Performance evaluation criterion is one of the most important issues for design of network traffic control mechanisms and algorithms. Due to multiple performance objectives of network traffic control, performance evaluation criteria must include multiple performance metrics executed simultaneously, which is called integrated performance evaluation criteria. In this paper, we analyze various performance metrics of network traffic control, and propose three integrated performance evaluation criteria. One is the improvement on original Power formula; our new Power formula is based on the multi-service-class model. Another is about the fairness of user's QoS (Quality of Service) requirements (queuing delay and loss rate); especially the detailed discussion on Proportional Fairness Principle is given. And the third one is the integration of preceding two, in which the throughput, queuing delay, packet loss rate, and the fairness are considered simultaneously.

In this letter we examine two transport protocols, HighSpeed TCP [1] and Scalable TCP [2] which are both sender-side varieties of TCP. Based on the fluid flow theory, we develop a general nonlinear model and use gain margin and phase margin to evaluate the stability of a closed-loop system which is composed of a transport protocol and an active queue management scheme. Our results indicate that HSTCP and STCP are stabler than standard TCP when link bandwidth, flow number and round-trip time vary.

The letter describes a phase perturbation attack to the Discrete Fourier Transform (DFT) and Phase Shift Keying (PSK) based watermarking scheme which is proposed in [3]. In that paper the watermark information is embedded in the phase of the DFT coefficients. But this kind of PSK based watermarking scheme is very vulnerable to the phase perturbation attack, when some noise is added on the phase of the DFT coefficients, the watermark can't be correctly extracted anymore, while the quality degradation of the attacked watermarked image is visually acceptable.

The guard channel scheme in wireless mobile networks has attracted and is still drawing research interest owing to easy implementation and flexible control. Dynamic guard channel schemes have already been proposed in the literature to adapt to varying traffic load. This paper presents a novel control-theoretic approach to dynamically reserve guard channels called PI-Guard Channel (PI-GC) controller that maintains the handoff blocking probability (HBP) to a predefined value; while it still improves the channel resource utilization.

In this paper, new integrated schemes of scheduling real-time traffic and cell loss control in high speed ATM networks are proposed for multiple priorities based on variable queue length thresholds for scheduling and the Partial Buffer Sharing policy for cell loss control. In our schemes, the queues for buffering arriving cells can be constructed in two ways: one individual queue for each user connection, or one physical queue for all user connections. The proposed schemes are considered to provide guaranteed QoS for each connection and cell sequence integrity for virtual channel/path characteristics. Moreover, these new schemes are quite flexible and can realize different scheduling algorithms. This paper also provides the Stochastic Petri Net models of these integrated schemes and an approximate analysis technique, which significantly reduces the complexity of the model solution and can be applied to real ATM switch models. From the numerical results, we can see that our schemes outperform those well-known schemes such as the head-of-line (HOL) priority control and the queue length threshold (QLT) policy.

MPEG-4 emphasizes on coding efficiency and allows for content-based access and transmission of arbitrary shaped object. It addresses the encoding of video object using shape coding, motion estimation, and texture coding for interactivity, high compression ratio, and scalability. In this letter, an advanced object-adaptive vertex-based shape coding method is proposed for encoding the shape of video objects. This method exploits octant-based representation to represent the relation of adjacent vertices and that relation can be used to improve coding efficiency. Simulation results demonstrate that the proposed method may reduce more bits for closely spaced vertices.

Available Bit Rate (ABR) flow control is an effective measure in ATM network congestion control. In large scale and high-speed network, the simplicity of algorithm is crucial to optimize the switch performance. Although the binary flow control is very simple, the queue length and allowed cell rate (ACR) controlled by the standard EFCI algorithm oscillate with great amplitude, which has negative impact on the performance, so its applicability was doubted, and then the explicit rate feedback mechanism was introduced and explored. In this study, the model of binary flow control is built based on the fluid flow theory, and its correctness is validated by simulation experiments. The linear model describing the source end system how to regulate the cell rate is obtained through local linearization method. Then, we evaluate and analyze the standard EFCI algorithm using the describing function approach, which is well-developed in nonlinear control theory. The conclusion is that queue and ACR oscillations are caused by the inappropriate nonlinear control rule originated from intuition, but not intrinsic attribute of the binary flow control mechanism. The simulation experiments validate our analysis and conclusion. Finally, the new scheme about parameter settings is put forward to remedy the weakness existed in the standard EFCI switches without any change on the hardware architecture. The numerical results demonstrate that the new scheme is effective and fruitful.

Nonmonotonic reasoning is a logical inference system which attempts to approximate human commonsense reasoning and is characterized as defeasible: having reasonably drawn a conclusion from some premises we may be forced to retract that conclusion upon learning new facts. This paper introduces a Petri net model for nonmonotonic reasoning with nonmonotonic rules generated by annotated logic programs and the unless operator. In the Petri net model, a fixpoint of a nonmonotonic theory can be represented as a maximal and consistent support of a firing sequence. We propose a structural method for finding extensions (coherent consequences) for a given set of nonmonotonic logic rules. It is based on the T-invariant technique for testing fireability of a goal transition in the Petri net model of Horn clause logic programs.

With the popularity of BitTorrent-like P2P applications, improving its performance has been an active research area. Super-seeding, a special upload policy for the initial seeder, improves the efficiency in producing multiple seeds and reduces the uploading bytes of content initiators, thus being highly expected as a promising solution for improving downloading performance while decreasing uploading cost. However, the overall impacts of super seeding upon BitTorrent performance remain a question and have not been analyzed so far in literature. In this paper, we present an analytical and experimental study over the performance of super-seeding scheme. We attempt to answer the following questions: whether and how much super-seeding saves uploading cost, whether the overall downloading time is decreased by super-seeding, and in which circumstances super-seeding performs worse. Based on the seeding process, our analytical study gives formulas on the new piece distribution time, average downloading time and minimum distribution time for heterogeneous P2P file distribution system with super-seeding. Robust evidence supporting the use (or not) of super-seeding is given based on our worldwide Internet experiments over wide distribution of 250 PlanetLab nodes. With a well-designed experimental scenario, we study the overall download time and upload cost of super seeding scheme under varying seed bandwidth and peer behavior. Results show that super-seeding can save an upload ratio of 20% and does help speeding up swarms in certain modes. Tentative conclusions about the effectiveness of super-seeding and its optimal working circumstances are given with inside mechanism analyzed and negative factor identified. Our work not only provides reference for the potential adoption of super-seeding in BitTorrent and other P2P applications, but also much insights for the tussle of enhancing of Quality of Experience (QoE) and saving cost for a large-scale BitTorrent-like P2P commercial application.

With the rapid growth of wireless networks and great success of Internet video, wireless video services are expected to be widely deployed in the near future. As different types of wireless networks are converging into all IP networks, i.e., the Internet, it is important to study video delivery over the wireless Internet. This paper proposes a novel end-system based adaptation protocol called Wireless Hybrid Adaptation Layered Multicast (WHALM) protocol for layered video multicast over wireless Internet. In WHALM the sender dynamically collects bandwidth distribution from the receivers and uses an optimal layer rate allocation mechanism to reduce the mismatches between the coarse-grained layer subscription levels and the heterogeneous and dynamic rate requirements from the receivers, thus maximizing the degree of satisfaction of all the receivers in a multicast session. Based on sampling theory and theory of probability, we reduce the required number of bandwidth feedbacks to a reasonable degree and use a scalable feedback mechanism to control the feedback process practically. WHALM is also tuned to perform well in wireless networks by integrating an end-to-end loss differentiation algorithm (LDA) to differentiate error losses from congestion losses at the receiver side. With a series of simulation experiments over NS platform, WHALM has been proved to be able to greatly improve the degree of satisfaction of all the receivers while avoiding congestion collapse on the wireless Internet.

Resilient Packet Ring (RPR) is a new technology currently being standardized in the IEEE 802.17 working group. The existed bandwidth allocation algorithms for RPR networks are not able to provide satisfactory solutions to meet the performance requirements. In this paper we propose one fair bandwidth allocation algorithm, termed PID-RPR, which satisfies the performance goals of RPR networks, such as fairness, high utilization and maximal spatial reuse. The algorithm is operated at each RPR node in a distributive way; the proportional, integral and differential (PID) controller is used to allocate bandwidth on the outgoing link of the node for the flows over the link in a weighted manner. To achieve the global coordination, one control packet containing every node's message runs around the ring in order to update the relevant message for all nodes on the ring. When the packet reaches one node, this node adjusts its own rate according to its own message in the control packet; in the meantime it updates other nodes' control message in the control packet. As the control packet propagates around the ring, each node can eventually adjust its sending rate to reach its fair share according to the fairness criterion, and the buffer occupancy at each node is kept within the target value. Our algorithm is of distributed nature in the sense that upstream ring nodes inject traffic at a rate according to congestion and fairness criteria downstream. The simulation results demonstrate that satisfactory performance of RPR networks can be achieved under the proposed bandwidth allocation scheme.

Active Queue Management (AQM) can maintain smaller queuing delay and higher throughput by purposefully dropping packets at the intermediate nodes. Most of the existing AQM schemes follow the probability dropping mechanism originated from Random Early Detection (RED). In this paper, we develop a novel packet dropping mechanism for AQM through designing a two-category classifier based on the Fisher Linear Discriminate approach. The simulation results show that the new scheme outperforms other well-known AQM schemes, such as RED, AdaptiveRED, AVQ, PI, REM etc., in the integrated performance. Additionally, our mechanism is simple since it requires few CPU cycles, which makes it suitable for the high-speed routers.

The letter proposes a novel subsampling-based digital image watermarking scheme resisting the permutation attack. The subsampling-based watermarking schemes have drawn great attention for their convenience and effectiveness in recent years, but the traditional subsampling-based watermarking schemes are very vulnerable to the permutation attack. In this letter, the watermark information is embedded in the average values of the 1-level DWT coefficients to resist the permutation attack. The concrete embedding process is achieved by the quantization-based method. Experimental results show that the proposed scheme can resist not only the permutation attack but also some common image processing attacks.

As an enhancement mechanism for the end-to-end congestion control, AQM (Active Queue Management) can keep smaller queuing delay and higher throughput by purposefully dropping the packets at the intermediate nodes. Comparing with RED algorithm, although the PI (Proportional-Integral) controller for AQM designed by C. Hollot improves the stability, it seems unscientific to tune the controller parameters through trial-error, moreover the transient performance of the PI controller is not perfect, such as the regulating time is too long. In order to overcome this drawback, in this paper, the PID (Proportional-Integral-Differential) controller is proposed to speed up the responsiveness of AQM system. The controller parameters are tuned based on the determined gain and phase margins. The simulation results show that the integrated performance of the PID controller is obviously superior to that of the PI controller.

Adaptive Virtual Queue (AVQ) introduces a novel implementation algorithm for Active Queue Management (AQM). The stability criterion for AVQ was deduced in literature [1], but it lacks practicability due to the difficulty of solving the transcendental equation. In this letter, the AVQ stability is further investigated based on the characteristic roots of delay-differential equation. Another stability criterion explicitly associated with parameters of network configuration is deduced and the upper bound of delay time for stable AVQ algorithm is determined. Finally, the conclusion is validated through simulation experiments.