基于实时业务挤占的OFDMA系统的无线资源分配方案

为了在实时业务和非实时业务共享无线资源的场景中增加系统吞吐量,该文提出了一种基于实时业务挤占的无线资源分配方法,该方案首先实施统一调度,然后进行实时业务挤占过程。在保证对实时业务服务的情况下,实时业务挤占的无线资源分配方案提高了多用户分集效果,增加了系统的吞吐量。理论和仿真分析表明,与已有的传统的实时业务和非实时业务共享无线资源的调度方案相比,该方案能够提供更高的系统吞吐量和频谱效率。在实际应用中,该方案具有一定的可行性和可操作性。     

一种新的基于虚拟队列的无线多播网络编码调度策略

网络编码由于其传输效率高的特性,近年来在无线多播网络中得到广泛的应用。针对无线多播网络中丢包自动重传效率低的问题,该文提出一种新的基于虚拟队列中数据包到达时间的编码调度策略(CSAT)。在CSAT策略中,为了提高编码效率,采用虚拟队列来存放初始以及未被所有接收者接收到的数据包。考虑到队列的稳定性,CSAT策略按照一定的比率从主次队列选择发送;在次队列发送数据包时,结合了编码和非编码两种方式,根据数据包到达队列的先后,选取能够使较多数据包参与编码的方式发送。仿真结果表明,该文所提的CSAT编码调度策略在有效提高了数据包传输效率的同时,提高了网络的吞吐量并降低了平均等待时延。

     

一种具有小尺度公平的无线分组调度算法

本文在调度判决时考虑到用户的访问时延限制,比例公平调度算法基础上提出了M-PF算法。本文建立了无线分组调度系统模型,通过仿真对新算法在小尺度服务时间保证、大尺度服务时间公平和系统吞吐量等方面的性能进行分析,研究了系统参数对算法性能的影响。结果证明,新算法在保证系统吞吐量和大尺度公平性的同时可以提供更好的小尺度服务时间保证。     

一种按比例补偿的无线公平调度算法

该文提出了一种按比例补偿的无线公平调度算法,算法区分不同的服务类别并可根据其业务需要进行不同的调度。考虑到无线信道的特殊性,算法引入了补偿和再分配模式。其中补偿模式采用了针对滞后流按照其预约速率的固定比例进行补偿的方式。     

一种抑制小区间干扰的比例公平调度算法

针对LTE-Advanced系统中小区间干扰及用户公平性问题,提出了基于多小区联合预编码和静态功率控制的比例公平(MCPPC-PF)调度算法。通过干扰空间迫零和静态控制发射功率的方法抑制小区间干扰,并结合比例公平(PF)调度算法,提高用户的公平性。仿真结果表明,与传统算法相比,MCPPC-PF算法提升系统容量的同时还提高了用户的公平性;与基于多小区联合预编码和静态功率控制的最大化吞吐量调度算法相比,MCPPC-PF算法在系统容量损失了4.6%的情况下,边缘用户容量提高了约45%。     

一种新型的OFDMA比例公平资源分配算法

针对已有算法对系统容量和高公平性兼顾较差的情况,提出了一种满足公平性的系统容量最大化资源分配算法。在子载波分配中通过建立信道效率控制模型,给当前用户分配信道效率最高的子载波,将信道增益低于门限值的子载波重新分配,改进了最大化最小(max-min)用户速率模型。在功率分配中将系统模型转化成用注水线表示的数学模型,首先求解各用户的注水线,再求解各用户的功率分配,保证了用户间比例公平性。两种信噪比情形下的仿真和分析表明,整个方案计算复杂度稍低,系统容量获得较大提升,并且用户间的公平性始终为1。     

一种基于比例公平的多跳OFDMA系统资源分配算法

为解决多跳OFDMA系统的资源分配问题,本文提出一种基于比例公平的资源分配算法,该算法将一个联合优化的问题分解为两个步骤,首先在等功率分配的条件下求出最优的子载波分配以及中继节点选择方案,然后再根据注水定理进行功率分配,以提高系统的性能.仿真结果表明,该算法能够在保障不同用户间公平性的条件下,有效地提高系统的容量.     

高速无线个域网中一种基于效用公平的机会调度算法

基于对无线高速个域网中机会调度的研究,提出了一种适用于WPAN的机会主义时隙调度算法FPTS。该算法充分考虑了信道状态的波动和用户间的公平性,由参数更新模块和调度分配模块组成。参数更新模块根据调度结果更新控制参数,维护用户的公平性和自适应的跟踪信道的变化;调度分配模块负责计算每个用户的公平效用权值,并按照权值向各用户比例分配信道资源。仿真结果表明：所提调度方案能够在保证系统高吞吐量的前提下,获得LLPTS算法更好的公平性和信道使用效率。     

一种针对用户数量变化而改进的比例公平算法

针对复杂环境下用户数量改变的情况,对用户数量和不同资源分配算法吞吐量之间的关系进行了分析,找出其变化趋势,在现有比例公平算法的基础上,提出了一种调节因子,在公平性指标可以接受的范围内,使得改进后的比例公平算法可以良好适应100以内的用户数量变化,避免过于逼近吞吐量的理论下限值,在吞吐量较低时最高可以获得接近9%的性能提升。提出的算法将能够更好地适应时变环境,有效改善用户数激增带来的系统性能下降问题。     

一种支持服务类别的无线公平调度算法

本文提出了一种支持服务类别的无线公平调度算法:CoSB－WFS(基于服务类别的无线公平调度).算法区分不同的服务类别并可根据其业务需要进行不同的调度.考虑到无线信道的特殊性,算法引入了补偿和再分配模式.在仿真工具OPNET上模拟了算法并得到了性能改良的结果.     

多用户多服务无线网络中感知用户体验的比例公平调度

The effective radio resource allocation algorithms, which satisfy diversiform requirements of mobile multimedia services in wireless cellular networks, have recently attracted more and more attention. This paper proposes a service-aware scheduling algorithm, in which the Mean Opinion Score (MOS) is chosen as the unified metric of the Quality of Experience (QoE). As the network needs to provide satisfactory services to all the users, the fairness of QoE should be considered. The Proportional Fair (PF) principle is adopted to achieve the trade-off between the network performance and user fairness. Then, an integer programming problem is formed and the QoE-aware PF scheduling principle is derived by solving the relaxed problem. Simulation results show that the proposed scheduling principle can perform better in terms of user fairness than the previous principle maximizing the sum of MOS. It also outperforms the max-min scheduling principle in terms of average MOS.     

一种基于数据重传率的无线自组织网络TCP公平性策略

IEEE 802.11 MAC协议被广泛应用于多跳无线网络的研究与示范网中,802.11协议采用RTS/CTS策略减少了隐终端 问题对无线TCP性能的影响。但在多条并行链路间,隐终端问题的存在使得中间链路节点不能有效的接入到信道,导致TCP性能和公平性严重下降。该文提出了一种新的基于传输层数据重传率方法,对于受到严重干扰的中间链路不断获取它的数据重传率,在重传率增加时动态减少802.11退避计时器竞争窗口大小,增加其接入信道能力,从而提高其TCP性能和公平性。仿真结果证明,使用基于传输层数据重传率方法,不仅能基本上保证并行链路TCP的稳定性,还可以极大地提高中间链路TCP公平性。     

A Heuristic Method for Channel Allocation and Scheduling in an OFDMA System

In this letter, a heuristic channel allocation and scheduling scheme is proposed. By comparing the size of the alternative‐factor assessment, which is obtained by simple calculation, we can easily find the most appropriate channel for each user for overall throughput enhancement. Numerical results show that the downlink throughput of the proposed scheme is higher than that of proportional fairness and is almost the same as that of the maximum C/I scheme, while user fairness remains better than that of the maximum C/I scheme.     

一种针对HSDPA中继系统的比例公平调度算法

由于系统在资源分配上的差异,现有的3GPP长期演进项目的后续演进(Long Term Evolution Advanced,LTE-A)中继系统中的调度算法并不能直接应用于高速下行链路分组接入(High Speed Downlink Packet Access,HSDPA)中继系统。提出了一种适合HSDPA中继系统的比例公平调度算法,并给出了算法流程。通过系统级仿真,比较了该算法与没有中继时的PF调度算法和两层比例公平(THPF)调度算法的性能。仿真结果表明,所提出的调度算法能够在提高用户吞吐率的同时更好地保证用户公平性要求。     

Channel-Aware Earliest Deadline Due Fair Scheduling for Wireless Multimedia Networks

Providing delay guarantees to time-sensitive traffic in wireless multimedia networks is a challenging issue. This is due to the time-varying link capacities and the variety of real-time applications expected to be handled by such networks. We propose and evaluate the performance of a channel-aware scheduling discipline and a set of policies that are capable of providing such delay guarantees in TDM-based wireless networks. First, we introduce the Channel-Dependent Earliest-Due-Date (CD-EDD) discipline. In this discipline, the expiration time of the head of line packets of users' queues is taken into consideration in conjunction with the current channel states of users in the scheduling decision. This scheme attempts to guarantee the targeted delay bounds in addition to exploiting multiuser diversity to make best utilization of the variable capacity of the channel. We also propose the violation-fair policy that can be integrated with the CD-EDD discipline and two other well-known scheduling disciplines [1, 2]. In this policy, we attempt to ensure that the number of packets dropped due to deadline violation is fairly distributed among the users. The proposed schemes can provide statistical guarantees on delays, achieve high throughput, and exhibit good fairness performance with respect to throughput and deadline violations. We provide extensive simulation results to study the performance the proposed schemes and compare them with two of the best known scheduling disciplines [1, 2] in the literature. Khaled M. F. Elsayed (S90-M95-SM02) received his B.Sc. (honors) in electrical engineering and M.Sc. in engineering mathematics from Cairo University in 1987 and 1990 respectively. He received his Ph.D. in computer science and computer engineering from North Carolina State University in 1995. He is now an Associate Professor in Cairo University, Egypt and is an independent telecommunications consultant. Between 1995 and 1997, he was a member of scientific staff with Nortel Wireless Systems Engineering in Richardson, TX.Dr. Elsayed was the editor for the Internet technology series of the IEEE Communications Magazine from 1998 until 2002. He has served on technical program committees for several IEEE, IFIP, and ITC conferences. He was the technical co-chair for IFIP MWCN 2003 conference in Singapore. He also served as an expert evaluator for the European Commission FP5 and FP6 programmes. His research interest is in the area of performance evaluation of communication networks including IP, wireless and optical networks. Ahmed Khattab received his B.Sc. (honors) and MS.C in Electronics and Communications Engineering from Cairo University in 2002 and 2004 respectively. Since August 2005, he is pursuing his PhD degree at Rice University, Texas. His research interests are in wireless networking and radio resource management.     

一种基于子载波合并的多播资源调度算法

针对无线OFDM多播系统,该文提出一种基于子载波合并的多播资源调度算法。该算法通过提前将子载波分组,避免了不必要的子载波配对;自适应地选择子载波合并\非合并,在分集和复用两种模式中选取最优方案;同时根据子载波功率分配的特点,将其解耦为配对子载波集合内功率分配和集合间功率分配两个子问题,进一步优化了算法性能。仿真结果表明,与现有方案相比,所提方案能够在复杂度较低的情况下,较好地提升系统性能。     

OFDMA‐Based Reliable Multicast MAC Protocol for Wireless Ad‐Hoc Networks

Compared with unicast, multicast over wireless ad‐hoc networks do not support reliability due to their inability to exchange request‐to‐send/clear‐to‐send (RTS/CTS) and ACK packets with multiple recipients. Although several media access control (MAC) layer protocols have been proposed to provide reliable multicast, these introduce additional overhead, which degrades system performance. A novel MAC protocol for reliable wireless multicast is proposed in this paper. By adapting orthogonal frequency division multiple access characteristics in CTS and ACK packets, the protocol achieves reliability over wireless multicast with minimized overhead.