智能安防报警系统的研究与应用

基于短距无线网络的智能安防系统运用zigBee无线技术的协议,本文对终端节点通信物理层、MAC层、网络层进行了研究,论述了物理层、MAC层的节能效果并在MAC＆选用SMAC协议,网络层选用SPIN路由协议的目的,然后从安防系统的应用角度来研究采用GPRS无线通信模块与新一代无线网络通信技术ZigBee相结合智能控制网络。     

Ad Hoc网络功率控制与跨层优化

无线自组织网节点功率有限,如何有效利用节点电量、改善网络性能是自组网领域研究的关键问题。在功率控制中引入跨层优化的机制,可以有效地开发现有资源,提高网络性能。阐述Ad Hoc网络功率控制的意义与作用,详细论述MAC层的功率控制,网络层的功率控制,和采用跨层优化的混合功率控制技术,并提出一些值得关注的研究课题。     

甚低功耗无线通信技术——ZigBee

ZigBee技术作为无线传感器网络的主要支撑技术获得人们广泛的关注.完整的ZigBee协议套件由高层应用规范、应用会聚层、网络层、数据链路层和物理层组成.网络层以上协议由ZigBee联盟制订,物理层和媒体访问控制(MAC)层采用IEEE 802.15.4标准.IEEE802.15.4物理层简单采用比特到符号映射技术、符号到码片序列转换技术、偏移正交相移键控(OQPSK)调制技术,无须信道编码等复杂算法;MAC层采用载波监听多址-冲突避免技术,支持休眠模式.整个协议的设计使得ZigBee技术具有数据传输速率低、功耗低、成本低等特点,更加适合于工业监控系统、传感器网络、家庭监控系统、安全系统等应用.     

车载自组织网络的体系结构和通信协议研究

在对车载自组织网络的特点和研究现状分析的基础上,文章给出了车载自组织网络（VANET）中多维多层的理论模型和网络体系结构,讨论了物理层技术及其相关标准以及MAC层、网络层协议设计的重点和难点,阐述了广播协议的设计思路。     

WiMAX标准跟踪研究

本文主要介绍了WiMAX的物理层、MAC层以及网络层标准发展历史和目前最新的进展情况。     

甚低功耗无线通信技术——ZigBe

ZigBee技术作为无线传感器网络的主要支撑技术获得人们广泛的关注。完整的ZigBee协议套件由高层应用规范、应用会聚层、网络层、数据链路层和物理层组成。网络层以上协议由ZigBee联盟制订，物理层和媒体访问控制（MAC）层采用IEEE80215．4标准。IEEE802．15．4物理层简单采用比特到符号映射技术、符号到码片序列转换技术、偏移正交相移键控（OQPSK）调制技术，无须信道编码等复杂算法；MAC层采用载波监听多址一冲突避免技术，支持休眠模式。整个协议的设计使得ZigBee技术具有数据传输速率低、功耗低、成本低等特点，更加适合于工业监控系统、传感器网络、家庭监控系统、安全系统等应用。     

基于时分复用的无线传感器网络生命周期研究

在无线传感器网络中,综合考虑网络层、MAC层、物理层的网络生命周期最大化问题是一个非凸优化问题。文章基于同步小规模网络,采用没有链路干扰的时分复用（TDMA）调度技术和可变调制星座体积的传输方案,将非凸优化问题转换为一个凸优化问题。毫无疑问,物理层参数的适应性可以提高网络生命周期,但是当物理层不存在适应性的情况下,文章提出一种迭代算法,能够使网络生命周期接近物理层参数变化时所获得的最大网络生命周期。     

PTR3224光工作站

九州公司推出的HFC-NetMan1．0网络管理系统．首次实现从物理层、MAC层、网络层、传输层、应用层完全标准化。该系统主要包括：计算机管理系统、前端控制器、数据调制解调器、网管应答器等部分。     

基于交叉层设计的MIMO Ad—hoc网络的MAC层调度算法

在应用多入多出(MIMO)技术的无线Ad-hoc网络中,基于交叉层优化,设计了介质访问控制(MAC)层的优化调度算法。通过网络层、MAC层及物理层交换关键参数信息,在各无线节点分布式地进行优化调度,以选择发送节点以及在这些节点上进行流分配,选择用于发送数据的天线阵列子集,从而提高整体网络的性能。仿真结果显示,与简单单链路算法相比,交叉层设计优化算法可以显著提高MIMOAd-hoc网络的整体容量。     

光纤无线混合宽带接入网络节能关键技术研究

为减少光纤无线混合宽带接入网络(FiWi)中的能源消耗,在研究了FiWi网络中主要的接入技术及其网络架构的基础上,就FiWi节能技术所涉及的相关标准、MAC层休眠控制机制、网络层节能路由以及新型网络编码实现节能等关键技术进行了深入研究和展望。     

Energy consumption of the IEEE Std 802.15.3 MAC protocol in communication link set-up over UWB radio technology

This paper examines the overhead associated with the IEEE Std 802.15.3 medium access control (MAC) protocol when used in conjunction with Ultra Wide-Band (UWB) radio technology. Particular features of the protocol examined include establishing, modifying and terminating data streams. The main focus of the paper is to investigate the overhead introduced in terms of energy consumption to manage the communication links. One of the main UWB technology candidates, Impulse-Radio (IR-UWB), utilizes very short time domain pulses which are low power and difficult to detect. This raises the question of how to design an efficient MAC protocol to harness the potential of the physical layer (PHY). For high data rate WPAN applications, the IEEE Std 802.15.3 protocol has been proposed as a suitable MAC. In the simulations the data source rate and the number of devices in the network are varied and the considerable overhead produced by command frames is observed.     

Signal processing in random access

In this paper, a cross-layer view for roles of signal processing in random access network and vice versa is presented. The two cases where cross-layer design has a quantifiable impact on system performance are discussed. The first case is a small network (such as wireless LAN) where a few nodes with bursty arrivals communicate with an access point. The design objective is to achieve the highest throughput among users with variable rate and delay constraints. The impact of PHY layer design on MAC protocol is examined and illustrates a tradeoff between allocating resources to the PHY layer and to MAC layer. The second case, in contrast, deals with large-scale sensor networks where each node carries little information but is severely constrained by its computation and communication complexity and most importantly, battery power. This paper emphasizes that the design of signal processing algorithms must take into account the role of MAC and the nature of random arrivals and bursty transmissions.     

Cross-Layer Design of Wireless Multihop Backhaul Networks With Multiantenna Beamforming

A cross-layer design approach is considered for joint routing and resource allocation for the physical (PHY) and the medium access control (MAC) layers in multihop wireless backhaul networks. The access points (APs) are assumed to be equipped with multiple antennas capable of both transmit and receive beamforming. A nonlinear optimization problem is formulated, which maximizes the fair throughput of the APs in the network under the routing and the PHY/MAC constraints. Dual decomposition is employed to decouple the original problem into smaller subproblems in different layers, which are coordinated by the dual prices. The network layer subproblem can be solved in a distributed manner and the PHY layer subproblem in a semidistributed manner. To solve the PHY layer subproblem, an iterative minimum mean square error (IMMSE) algorithm is used with the target link signal-to-interference-and-noise-ratio (SINR) set dynamically based on the price generated from the upper layers. A scheduling heuristic is also developed, which improves the choice of the transmission sets over time. Simulation results illustrate the efficacy of the proposed cross-layer design.     

MIMO-OFDM中基于业务类型的跨层资源分配研究

提出了一种基于PHY层和MAC层的跨层资源自适应方案。该方案首先把业务类型划分为实时业务和非实时业务,并在此基础上针对业务类型在MAC层对分组进行调度和在PHY层对子载波和功率分配。     

Cross-layer resource allocation for real-time services in OFDM-based cognitive radio systems

The resource allocation problem on the downlink of a multiuser OFDM-based cognitive radio (CR) system is formulated using a cross-layer (MAC and PHY layers) approach with the aim of satisfying quality of service (QoS) requirements in real-time applications. The number of subchannels available to the CR system is time-varying as a result of the stochastic nature of the activities of the primary users (PUs). The MAC layer QoS requirements are dynamically converted to PHY layer rate requirements; the conversion depends on the delivery status of queued packets as well as the number of available subchannels. Simulation results show that the proposed cross-layer resource allocation algorithm can provide substantial transmit power reductions compared to existing PHY layer and MAC layer solutions designed for multiuser OFDM systems.     

E‐CLEMA: A cross‐layer design for improved quality of service in mobile WiMAX networks

In this paper, an efficient cross‐layer design that performs joint adaptation of the physical (PHY) and application layers of a mobile WiMAX network is proposed. The design takes into account channel state and performance information from the PHY and medium access control (MAC) layers, respectively. It uses a decision algorithm to evaluate this information, specify unfavorable conditions regarding low channel quality and increased congestion, and take measures by coordinating modulation order, transmission power, and media encoding rate, toward improved overall quality of service (QoS) offered to the user. Extensive simulation results show that the proposed design achieves considerably reduced packet loss and power consumption, combined with increased throughput as compared to a typical mobile WiMAX system. Copyright © 2008 John Wiley & Sons, Ltd.     

PLC家庭网络MAC协议与QoS保证

由于电力线介质条件恶劣,物理信道传输不稳定,PLC MAC协议的设计较为困难.本文首先介绍了PLC家庭网络的拓扑结构和多媒体业务的QoS要求,然后分析和比较了各类MAC协议对PLC家庭网络的适用性和QoS保证能力,并对有竞争与无竞争的PLC MAC协议研究的最新成果及其采用的QoS保证机制进行了分析.本文认为有竞争与无竞争方式相结合的混合型MAC协议是最适合PLC家庭网络的MAC协议.     

基于DOCSIS的CM和CMTS的设计与实现

HFC（Hybrid Fiber Coax)为多媒体和宽带业务提供了一种宽带接入方式。本文论述了HFC接入网的结构和频谱安排,并结合HFC接入网的双向改造,对媒体接入层（MAC）和物理层（PHY）进行了具体分析,同时给出DOCSIS（Data-Over-Cable Service Interface Specification)规范中MAC协议解决上行信道分配问题的实现方法以及物理层的方案;最后,给出了符合DOCSIS规范的CM（Cable Modem）和CMTS（Cable Modem Terminal System)的软件和硬件实现方案。