无线传感器网络中ARQ协议能量有效性分析

综合无线传感器网络节点电路能耗和信道传输能耗,建立了ARQ协议传输每比特负载数据的等效能耗数学模型和以链路最低能耗为有效性优化目标,通过MATLAB仿真计算,分析研究了高斯白噪声信道条件下,ARQ协议的能耗与传输帧长和误帧率的关系以及一定范围内电路参数对能耗性能的影响,讨论了最低能耗状态下的最佳帧长和最佳误帧率。     

Common data communications protocols in the FRG

To provide data communications between computer centres with hardware from different suppliers and access to these centres from various terminals, common data communications protocols have been proposed by a working group of the public administration of the Federal Republic of Germany. Protocols corresponding to layers 4, 5 and 6 of the OSI reference model have been passed by the Coordination Committee for Data Processing (KoopA ADV). The paper reports on the use of the protocols in the projects Datenvermittlungssystem Nordrhein-Westfalen and Interactive Videotex, as well as on how to implement open systems communications protocols into the teleprocessing software systems of EDP suppliers.     

Performance of stop-and-wait protocols over high-delay links

The performance of stop-and-wait protocols over links with high propagation delay such as satellite links is discussed. Primary focus is placed on situations where a large block size is employed to compensate for the loss of throughput caused by the large propagation delay. Possible loss in data intergrity due to undetected errors is investigated. The results show that in most environments, acceptably high throughput can be obtained without sacrificing data integrity.     

Performance evaluation of two multiple-access protocols

A real-time, microprocessor-based simulator was designed to study the packet transmission of voice on a broadcast type local area network, based on the CSMA/CD and Hymap multiple-access protocols. The speech quality is evaluated subjectively. A packetization-frozen protocol is used to eliminate the successive collisions due to possible synchronization of packet generation among stations. The variance of the network delay is bounded by discarding packets which have not been transmitted within a certain amount of time. Smooth speech output can be obtained by introducing additional buffer delay at the receiver.     

两跳双中继协同ARQ策略研究*

基于中继择优选择,提出一种新型协同通信系统传输方案：两跳双中继协同ARQ策略。该方案是传输时延和传输效率的优化折中。理论分析和仿真结果说明,在时间相关瑞利衰落信道模型下,两跳双中继协同ARQ策略无论是在源到中继链路质量较好时,还是源到中继链路衰落较为严重时,给系统带来的性能增益都远优于单中继协同ARQ策略和双中继协同系统。     

一种水声通信中的自适应ARQ方案

在水声通信系统中,由于水声信道的半双工、时变和长传播时延等特性,导致用于水声通信中的停等自动重传请求(SW ARQ)方案的吞吐性能显著下降。本文首先利用扩频通信技术,将单个信道分成两个子信道：一个用于前向信道(从发送方到接收方),另一个用于反向信道(从接收方到发送方),充分地利用水声信道。在此基础上,结合选择自动重传请求(SRARQ)方案与返回-n自动重传请求(GBNARQ)方案的混合式自动重传请求(SR GBNARQ)方案的优良性能,提出了一种随水声信道的时变特性改变分组长度的自适应ARQ方案。仿真结果表明：该方案能有效地提高水声通信系统的吞吐性能。     

Replay tolerance of authentication protocols

This research note addresses the problem of message replay in distributed authentication. It discusses the merits and defeats of three most widely accepted approaches to the replay problem. It then presents a different approach which, though difficult to achieve in practice, has been accepted to be most tolerant to replays in distributed systems. This note also describes a practical implementation of this replay-tolerance approach.     

Queueing analysis of buffered slotted multiple access protocols

Much of the literature on the performance evaluation of multiple access protocols has assumed a buffer capacity of one unit. This assumption is not realistic. In practice the buffer capacities used are larger than one unit in order to reduce the probability of packet rejection. This is more crucial for multiple access protocols, which allow moderate to high values of the expected throughput (URN, Random TDMA etc.).In this paper, a model appropriate for the analysis of buffered slotted multiple access schemes is proposed. The method can be applied to several multiple access protocols such as the URN protocol, the ALOHA protocol, Random TDMA etc. The cases of infinite and finite buffer capacity are examined separately but under the same basic assumptions. The analysis is based on the assumption that each user process can be modelled as an M/G/1 queueing system. The proposed method requires a small amount of computation and is characterized by a high speed, a fact that simplifies the buffer's design as well. The solution obtained is extremely accurate and exhibits excellent agreement with simulation results, which corroborate the accuracy of the model. The special case when the buffer capacity is equal to 1 is examined. In that case, the present approach also allows for computation of the packet delay distribution.     

无线传感器网络中分集传输的ARQ协议能耗分析

根据ARQ协议传输每比特数据的等效能耗数学模型,针对无线传感器网络结构特点,分析研究了在高斯白噪声和瑞利衰落噪声信道中MIMO和协作SIMO分集的传输能耗与误帧率的关系特性;通过数学论证和计算机仿真,指出MIMO分集传输较之单路非分集传输消耗更多的能量,而协作SIMO分集传输则使得能耗更低,且最低能耗均与误帧率有关。     

多重抑制自动重传请求协议的实现与仿真

对采用多重抑制ARQ协议的宽带无线接入系统进行研究。实现了一种能为上层提供可控时延、高吞吐量、可控丢包率的链路传输结构。对影响协议算法仿真性能的因素进行了分析讨论。     

Protocol implementation for Universe

The communications protocols used on the Universe network and the implementor's experiences with them are described. By examining ‘lightweight’ and ‘heavyweight’ protocols, the paper examines the problems of protocols for mixed networks.     

Transducer-based analysis of cryptographic protocols

Cryptographic protocols can be divided into (1) protocols where the protocol steps are simple from a computational point of view and can thus be modeled by simple means, for instance, by single rewrite rules—we call these protocols non-looping—and (2) protocols, such as group protocols, where the protocol steps are complex and typically involve an iterative or recursive computation—we call them recursive. While much is known on the decidability of security for non-looping protocols, only little is known for recursive protocols. In this paper, we prove decidability of security (with respect to the standard Dolev–Yao intruder) for a core class of recursive protocols and undecidability for several extensions. The key ingredient of our protocol model is specifically designed tree transducers which work over infinite signatures and have the ability to generate new constants (which allow us to mimic key generation). The decidability result is based on an automata-theoretic construction which involves a new notion of regularity, designed to work well with the infinite signatures we use.     

混合ARQ机制的性能分析

高速无线数据服务的需求的增长,要求下一代无线网络显著提高其吞吐量。文章研究了自动重发请求(ARQ)机制,来满足这些新的要求。针对基于速率兼容纠错码的速率自适应I类混合ARQ机制和增量冗余重传II类混合ARQ机制,提出了一种系统框架,并对其在无线瑞利衰落信道上的性能进行了分析。数值结果表明,增量冗余重传(IRR)II类HARQ机制与速率自适应(RA)I类HARQ机制相比,有较高的吞吐量,而RAI类HARQ机制的延迟较小。     

功率受限和自动重传请求条件下系统吞吐量最大化的研究

本文研究了具有ARQ功能的基于衰落信道和数据链路层缓冲区队列状态的资源最优分配问题，目标是通过自适应调整功率分配和调制方式，在系统平均功率的限制下，使系统的吞吐量达到最大。在这个系统中并不限制ARQ的重发次数，所以最大化系统的吞吐量等效于使链路层的缓冲区溢出的数据包最小。本文把这样一个优化问题构造为马尔可夫决策过程，并提出了用动态规划解决该问题的方法。出于实用性的考虑，本文还提出了一种简单的次优资源分配方法，仿真结果显示这种方法与最优的调度方法性能非常接近。     

基于离散时间排队的ARQ性能分析

基于自动请求重传(ARQ)协议的工作原理,提出基于离散时间带有启动机制的Geom/G/1排队模型。使用嵌入马尔可夫链方法推导出排队系统的稳态队长、等待时间、忙期和忙循环等性能指标的解析表达式,给出ARQ协议中数据帧的平均响应时间、信道利用率、系统吞吐量等性能指标的解析表达式。利用仿真工具Matlab进行计算机仿真,数值例子证明了性能指标解析表达式的正确性。     

基于UDP的高速网络传输协议研究

分析了基于UDP的改进高速网络传输协议的基本原理, 详细阐述了近年来提出的一些典型的基于UDP改进传输协议的主要设计思想。通过建立端到端的高速网络试验床, 评价了RTT及丢包率对RUBDP、Tsunami、 UDT、PA-UDP四种传输协议吞吐率的影响, 实验结果表明丢包率对于四种传输协议的吞吐率影响比较大。     

基于TLA的ARQ协议描述与验证

根据停止等待ARQ协议的算法,用基于TLA的系统描述语言TLA＋对ARQ协议进行建模,用TLC验证了ARQ协议应该满足的两条基本属性。根据ARQ协议的弱点在协议中加入一个攻击者行为Intuder,用TLC验证后,出现死锁造成ARQ拒绝服务攻击。