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。     

一种TCP友好的无线多跳网络拥塞控制算法

为了改进流媒体在无线多跳网络中的传输质量,提出一种TCP友好的拥塞控制算法.该算法考虑了MAC层的信道竞争,节点通过标记数据包来通知数据流它的竞争状态,数据流基于所估计的竞争状态来控制传输速率.仿真结果表明所提出的算法能更有效地利用带宽,与已存在的算法相比,有较高的吞吐量和较好的平滑性.     

多跳蓝牙设备分散网的动态组网算法

近几年无线自组网络发展迅速,而蓝牙自组网的拓扑构建问题已成为无线自组网络研究的一个重要分支.目前已有很多学者提出了蓝牙设备在多跳环境下的不同组网协议的算法,但大多是针对静态的组网问题.对于蓝牙设备不在直接通讯范围内的多跳通讯要求以及节点的动态变化情况,提出了一种新的蓝牙设备分散网的分布创建思想,同时该算法满足动态性的要求.形成的分散网的拓扑结构采用类似树形结构、没有根节点的无环连通图,因而具有控制简洁,组网快捷的特点.     

Anchor‐free distance estimation: A new approach to distance estimation for multihop ad hoc wireless networks

In ad hoc wireless networks, devices that normally cannot directly communicate route their messages through intermediate nodes. The number of those nodes is called hop count, a useful metric in estimating the distance between 2 nodes. Current methods usually depend on special nodes, called anchors, that need accurate localization information, in order to calculate an estimate for the average distance traversed per hop. The drawback of this approach is that anchor nodes increase the overall cost and complexity of the system. To address this problem, this letter proposes a novel, anchor node–free algorithm that can achieve a useful estimate for actual distance between 2 nodes, by analytically finding an estimate for the average maximum distance traveled per hop and multiplying with the hop count. The only requirement is the a priori knowledge of the networks' node density and the node range. The performance of our method is compared with a recent anchor node–based method and is shown to yield similar location estimation accuracy, despite the fact that it does not use anchor nodes.     

一种Ad—hoc密钥维护优化方案

Ad-hoc网络节点之间的无线连接越多，网络通信跳数相对越少，但网络需要的密钥量越大，加重了密钥维护的负担，因此在通信跳数可接受的情况下应该尽量减少密钥量。定义了网络付出的代价，用来描述通信跳数和密钥量。以网络付出的代价最小为原则，设计了一种简单的密钥维护优化方案。将方案应用于一个Ad-hoc场景，推算结果表明该方案对密钥维护的优化是有效的。     

Hierarchical micro-mobility management in high-speed multihop access networks

1 Introduction A wireless multihop network or Ad-hoc network [1, 2] is a network of independent mobile hosts without any network infrastructure or connection to base stations. In many application areas, however, Internet connectivity and access to service…     

A Clock Synchronization Algorithm for Multihop Wireless Ad Hoc Networks

In multihop wireless ad hoc networks, it is important that all mobile hosts are synchronized. Synchronization is necessary for power management and for frequency hopping spread spectrum (FHSS) operations. IEEE 802.11 standards specify a clock synchronization protocol but this protocol suffers from the scalability problem due to its inefficiency contention mechanism. In this paper, we propose an automatic self-time-correcting procedure (ASP) to achieve clock synchronization in a multihop environment. Our ASP has two features. First, a faster host has higher priority to send its timing information out than a slower one. Second, after collecting enough timing information, a slower host can synchronize to the faster one by self-correcting its timer periodically (which makes it becoming a faster host). Simulation results show that our ASP decreases 60% the average maximum clock drift as compared to the IEEE 802.11 and reduces 99% the number of asynchronism in a large-scale multihop wireless ad hoc networks.     

一种自适应的多跳蜂窝网络模型

提出了一种自适应的多跳蜂窝网络模型，通过动态的网络模式切换机制，终端可以根据网络状态在蜂窝和多跳两种网络模式间切换。该模型结合了蜂窝和多跳网络的优点，可以有效地提升无线数据网络的传输性能。仿真结果表明，该模型在增加了网络吞吐量、减少功耗的同时还具有较好的公平性。     

A Cooperative Nearest Neighbours Topology Control Algorithm for Wireless Ad Hoc Networks

In this article, we introduce a simple distributed algorithm that assigns appropriate individual transmission powers to devices in a wireless ad hoc network. In contrast to many other proposed algorithms, it does without special hardware. It requires only local neighbourhood information and therefore avoids flooding information throughout the network. Finally, the cooperative nature of the algorithm avoids that devices cause excessive interference by using unnecessarily high transmission powers. By means of simulation, we show that the topologies created by this algorithm without any global knowledge are as effective as topologies resulting from a good choice of a common transmission power (which would require global knowledge) in terms of the achievable throughput. This work was supported in part by the German Federal Ministry of Education and Research (BMBF) as part of the IPonAir project.