may cause traffic congestion and introduce large blocking probability in a hot-spot area. We also propose a feasible main beamwidth deployment and a beam reassignment (BR) method to mitigate the hot-spot beam, named the hot-beam. The feasible main beamwidth deployment suggests that we can relieve the hot-beam situation by deploying the feasible main beamwidth which can guarantee below 1% blocking probability. Using the BR method, the blocking probability of hot-beam and total blocking probability over a cell are significantly reduced. Further, it is shown that the feasible traffic load ratio of the hot-beam to the lightly loaded beam is significantly enhanced when the total blocking probability of the cell is maintained below 1%. Hyunduk Kang received the B. Eng. degree in electronics engineering from the Dong-A University, Busan, South Korea, in 1997, and the M.S. degrees in information and communications engineering from the Gwangju Institute of Science and Technology (GIST), Gwangju, South Korea, in 1999. He is currently a Ph.D. candidate in information and communications engineering from the GIST. His current research interests include performance analysis and resource management of next generation mobile communications and wireless sensor networks. Seokjin Sung received the B.Eng. degree in radio science and communication engineering from the Hong-Ik University, Seoul, South Korea in 2002, and the M.S. degree in information and communications engineering from the GIST, Gwangju, South Korea in 2004. He is currently a Ph.D. candidate in information and communications engineering from the GIST. His research interests are in the areas of adaptive smart antenna system design and analysis for moving-user environments. Insoo Koo received the B.Eng. degree in electronics engineering from the Kon-Kuk University, Seoul, South Korea, in 1996, and the M.S. and Ph.D. degrees in information and communications engineering from the GIST, Gwangju, South Korea, in 1998 and 2002, respectively. From 2002 to 2004, he was with the GIST as a Research Professor. In 2005, he joined the University of Ulsan where he is presently an Assistant Professor. His current research interests include next generation mobile communications and wireless sensor networks. Kiseon Kim received the B.Eng and M.Eng from the Seoul National University, all in electronics engineering, in 1978 and 1980, and the Ph.D. degree from the University of Southern California, Los Angeles, in 1987, in electrical engineering-systems. From 1988 to 1991, he was with Schlumberger in Texas, as a Senior Development Engineer where he has been involved in development of telemetry systems. From 1991 to 1994, he was a Computer Communications Specialist for Superconducting Super Collider Lab., in TX, where he has built telemetry logging and analysis systems for high energy physics instrumentations. Since joining the GIST, in 1994, he is presently a Professor. His research interests include wideband digital communications system design, analysis and implementation.     

CDMA功率控制研究中目标SIR设置的上限

基于SIR平衡的功率控制可能存在正反馈的问题,从而使得系统不稳定.讨论了在加性高斯白噪声及Rayleigh衰落信道下,CDMA上行链路闭环功率控制系统的SIR上限问题.通过折衷考虑系统的容量与QoS要求,可以确定临界稳定时的目标SIR上限,在设计功率控制算法时,目标SIR只有满足上限要求,才能确保CDMA系统稳定.     

Performance Analysis of Trunk Network for Inter-MSC Soft Handoffs in CDMA Cellular Communication Systems

The soft handoffs between two adjacent MSC's should be employed to support the calls requesting handoffs to an MSC while minimizing the undesirable “ping pong” phenomenon of back-and-forth handoffsbetween two adjacent cells in conventional hard handoffs. In this paper, the soft handoff scheme between two MSC's is considered using the trunk between the packet routers for the two MSC's. The trunk network is proposed to support the inter-MSC soft handoff scheme in the service area with many MSC's. The probability that a°soft handoff to an adjacent MSC will be blocked due to the shortage of the trunk capacity is derived.     

Call Admission Control Algorithms in OFDM-based Wireless Multiservice Networks

Orthogonal frequency division multiplexing (OFDM) is becoming a fundamental technology in future generation wireless communications. Call admission control is an effective mechanism to guarantee resilient, efficient, and quality-of-service (QoS) services in wireless mobile networks. In this paper, we present several call admission control algorithms for OFDM-based wireless multiservice networks. Call connection requests are differentiated into narrow-band calls and wide-band calls. For either class of calls, the traffic process is characterized as batch arrival since each call may request multiple subcarriers to satisfy its QoS requirement. The batch size is a random variable following a probability mass function (PMF) with realistically maximum value. In addition, the service times for wide-band and narrow-band calls are different. Following this, we perform a tele-traffic queueing analysis for OFDM-based wireless multiservice networks. The formulae for the significant performance metrics call blocking probability and bandwidth utilization are developed. Numerical investigations are presented to demonstrate the interaction between key parameters and performance metrics. The performance tradeoff among different call admission control algorithms is discussed. Moreover, the analytical model has been validated by simulation. The methodology as well as the result provides an efficient tool for planning next-generation OFDM-based broadband wireless access systems.

码分多址（CDMA）技术和公用空中接口综述

本文主要讨论数字移动通信中扩频码分多址技术，阐明了ＣＤＭＡ体制的优越之外，分析了ＣＤＭＡ的关键技术，全面介绍了ＣＤＭＡ系统设计的基本原则和ＩＳ－９５－Ａ空中接口标准的含义。     

基于CDMA的IMT-2000空中接口方案简介

围绕第三代移动通信系统IMT - 2 0 0 0标准 ,各国间正展开激烈的竞争 ,提交ITU的地面候选方案多达 10种。由于CDMA具有容量大、频谱利用率高、频率规划方便等优点 ,IMT - 2 0 0 0候选标准已基本上统一到基于CDMA方案上。本文先简要介绍了第三代CDMA空中接口的特征 ,然后分别介绍呼声最高的两种方案的空中接口标准 :W -CDMA和cdma2 0 0 0。     

分布式数字交换网络阻塞概率的研究

全分散控制数字程控交换系统广泛采用分布式数字交换网络，其阻塞概率和设备配置是设计中必须考虑的重要问题。本文对近期报导的基于３ 种阻塞成分的算法作了明显改进，提出了不受通信模块数量限制的通用计算方法，并使得计算简化和规则化     

时隙光突发交换网络阻塞性能分析模型

文章介绍了基于时隙的光突发交换网络的结构及其特点，提出了相应的时隙化多波长多光纤系统阻塞分析模型，仿真结果表明该模型准确地反映了光纤数和帧长等网络参数变化对网络阻塞特性的影响．对于评估时隙突发交换网络性能和设计实现参数具有重要意义。     

UMTS/WCDMA空中接口方案的物理层协议

简要介绍第三代移动通信系统的研究现状,并对欧洲通用移动通信系统ＵＭＴＳ／ Ｗ ＣＤＭＡ 空中接口方案的物理层协议进行深入探讨。     

截断差分概率的上界估计与应用

截断差分分析是差分分析的一个变形。为说明一个密码算法能够抵抗截断差分分析,需要给出截断差分概率的上界。Masayuki Kanda等人就密码算法中S盒为GF(256)上的乘法逆变换和仿射双射变换复合而成时,提出了截断差分概率的上界一个猜想。该文就一般双射S盒给出了该概率上界问题的一个估计,Masayuki Kanda的猜想是该估计所考虑问题的一个特例,在一些情况下,该估计给出的上界与Masayuki Kanda的猜想接近。利用该结论可以衡量密码算法截断差分传递链概率的上界。该结论为分组密码抗截断差分分析的可证明安全性提供了理论依据。     

CDMA2000 1x空中接口信息加密及其实现

研究了CDMA2000 1x空中接口加密机制的原理和过程,完成了空中接口部分信患加密的软件实现,在测试的基础上分析了加密机制的安全性,并指出了其中存在的安全漏洞。     

基于Erlang-B的阻塞率仿真实现

本文根据爱尔兰B公式,分析实现了阻塞率仿真,仿真结果表明：随着话务量的增加,阻塞率也在增加,当话务量增加到一定大小时,阻塞率增加趋势有所减缓。     

An Evaluation Model for Integrated Services on Wireless Broadband CDMA Networks

This paper proposes a performance evaluation approach for integrated voice and data services on a broadband code division multiple access (CDMA) network. For random access schemes, the dynamic behavior of a CDMA channel infers that we must be cautious with a performance judgment. We must be especially careful when choosing a mathematical model that has to include the effect of dynamic error rates. The approach shown in this paper is to employ a Poisson error model that takes the occurrence of errors as a Poisson process with the occurring rate dependent on the channel traffic. Based on this assumption, we developed a continuous-time Markov chain model to evaluate the throughput and delay performance. This approach can certainly apply to the evaluation of many integrated services protocols.     

A Framework for JRRM with Resource Reservation and Multiservice Provisioning in Heterogeneous Networks

Inter-working and convergence of heterogeneous wireless networks are paving the way to scenarios in which end users will be capable of using simultaneously services through different Radio Access Technologies (RATs), by means of reconfigurable mobile terminals and different network elements. In order to exploit the potential of these heterogeneous networks scenarios, optimal RAT selection and resource utilization mechanisms are required. As a result, the heterogeneous networks are introducing a new dimension to the Radio Resource Management (RRM) problem, so that new algorithms dealing with the dissimilarities and complementarities of the multiple RATs from a joint perspective have to be considered. In this sense, this paper proposes a Joint Radio Resource Management (JRRM) strategy in a multi-RAT, multicellular and multiservice scenario. An approach based on Fuzzy Neural methodology is presented. Firstly, the way how the proposed Fuzzy Neural framework deals with the multiservice allocation in a heterogeneous scenario is presented. A reinforcement learning algorithm based on neural networks allows guaranteeing a multidimensional QoS focusing on those QoS requirements which mainly affect the user perception of the service. In addition to this, the performances obtained by the Fuzzy Neural JRRM for both real-time and non real-time services, are compared to the ones offered by alternative JRRM strategies. Secondly, special attention is paid to real-time services and to mechanisms to improve their performances. An approach based on predicting future JRRM decisions and on accordingly reserving radio resources for handoff calls is presented. Simulation results will show improvements in terms of both new connection blocking and handoff call dropping probabilities. Finally, the full set of results provides the sufficient insight into the problem to allow stating that the present Fuzzy Neural framework can be a firm candidate for JRRM.

Delay-on-Demand: A Signaling Protocol to Reduce Blocking Probability in Optical Burst-Switching Networks

Optical burst switching (OBS) is emerging as one promising switching paradigm for the next generation optical networks. To support multiple services in burst-switching networks, the OBS paradigm should support some quality-of-service (QoS) provisioning. A major design issue in such networks is to reduce the blocking probability of the bursts arising due to resource contention at the intermediate core router. In this paper, we propose a signaling protocol which we call ‘Delay-on-Demand’ (OBS-DoD), to reduce blocking probability and support QoS in optical burst-switching networks. The proposed scheme guarantees that at least one of the bursts succeeds depending on its priority, propagation delay from the ingress router, and the burst-size when contention occurs at the core router. For this, we use a control packet to delay, in case of a contention, the transmission of bursts at the ingress router. We compare the performance of our proposal, by simulation, with an earlier proposed scheme, and show that the proposed OBS-DoD outperforms the earlier scheme in reducing the blocking probability. For simulation, we generated bursty traffic using an M/Pareto distribution.     

CDMA/OFDMA异构网络中最小化中断概率的网络选择方案

该文针对采用周期式负载测量机制的CDMA/OFDMA异构网络场景,提出了一种最小化SIR中断概率(Minimizing SIR Outage Probability, MSOP)网络选择方案。该算法采用Wilkinson近似方法得出呼叫最佳接纳概率。仿真结果证明,在较长的测量周期下,该算法能有效实现负载均衡,获得更高的中继增益,提高资源的使用效率;同时,该算法也能大大降低呼叫的平均中断概率,使用户获得更好的通信体验。     

Approximating the Outage Probability of the Pilot Channel for IS‐95‐Based Cellular CDMA Systems in the Soft Handover Region

This letter presents an approximation of the outage probability of the pilot channel that can be used for CDMA cell planning. The approximation can determine system parameters for soft handover in IS‐95‐based cellular CDMA downlink design. Computer simulations show that our analytical results agree with empirical results.     

基于CDMA技术的光接入网

提出了采用ＣＤＭＡ实现光纤搪入网的一般方案，讨论了光ＣＤＭＡ中的光扩频编码技术，信道间干扰的消除，功率控制等关键技术，并对光纤接入网的几种接入方法作了详细的分析比较。