基于多信道预约的传感器网络MAC协议研究

针对传感器网络中三重隐终端问题,提出了一种基于自适应占空比的多信道MAC协议—MCR,MCR通过多信道预约机制高效地解决了该问题。在理论分析中,通过最小化节点平均信道切换次数的下界得出了节点的最优占空比。为验证MCR中多信道预约和自适应占空比机制的性能,进行了模拟和真实实验,实验结果表明,与其他MAC协议相比,随着信道数及网络负载的增加,MCR提高了网络吞吐量,降低了传输所消耗的能量。     

IEEE802.11标准MAC性能分析和一种改进方法

介绍了IEEE802.11标准MAC协议的功能,详细分析在网络站点数量增加的环境下,影响这个网络运行性能的主要因素是冲突的增加和空闲时间段所造成的无线信道资源的浪费。在此基础上,可以采用较容易实现的方法对MAC协议进行改进,以获得更好性能。     

面向应用的车载自组织网络跨层多信道MAC协议

提出了一种面向应用的车载网络跨层多信道MAC协议。对来自应用层不同类型的消息进行实时统计,预测出最优控制信道周期,确保控制信道上安全消息的及时、可靠传输,同时采用预约机制实现消息在服务信道上的无竞争传输,提高服务信道的吞吐量。本协议适合饱和与非饱和的一般VANET环境,具有较低的计算复杂度,扩展性较好。与现存的其他协议相比较,仿真结果证实了所提协议的优越性。     

认知无线多跳网中结合QoS查找的跨层多信道MAC协议

针对认知无线多跳网中频谱资源具有较大时变性及差异性的问题,设计了一种结合QoS查找的跨层多信道MAC协议。该协议将按需QoS查找与动态频谱分配跨层相结合,仅让参与传输的节点执行频谱分配并按QoS要求获取频谱资源。此外,协议使用频分双工收发机实现了对公共控制信道的不间断监听,并设计了一套支持不同数量收发机节点间混合通信的接入算法。大量仿真结果表明,该协议能有效保证对端到端传输的QoS要求的满足,并显著提高端到端吞吐量及时延。     

基于规则与感知的水声网络MAC协议

针对水声网络(UAN)媒体访问控制(MAC)协议采用RTS/CTS握手机制,导致信道利用率和网络吞吐量较低的问题,提出一套信道访问规则,基于该规则设计了节点状态感知的水声网络MAC(RP-MAC)协议.当接收节点不在收发状态,并且其他邻居节点也都不在接收状态时,发送节点才会尝试发送一到多个报文给接收节点.节点通过侦听和...     

基于信道状态感知的多信道认知多址接入协议

摘 要：针对多信道认知无线网络中预约信道与多个数据传输信道的状态不一致会降低认知多址协议性能的问题,提出了基于数据信道状态感知的多信道认知多址协议——CAM-MAC协议。该协议在预约信道上优化握手机制来减少平均成功预约时长;而在Nakagami衰落数传信道上采用跨层方法设计了基于瞬时SNR的自适应传输机制来提高数据传输速率。通过上述机制,CAM-MAC协议可以有效提升系统性能。分析与仿真均表明：该协议在饱和吞吐量上有较大提升,在特定场景下可提高约50%。     

一种基于功率控制的无线传感器网络MAC协议

提出了一种基于功率控制机制的无线传感器网络MAC协议 Distance Prediction Power Control MAC (DPPC-MAC).DPPC-MAC协议基于目前十分成熟的SMAC协议[1-2],引入了功率控制机制以降低数据包发送时的能耗,并且提出了一种新的通过功率预测距离来解决暴露终端和隐藏终端的方法.仿真结果表明,DPPC-MAC能有效降低网络能耗,同时吞吐量性能也得到了一定的改善.     

Performance analysis of adaptive MAC protocol in VANETs considering the potential impact on throughput and transmission delays

The existing adaptive multichannel medium access control (MAC) protocols in vehicular ad hoc networks can adjust themselves according to different vehicular traffic densities. These protocols can increase throughput and guarantee a bounded transmission delay for real‐time safety applications. However, the optimized control channel interval is computed based on the maximum throughput while ignoring the strict safety packet transmission delay requirements. In this paper, we analyze the effects of the throughput and strict safety packet transmission delay with adaptive multichannel MAC protocols, such as connectivity‐aware MAC (CA MAC), adaptive multi‐priority distributed MAC (APDM), multi‐priority supported p‐persistent MAC (MP MAC), and variable control channel interval MAC (VCI) protocols. The performance and analysis results show that: (a) under a low data rate condition, CA MAC does not guarantee a strict safety packet transmission delay; (b) APDM not only satisfies the safety packet transmission requirement, but also provides the lowest safety packet transmission delay; (c) under a high data rate condition, we suggest APDM for use as an adaptive MAC protocol because it allows for high throughput for nonsafety packets and preserves low safety packet transmission delay; (d) under a low data rate condition with various data packet sizes, we suggest MP MAC for high throughput, which satisfies the safety packet transmission requirement; and (e) under low vehicle density and low data rate conditions, VCI can support high throughput. A balance between transmission delay and throughput must be considered to improve the optimal efficiency, reliability, and adaptability.     

RSU-coordinated multichannel MAC protocol in vehicular ad hoc network

A road side unit (RSU)-coordinated multichannel media access control (MAC) (RMM) protocol was proposed in vehicular ad hoc network,which aimed to improve the transmission efficiency of non-safety messages.Under the coordination of RSU,nodes had more opportunities to make SCH reservations on control channel,and the contention-free message transmissions were thus realized.The proposed RMM protocol could use the service channel during the whole synchronization interval for non-safety message transmissions,and thus the saturated network throughput and channel utilization were improved,and the transmission delay was reduced.Compared with other existing protocols,extensive analysis and simulation results demonstrate the superiority of the RMM protocol.     

RPCP‐MAC: Receiver preambling with channel polling MAC protocol for underwater wireless sensor networks

To design a reliable and energy efficient medium access control (MAC) protocol for underwater wireless sensor networks (UWSNs) is an active research area due to its variety of applications. There are many issues associated with underwater acoustic channels including long and variable propagation delay, attenuation, and limited bandwidth which pose significant challenges in the design of MAC protocol. The available sender‐initiated asynchronous preamble‐based MAC protocols for UWSNs are not reliable and energy‐efficient. This is due to the problems caused by transmission of preambles for longer duration and collision of preambles from hidden nodes in sender‐initiated preamble‐based MAC protocols. To resolve these issues, the paper proposed an asynchronous receiver‐initiated preamble‐based MAC protocol named Receiver Preambling with Channel Polling MAC (RPCP‐MAC) protocol for shallow underwater monitoring applications with high data rates. The protocol is proposed to resolve data packet collision and support reliability in an energy‐efficient way without using any transmission schedule. The proposed protocol is based on the following mechanisms. Firstly, receiver preambling mechanism is adopted to reduce idle listening. Secondly, channel polling mechanism is used to determine missing data frame during its sleeping period and to minimize the active time of node and reduces energy wastage. Finally, a back‐off mechanism is applied to resolve collision when preambles are received simultaneously. In addition, performance analysis through Markov chain together with its validation with simulation‐based studies is reported in the paper. Both the analytical and simulation results have demonstrated the reliability achievable with RPCP‐MAC while providing good energy efficiency.     

APON接人系统的一个介质访问控制协议

作为共享介质的接入网络,APON需要介质访问控制协议用于协调各终端对介质的存取.本文提出了一个符合ITU-T建议的MAC协议,采用了时延分优先级,对高优先级的实时业务按照的均匀间隔的原则分配带宽,低优先级业务的带宽按次序循环分配.上行帧长度根据处于连接的用户数动态变化,各终端的带宽申请时隙由系统动态分配.最后给出了由该协议确定的网络性能的计算机仿真结果.     

支持TDD的无线局域网MAC协议

本文在分析无线局域网媒体接入控制（MAC）协议的基础上,提出支持时分双工（TDD）的MAC协议：EDCF-TDD。IEEE802．11增强型分布式协调功能（EDCF）只支持单工通信,即数据帧只能由发送方传送到接收方。EDCF-TDD利用IEEE802．11点协调功能（PCF）提供的数据帧格式,可以实现数据帧的双向传输。EDCF-TDD更适合传输对称的实时业务和面向连接的TCP业务,而且与IEEE802．11完全兼容。仿真结果表明：EDCF-TDD可以提高吞吐量和实现时延、时延抖动和丢组率分级;理论分析结果基本准确。     

Throughput enhancement with a modified 802.11 MAC protocol with multi-user detection support

A modification to the traditional CSMA-based media access control protocol, named 802.11-MUD, is proposed in this paper which differs from the IEEE 802.11 in its support of simultaneous transmissions/receptions with multi-user detection (MUD). A joint information and renewal theoretic analysis framework is introduced to study the performance of 802.11-MUD. While the information theoretic part is useful for modeling the increase in sum capacity attributed to MUD, the renewal theoretic part is good for modeling the impact of MUD on alleviating the collision probability and increasing the network throughput. In addition, this analytical framework helps us finetune the 802.11-MUD system (called 802.11-MUD^* after the optimal tuning) and achieve significantly enhanced network throughput especially in busy networks.     

基于优先级的无线传感器网络动态轮询信道接入方案

In Wireless Sensor Networks(WSNs), polling can obviously improve the throughput and decrease average access delay by allocating bandwidth efficiently and reasonably. In this paper, a Dynamic Polling Media Access Control (DPMAC) scheme designed according to WSNs'features is proposed. DPMAC is a priority based access control protocol with the characteristics that its polling table is dynamically refreshed depending on whether the sensor node is active and that the bandwidth is dynamically allocated according to the traffic types. The access priorities are determined by the emergency levels of events and the scheduler proposed in our MAC is preemptive based on the deadline of the events. Simulation results show that DPMAC can efficiently utilize bandwidth and decrease average access delay and response time for emergency events with different access priorities in WSNs.     

Ad Hoc网多信道MAC协议的分析与改进

对现有的多信道MAC协议进行了分类总结,重点分析了CMCT协议,在CMCT协议的基础上对其进行了改进,提出了PC-CMCT协议.PC-CMCT支持功率控制和业务的优先级,并解决了CMCT协议中存在的问题.     

基于多信道预约可冲突避免的多址接入协议

本文为多跳分布多无线网络提出了一套灵活而有效的自适应获取冲突避免（AACA）的多址接入协议。在该协议中，各节点竞争公共信道，利用RTS/CTS对话形式来预约各业务信道，成功预约后的分组传输不会受到其他节点的干扰。它使用任意确定数目信道，以异步方式工作，并且使得各节点利用半双工无线电台就可以灵活、简便地实现资源预约。分析和比较结果说明，所提出的多信道预约协议可以有效地解决隐藏终端、暴露终端以及侵入终端的问题。     

基于宽带多媒体卫星网络的MAC协议

提出了一种基于MF-TDMA的宽带卫星MAC协议联合随机预约接入协议(CRRAP)。协议采用随机预约和捎带预约结合,按需分配和自由分配结合来实现的。仿真结果表明,相对于现有的方法,CRRAP减少了高信道负荷下的时延,提高了吞吐性能,并具有较高的信道利用率。     

一种基于Ad Hoc网络的协作MAC方案

在 IEEE 802.11b MAC层协议的研究基础上,提出了一种基于无线Ad Hoc网络的最佳中继选择策略,该策略综合考虑瞬时信道信息和节点剩余能量,能够有效防止信道条件好的节点的过度使用,并能保证系统高吞吐量。文中以饱和吞吐量和网络生存时间为性能指标,对新算法和以往协作MAC算法进行仿真和比较,结果表明新算法在网络吞吐量下降不明显的情况下,能大大增加网络生存时间。     

An efficient MAC protocol with cooperative retransmission in mobile ad hoc networks

In emerging wireless networks, cooperative retransmission is employed to replace packet retransmission between a pair of sender and receiver with poor channel condition. A cooperative MAC protocol which utilizes such benefit is proposed in this paper to improve the network performance in mobile ad hoc networks. In the proposed protocol, relay nodes between sender and receiver are used if the sender cannot communicate with the receiver reliably. Furthermore, the receiver may also stop forwarding the received data frame if the frame is received by the next‐hop receiver on the route to the final destination node. Simulation results show that the proposed protocol outperforms previous works in terms of increased transmission reliability and reduced delay time. Copyright © 2010 John Wiley & Sons, Ltd.     

A short-term fair MAC protocol for WLANs

Designing a medium access control (MAC) protocol that simultaneously provides high throughput and allows individual users to share limited spectrum resources fairly, especially in the short-term time horizon, is a challenging problem for wireless LANs. In this paper, we propose an efficient cooperative MAC protocol with very simple state information that considers only collisions, like the standard IEEE 802.11 MAC protocol. However, contrary to the IEEE 802.11 MAC, the cooperative MAC gives collided users priority to access the channel by assigning them shorter backoff counters and interframe-spaces than users who did not participate in the collision event. In other words, collided users are the only ones allowed to transmit in the following contention period. For the cooperative MAC protocol, we utilize an analytical throughput model to obtain the optimal parameter settings. Simulation results show that the cooperative MAC provides significant improvement in short-term fairness and access delay, while still providing high network throughput.