固定宽带无线接入LMDS的MAC协议与QoS

介绍了基于IP的固定宽带无线接入技术的MAC协议的原理,分析了MAC协议保证服务质量(QoS)的机制。     

固定宽带无线接入技术及其标准的分析

在多种“最后一公里”宽带接入解决方案中,宽带无线接入技术以其经济和易于实施等优点越来越受到人们的关注。本地多点分配业务(LMDS)是一种新型的固定宽带无线接入技术。该技术提供双向语音、数据以及视频图像业务,能够实现2Mbit／s的用户接入速率,具有很高的可靠性。IEEE802委员会专门为固定宽带无线接入的无线接口制定了802．16d标准。本文介绍了802．16d的协议结构及各层功能,重点分析了802．16d的MAC层。     

无线传感器网络基于竞争的MAC协议综述

随着无线传感器网络技术的逐步发展,对它的介质接入控制技术的研究也逐步成为无线传感器网络研究中的热点。主要介绍了无线传感网MAC协议的特点以及分类,然后对其中基于竞争的一类MAC协议进行了一一介绍,并作了性能对比。最后阐明了无线传感网基于竞争的MAC协议的发展趋势。     

某小区宽带EPON接入技术方案研究

近年来，EPON作为一种新兴的宽带接入技术，它是以太网技术与PON技术相结合的产物，主要是通过用来实现数据、语音及网络视频等综合业务接入。由于EPON技术具有良好的经济适用性、可扩展性等优点。文章主要从阐述了EPON技术的概念及组成，从中结合笔者的工作实践，针对宽带EPON接入技术在某住宅小区中的应用方案进行了研究。     

移动宽带无线接入技术IEEE 802.16e综述

介绍了实现移动宽带无线接入的关键技术、IEEE802．16e移动无线宽带接入标准及其物理层与MAC层技术，并与IEEE802．20移动无线宽带接入标准进行了简单比较。     

无线ATM中基于FDD的MAC层协议

在无线ATM中,媒介接入控制（MAC)协议是其中的一项关键技术,近年来提出多种适合无线ATM的MAC层协议。本文分析三种基于FDD的MAC层协议,探讨了各种协议的实现过程和优缺点,最后比较了它们之间的性能,得出了一些有意义的结论。     

无线局域网MAC接入性能研究

主要研究无线局域网MAC接入性能,从IEEE 802.11协议、无线局域网接入性能两个方面对这个问题进行了研究,无线局域网灵活,安全性高,扩展方便的优势是有线网络不能比的,但是无线局域网MAC接入性能在复杂的网络运行环境下存在较大的波动,有必要对其进行深入研究。     

一种固定宽带无线接入系统中话音业务的动态接入技术

在简单介绍固定宽带无线接入系统之后 ,给出了一个 3.5GHz固定宽带无线接入系统中的MAC实现方案 ,着重研究了话音业务如何动态地接入骨干网 ;最后给出了话音业务通过E1接口接入PSTN的实现框图。本系统工作在 3.5GHz频段 ,采用FDD的双工技术、TDM/TDMA的复用多址技术、MAC技术实现了数据 /话音混合传送 ,并且通过动态资源分配保证了带宽的有效利用。     

基于WDM/OCDMA-PON的光纤无线混合接入网结构

通过分析波分多址技术、码分多址技术的PON光纤接入技术和宽带无线技术相结合的混合光纤无线接入网技术的优越性和可行性,提出了基于WDM/OCDMA-PON光纤无线混合(HOWBAN)接入网技术的基本结构,给出WDM/OCDMA-PON光纤无线混合接入网系统的实现方案,提出了应用前景等.     

宽带无线接入标准IEEE 802.16/16A综述

首先介绍了宽带无线接入(BWA)技术标准IEEE 802.16/16A的发展,然后描迷了该协议的底层标准规范,重点分析了其按需动态带宽分配和多业务QoS(服务质量)保障机制下的物理层(PHY)和介质接入控制(MAC)层的技术特点,并介绍了其移动性的新发展方向,既移动宽带无线接入(MBWA)技术,最后展望了它的市场应用前景和进一步研究的课题。     

EPON和WiMAX融合架构下带宽分配和调度机制的研究

以太网无源光网络(EPON)和IEEE 802.16(WiMAX)的融合网络在固定移动混合接入网中被认为是很有前景的接入方式.文中提出了3种WiMAX无线网络与EPON网络系统融合架构,融合系统同时具有光网络的高带宽和无线网络的灵活性.为了在接入网中支持QoS,本文为融合结构提出了一种动态带宽分配算法(DBA)和调度机...     

Novel MAC protocol for terahertz ultra-high data-rate wireless networks

Due to having a large bandwidth to support Gbps-level data rate, terahertz communication attracts more and more attention in recent years. However, there are few medium access control （MAC） protocols for terahertz ultra-high data-rate wireless networks, which affects the research and application of terahertz communications. To address this problem and to achieve ultra-high data-rate wireless access with terahertz communication, a novel MAC protocol, called medium access control for terahertz communication （MAC-TC）, is proposed. Through designing a new channel access scheme, a new superframe structure, and related key parameters, MAC-TC can support a maximum data rate up to 10 Gbit/s even higher. Theoretical analysis and simulation results show that our proposed MAC protocol realizes the function of medium access control and attains a maximum data rate of 18.3 Gbit/s, which is 2 times higher than 5.78 Gbit/s, the theoretical maximum data rate of IEEE 802.15.3c standard.     

Scheduled WiFi using distributed contention in WLANs: algorithms,experiments, and case-studies

The ubiquitous adoption of WiFi introduces large diversity in types of application requirements and topological characteristics. Consequently, considerable attention is being devoted to making WiFi networks controllable without compromising their scalability. However, the main MAC protocol of WiFi, distributed coordination function (DCF), is a contention-based protocol using random backoff. Thus, operating under DCF, the access of channel is hard to control and nonpredictable. In order to provide controllability of channel access in WiFi, we propose Rhythm, a MAC protocol that achieves scheduled WiFi efficiently using distributed contention. By achieving scheduled WiFi, channel access can be controlled by manipulating the schedule decision. We evaluate the performance of Rhythm through analysis, experiments, and case-studies.     

Fixed Mobile Convergence Architectures for Broadband Access: Integration of EPON and WiMAX [Topics in Optical Communications]

EPON and WiMAX are two promising broadband access technologies for new-generation wired and wireless access. Their complementary features motivate interest in using EPON as a backhaul to connect multiple dispersed WiMAX base stations. In this article we propose four broadband access architectures to integrate EPON and WiMAX technologies. The integrated architectures can take advantage of the bandwidth benefit of fiber communications, and the mobile and non-line-of-sight features of wireless communications. Based on these integrated architectures, we elaborate on related control and operation issues to address the benefits gained by this integration. Integration of EPON and WiMAX enables fixed mobile convergence, and is expected to significantly reduce overall design and operational costs for new-generation broadband access networks.     

QoS-oriented access control for 4G mobile multimedia CDMAcommunications

An efficient medium access control protocol with fair packet loss sharing packet scheduling is proposed for wireless code-division multiple access communications. The proposed MAC protocol exploits both time-division and code-division statistical multiplexing. The FPLS scheduler uses the information of traffic rate distribution and quality of service requirements to assign priorities to the users and determines an efficient combination of the packets for transmission in the time slots of each frame, so the number of the served users is maximized under the QoS constraints. Simulation results demonstrate the effectiveness of the FPLS scheduler, in comparison with other previously proposed scheduling algorithms     

Efficient silence suppression and call admission control through contention-free medium access for VoIP in WiFi networks

In view of the rapidly growing trend of migrating customers from traditional wired phones to mobile phones and then to VoIP services in the recent past, there is a tremendous demand for wireless technologies to support VoIP, specially on WiFi technologies which have already matured commercially. This has put forth great research challenges in the area of wireless VoIP. In this article we have addressed two core issues, efficient silence suppression and call admission control, in QoS provisioning for VoIP services in WiFi networks. In this connection we present a QoS-aware wireless MAC protocol called hybrid contention-free access (H-CFA) and a VoIP call admission control technique called the traffic stream admission control (TS-AC) algorithm. The H-CFA protocol is based on a novel idea that combines two contention-free wireless medium access approaches, round-robin polling and TDMA-like time slot assignment, and provides substantial multiplexing capacity gain through silence suppression of voice calls. The TS-AC algorithm ensures efficient admission control for consistent delay bound guarantees and further maximizes the capacity through exploiting the voice characteristic so that it can tolerate some level of non-consecutive packet loss. We expose the benefits of our schemes through numerical results obtained from simulations.     

基于TDD-CDMA的集成可变速率多媒体业务传输的MAC协议

文章给出了一种应用于移动多媒体通信的无线媒体接入控制(MAC)协议.该MAC协议采用混合TDMA/CDMA结构,以提高资源利用率;采用多码并行传榆提供可变速率,以支持集成多媒体业务.系统仿真表明,该协议具有较高的码利用率和良好的灵活性,适用于可变速率多媒体业务集成传输.     

Saturation throughput analysis of a carrier sensing based MU-MIMO MAC protocol in a WLAN under fading and shadowing

In wireless local area networks (WLANs), the traditional carrier sense multiple access with collision avoidance (CSMA/CA) medium access control (MAC) protocol cannot use the full benefits from multiuser multiple-input multiple-output (MU-MIMO) technique due to random medium access of the users. In this paper, we propose a carrier sensing based MAC protocol for a MU-MIMO based WLAN with full utilization of MU-MIMO technique. By modeling the WLAN system under the proposed MAC protocol as a discrete time Markov chain, we develop an analytical model for computing the saturation throughput in presence of path loss, Rayleigh fading and log-normal shadowing. The analytical model is then validated via simulation. By means of numerical and simulation results, we demonstrate that the proposed MAC protocol significantly improves throughput performance than the traditional CSMA/CA MAC protocol. Further, we compare the performance of the proposed MAC protocol with a MU-MIMO MAC protocol called Uni-MUMAC protocol and find that the proposed MAC protocol performs better than the Uni-MUMAC protocol. We also explore the effect of some of the network and wireless channel parameters on the performance of the proposed MAC protocol.

     

Highly Efficient Voice—Data Integration over Medium and High Capacity Wireless TDMA Channels

A new medium access control (MAC) protocol for mobile wireless communications is presented and investigated. We explore, via an extensive simulation study, the performance of the protocol when integrating voice and data traffic over two wireless channels, one of medium capacity (referring mostly to outdoor microcellular environments) and one of high capacity (referring to an indoor microcellular environment). Data message arrivals are assumed to occur according to a Poisson process and to vary in length according to a geometric distribution. We evaluate the voice packet dropping probability and access delay, as well as the data packet access and data message transmission delays for various voice and data load conditions. By combining two novel ideas of ours with two useful ideas which have been proposed in other MAC schemes, we are able to remarkably improve the efficiency of a previously proposed MAC scheme [5], and obtain very high voice sources multiplexing results along with most satisfactory voice and data performance and quality of service (QoS) requirements servicing. Our two novel ideas are the sharing of certain request slots among voice and data terminals with priority given to voice, and the use of a fully dynamic low-voice-load mechanism.     

A novel medium access control protocol for passive optical network supporting local area networking capabilities

An alternate solution for Ethernet passive optical networks (EPON) providing local area networking (LAN) capabilities is proposed in this article. Our solution adopts a star coupler-based PON architecture and uses radio frequency subcarrier multiplexed transmission for the LAN traffic delivery. The proposed medium access control (MAC) protocol supports a fully distributed control plane among the optical network units (ONUs) for ONU–ONU communication as well as upstream access to the OLT. The simulation results indicate that the proposed MAC protocol outperforms the others in terms of the average packet end-to-end delay, especially for LAN traffic.