Architectures,protocols and design for highly dynamic optical networks

In order for dynamic optical networks to be commercially viable, it will be essential to have signaling protocols that can establish connections quickly and minimize the use of transponders for wavelength conversion and regeneration. Rough estimates indicate that in dynamic optical networks, transponders will comprise a significant component (e.g., 60%–70%) of the cost of the optical networking infrastructure. A key performance metric in dynamic networks is the connection blocking probability, and therefore a dynamic optical network infrastructure must be designed to meet stringent blocking requirements (e.g., <10^?3 blocking probability). A key element in achieving that blocking objective is the ability to design the network to support shared transponder pools at selected network nodes, and have the capability to efficiently size those transponder pools to meet the required blocking probabilities. This paper addresses how to size shared transponder pools once the nodes that support those pools have been determined. The methodology can efficiently design for very small transponder-related blocking probability (e.g., <10^?4) by using simple, straightforward simulation and analysis techniques. We also describe a 3-Way-Handshake (3WHS) signaling protocol that can quickly set up connections (e.g., in <100 ms) and identify available resources (available wavelengths, transponders) so the connection setup process minimizes the use of transponders.     

ARQ-based cooperative spectrum sharing protocols for cognitive radio networks

Wireless Networks - In this paper, we propose two cooperative spectrum sharing protocols for cognitive radio networks which consist of an automatic repeat request based primary user with a primary...     

Decentralized dynamic spectrum access for cognitive radios: cooperative design of a non-cooperative game

We consider dynamic spectrum access among cognitive radios from an adaptive, game theoretic learning perspective. Spectrum-agile cognitive radios compete for channels temporarily vacated by licensed primary users in order to satisfy their own demands while minimizing interference. For both slowly varying primary user activity and slowly varying statistics of ?fast? primary user activity, we apply an adaptive regret based learning procedure which tracks the set of correlated equilibria of the game, treated as a distributed stochastic approximation. This procedure is shown to perform very well compared with other similar adaptive algorithms. We also estimate channel contention for a simple CSMA channel sharing scheme.     

Distributed space-time-coded protocols for exploiting cooperative diversity in wireless networks

We develop and analyze space-time coded cooperative diversity protocols for combating multipath fading across multiple protocol layers in a wireless network. The protocols exploit spatial diversity available among a collection of distributed terminals that relay messages for one another in such a manner that the destination terminal can average the fading, even though it is unknown a priori which terminals will be involved. In particular, a source initiates transmission to its destination, and many relays potentially receive the transmission. Those terminals that can fully decode the transmission utilize a space-time code to cooperatively relay to the destination. We demonstrate that these protocols achieve full spatial diversity in the number of cooperating terminals, not just the number of decoding relays, and can be used effectively for higher spectral efficiencies than repetition-based schemes. We discuss issues related to space-time code design for these protocols, emphasizing codes that readily allow for appealing distributed versions.     

编码协作通信的码字选择

用户编码协作通信能提供很好的空间分集增益,克服信号在在无线网络中传输遭受的衰落.基于正交频分复用OFDM系统实现编码协作通信.在协作通信过程中,由于伙伴在用户间信道侦听到的信息受到噪声和衰落特性的干扰,所以用于协作通信的码字需经过合理选择、设计以提供最优的性能.基于重新编码和打孔卷积编码两种信道编码方法分析了用于编码协作通信的码字设计方法,并给出了编码协作通信的误帧率FEP仿真性能.     

New multiparty authentication services and key agreement protocols

Many modern computing environments involve dynamic peer groups. Distributed simulation, multiuser games, conferencing applications, and replicated servers are just a few examples. Given the openness of today's networks, communication among peers (group members) must be secure and, at the same time, efficient. This paper studies the problem of authenticated key agreement in dynamic peer groups with the emphasis on efficient and provably secure key authentication, key confirmation, and integrity. It begins by considering two-party authenticated key agreement and extends the results to group Diffie-Hellman (1976) key agreement. In the process, some new security properties (unique to groups) are encountered and discussed     

Procedures and protocols for a CDMA geo-stationary satellite system for personal communication services

In third generation mobile systems the integration of satellite systems with cellular networks will permit to provide wider and more efficient area coverage. Code Division Multiple Access (CDMA) is one of the two candidate access techniques for third generation mobile systems. This paper presents a satellite system for personal communication services, based on the asynchronous CDMA technique, suitable for the integration with the terrestrial cellular network. The paper highlights the network facilities offered by the asynchronous CDMA technique and shows how such facilities can be efficiently exploited in a very simple spot-beam transparent geo-stationary satellite system. The presented issues are fully compatible with the European Mobile System (EMS) payload and the L-band Land Mobile (LLM) payload.     

Distributed collaborative key agreement and authentication protocols for dynamic peer Groups

We consider several distributed collaborative key agreement and authentication protocols for dynamic peer groups. There are several important characteristics which make this problem different from traditional secure group communication. They are: 1) distributed nature in which there is no centralized key server; 2) collaborative nature in which the group key is contributory (i.e., each group member will collaboratively contribute its part to the global group key); and 3) dynamic nature in which existing members may leave the group while new members may join. Instead of performing individual rekeying operations, i.e., recomputing the group key after every join or leave request, we discuss an interval-based approach of rekeying. We consider three interval-based distributed rekeying algorithms, or interval-based algorithms for short, for updating the group key: 1) the Rebuild algorithm; 2) the Batch algorithm; and 3) the Queue-batch algorithm. Performance of these three interval-based algorithms under different settings, such as different join and leave probabilities,is analyzed. We show that the interval-based algorithms significantly outperform the individual rekeying approach and that the Queue-batch algorithm performs the best among the three interval-based algorithms. More importantly, the Queue-batch algorithm can substantially reduce the computation and communication workload in a highly dynamic environment. We further enhance the interval-based algorithms in two aspects: authentication and implementation. Authentication focuses on the security improvement, while implementation realizes the interval-based algorithms in real network settings. Our work provides a fundamental understanding about establishing a group key via a distributed and collaborative approach for a dynamic peer group.     

协作频谱感知中的动态信任评估机制

针对动态性SSDF攻击对协作频谱感知技术的危害性,实时观察分析认知用户的感知行为,提出一种动态信任评估机制.根据认知用户的历史感知变化情况,引入时间衰减因子、加性奖励因子和加性惩罚因子,计算出随时间和协作次数不断变化的动态信任值,选取可信认知用户参与协作感知,提高了数据融合中心的协作判决准确性.仿真结果表明,动态信任机制可以有效抑制恶意用户的信任值增长,降低对“OR”、“AND”和“Majority”3种常用协作频谱感知数据融合准则的攻击成功率.     

Distance criterion-based quantizer design for cooperative spectrum sensing

In terms of sensing node’s energy and reporting channel’s bandwidth constrains problem for cooperative spectrum sensing in cognitive radio networks,an optimal quantizer design method based on distance criterion was proposed.First of all,the Bhattacharyya distance of received quantized data at the fusion center (FC) was calculated as performance criteria,the optimization mathematical model of the quantizer was constructed,and the optimum quantization thresholds were obtained by using particle swarm optimization algorithm.According to received sensing nodes’ quantized data at the FC,a log-likelihood ratio detector was constructed to decide the presence or absence of primary user signal,the upper bound to sensing performance of energy detector that without quantization was derived.Compared with the existing methods in literatures,the performance of proposed 3-bit quantization method approaches to the upper bound performance of energy detector,under the premise of obtaining comparable detection performance,the requirement of communication bandwidth is reduced.     

System design for cooperative control of a microactuator array

A system design is presented with the aim of controlling many microactuators as autonomous distributed micromachines (ADMs). ADMs consist of many microcells which are smart enough to control their own motions and to cooperate with each other. A conveyance system in a plane is selected as an example of ADMs. We have developed a practical design of ADMs composed of many microcells integrated with actuators, sensors, and circuits which can be fabricated by IC-compatible micromachining. The behavior of the system is examined by simulation on a computer model. A fluidic microactuator array for a conveyor has also been fabricated and operated successfully     

A modelling language for cooperative plans in highly dynamic domains

Cooperative behaviour is one of the challenges most pronounced in the RoboCup Middle Size League. Especially the dynamic nature of the domain, which calls for swift adaptation by each robot and the team as a whole, is a distinctive property of the league. The ability to establish highly responsive teamwork while facing unreliable communication and sensory noise is a key to successful soccer teams. Moreover, modelling such responsive, cooperative behaviour is difficult. In this work, we specify a novel model for cooperative behaviour geared towards highly dynamic domains, focussing on the language syntax and semantics. In our approach, agents estimate each other’s decision and correct these estimations once they receive contradictory information. We provide a comprehensive approach for agent teamwork featuring intuitive modelling capabilities for multi-agent activities, abstractions over activities and agents, and a clear operational semantics. Moreover, we briefly present a graphical modeling tool for cooperative strategies, which is based directly on the theory laid out, together with a practical framework for executing said strategies. We show experimentally the responsiveness and coherence of the resulting team play.     

Robust dynamic experimental identification of robots with set membership uncertainty

This paper focuses on robust dynamic identification of robots with set membership uncertainty. The error, taken additive on model output (input motor torque), is only assumed to be bounded. Three bounded-error recursive algorithms are implemented to outer-bound the solution parameter set with ellipsoids or parallelotopes. Experimental results are presented for a two degrees-of-freedom SCARA robot.     

Performance and buffering requirements of Internet protocols overATM ABR and UBR services

ATM networks are quickly being adopted as backbones over various parts of the Internet. This article studies the dynamics and performance of the TCP/IP protocol over the ABR and UBR services of ATM networks. Specifically the buffering requirements in the ATM switches as well as the ATM edge devices. It is shown that with a good switch algorithm, ABR pushes congestion to the edges of the ATM network while UBR leaves it inside the ATM portion. As a result, the switch ABR buffer requirement for zero-packet-loss high-throughput TCP transmission is a sublinear function of the number of TCP connections     

区分服务模型中的一种动态队列管理算法

在对区分服务模型和RED算法进行分析的基础上，提出了一种基于RED算法的动态队列管理算法。实验结果证明，我们提出的算法在不损害高优先级数据流量的情况下，能较好地实时调整各优先级的门限值，减少网络资源的消耗，提高网络资源的利用率。     

一种面向多类型服务的动态负载均衡算法

针对航空物流ILink数据平台交易复杂性高、服务种类多、业务规模大等特点,提出一种面向多类型服务的动态负载均衡算法。通过分析四种基本服务类型以及实时采集四种服务类型的资源消耗,根据用户服务请求类型的不同动态调整各服务器的负载,引入了过载服务器节点缓冲机制缓冲负载过重节点,有效解决了航空物流ILink数据平台可能出现的用户等待时间过长、局部负载过重、甚至个别服务器节点崩溃的问题,达到了集群的负载均衡。仿真实验结果表明,提出的算法在系统吞吐量、系统响应时间、负载率等关键指标上优于经典的比率算法和遗传算法。     

协作式磁感应通信的线圈阵列优化设计

Magnetic induction communication is an emerging underwater wireless communication technology, but the traditional magnetic induction communication system has high path loss and limited transmission distance. In this paper, the point-to-point and cooperative magnetic induction communication models of the coreless circular coil are analyzed theoretically, and the optimal design methods of the coil placement angle in the cooperative communication model is proposed, so as to maximize the communication distance. At the same time, a correction mechanism is proposed to dynamically eliminate the influence of water flow under the actual underwater application environment. The research results show that for the general cooperative mode, when the interval angle is greater than 38.53°, the increase of magnetic flux of transmitting coil T₂ to receiving coil R₁ is less than 20%; the relative growth rate of magnetic flux at the receiver can be increased by changing the placement angle of T₂ and R₁, and can be increased by 20.3% and 12.66% respectively compared with the general cooperative mode at most, and the method of changing the placement angle of T₂ is more effective to improve the whole communication ability; when the minimum sensitivity of the receiver is 0.1 nT, the transmission distance of the cooperative magnetic induction communication with changing the placement angle of T₂ (coil spacing is 100 m) can be increased by 9.96% compared with the point-to-point mode under the same transmitting power.