Automatic road crack detection using image/video data plays a crucial role in the maintenance of road service life and the improvement of driving experiences. In this paper, an improved automatic road crack detection system is proposed to reduce false detection under various noisy road surface conditions and to improve sensitivity in detecting light and thin cracks. The proposed system combines a variety of traditional image processing techniques, such as filtering and morphological processing, with scalable and efficient machine learning algorithms. Real road images with various noise conditions are taken to evaluate the performance of the proposed system. Experimental results have shown that the proposed system improved detection sensitivity and reduced false detection compared to some existing system, thus achieving higher detection accuracy.
In this paper, we propose an optimal routing discovery algorithm for ad hoc multimedia networks whose resource keeps
changing, First, we use stochastic models to measure the network resource availability, based on the information about
the location and moving pattern of the nodes, as well as the link conditions between neighboring nodes. Then, for a
certain multimedia packet flow to be transmitted from a source to a destination, we formulate the optimal soft-QoS
provisioning problem as to find the best route that maximize the probability of satisfying its desired QoS requirements in
terms of the maximum delay constraints. Based on the stochastic network resource model, we developed three
approaches to solve the formulated problem: A centralized approach serving as the theoretical reference, a distributed
approach that is more suitable to practical real-time deployment, and a distributed dynamic approach that utilizes the
updated time information to optimize the routing for each individual packet. Examples of numerical results demonstrated
that using the route discovered by our distributed algorithm in a changing network environment, multimedia applications
could achieve better QoS statistically.
In this work, we consider the problem of assigning OVSF (Orthogonal
Variable Spreading Factor) codes to arriving calls for multi-rate
code-division multiple access systems, and propose a sequence of
algorithms to solve this problem from different angles. First, we
introduce two new policies, called FCA (Fixed Code Assignment) with
fixed set partitioning and DCA (Dynamic Code Assignment) with call
admission control under an objective to maximize the average data
throughput of the system. Numerical simulation confirms that optimized
FCA and DCA perform better than DCA with a greedy policy as the traffic load increases and high-rate calls become dominant. Second, a
suboptimal DCA with call admission control is examined. The objective
is to generate an average data throughput of the system close to that of the optimal scheme while demanding much lower design and implementation complexity than the optimal scheme. By means of capacity or class partitioning and partial resource sharing, we can significantly reduce the computational complexity, thus achieving good design and implementation scalability. Numerical evaluation shows the superior performance of the proposed schemes with low complexity.
A scheme that uses the hidden Markov model (HMM) is proposed in this work to detect unauthorized nuisance packets in IP networks, which waste network resources and may result in the denial of service (DoS) attack. The proposed HMM is designed to differentiate the attack traffic from the normal traffic systematically. The design of the basic HMM model is first introduced, and the operations of the detector are then described in detail. Finally, we show that the detector using HMM is not sensitive to various attack types and able to detect the attack at an earlier stage.
Elliptic curve cryptography (ECC) is an excellent candidate for secure embedded multimedia applications due to its small key size and high security protection. The performance profiling of the ECC implementation, such as execution time and data cache stalls, on TriMedia TM1300 and Intel Pentium 4 is conducted in this research. Based on this study, we identify the main bottlenecks of the EEC implementation, and propose some favorable micro-architecture for this application. Moreover, several integer multiplication schemes are presented for the TM1300 processor for performance enhancement. In particular, the FIR-based multiplication is built with the special FIR instruction provided by TM1300. The performance improvement of the proposed schemes is reported and discussed. Overall, we aim at providing a good understanding of the system architecture of secure embedded multimedia applications, hardware and software cryptography implementation with ECC as an example.
The third-generation (3G) wireless network is a convergence of
several types of telecommunication networks to support various
wireless data services. Wireless LAN also supports mobility via
mobile IP. As a result, the convergence and mobility have
potential vulnerability in security. In this paper, a
Denial-of-Service (DoS) attack which can waste wireless resource
by sending a large number of nuisance packets to the spoofed
destination address of IP packets is introduced. To effectively
prevent the attack, fast detection, reliability, and efficiency
with small overhead are suggested as requirements in a detection
system. We propose a detector using Hidden Markov Model (HMM) to
achieve these requirements and reduce the influences of the attack
as fast as possible. The generation of the HMM for the detector
are discussed and the operation of the detector are described.
Weighting factors and second order Markov models are employed to
improve the reliability of the detector. The proposed system is
compared with the existing sequential detection approach in terms
of the false alarm rate and optimum detection time interval to
evaluate the performance of the detectors. Our simulation results
using ns-2 simulator shows that the proposed HMM detector is
reliable and fast to detect the attack due to its dynamic
property.
Quality of Service (QoS) is an important issue in the next
generation wireless networks providing multimedia services. To
address this complex problem, we consider QoS in wireless
multimedia networks at two levels: connection-level QoS, measured
by the connection blocking and dropping probabilities, and
packet-level QoS, measured by bandwidth, delay/jitter and loss
sensitivity. First, different multimedia applications are
classified into three service classes, namely CBR, VBR and UBR,
according to their bandwidth, delay/jitter and reliability
requirements. Then, network can choose appropriate resource
management schemes for different service classes accordingly in
order to meet their QoS requirements. CBR traffic requires a
constant bit rate available during the entire lifetime of the
connection. Both connection-level and packet-level QoS is
guaranteed by connection-oriented service. Thus the joint
optimization problem can be reduced to optimization of
connection-level QoS (handoff dropping probability and new call
blocking probability) for CBR traffic. VBR traffic could generally
tolerate a certain amount of delay or packet loss, thus improve
resource utilization by connection-less service. We formulate the
trade-off of the QoS parameters on both levels based on a VBR
traffic model, and find the near-optimal solutions for the joint
optimization problem. UBR traffic does not have specified
requirement on QoS, thus being served by the best-effort service.
Network uses whatever the resource not being used to improve the
overall system utilizations.
Quality of Service (QoS) is an important issue in the next generation wireless networks providing multimedia services. In this paper, we address the connection-level QoS provisioning in wireless multimedia networks, measured by the connection blocking and dropping probabilities. The connection-level QoS for multimedia services are guaranteed by achieving the minimum connection blocking probability subject to the constraint on the handoff dropping probability. A dynamic call admission control scheme is proposed to provide connection-level QoS in wireless multimedia networks. This scheme adopts a novel strategy called prompt-decreasing/timer-increasing (PDTI) to dynamically adjust the threshold for handoff channel reservation. It can maintain the handoff dropping probability at a target rate predefined in the system specification, while maximizing resource utilization and minimizing the new call blocking rate. The proposed solution is a measurement-based method that is practical for real-world deployment. Simulations are carried out to prove the efficiency of the proposed PDTI scheme.
KEYWORDS: Multimedia, Network architectures, Mathematics, Local area networks, Mathematical modeling, Berkelium, Performance modeling, Wireless communications, 3D modeling, System integration
In this research, we first address the QoS issue in different levels of wireless multimedia networks, and present a generic QoS framework to meet the requirements of different applications and services adaptively. Then, we focus on the connection-level QoS, measured by the connection blocking and dropping probabilities. A service model consisting of three service classes designed for connection-level QoS provisioning is proposed. The underlying network of consideration employs different call admission control and resource reservation schemes to allocate resources adaptively to each service class according to their haracteristics and requirements. The system is analyzed by a multi-dimensional model. Simulations are conducted based on the model analysis to evaluate the system performance.
KEYWORDS: Multimedia, Wireless communications, Networks, Mathematical modeling, Telecommunications, Model-based design, Network architectures, Mobile communications, Standards development, Global system for mobile communications
An adaptive system to support multimedia applications in a wireless
network environment is investigated in this research. The proposed
system is hierarchical in nature with a cluster of mobile end-hosts
connected to a base station, and base stations are connected to a
supervisory node, which is in turn connected to a wired infrastructure.
Based on our previous experience, the system is designed with an
improved service model and a novel call admission scheme that enables
more efficient radio channel usage. The service model takes into
account both user mobility and the nature of multimedia traffic.
Specifically, delay- and/or rate-adaptive services are explored to
increase the network performance and utilization under highly variable
network connectivity and transmission capacity. The new call admission
control scheme is developed under a hybrid call admission control
framework. Together with an adaptive resource reservation scheme, it
can be adapted to the network situation as well as application
requirements. Simulation studies are conducted to show the performance
improvement of the proposed scheme.
The provisioning of quality of service (QoS) in future wireless communication networks is a complex problem due to the presence of changing network connectivity, user mobility, and shared, noisy, highly variable and limited communication links. In this paper, we propose a QoS management framework in wireless multimedia networks. A new comprehensive service model considering both traffic characteristics and user mobility for wireless multimedia networks is proposed. Based on this proposed service model, adaptive resource scheduling, admission control and resource reservation schemes are applied appropriately. Simulation results show that the proposed scheme can achieve higher network utilization and the resulting multimedia traffic can get better quality of service guarantees at different levels.
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