基于冲突消解多无人机协同航路规划算法仿真

针对多架无人机同时攻击同一目标的问题,提出了一种基于冲突消解机制的航路规划算法.通过分析协同规划中的各种约束条件及任务要求,从规划终点同时、同步扩展每架无人机的飞行航迹,并采用不等步长扩展法反映每架无人机的飞行速度,在扩展节点的同时进行各项约束条件的检查和消除,保证多条航迹间的时空协同;最后通过数学仿真验证了该算法的可...     

A Collision Resolution Protocol for Random Access Channels with Energy Detectors

In this paper, we consider the random accessing of a single slotted channel by a large number of packet-transmitting, bursty users. We assume that feedback broadcasting is available where some different information, in addition to the information assumed by the Capetanakis, Gallager, Massey, etc., models, is included in the feedback. In particular, we assume that the existence of energy detectors permits the broadcasting of the number of collided packets within each collision slot, whenever this number is below a certain limit. We first consider this limit to be infinity, and then a finite small number. For the model considered, we propose and analyze a collision resolution protocol (CRAI), whose implementation is simple. For Poisson input traffic and infinite number of energy detectors, we found that the CRAI is stable for input rates below 0.53237. For finite number of energy detectors, we propose a modified version of the CRAI (MCRAI). We found that the MCRAI reaches the throughput 0.53237, through the utilization of only about eight energy detectors. These protocols, like the ones introduced by Capetanakis, Gallager, Massey, etc., have good delay properties.     

A Collision Arbitration Protocol Based on Specific Selection Function

Fast and eff ective identifications of a large number of items are required in many Radio-frequency identification (RFID) applications. Simultaneous responses from multiple tags are corrupted by collisions and thus re-sult in low identification efficiency. To address the prob-lem of low identification eifficiency, many existing tag anti-collision algorithms try to schedule the identification pro-cess to avoid collisions. A novel anti-collision scheme based on specific selection function is presented, in which tags pick a slot according to a selection function instead of be-ing randomly assigned to slots within a frame. If collision occurs, the reader sends the custom command SETBM ac-cording to the collision information. When probed by the SETBM, the tags apply the selection function to its partial ID and send the mapped result to the reader. According to the mapped result, the reader assigns the time slot to the tags. All tags collided in the same slot will be identified by the tree traversal scheme. Compared to the most of exist-ing anti-collision algorithms, simulation results show that our proposed algorithm can achieve better performance in terms of identification efficiency, time efficiency, and en-ergy consumption.     

一种基于秘密共享的量子强盲签名协议

提出了一种基于秘密共享原理的量子强盲签名协议。每一组GHZ (Greenberger-Horne-Zeilinger)中的三个光子依次分发给消息拥有者Alice、签名者Trent及验证者Bob,Alice测量自己的光子将消息盲化,Trent测量自己的光子对盲消息进行签名,而Bob根据手中光子的测量结果及量子态的关联性验证签名,但其行为受到量子指纹及审计程序的约束。本协议实现了签名的盲性以及消息拥有者无法被追踪,其安全性不受攻击者所拥有的计算资源的影响。     

一种基于跨层设计的协作多址接入方案

协作通信容许移动节点共享彼此间的天线以构建虚拟多入多出系统,可以有效获得空间分集增益。提出了一种结合网络分集多址接入(NDMA)和协作通信的随机接入方案,利用多天线接收,可以快速分离冲突数据包,实现多包接收的能力。理论分析和仿真结果表明,所提方案能充分利用空间资源,相比传统NDMA方案和TDMA方案,可以显著提高系统的有效吞吐量。     

无线传感器网络中基于最优转发集的协作式编码传输协议

针对当前大多数据传输协议没有充分利用无线信道的广播特性这一问题,本文提出了基于网络编码的机会路由协议NCOR（Network Coding based Opportunistic Routing protocol）.首先,通过分析网络端到端传输代价,本文提出了最优转发集构造机制以最小化传输代价.此后,NCOR在转发集内执行节点协作式编码传输以保证传输可靠性.最后,理论分析了NCOR的传输可靠性结论.仿真实验表明NCOR可适用于不同的链路环境,且在保证可靠传输的同时,大幅降低了网络能耗.     

一种基于权值矩阵的序列图像超分辨率盲复原算法

 建立准确的观测模型是提高现有超分辨率复原算法性能的关键.本文提出一种基于权值矩阵的超分辨率盲复原算法:定义了一种新的基于权值矩阵和运动补偿矩阵的观测模型,在最大后验概率框架下,采用交替最小化方法对权值矩阵和高分辨率图像进行联合优化求解.静止和动态图像序列的测试结果表明,该方法能够实现对低分辨率图像降质过程的准确描述,其复原性能明显优于传统基于理想观测模型的算法,部分结果甚至超过了观测模型已知的算法.     

冲突消弱分组预约多址协议及其性能分析

本文讨论了分组预约多址接入（ＰＲＭＡ）协议的缺点,提出了一种突消弱分组预约多址接入（ＣＲ－ＰＲＭＡ）协议,理论分析和计算机仿真均表明ＣＲ－ＰＲＭＡ的性能优于ＰＲＭＡ。     

基于网络编码的协作HARQ协议

该文基于网络编码技术提出了一种新的协作HARQ协议。在中继节点的协助下两个用户与基站进行通信。中继节点响应基站的重传请求,对两用户的增加冗余帧采用物理层网络编码即信号重叠调制技术进行处理,然后发送至基站。基站对接收信号采用多用户联合检测以及联合软判决译码。在平坦瑞利衰落信道下,该网络编码协作HARQ协议较传统的非协作HARQ协议可获得较大的性能改善,其性能接近没有采用网络编码的协作HARQ协议,且需要较少的硬件和带宽资源。     

嵌入式蓝牙协议的数据传输实现

文中首先介绍了蓝牙协议栈中的主机控制器接口（HCI）,服务发现协议（SDP）及逻辑链路控制与适配协议（L2CAP）,并通过一个具体的嵌入式蓝牙数据传输系统,实现了这些协议。文章给出了该系统的硬件框图、软件的总体设计模块（主机控制器接口模块、服务发现模块和数据传输模块）、以及软件设计流程,最终实现了两个蓝牙模块之间的无线数据传输。     

基于ADS-B的通用航空飞行冲突解脱算法

为了解决通航实际飞行中出现冲突情况复杂的问题,提出基于广播式自动相关监视（ADS-B）技术监视状态下的飞行冲突解脱算法。首先,将两机的冲突场景分成交叉、相向和追及冲突三种,利用相对运动调整航向和调节速度法,针对不同冲突场景给出相应可行的解脱模型。然后,基于空中交通管制防撞相关规定,建立不同解脱策略的选择标准,提升了算法的实际可行性。对不同解脱策略的解脱情况进行仿真和比较,表明该算法能够为具体的飞行冲突场景提供可行的解决方案。      

基于模式分组和分辨率调整的盲图像水印算法

提出了一个新的基于分组模式编码和分辨率调整的盲数字图像水印算法,该算法首先在图像的空间域中随机选取相应位置系数的比特位作为水印的嵌入区间,对选出的比特位根据分组编码原理生成预嵌入模式,然后将一个二值水印图像嵌入到模式中并对其进行分辨率调整.实验证明通过模式分组编码和分辨率调整相结合的方法,可达到水印图像透明性和鲁棒性之间较好的折衷,对于各种常见的图像处理操作具有较好的抵抗能力.     

A Wireless MAC Protocol with Collision Detection

The most popular strategies for dealing with packet collisions at the medium access control (MAC) layer in distributed wireless networks use a combination of carrier sensing and collision avoidance. When the collision avoidance strategy fails, such schemes cannot detect collisions and corrupted data frames are still transmitted in their entirety, thereby wasting the channel bandwidth and significantly reducing the network throughput. To address this problem, this paper proposes a new wireless MAC protocol capable of collision detection. The basic idea of the proposed protocol is the use of pulses in an out-of-band control channel for exploring channel condition and medium reservation and achieving both collision avoidance and collision detection. The performance of the proposed MAC protocol has been investigated using extensive analysis and simulations. Our results show that, as compared with existing MAC protocols, the proposed protocol has significant performance gains in terms of node throughput. Additionally, the proposed protocol is fully distributed and requires no time synchronization among nodes.     

基于交叉传输的水声通信网络MAC协议

为了解决传统TDMA协议在水下环境信道利用率低的问题,提出了交叉传输的TDMA (I-TDMA)协议.该协议利用水声信道长传输时延的特性,采用数据分组交叉传输的方法改善信道利用率,同时引入了拓扑扩展和循环同步机制,增强了网络系统的可扩展性.仿真结果表明,该协议与传统的TDMA协议相比减少了数据分组时延以及同步开销,具有更好的性能.     

一种基于非否认协议的电子邮件传输方案

在电子邮件传输中,发信人和收信人的不可否认性是一个重要的安全问题。该问题可以通过采用数据传输中的非否认协议来解决。目前多数非否认协议基于可信第三方,并且对可信第三方的安全性、通信能力要求很高,因而难以在实际中应用。提出了一种基于安全第三方的非否认协议,该协议适合于电子邮件传输的特定应用;同时该协议减少了通信流量,降低了对可信第三方的安全性要求。随后结合安全多用途邮件扩展技术,得出了基于该协议的电子邮件传输实现方案。     

WSN中一种基于能量效率的协同中继传输方案

本文针对分簇无线传感器网络,提出了一种基于能量效率的协同中继传输方案,该方案中源簇头根据源到邻簇头之间的信道状态信息选择最优中继节点;协同传输数据时,目的节点接收到两个时隙的信号后进行最大比合并,并根据设定的接收信噪比门限范围在确认帧中给中继节点反馈功率调整信息,以减少重传次数或降低中继节点的发射功率,在不增加开销的情况下可以减少系统总的能量消耗。文章利用概率密度函数推导了基于部分信道状态信息选择中继协同的误符号率闭式表达式,最后通过蒙特卡洛仿真进行了验证。结果表明:误符号率的理论推导值与仿真值一致,在相同的接收信噪比门限时,本文所提方案能够明显提高系统的能效性。      

一种采用复合中继激励的协作下行传输机制

为了解决现有中继激励机制中长期回报存在不确定性,以及即时回报导致资源利用效率降低的问题,该文针对协作下行通信系统提出一种复合中继激励机制(CCRI)。首先利用链路不平衡产生的瓶颈,将第1跳链路超过第2跳的数据速率部分作为即时回报,用于中继节点自身数据的传输;同时针对即时回报量不足,过量或瓶颈存在于第1跳导致即时回报失效的情况,采用基于比例公平的长期回报作为补充,进一步调整中继节点的调度权重。仿真结果表明,所提机制能够给予中继节点合理的回报,并实现系统频谱效率和生存时间,以及中继能量效率的改善。     

Collision Resolution Protocols Utilizing Absorptions and Collision Multiplicities

In this correspondence, we consider the random accessing of a single slotted channel by a large number of packet transmitting users, whose cumulative traffic is Poisson. We assume the existence of the same feedback as that of the MCRAI protocols of Georgiadis, and full channel sensing, and we develop collision resolution algorithms that utilize the absorption concept of Gallager. We observe the improvement in the throughputs induced by the absorption, as well as the improved delay characteristics. Finally, we draw some conclusions about the limitations of the absorption idea.     

A BER Based Selection Combining Protocol for Adaptive Cooperative Cognitive Radios

This paper illustrates the performance of bit error rate based selection combining (BER-SC) protocol for adaptive cooperative cognitive radios. In the proposed framework, the unlicensed (i.e. secondary) system utilizes an adaptive mode of transmission to help the licensed (i.e. primary) system to achieve the desired quality of service in exchange for opportunistic spectrum access. The total transmission is divided in two phases. In Phase I, the primary transmitter (PT) broadcasts the data to the primary receiver (PR), which is overheard by the secondary transmitter (ST) and secondary receiver (SR). In Phase II, ST decodes the primary data and linearly combines its own data with the primary data. Using M-QAM the combined data is adaptively modulated, where M = 4, 16 or 64 depending on the received channel feedback, and relayed to PR and SR. At PR, BER-SC is employed to retrieve the primary data, and at SR interference cancellation is used to retrieve the secondary data. The analytical expressions are derived for the BER and the outage probability. The obtained results demonstrate the higher performance gains for both primary and secondary system by using adaptive mode of transmission at ST and BER-SC at PR.

     

一种基于源端网络编码和交替传输的中继协作方案

针对源节点通过两个中继向目的节点发送数据的无线通信系统,为了减小传统中继协作方案的复用损失,提出了一种将源端网络编码和交替传输有效结合起来的新方案,称为交替源端网络编码(SSNC)。该方案在源端每三个时隙对发送数据进行一次网络编码,并且两个中继在相邻的时隙中交替的发送和接收数据,每个时隙中,一个中继接收源端数据的同时另一个中继转发上一个时隙其接收到的数据给目的端。通过对该方案的中断概率和分集复用折中性能的推导和分析,发现该方案相对于传统的重复编码和分布式空时码方案在获得相同分集阶数的情况下有更高的传输效率,在实际的通信系统中可以兼顾性能和效率。仿真结果证实了我们的结论。