A Novel Bandwidth Allocation Algorithm for IEEE 802.16 TDD Mode Wireless Access Networks

In this paper, we propose a novel bandwidth allocation algorithm for a two-tier hierarchy in IEEE 802.16 time division duplex mode wireless access networks under symmetric and/or asymmetric uplink and downlink traffic input. We demonstrate the performance of the new bandwidth allocation algorithm in terms of accumulated throughput (cumulative bandwidth) and fairness in both infinite and finite buffer cases compared with others by simulations. The simulation results show that the proposed algorithm not only can provide much better fairness and maintain satisfactory QoS support and high cumulative bandwidth but also in the case of finite buffer depth is less buffer-consuming than the others, meaning that the hardware cost can be reduced by employing the proposed algorithm.     

无线宽带通信系统的上行带宽资源分配方案

提出了一种适用于宽带无线通信系统的上行无线带宽资源分配方案。在详细描述算法的基础上，建立了对应的仿真系统对算法进行验证。该方案较好地解决了多业务并发时的上行带宽分配问题。兼顾了不同实时业务对时延和带宽的不同需求，与传统技术相比较，提高了带宽利用率，并减少了协议开销和传输时延。     

ADSL宽带接入动态带宽分配技术

随着“三网融合”不断推进,互联网业务向多媒体方向发展,用户对宽带上网的带宽需求呈现出多样化的发展趋势,提供动态带宽的宽带接入业务将成为运营商差异化竞争的手段。文章论述了动态带宽实现的技术,带宽分配的主要形式和系统功能。通过动态带宽分配技术使电信运营商能够更灵活高效地满足用户需求,提升运营商的服务质量,使宽带资产创造更大的价值。关键词：BAS,ADSL,宽带接入     

宽带技术与应用讲座第二讲宽带无线接入技术及其展望

本文介绍了各种(宽带)无线接入技术,并分别讨论了他们的优缺点,对现有无线宽带接入技术作了概括,并对宽带无线接入技术的未来进行了展望和预测。     

A Scheduling Technique Wireless Personal for Bandwidth Communication Allocation in Networks

Future generation wireless personalcommunication networks (PCN) are expected to providemultimedia capable wireless extensions of fixedATM/B-ISDN. This paper presents a scheduling techniquefor PCN based on TDMA and the leaky bucket regulator, thewell known bandwidth enforcement mechanism for fixedATM. The main objective of the proposed technique is toensure fair and efficient treatment of various types oftraffic on the air interface, includingconstant-bit-rate (CBR) voice and variable-bit-rate(VBR) video. Two alternative priority mechanisms areintroduced and their performance is evaluated. Theperformance comparison of the alternatives reveals aninteresting tradeoff between fairness and quality ofservice (QoS).     

A Bandwidth Reservation Multiple Access Protocol for Wireless ATM Local Networks

A bandwidth reservation multiple access scheme(BRMA) is proposed to resolve contention and assignbandwidth among multiple users trying to gain access toa common channel such as in mobile users contending for resources in an ATM-based cellular networkor a wireless local area network (LAN) with shortpropagation delays. The protocol is best suited tosupport variable-bit-rate (VBR) traffic that exhibits high temporal fluctuations. Each mobile user isconnected end-to-end to another user over virtualchannels via the base station that is connected to thewired ATM B-ISDN network. The channel capacity is modeled as a time frame with a fixed duration.Each frame starts with minislots, to resolve contentionand reserve bandwidth, followed by data-transmissionslots. Every contending user places a request for data slots in one of the minislots. If therequest is granted by the base station through adownlink broadcast channel, the user then startstransmission in the assigned slot(s). The number ofassigned slots varies according to the required qualityof service (QoS), such as delay and packet lossprobability. A speech activity detector is utilized inorder to indicate the talkspurts to avoid wastingbandwidth. Due to its asynchronous nature, BRMA is ratherinsensitive to the burstiness of the traffic. Since theassignment of the minislots is deterministic, therequest channels are contention-free and the data channels are collision-free. Hence, in spite ofthe overhead (minislots) in each frame, BRMA provideshigher throughput than Packet Reservation MultipleAccess (PRMA) for the same QoS, especially for high-speed systems. A better delay performance is alsoachieved for data traffic compared to Slotted Alohareservation-type protocol PRMA. In addition, BRMAperforms better in terms of bandwidth efficiency thanthe conventional TDMA or the Dynamic TDMA, wherespeech activity detectors are very difficult toimplement.     

一种基于新一代蜂窝移动通信的无线资源分配方案

新一代的蜂窝移动通信系统要求支持多种业务,从高质量的交互式实时业务到基于TCP连接的完全可靠服务。对于现有的无线链路,用户各种业务量的增加造成无线资源相对使用不平衡,大大降低了无线网络的吞吐量。本文提出了一种基于新一代蜂窝通信的无线资源分配方案,并利用OPNET建立仿真平台对该方案进行验证。仿真结果表明,各种不同优先等级的业务都能得到自己满意的服务质量,链路总的吞吐量达到了1 0 0 Mbit/s     

A Generic Framework for Modeling MAC Protocols in Wireless Broadband Access Networks

In this article we present a simple yet accurate generic analytical model for a family of slotted CSMA/CA-based MAC protocols widely used in various wireless broadband access networks. The proposed model is based on a hierarchical three-level renewal process concept, which leads directly to some important MAC protocol performance metrics, such as throughput and average frame service time. The applicability of the model is demonstrated by extensive simulation results.     

Auction-Based Bandwidth Allocation in Multi-Hop Wireless Ad Hoc Networks

In this paper, we propose a multi-hop auction-based bandwidth allocation mechanism to address the flow contention problem in wireless ad hoc networks. By modeling the problem as an iterative auction-based structure, it enables us to derive fair and efficient bandwidth allocation to each node on the basis of only local information. Further, a multi-hop flow coordination mechanism is then developed to optimize the network performance. Simulation results suggest that the proposed mechanism outperforms other approaches in terms of network throughput, bandwidth utilization, fairness, end-to-end delay, packet loss rate, and robustness.     

一种IEEE 802.16无线网络的优化带宽调度策略

提出了一种基于预测的自适应实时轮询业务带宽分配机制:SS依据当前带宽需求和以往的实际分配带宽,对实时业务数据包所需求的确切带宽进行预测并调度.给出了数学分析模型和仿真,结果表明,与传统的带宽分配机制相比,该自适应的带宽分配算法能更好地改善系统性能,提高吞吐量,减少时延,减少缓冲区需求.     

TCP-BIAD for Enhancing TCP Performance in Broadband Wireless Access Networks

In this paper a new TCP variant, named TCP-Binary Increase, Adaptive Decrease is presented. The suggested congestion control algorithm is a joint approach of Westwood and an enhanced version of BIC, for improving TCP performance in broadband wireless access networks. BIAD has been evaluated with respect to other TCP variants such as Reno, Westwood, BIC, CUBIC, HSTCP and STCP with the use of network simulator 2. The results indicate that the proposed solution achieves high network utilization levels in a wide range of network settings, including wireless channel errors, link asymmetry and congestion. We also evaluated TCP-BIAD when multiple flows share a bottlenecked access link and we show that it demonstrates the fairness features required for network deployment.     

Optical Coding for Enhanced Real-Time Dynamic Bandwidth Allocation in Passive Optical Networks

In this paper, optical pulse encoding and decoding technology is proposed to enable real-time signaling in a passive optical network (PON) setting. Unique optical codes are assigned to selected optical network units (ONUs) equipped with the corresponding encoders. An out-of-band pulse train is broadcast from the optical line terminal (OLT) and is modulated by ONU-based switches. The encoded reflections of pulses are thus used to update the status of the OC-enabled queues at the OLT in real time. We explore the enhanced PON architecture and define its major design parameters. Through extensive simulations, we investigate the design principles and limits of our system parameters. Through a performance comparison of native interleaved polling with adaptive cycle time with its OC-enhanced counterpart, we show that our OC enhancement breaks the fundamental delay lower bound associated to the polling cycle. We propose and investigate new dynamic bandwidth allocation (DBA) algorithms that exploit real-time queue updates enabled through OC-enhanced polling. We also explore the pay-as-you-grow implementation of OC-enhanced polling to realize quality-of-service (QoS) differentiation, elaborate on possible migration paths from conventional PONs, and investigate absolute QoS performance guarantee improvements achieved through OC-enabled real-time DBA algorithms.     

Providing Real-Time Service in CDMA Wireless Networks

Medium Access Control (MAC) protocol design plays a very important role in the design of wireless networks. In this paper, we propose a new MAC protocol to provide real-time service for a CDMA wireless network. This protocol has been designed based on the distributed queuing random access protocol for CDMA wireless networks (DQRAP/CDMA). As real-time scheduling schemes have been introduced into the protocol design, the new protocol has an ability to accommodate real-time traffic in the CDMA wireless networks. A series of simulation experiments have been carried out to evaluate the performance of the proposed protocol. The results reveal that the proposed protocol can efficiently provide real-time service to the traffic composed of time constrained messages in the CDMA wireless networks.     

一种面向业务的移动数据业务带宽分配方法

针对移动数据业务未在核心网侧部署区分业务的带宽分配策略问题,提出了一种基于GGSN的面向业务的带宽分配方法。该方法利用分形布朗运动模型和G/D/1(n)排队模型分析不同业务的带宽需求,并结合GGSN设备功能及带宽资源情况,实现了面向业务的移动数据业务带宽分配。理论分析和仿真结果表明,该方法能有效地区分不同业务的服务质量并保障高价值业务的带宽需求。     

无线供电混合多址接入网络的资源分配

无线供电技术是延长无线网络节点寿命的有效方案。该文研究一个由基站和多个分簇用户组成的无线供电混合多址接入系统。系统的传输分为两个阶段。在第1阶段,基站向用户广播能量;在第2阶段,用户向基站传输信息。用户簇和用户簇之间采用时分多址接入,分时传输;同一簇内多个用户采用非正交多址接入,同时传输。该文研究联合优化系统的各阶段的传输时间、基站的发射功率、用户的发射功率等资源,分别以优化网络频谱效率和用户簇之间的公平性为目的,提出最大化网络吞吐量和最大化用户簇的最小吞吐量的联合资源分配算法。研究结果表明所提的两种算法分别能有效提高系统的频谱效率和保证用户簇之间的公平性。     

Optimal Relay Station Placement in Broadband Wireless Access Networks

To satisfy the stringent requirement of capacity enhancement in wireless networks, cooperative relaying is envisioned as one of the most effective solutions. In this paper, we study the capacity enhancement problem by way of Relay Stations (RSs) placement to achieve an efficient and scalable design in broadband wireless access networks. To fully exploit the performance benefits of cooperative relaying, we develop an optimization framework to maximize the capacity as well as to meet the minimal traffic demand by each Subscriber Station (SS). In specific, the problem of joint RS placement and bandwidth allocation is formulated into a mixed-integer nonlinear program. We reformulate it into an integer linear program which is solvable by CPLEX. To avoid exponential computation time, a heuristic algorithm is proposed to efficiently solve the formulated problem. Numerical analysis is conducted through case studies to demonstrate the performance gain of cooperative relaying and the comparison between the proposed heuristic algorithm against the optimal solutions.     

Intercell Radio Interference Studies in Broadband Wireless Access Networks

Capacity has become of primary importance in broadband wireless access (BWA) networks due to the ever-increasing demand for multimedia services and the possibility of providing wireless Internet, leading to their standardization by IEEE (802.16 WirelessMAN) and ETSI (BRAN HIPERACCESS). The major factor limiting capacity in such systems is interference originating from adjacent cells, namely intercell interference. This paper presents a general analysis of intercell interference for a spectrally efficient BWA cellular configuration. It examines the statistical properties of the carrier-to-interference ratio in both downstream and upstream channels. The focus is on the spatial inhomogeneity of rain attenuation over multiple paths, which is the dominant fading mechanism in the frequency range above 20 GHz, especially when two-layered [i.e., line-of-sight (LOS) and non-LOS] architectures are involved. Besides attenuation from precipitation, various architectural and propagation aspects of local multipoint distribution service systems are investigated through simulations, and worst-case interference scenarios are identified