Versatile Analytical Model for Delay and Energy Evaluation in WPANs: A Case Study for IEEE 802.15.4 CSMA-CA

This paper proposes a versatile analytical model to predict the medium access control (MAC) layer performance metrics (throughput, average MAC service time, successful transmission probability) as well as the energy consumption of wireless personal area networks (WPANs) under all possible transmission modes (unacknowledged, limited and unlimited acknowledged modes) with both saturated and unsaturated traffic patterns. This rigorous analytical approach produces straightforward equations that are used to predict the operational parameters required to optimise the throughput of networks. This paper uses the state-of-the-art IEEE 802.15.4 CSMA-CA protocol to demonstrate the use of the modelling approach. The numerical results obtained from the analytical model are verified through comparison with simulation.     

基于IEEE802.15.4的嵌入式IPv6技术

IEEE802.15.4是针对低速无线个人区域网络制定的标准.作为网络层互连IEEE802.15.4的设备的解决方案之一,嵌入式IPv6技术引起了广泛的关注.在简要介绍了IEEE802.15.4标准的基础上,首先分析了基于IEEE802.15.4的嵌入式IPv6技术,并讨论了其在普及性、适用性、开放性、地址空间、地址配置、可接入性、可开发性七个方面的技术优势,随后重点研究了其关键技术,主要包括：报文格式协同、地址配置和地址管理、网络管理、动态路由和自适应拓扑、安全机制等,最后对其在家庭、环境等领域的应用前景进行了展望.     

A Multi-channel Scheduling Scheme for Collision-Free High-Rate WPANs

Ultra wide-band (UWB) technologies are being feverishly developed in the technical community. UWB devices are expected to operate at rates of up to 0.5 Gb/s and communicate with other devices at a range of up to 10 m. Thus, UWB technologies are being developed as core technology for high-speed wireless personal area networks. The salient features of UWB networks—high-rate communications, low interference with other radio systems, and low power consumption—bring many benefits to users. Thus, they enable consumers to experience new applications such as wireless universal serial bus for connecting personal computers to their peripherals and the consumer–electronics in people’s living rooms. However, if multiple WiMedia logical link protocol Service Sets (WSSs) coexist in an adjacent area, various conflicts among independent WSSs can occur frequently. In order to solve this problem, we propose a multi-channel scheduling scheme (MCS) for the coexistence of adjacent WSSs. The proposed MCS scheme can scan new idle channel and detect its time offset where a WSS device can transmit a new beacon frame and data frames without conflicts. We also evaluate the performance of the proposed MCS scheme through various simulations in terms of several metrics. Simulation results demonstrate that the MCS scheme can minimize the possibility of data frame collisions by efficiently managing the multiple available channels in a hybrid manner combining proactive and reactive methods.     

Distributed Borrowing Addressing Scheme for ZigBee/IEEE 802.15.4 Wireless Sensor Networks

This paper proposes a distributed borrowing addressing (DIBA) scheme to solve problems of failure in address assignments resulting from limited tree depth and width when the distributed address assignment mechanism is used in a ZigBee/IEEE 802.15.4 wireless sensor network. DIBA is a method of borrowing addresses from neighbor nodes for newly entering nodes and assigning the borrowed addresses. Its network or sensing coverage can increase with almost the same overhead as the existing method. DIBA is a simple and lightweight means of addressing and routing, making it suitable for wireless sensor networks. Simulations showed that DIBA is a distributed addressing scheme with consistently excellent performance.     

一种符合IEEE 802.15.4a标准的脉冲发生器

设计了一种基于IEEE 802.15.4a标准的脉冲发生器,包括脉冲产生、BPSK调制、低通滤波三个部分。提出多路脉冲合成方法,降低了对基带工作速度的要求。提出一种适用于该协议的BPSK调制电路,将极性调制到脉冲上,同时可实现脉冲的单端转差分功能和脉冲幅度调节。设计了基于反相器跨导的G_m-C滤波器,滤除脉冲的高频成分。最后研究了电路的低功耗方案,可动态开启或关闭电路,降低了电路功耗。基于0.18 μm CMOS工艺进行电路设计。后仿真结果表明,产生的脉冲经过互相关后,主瓣宽度为1.35 ns,消耗电流约为7.1 mA,通过动态管理,电流最低可降至0.3 mA左右。     

基于信标信息广播的会合算法仿真

会合是基于认知无线电网络的一个基础核心问题.近年来,会合算法一直是研究的重点方向.提出了一种基于信标信息广播的会合算法,通过建模仿真,对会合时间特性进行了统计分析,从统计结果得出:当公共信道数远小于可用信道数时,基于信标信息广播的会合算法远优于增强型跳转停止(EJS)算法;当公共信道数与可用信道数基本相等时,EJS会合算法优于基于信标信息广播的会合算法;当公共信道数与可用信道数之比接近1/2时,2种算法的会合性能基本接近的结论.因此,在公共信道数稀少的恶劣电磁环境下,基于信标信息广播的会合算法具有优良的会合能力,对今后的算法研究可提供有意义的启示.     

基于UKF的移动信标辅助节点定位算法

常用的节点定位方法通常要求较多的信标节点,因此容易造成资源浪费.提出一种基于目标跟踪的移动信标辅助节点定位算法,信标节点在移动过程中周期性地发布自身位置信息,未知节点首先获取自身位置的近似估计,然后再利用无迹卡尔曼滤波(UKF)方法对移动信标进行跟踪,并完成进一步位置求精.在该算法中,未知节点之间无需相互通信,降低了能...     

Hybrid Distributed Stochastic Addressing Scheme for ZigBee/IEEE 802.15.4 Wireless Sensor Networks

This paper proposes hybrid distributed stochastic addressing (HDSA), which combines the advantages of distributed addressing and stochastic addressing, to solve the problems encountered when constructing a network in a ZigBee‐based wireless sensor network. HDSA can assign all the addresses for ZigBee beyond the limit of addresses assigned by the existing distributed address assignment mechanism. Thus, it can make the network scalable and can also utilize the advantages of tree routing. The simulation results reveal that HDSA has better addressing performance than distributed addressing and better routing performance than other on‐demand routing methods.     

Enhancement of the Traffic Differentiation Architecture for WBAN Based on IEEE 802.15.4

In the healthcare domain, Wireless Body Area Network has emerged as a vital technology that is capable of providing better methods to diagnose various hazardous diseases. The CANet projet is a project that proposes alternative monitoring solutions. This paper studies the possibility of transmitting different types of information through an IEEE 802.15.4 MAC layer that not supports the transmission of heterogeneous information. We have proposed an extension to the MAC layer which makes possible the transmission of various information types. This solution designed by “diffrentiation layer” uses a purge function to ensure the use of CAP and CFP by the same node in the same superframe and allows the differentiation between several information. Our results show that our solution is reliable under worst-case.     

Multiuser OFDM Using Cyclic Time Shift for Wireless Uplink Broadcasting

A combination of orthogonal frequency division multiplexing (OFDM) with frequency-division multiple access (FDMA) called orthogonal frequency-division multiple access (OFDMA) is regarded as a promising solution for improving the performance of interactive wireless broadcasting systems. This paper presents our investigation into reducing the multiple access interference (MAI) introduced by symbol timing misalignment in an OFDMA uplink system. To combat the MAI, we provide a new OFDMA symbol frame employing a simple symbol repetition coupled with a cyclic time shift for typical OFDMA uplink scenarios. Theoretical analysis and computer simulations are used to assess the performance of the proposed OFDMA uplink system. It is found that this scheme can decrease the probability of destroying the orthogonality among the users and provide the MAI-free reception.     

基于EPA与IEEE802.15.4两用手抄器的设计

本设计是基于EPA和IEEE802.15.4两种协议的手抄器的解决方案,用于工业以太网现场和工业无线通信现场.该设计方案采用AT91R40008芯片作为CPU,将两种协议集于一款手抄器,为设备维护带来方便.     

A New QoS Resource Allocation Scheme Using GTS for WPANs

IEEE 802.15.4 (for low-rate Wireless Personal Area Networks??WPANs) (IEEE 802.15.4 Standard-2003) and IEEE 802.15.7 (for Short-Range Wireless Optical Communication Using Visible Light) (IEEE 802.15.7 Standard??2011) are two typical standards for WPANs that support Quality-of-Service (QoS) through a Guaranteed Time Slot (GTS) mechanism to allocate a specific duration within a superframe structure for a time division multiplexing transmission. The low bandwidth utilization problem may occur in the GTS mechanism when the allocated bandwidth is less than the available bandwidth. However, this problem has not been resolved thoroughly in any of the standard or current research thus far. This paper analyzes GTS performance in QoS-guaranteed transmission and proposes a new GTS allocation scheme named Unbalanced GTS Allocation Scheme (UGAS), which improves the bandwidth resource efficiency. Our scheme tries to solve the bandwidth under-utilization problem by using Network Calculus theory based on the fluid model and greedy algorithm. The UGAS scheme divides the Contention-Free Period into time slots of different durations to support various bandwidth requirements. Time slots are allocated using an approximation QoS model to minimize under-utilization. Compared with the standard GTS allocation scheme, UGAS makes an efficient bandwidth allocation with the QoS-guaranteed model and without breaking the standard protocol. The numerical results show that the average bandwidth utilization using UGAS can be improved by 30 % as compared with the standard scheme.     

Simple Design of Detector in the Presence of Frequency Offset for IEEE 802.15.4 LR-WPANs

A simple detector for orthogonal modulation that is robust to large frequency offsets is proposed. The complexity of the detector is significantly reduced by implementing the correlator using multiplexers instead of complex floating-point multiplications. The performance of this design is comparable to the optimal value obtained by double correlation in offset quadrature phase-shift keying (O-QPSK) and nearly reaches that of noncoherent maximum likelihood (NCOHML) detection with 10-ppm frequency offset in the additive white Gaussian noise (AWGN) channel. Therefore, the proposed design can be used in low-cost and low-power IEEE 802.15.4 low-rate wireless personal area network (LR-WPAN) applications.     

基于IEEE802.15.4协议的延时线问题探讨

IEEE802.15.4协议引入了延时线的概念,给协议带来了一定的影响.通过探讨工作在饱和状态、星形拓扑、信标使能的传感器网络下带时隙的马尔可夫链模型,推导出了该状态下的延时计算公式.仿真表明,延时线对延时的影响可以忽略,主要起节能作用.针对延时线的引入导致接入概率降低的问题,提出了让接入时隙的分布和节点数据长度相关的解决方案.     

ZigBee和6LowPan--基于IEEE 802.15.4的两种新技术

IEEE 802.15.4是一种新兴的低速率、短距离无线标准,基于它可以产生许多令人激动不已的新技术.其中,ZigBee和6LowPan就是典型的代表.在详细分析了IEEE 802.15.4标准、ZigBee和6LowPan这两种新技术各自的特点之后,重点介绍了这两种技术互联互通时需要考虑的因素,并探讨了两种可行的互通方案.最后,还对这两种技术在工业、家庭及办公自动化等领域的应用前景做了分析和展望,指出二者的融合是一个必然的趋势.     

基于二次碰撞的CSMA/CA算法的优化

基于时隙的载波监听多址接入/冲突检测（Carrie Sense Multiple Access with Collision Avoid,CSMA/CA）算法在处理第一次CCA检测信道为闲,第二次CCA检测信道为忙的情况时存在两个主要的缺陷,针对这两个缺陷引入两个参数FN、SN来提高节点成功接入信道的概率.最后应用NS-2软件进行仿真结果表明,改进的CSMA/CA算法在吞吐量和平均网络时延方面优于原算法.     

一种适用于IEEE802.15.4协议的全集成CMOS复数滤波器

复数滤波器是低中频结构接收机中的一个重要模块,起到镜像抑制的作用。该文针对IEEE802.15.4的低功耗要求,提出了一种可以灵活配置共模反馈模块的伪差分结构OTA,该OTA具有内部共模前馈和共模检测功能,适用于级联应用。基于该OTA结构实现了一个3阶巴特沃斯Gm-C复数滤波器,中心频率在1 MHz,带宽1.3 MHz,带内群延时波动小于0.16 s,镜像抑制能力满足IEEE802.15.4协议要求。该文还提出了一种频率调节方法,用于控制复数滤波器的中心频率,与传统的锁相环结构相比,该调谐电路结构简单,适合在低功耗应用场合。     

基于IEEE 802.15.4的无线传感器网络的设计与实现

利用基于IEEE 802.15.4的IP-Link1200模块,设计并实现了能够实时接入现有蜂窝网络的无线传感器网络的验证系统。该方案工作于900 MHz或1 800 MHz的GSM(全球移动通信系统)网络的SMS(短消息业务)平台,把从目标区域采集到的温湿度参数传送给位于远程的任务管理中心。用户只需用普通的支持短消息的手机,向任务管理中心发送固定格式的短消息,就可以实时地获得任意一指定节点的温湿度参数。另外,也可以通过Internet打印历史报表。     

一种用于低功耗低成本的IEEE802.15.4接收器的新颖解调算法

提出了一种基于低中频、适用于ISM2.4 GHz频段ZigBee接收机的新型解调算法,满足IEEE802.15.4标准.作为数字相位解调,本算法采用相位差分、频率补偿和符号恢复,不用分别恢复出I路和Q路的码序列,而直接提取出相位斜率码,恢复出符号,从而简化了解调结构、降低了功耗和成本.通过与零中频过零检测算法的比较,本算法具有更低复杂度,更好的误符号率和误包率,完全满足IEEE802.15.4/ZigBeeTM标准的要求.     

Resource Allocation Scheme for Millimeter Wave–Based WPANs Using Directional Antennas

In this paper, we consider a resource allocation scheme for millimeter wave–based wireless personal area networks using directional antennas. This scheme involves scheduling the reservation period of medium access control for IEEE 802.15.3c. Objective functions are considered to minimize the average delay and maximize throughput; and two scheduling algorithms—namely, MInMax concurrent transmission and MAxMin concurrent transmission—are proposed to provide a suboptimal solution to each objective function. These are based on an exclusive region and two decision rules that determine the length of reservation times and the transmission order of groups. Each group consists of flows that are concurrently transmittable via spatial reuse. The algorithms appropriately apply two decision rules according to their objectives. A real video trace is used for the numerical results, which show that the proposed algorithms satisfy their objectives. They outperform other schemes on a range of measures, showing the effect of using a directional antenna. The proposed scheme efficiently supports variable bit rate traffic during the reservation period, reducing resource waste.