在如同全IP網路(ALL-IP Network)這類的分封交換網路(packet-switching network)中提供具時效性的服務(time-sensitive services)必須嚴格的控制時間。路由規劃是網路管理中重要的一環，所以這類網路的路由規劃必須考慮網路延遲。然而就我們目前所知，多數的傳統路由演算法並不以傳輸延遲(path delay)為主要考量因素；例外少數有考量延遲時間的演算法也僅限於鍊結延遲(link delay)，而未考慮節點延遲(node delay)。此乃肇因於以往頻寬的成本極為昂貴，因而造成演算法設計者在設計時會儘可能有效利用頻寬，如此免不了會犧牲傳遞速度。在過去幾年間，由於光通訊技術的提升，網路頻寬的成長速度遠遠已超過路由器(router)處理能力的成長。在這樣不對等的成長比例驅使下，節點延遲，亦即路由器處理封包時所耗時間，在傳輸延遲中所佔的比例亦隨之快速增長。也因此我們認為，在為高速封包交換網路設計路由演算法時，必須同時考量鍊結延遲和節點延遲。在本論文中，我們設計了一個訊務流為基礎的路由演算法(flow-based routing algorithm)，KLONE，來驗證我們的論點。在規劃路由時，KLONE會把發生在鍊結和節點上的延遲時間一併列入計算，並以全體延遲時間為主要考量。透過我們反覆的測試實驗，我們發現其較之於常用的OSPF演算法，可以在效能上有30%的勝出。藉此，我們的論點得到初步的證實。 / Providing time sensitive services becomes an essential task for some packet-switching networks such as All-IP networks, which will carry all the traffics supported by both circuit-switching and packet-switching networks. To fulfill this demand, such networks require a delay sensitive routing mechanism to provide time-related QoS for delay sensitive services. However, most of traditional routing algorithms do not take delay time as a major concern. Only a few are designed for time sensitive services. These time sensitive routing algorithms are designed at the time when the link bandwidth is the only scarce resource. As the bandwidth of communication links grows rapidly in recent years due to the advance of optical communication technologies, link bandwidth is no longer the only scarce resource. The processing speed of nodes, for example, routers, becomes another critical source of delay time. In this thesis, we designed a new flow-based routing algorithm, the KLONE algorithm, which takes average delay time as its minimization objective and takes both nodes and links as delay components. Through an intensive evaluation using simulation method, we demonstrate that a routing algorithm that considers both link and node delay might outperform the traditional OSPF algorithm.

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The stability and boundedness theories are developed for impulsive differential equations with time delay. Definitions, notations and fundamental theory are presented for delay differential systems with both fixed and state-dependent impulses. It is usually more difficult to investigate the qualitative properties of systems with state-dependent impulses since different solutions have different moments of impulses. In this thesis, the stability problems of nontrivial solutions of systems with state-dependent impulses are ``transferred" to those of the trivial solution of systems with fixed impulses by constructing the so-called ``reduced system". Therefore, it is enough to investigate the stability problems of systems with fixed impulses. The exponential stability problem is then discussed for the system with fixed impulses. A variety of stability criteria are obtained and`numerical examples are worked out to illustrate the results, which shows that impulses do contribute to the stabilization of some delay differential equations. To unify various stability concepts and to offer a general framework for the investigation of stability theory, the concept of stability in terms of two measures is introduced and then several stability criteria are developed for impulsive delay differential equations by both the single and multiple Lyapunov functions method. Furthermore, boundedness and periodicity results are discussed for impulsive differential systems with time delay. The Lyapunov-Razumikhin technique, the Lyapunov functional method, differential inequalities, the method of variation of parameters, and the partitioned matrix method are the main tools to obtain these results. Finally, the application of the stability theory to neural networks is presented. In applications, the impulses are considered as either means of impulsive control or perturbations.Sufficient conditions for stability and stabilization of neural networks are obtained.

Timeliness in delivering packets for delay-sensitive applications is an important QoS (Quality of Service) measure in many systems, notably those that need to provide real-time performance. In such systems, if delay-sensitive traffic is delivered to the destination beyond the deadline, then the packets will be rendered useless and dropped after received at the destination. Bandwidth that is already scarce and shared between network nodes is wasted in relaying these expired packets. This thesis proposes that a deterministic per-hop delay can be achieved by using a dynamic queue threshold concept to bound delay of each node. A deterministic per-hop delay is a key component in guaranteeing a deterministic end-to-end delay. The research aims to develop a generic approach that can constrain network delay of delay-sensitive traffic in a dynamic network. Two adaptive queue management schemes, namely, DTH (Dynamic THreshold) and ADTH (Adaptive DTH) are proposed to realize the claim. Both DTH and ADTH use the dynamic threshold concept to constrain queuing delay so that bounded average queuing delay can be achieved for the former and bounded maximum nodal delay can be achieved for the latter. DTH is an analytical approach, which uses queuing theory with superposition of N MMBP-2 (Markov Modulated Bernoulli Process) arrival processes to obtain a mapping relationship between average queuing delay and an appropriate queuing threshold, for queue management. While ADTH is an measurement-based algorithmic approach that can respond to the time-varying link quality and network dynamics in wireless ad hoc networks to constrain network delay. It manages a queue based on system performance measurements and feedback of error measured against a target delay requirement. Numerical analysis and Matlab simulation have been carried out for DTH for the purposes of validation and performance analysis. While ADTH has been evaluated in NS-2 simulation and implemented in a multi-hop wireless ad hoc network testbed for performance analysis. Results show that DTH and ADTH can constrain network delay based on the specified delay requirements, with higher packet loss as a trade-off.

This thesis is concerned with changes in the behaviour of solutions to parameter-dependent stochastic delay differential equations.

International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Group delay variations are a potential problem in many communication systems. This paper is slanted towards the effects of group delay variations in analog magnetic recorder/reproducer systems but the results are applicable in general. Because it is difficult to get an arbitrary group delay profile at the output of a recorder/reproducer, a method of generating arbitrary group delays for bit error probability (BEP) testing was developed. A 32-bit pattern in which all five-bit sequences appear with equal probability was selected as the test signal. The amplitude and phase of the discrete Fourier components were calculated for both non-return-to-zero-level (NRZ-L) and biphase-level (BI -L) waveforms. Filtering and group delay variations were computer generated by varying the amplitude and phase of the Fourier components. The modified signals were then programmed into an arbitrary waveform generator. Noise was added and the composite signal was applied to a bit synchronizer and bit error detector. BEPs were measured for various noise levels and group delay profiles.

International Telemetering Conference Proceedings / October 26-29, 1992 / Town and Country Hotel and Convention Center, San Diego, California / An improved ionospheric delay correction model for a transionospheric electromagnetic pulse (EMP) is used for estimating the total-electron-content (TEC) profile of the path and accurate ranging of the EMP source. For a known pair of time of arrival (TOA) measurements at two frequency channels, the ionospheric TEC information is estimated using a simple numerical technique. This TEC information is then used for computing ionospheric group delay and pulse broadening effect correction to determine the free space range. The model prediction is compared with the experimental test results. The study results show that the model predictions are in good agreement with the test results.

Approved for public release; distribution is unlimited / The estimation of time delay and Doppler difference of a signal arriving at two physically separated sensors is investigated in this thesis. Usually, modified cross power spectrum coupled with Doppler compensation is used to detect a common, passive signal received at two separated sensors. Another successful approach uses the cross coherence to achieve this goal. This thesis modifies these two techniques to model the Doppler difference via an autoregressive (AR) technique. Analytical results are derived and experimentally verified via a computer simulation. Performance at high and low signal to noise ratios (SNRs) is examined. / http://archive.org/details/armodelingofcohe00leej / Captain, Korea Air Force

This thesis presents a general framework and method for detection of an object in a video based on apparent motion. The object moves, at some unknown time, differently than the “background” motion, which can be induced from camera motion. The goal of proposed method is to detect and segment the object as soon it moves in an online manner. Since motion estimation can be unreliable between frames, more than two frames are needed to reliably detect the object. Observing more frames before declaring a detection may lead to a more accurate detection and segmentation, since more motion may be observed leading to a stronger motion cue. However, this leads to greater delay. The proposed method is designed to detect the object(s) with minimum delay, i.e., frames after the object moves, constraining the false alarms, defined as declarations of detection before the object moves or incorrect or inaccurate segmentation at the detection time. Experiments on a new extensive dataset for moving object detection show that our method achieves less delay for all false alarm constraints than existing state-of-the-art.