基于HSDPA的信道相关分组调度算法研究

针对HSDPA(高速下行分组接入)系统中几种支持非实时业务的经典分组调度算法Max C/I(最大载干比)和PF(正比公平)算法缺乏系统公平性的问题,提出一种基于HSDPA的快速公平分组调度算法。此算法在保证信道瞬时条件和系统吞吐量的前提下,旨在为那些平均吞吐量低于某一阈值的用户提供优先被服务的机会。仿真结果表明,此算法较之Max C/I和PF算法能够保证用户间的长期公平性。     

HSDPA中的分组调度算法

HSDPA系统采用了AMC、HARQ、快速调度等技术以支持有效的数据业务,因此对传统的调度算法提出了新的挑战,分组调度成为影响系统性能的一个重要因素.介绍了两种针对HSDPA系统的调度算法：自适应正比公平算法（APF）和M-LWDF算法,并简单分析了它们的性能.     

一种HSDPA系统中依赖负载的正比公平调度算法

研究和仿真了HSDPA系统中分组调度算法(RR,Max C/I和PF)的系统吞吐量和用户公平性,仿真结果与理论分析表明在HSDPA系统中RR算法调度结果的公平性略逊于PF算法.为了补偿正比公平调度算法公平性,提出了依赖负载的正比公平(LDPF)调度算法.该算法旨在通过低负载时牺牲系统吞吐量换取用户间公平性.然后用扩展了爱立信EUPLANE模块的NS2网络仿真软件对LDPF算法进行了仿真.仿真结果表明LDPF调度算法在系统低负载时有效地补偿了先前的低速率用户,通过这种低负载和高负载时的时间分集,改善用户间的长时公平性.     

HSDPA系统中一种感知用户终端缓存状态的QoE保障调度算法

针对HSDPA系统中现有调度算法无法满足实时业务QoE的缺点,提出一种保障实时业务QoE的调度算法。该算法根据用户反馈的信道质量信息和在基站获取到的用户终端缓存状况信息。确定用户的优先级并据此调度优先级最高的用户,进而保证实时业务的吞吐量和QoE需求。仿真结果表明,与轮询调度算法、比例公平调度算法相比,提出的调度算法不仅能够保证实时业务的QoE需求,而且能满足非实时业务基本的吞吐量需求。     

一种新的HSDPA分组调度算法研究

目前已提出的HSDPA调度算法仅是基于用户的优先级进行数据分组的调度.文章考虑了3G系统的业务多样性,综合考虑用户的优先级和业务的级别,创新性地提出将两类分组调度算法,即基于业务类别的分组调度算法--加权公平排队算法,与基于用户优先级的调度算法--最短队列算法或者最长队列算法相结合后的调度算法.仿真的结果显示,提出的调度算法能满足不同业务要求的QoS.从吞吐量和延时来看,最短队列算法与加权公平排队算法结合方案优于最长队列算法与加权公平排队算法结合的方案.     

HSDPA中的非实时业务无线分组调度算法分析

快速调度机制使系统可以根据所有用户的情况决定哪个用户可以使用信道,以何种速率使用信道,信道总是被与信道状况相匹配的用户所使用,这样在每个瞬间都可以达到最高的用户数据速率和最大的数据吞吐量,但同时兼顾每个用户的等级和公平性。文章首先对基于非实时业务无线分组调度算法进行分析,然后对各种算法在公平性方面进行了仿真。仿真分析表明：RR（轮询调度）、PF（正比公平）和APF（自适应正比公平）算法完全位于公平准则曲线的右侧,因此满足公平性准则的要求;RR算法具有最好的公平性。     

分布式天线系统中的分组调度算法研究

文章研究了分布式天线系统中的分组调度算法,通过计算机仿真,模拟了轮询、最大载干比和正比公平调度算法在分布式天线系统下行信道中的吞吐量和时延性能,指出正比公平调度是一种适合于分布式天线系统的调度方法。     

分布式天线系统中的分组调度算法研究

文章研究了分布式天线系统中的分组调度算法,通过计算机仿真,模拟了轮询、最大载干比和正比公平调度算法在分布式天线系统下行信道中的吞吐量和时延性能,指出正比公平调度是一种适合于分布式天线系统的调度方法。     

CDMA2000 1xEV-DO中的分组调度算法

移动通信系统需要更好地支持分组数据业务，并满足高速分组数据业务的服务质置要求。这可以通过采用好的调度算法提高平均业务速率和系统整体稳定性实现。针对CDMA2000 1x EV-DO系统的有代表性的调度算法有3种：正比公平算法、速率受限的最大载干比算法、加权公平排队-正比公平（WFQ-PF）联合算法。正比公平调度算法是一种算法简单实用的调度方案，但不能满足用户的服务质景保证；速率受限的最大载干比算法具有比正比公平算法更高的平均吞吐量，可方便地在吞吐量和公平性之间获得很好的折衷；WFQ-PF联合算法具有良好的综合性能，但算法较复杂。     

HSDPA中M-LWDF实时业务分组调度算法的改进

HSDPA是UMTS的最新演进。HSDPA采用先进的技术包括AMC、HARQ和快速小区选择以提供更高的数据速率。在HSDPA系统中,无线资源管理功能主要是由分组调度算法来实现,研究先进的分组调度算法是提高数据业务吞吐量、保证用户间的公平性、满足业务QoS的根本。主要介绍了实时业务算法M-LWDF,针对其在公平性方面的缺陷进行了改进,并对上述2种算法在中断率和吞吐量上进行了试验分析。     

Opportunistic packet scheduling algorithm for non-real-time service with a soft QoS requirement in a mobile broadband wireless access system

In this paper, we present a packet scheduling algorithm for a non-real-time service, with soft QoS requirements, which allows for degrading the QoS level, e.g., typically the packet delay, whenever necessary, in mobile broadband wireless Internet access systems. This algorithm is designed to properly trade off system throughput and delay performance, which can improve the system capacity by relaxing the delay constraint with respect to the underlying soft QoS requirement. This is as opposed to most of the existing packet scheduling algorithms for non-real-time service which are simply designed to maximize the system throughput without a delay constraint. The proposed adaptive exponential scheduling algorithm intentionally introduces additional delay to some users, especially under bad channel conditions, opportunistically allowing for serving users only under good channel conditions, as long as the resulting QoS degradation is acceptable for non-real-time service users. The results from a system-level simulation demonstrate that the system capacity can be significantly increased over existing algorithms, by as much as 65%, using the adaptive exponential scheduling algorithm while satisfying the given QoS-level requirements.     

QoS-guaranteed packet scheduling in wireless networks

To guarantee the quality of service (QoS) of a wireless network, a new packet scheduling algorithm using cross-layer design technique is proposed in this article. First, the demand of packet scheduling for multimedia transmission in wireless networks and the deficiency of the existing packet scheduling algorithms are analyzed. Then the model of the QoS-guaranteed packet scheduling (QPS) algorithm of high speed downlink packet access (HSDPA) and the cost function of packet transmission are designed. The calculation method of packet delay time for wireless channels is expounded in detail, and complete steps to realize the QPS algorithm are also given. The simulation results show that the QPS algorithm that provides the scheduling sequence of packets with calculated values can effectively improve the performance of delay and throughput.     

HSDPA中支持实时业务的调度算法在吞吐量方面的仿真分析

随着移动通信技术的飞速发展,未来的移动通信系统将以数据业务为主,所以无线分组调度算法将成为影响系统性能和保证用户服务质量的关键所在。在HSDPA系统中无线资源管理是通过分组调度算法来实现的。理想的调度算法应满足各类业务的QoS要求和用户之间的公平性,使系统资源利用率达到最大。主要介绍了EXP算法和M-LWDF算法,并对两种算法在吞吐量方面进行了仿真分析,说明了M-LWDF算法具有更高的吞吐量。     

Packet scheduling in 3.5G high-speed downlink packet access networks: breadth and depth

Forecasts for emerging mobile device markets anticipate that bandwidth will be squeezed by demanding applications like multimedia on demand. This will spur the need for data rates beyond what the upcoming 3G wireless cellular systems such as UMTS can offer. To boost the support for such high data rates, HSDPA, labeled as a 3.5G wireless system, has been introduced in Release 5 of UMTS technical specifications. HSDPA is a definite step toward meeting the "anywhere, anytime, and in any form" 4G communication concept. HSDPA promises a peak data rate of up to 10 Mb/s, five times larger than the data rate offered by 3G systems. In order to support such high data rates, HSDPA relies on many new technologies, among which is packet scheduling. In this article we provide breadth and depth related issues of packet scheduling in HSDPA, discuss state-of-the-art HSDPA scheduling algorithms in terms of their objectives, advantages, and limitations, and suggest further research issues that need to be addressed. In addition, we propose a packet scheduling algorithm for data traffic in HSDPA. Simulation results demonstrate the effectiveness of the proposed algorithm     

HSDPA分组调度算法与小区吞吐率研究

分组调度是HSDPA的核心技术之一,对网络性能有重要影响。在HSDPA分组调度功能和实现的基础上,重点分析对比3种典型分组调度算法原理及其对系统的影响,并通过实际测试验证,明确了不同调度算法对小区吞吐率的影响。结论:MAXCI算法下能够得到最大的系统吞吐量,公平性最差;RR算法公平性最好,系统资源利用率最低,吞吐率最小;EPF算法既考虑了用户的公平性,也能从一定程度上保证比较高的系统吞吐量,是一种实用的调度方法。     

An enhanced packet scheduling algorithm combined with HARQ for HSDPA system

High speed downlink packet access (HSDPA) is a packet-based data service that supports downlink data rates of up to 14 Mbps in the WCDMA (wideband code division multiple access) system. In HSDPA, the packet scheduler is a key element for high-speed and efficient transmissions. In addition, hybrid automatic request (HARQ) plays a significant role in improving system performance. We propose an enhanced scheduling algorithm combined with HARQ to reduce transfer delay without the degradation of system throughput.     

Content-Aware Resource Allocation and Packet Scheduling for Video Transmission over Wireless Networks

A cross-layer packet scheduling scheme that streams pre-encoded video over wireless downlink packet access networks to multiple users is presented. The scheme can be used with the emerging wireless standards such as HSDPA and IEEE 802.16. A gradient based scheduling scheme is used in which user data rates are dynamically adjusted based on channel quality as well as the gradients of a utility function. The user utilities are designed as a function of the distortion of the received video. This enables distortion-aware packet scheduling both within and across multiple users. The utility takes into account decoder error concealment, an important component in deciding the received quality of the video. We consider both simple and complex error concealment techniques. Simulation results show that the gradient based scheduling framework combined with the content-aware utility functions provides a viable method for downlink packet scheduling as it can significantly outperform current content-independent techniques. Further tests determine the sensitivity of the system to the initial video encoding schemes, as well as to non-real-time packet ordering techniques.