Energy efficient smart-relay-based cooperative MAC for wireless networks

An enormous number of papers investigated wireless cooperative networks over the last few years. Almost all have shown that cooperative transmission improves network performance significantly. However, none of these studies have considered the hidden and exposed terminal problems which appear due to the cooperative mechanisms of relay selection and transmission processes. The hidden terminal problems increase collisions and the exposed terminal problems increase bandwidth wastage, degrading the expected performance of cooperative networks. This paper addresses these problems of traditional wireless cooperative networks. We also propose a protocol called smart-relay-based-cooperative (SRcoop) MAC to optimally reduce the impacts of hidden and exposed terminal problems. We also illustrate an efficient relay selection mechanism that uses a back-up relay to increase transmission reliability. Our innovative model significantly improves the network throughput, end-to-end delay and energy efficiency over traditional cooperative MAC, 2rcMAC, LC-MAC, C-ARQ and Adere et al. protocols.     

Gossip-based cooperative caching for mobile applications in mobile wireless networks

Cooperative caching is an efficient way to improve the performance of data access in mobile wireless networks, by cache nodes selecting different data items in their limited storage in order to reduce total access delay. With more demands on sharing a video or other data, especially for mobile applications in an Internet-based Mobile Ad Hoc Network, considering the relations among data items in cooperative caching becomes more important than before. However, most of the existing works do not consider these inherent relations among data items, such as the logical, temporal, or spatial relations. In this paper, we present a novel solution, Gossip-based Cooperative Caching (GosCC) to address the cache placement problem, and consider the sequential relation among data items. Each mobile node stores the IDs of data items cached locally and the ID of the data item in use into its progress report. Each mobile node also makes use of these progress reports to determine whether a data item should be cached locally. These progress reports are propagated within the network in a gossip-based way. To improve the user experience, GosCC aims to provide users with an uninterrupted data access service. Simulation results show that GosCC achieves better performance than Benefit-based Data Caching and HybridCache, in terms of average interruption intervals and average interruption times, while sacrificing message cost to a certain degree.     

A cooperative CDMA-based multi-channel MAC protocol for mobile ad hoc networks

In this paper, we present CCM-MAC, a cooperative CDMA-based multi-channel medium access control (MAC) protocol for mobile ad hoc networks (MANETs) in which each node has one half-duplex transceiver. The protocol mitigates the multi-channel hidden and exposed terminal problems by using information about channel usage gleaned from overhearing (cooperating) neighbours. By accounting for the multiple access interference, CCM-MAC also addresses the near-far problem of CDMA in MANETs enabling concurrent transmissions on each channel. We provide an analysis of the maximum throughput of CCM-MAC and validate it through simulation in Matlab. We also compare the throughput it achieves to IEEE 802.11, a multi-channel MAC protocol, and a CDMA-based MAC protocol.     

成簇无线传感网中能量高效的协作通信

在成簇无线传感器网络中,会出现极大簇和极小簇并存的现象,从而导致整个网络的能量消耗不均衡,进而降低网络性能。通过采用邻近极大极小簇协作发送的方案,极大地均衡了网络的能量消耗,提高了通信的可靠性。仿真结果表明,基于邻近极大极小簇的协作发送方案是一种高能效协作方案,能够很好地均衡网络能量消耗,在延长网络生存周期方面具有更优越的性能。     

CCMAC: Coordinated cooperative MAC for wireless LANs

In wireless LANs, throughput is one of, if not the most, important performance metric. This metric becomes more critical at the bottleneck area of the network, which is normally the area around the Access Point (AP). In this paper, we propose CCMAC, a coordinated cooperative MAC for wireless LANs. It is designed to improve the throughput performance in the region near the AP through cooperative communication, where data is forwarded through a two-hop high data rate link instead of a low data rate direct link. The most unique feature is that, it can coordinate nodes to perform concurrent transmissions which can further increase the throughput. To optimize the performance, the coordination problem is formulated as a Partially Observable Markov Decision Process and solved by a Reinforcement Learning algorithm. Through analysis and simulation, we show that CCMAC can significantly shorten the transmission time for stations with low data rate links to the AP and CCMAC has better throughput performance than other MAC protocols, such as CoopMAC and legacy IEEE 802.11.     

Enhanced MAC protocol to support multimedia traffic in cognitive wireless mesh networks

With the advanced physical layer techniques such as multiple-input and multiple-output (MIMO) and orthogonal frequency-division multiplexing (OFDM), transmission real-time 2D/3D contents and applications becomes more and more necessary in wireless networks for the amazing growing in demand of customers. However, the low efficiency of medium access control (MAC) protocol degrades the performance of real-time traffic greatly in multihop, wireless and mobile environment. Focusing on supporting real-time multimedia traffic in cognitive wireless mesh networks (WMNs), an enhanced MAC protocol is proposed. And the contribution of this paper is twofold: (1) An efficient carrier sense multiple access with collision avoidance (CSMA/CA) compatible time division multiple access (TDMA)-like MAC protocol called T-MAC is proposed, which aims to improve the system performance by allocating more channel access time in centralized manner and decreasing overhead. (2) An optimal adaptive scheduling scheme is proposed to support real-time multimedia applications and guarantee QoS for different priority traffic, which aims to find the optimized schedule among all possible sequences of concurrent transmissions by minimizing the occupied resources. Detailed simulation results and comparison with IEEE 802.11e MAC scheme show that the proposed T-MAC can effectively improve quality of service (QoS) for multimedia traffic in terms of throughput, end-to-end delay and packet loss rate, which also manifests that T-MAC is an efficient multimedia applications transmission scheme for mobile terminals and MAPs in cognitive WMNs.     

Directional communication with movement prediction in mobile wireless sensor networks

By introducing mobility to some or all the nodes in a wireless sensor network (WSN), WSN can enhance its capability and flexibility to support multiple missions. In mobile wireless sensor networks, mobile nodes collect data and send data to a sink station. When the sink station employs directional antennas to send and receive data, its communication capability can increase. Using directional antennas implies the transmitters must know the direction or location of the receiver. It is necessary to predict a mobile receiver’s movement to keep the transmitter’s antenna pointing to the right direction. A mobility prediction algorithm is proposed in this paper, which is based on the knowledge extracted from real vehicles traces. The validation experiments indicate that the prediction accuracy rate of the algorithm is 96.5 % and the communication using directional antenna with movement prediction saves about 92.6 % energy consumption with a suitable beam-width and shakehand interval.     

Key distribution scheme for peer-to-peer communication in mobile underwater wireless sensor networks

Wireless Sensor Networks (WSN) consist of small battery-limited devices called sensor nodes. The communication between sensor nodes is a type of peer-to-peer communication, since each node has the same capability and role. One of the recent application areas of these nodes is underwater sensing. Communication in Underwater Wireless Sensor Networks (UWSN) is challenging since radio frequencies cannot be used. Instead acoustic waves, which cause extra challenges, are used in UWSN. Since UWSNs are deployed in hostile environment, nodes can be captured by an adversary. In order to secure UWSNs, key distribution problem must be addressed. Moreover, UWSNs are inherently mobile since the nodes may be drifted in the sea. In this paper, we propose a key distribution model which is applied for two group mobility models, namely nomadic mobility model and meandering mobility model. In both schemes hierarchical structure is used and communication is handled via well-known Blom’s key distribution scheme. Our simulation results show that mobility causes some temporary decreases in the connectivity, but our schemes help to heal the connectivity performance in time. Moreover, our schemes show good resiliency performance such that capture of some nodes by an adversary only causes very small amount of links between uncaptured nodes to be compromised.     

无线传感器与执行器网络中协同通信研究综述

首先介绍了WSANs协同通信的意义和作用; 然后根据协同级别对协同通信进行分类, 分别讨论了每一类中重要和有代表性的协议, 并从主要的网络性能方面进行对比分析; 最后提出了几个WSANs协同通信中需要进一步研究的问题。     

无线传感网中能量有效的免碰撞MAC协议

无线传感网络普遍使用CSMA/CA机制和二进制指数退避算法避免碰撞。提出了一种能量有效的免碰撞MAC协议ERC。该协议将数据传输划分为协商和节点排队传输两个阶段,通过碰撞避免、节点休眠和批量传输机制提升吞吐量并节省整体能耗。理论分析和仿真表明,该协议在各种负载情况下都能明显提升网络的吞吐量与能量效率。     

一种基于空间相关性的无线传感器网络MAC协议

在大规模无线传感器网络中传输的监测数据具有较大的空间相关性,数据的传输存在一定冗余.如何有效的减少冗余数据的传输来改善网络性能成为一个重要的研究课题.本文以环状空间相关性模型为基础,从节点的筛选策略研究入手,提出一种能量高效的无线传感器网络MAC协议SEMAC.SEMAC协议采用信号强度优先的节点选择算法和冲突避免机制...     

An asynchronous MAC protocol for wireless sensor networks

The MAC protocol for wireless sensor network plays a very important role in the control of energy consumption. It is a very important issue to effectively utilize power under the condition of limited energy. The most energy-wasting part of the MAC protocol for wireless sensor network is at the idling condition. Therefore it is crucial for power saving to be able to turn off the signal transducer of the wireless network when the equipment is idling. Pattern-MAC (PMAC) allows sensors that did not transfer for a long period of time to quickly enter a dormant state, so that the problem of sensor overhearing can be greatly improved, and the whole network structure can fully respond to the actual transfer rate without too much energy consumption, but this type of design requires precise time synchronization mechanism. Achieving time synchronization is a very energy consuming and very expensive mechanism in the sensor network structure, achieving the goal is coupled with excess energy consumption and reduction of the lifespan of the sensor. Additionally, the exchange action with the neighboring pattern after each cycle, not only generates additional energy consumption for data transfer, but is also accompanied by factors such as competition, collision and pattern exchange failure. We propose an asynchronous MAC protocol (AMAC) in this paper and expect to improve the problem of energy wasting and time synchronization due to sleeping schedule exchange under the PMAC basic protocol.     

Contention-free MAC protocols for asynchronous wireless sensor networks

A MAC protocol specifies how nodes in a sensor network access a shared communication channel. Desired properties of a MAC protocol are: it should be contention-free (avoid collisions); it should be distributed and self-stabilize to topological changes in the network; topological changes should be contained, namely, affect only the nodes in the vicinity of the change; it should not assume that nodes have a global time reference, that is, nodes may not be time-synchronized. We give a set of TDMA-based MAC protocols for asynchronous wireless sensor networks satisfying all of these requirements. The communication complexity, number and size of messages, for the protocols to stabilize is small, poly-logarithmic in the network size. A preliminary version of the paper appears in the Proceedings of the 18th Annual Conference on Distributed Computing (DISC 2004), LNCS 3704, pp 245–259, Trippenhuis, Amsterdam, The Netherlands, October 2004.     

接收端发起的异步无线传感器网络MAC协议

为了减少无线传感器网络中由于空闲侦听而产生的能量消耗,在接收端发起的介质访问控制(RI-MAC)协议基础上提出一种新的接收端发起的异步RP-MAC。该协议通过预测接收节点唤醒时间,采用随机数作为唤醒间隔,改进RI-MAC的重传机制,从而减少了空闲侦听和网络冲突。NS2仿真结果表明,改进后的MAC协议在在高负载网络中显著降低了节点工作的占空比,提高了包交付率,从而减少了网络能耗。     

一种低延时的无线传感器网络MAC协议

针对典型无线传感器网络X-MAC协议在多跳环境下累积延迟问题,提出一种具有低时延的Ex-MAC协议。利用管理邻居节点工作周期和虚通道算法,使得虚通道中的所有节点近似于同步,从而减少数据传输延迟,而且不需要交换同步控制帧。仿真结果与X-MAC协议相比,减少了端到端的延迟和数据包冲突的几率,提高了网络的吞吐量。     

一种新型无线Mesh网络多信道MAC协议

在基于IEEE 802.11s无线Mesh网络中,Mesh网络接入点（MAP）和门户（MPP）在网络负载较重时会出现严重的流量瓶颈。为了保证MAP流量的优先传输,提出了基于节点优先级的新型多信道MAC协议（NPBM-MAC）;为了减少在小规模组网时各BSS间频率干扰,设计了基于地理位置信息和网络负载的频率分配方案（LLBFA）。仿真结果表明,NPBM-MAC协议和LLBFA频率分配方案能够有效解决重负载网络下的MAP/MPP瓶颈问题,最大限度地满足音视频等大业务流的QoS需求。     

支持协作通信的MAC协议研究

协作通信被视为一种可以获取空间分集的有效方法。通过协作,单天线的节点可以共享天线组成一个虚拟的多天线系统,以获得更加可靠的数据传输。然而,通信中更多节点的介入不可避免地使得接入访问更加复杂,因此需要重新进行MAC协议的相关研究。介绍了一种支持协作通信的通用框架,并提出了一套协作MAC协议。该协议不仅可以支持各种不同的协作方式,而且可以支持不同个数的中继节点。仿真结果显示,协作MAC协议能够显著提高网络的性能。     

一种容迟移动传感器网络的MAC协议

根据容迟移动传感器网络中节点的能量消耗和传输延迟特性,提出一种减少能量消耗的媒体接入控制协议(ESMAC协议)。通过实验证明,依靠在MAC协议的帧结构中加入模式判别标识,减少了节点由于串音和竞争引起的能量消耗;通过节点发送的寻访报文,减少了由于空闲侦听引起的节点能量消耗,延长了网络的生命周期。     

一种低能耗低延时的无线传感器网络MAC协议

传感器网络中数据从多个源节点向sink节点的转发形成数据汇集树,针对此汇集树提出低能耗低延时的LD MAC（Low Delay MAC）协议,解决以往MAC协议中能耗和延时的矛盾问题。LD MAC一方面采用异步duty cycle机制降低能耗,另一方面,从源到sink节点的转发路径上的节点逐个推迟帧的发送起始时间,依次进行接收与发送,减少数据在传输过程中的延时。分析和实验表明LD MAC较好地解决了能耗和延时的矛盾问题。