Jingyuan Zhang

Internet Protocol Television (IPTV): The Killer Application for the Next-Generation Internet

Internet protocol television (IPTV) will be the killer application for the next-generation Internet and will provide exciting new revenue opportunities for service providers. However, to deploy IPTV services with a full quality of service (QoS) guarantee, many underlying technologies must be further studied. This article serves as a survey of IPTV services and the underlying technologies. Technical challenges also are identified.

Wireless telemedicine and m-health: technologies, applications and research issues

Telemedicine is not medicine, but it is used to compute, to communicate and to deliver high-quality medical care regardless of location. It reduces cost, time and resources. Furthermore, wireless technologies play significant roles in telemedicine, and they are therefore called wireless telemedicine or mobile-health. This paper provides a comprehensive survey on wireless telemedicine, including the relevant wireless technologies, applications and research issues.

A Linear Time Synchronization Algorithm for Underwater Wireless Sensor Networks

Large propagation delay and node movement are considered to be two significant attributes that differentiate an underwater wireless sensor network (UWSN) from a ground wireless sensor network (WSN). Considering the effects of both propagation delay and movement, we propose a time synchronization algorithm suitable for a UWSN. An underwater node can move out of and into another nodes range frequently. With the proposed algorithm, no time synchronization is necessary if the time stamps of the received data packets are within the tolerance. In this fashion, the network underwater does not need to perform global time synchronizations periodically, which reduces the time used to synchronize clocks among sensor nodes. The simulation results show the time cost for synchronization is linear to the data packets exchanged.

A Cross-Layer Approach for Prioritized Frame Transmissions of MPEG-4 Over the IEEE 802.11 and IEEE 802.11e Wireless Local Area Networks

In this paper, we study MPEG-4 transmissions over the IEEE 802.11 wireless local area networks (WLANs). First, we provide a simulation of MPEG-4 using OPNET over the WLANs in terms of throughput, impacts of multiple MPEG-4 streams, and compression rate on throughput. Our simulation results show that a higher throughput does not always yield a better quality MPEG-4 video. We further observe that if an I frame of MPEG 4 video is lost, the next N-1 frames (all P and B frames) are useless [where N is the total number of frames contained within one group of picture (GoP)]. Furthermore, we observe that the I, P, and B frames are in decreasing order of importance. Therefore, we propose a cross-layer approach to improve MPEG-4 trans missions over WLANs. In the proposed approach: 1) P and B frames will be discarded by the MPEG-4 decoder at the receivers medium access control (MAC) layer if the corresponding I fame is lost; 2) the individual MPEG-4 frames are prioritized at the MAC layer so that I frames have a higher priority than P frames, which have a higher priority than the B frames; 3) each frame (I, B, P) has a time deadline field so that if the deadline cannot be reached, the frame and other related P and B frames in the same GoP are deleted without further transmissions/re-transmissions; and 4) if the delay between an I frame and the next P frame is too long, then it may be better to drop the least important B frames in an attempt to allow the video to catch up. Finally, we study MPEG-4 transmissions over the IEEE 802.11e WLANs, and we adopt a measurement admission control scheme for IEEE 802.lie. Our results show the advantages of the proposed scheme.

A survey of cyber crimes

With the advancement of computer and information technology, cyber crime is now becoming one of the most significant challenges facing law enforcement organizations. Cyber crimes are generally referred as criminal activities that use computers or networks. An understanding of the characteristics and nature of cyber crimes is important in helping research communities find ways to effectively prevent them. Most existing research focuses more on attacks and attack models, including either actual attacks or imaginary/possible attacks over all layers of networks or computers, but there has been less work carried out on a comprehensive survey of cyber crimes. This paper provides a survey of cyber crimes that have actually occurred. First, cyber crimes in the digital world are compared with crimes in the physical world. Then, cyber crimes are categorized according to the roles of computers or networks. Furthermore, we also notice that some cyber crimes are actually traditionally non-cyber crimes that are facilitated by computers or networks. It is surprising that there are so many recurrent cyber crimes. More efforts are needed to protect people from cyber crimes. Copyright

A Cross-Layer Approach for Frame Transmissions of MPEG-4 over the IEEE 802.11e Wireless Local Area Networks

In this paper, we study MPEG-4 transmissions over the IEEE 802.11e wireless local area networks (WLANs). In (Y. Xiao et al., 2007), we provided a simulation of MPEG-4 using OPNET over WLANs, and simulation results show that a higher throughput does not always mean a better quality of MPEG-4 video. Therefore, in this paper, we propose two schemes to enhance MPEG4 transmissions over WLAN: 1) we propose a prioritized frame cross-layer transmission scheme between the medium access control (MAC) layer and the application layer, and 2) we adopt a measurement admission control scheme for IEEE 802.11e. Simulation results show advantages of the proposed schemes.

Variable bit rate VOiP in IEEE 802.11e wireless LANs

WLANs have become a ubiquitous networking technology deployed everywhere. Meanwhile. VoIP is one popular application and a viable alternative to traditional telephony systems due to its cost efficiency. VoIP over WLAN (VoWLAN) has been emerging as an infrastructure to provide low-cost wireless voice services. However, VoWLAN poses significant challenges due to the characteristics of contention-based protocols and wireless networks. In this article we propose two mechanisms to provide quality of service for variable bit rate VoIP in IEEE 802.11e contention-based channel access WLANs: access time-based admission control and access point dynamic access. Simulation results are conducted to study these schemes.

Stochastic event capturing with a single mobile robot in rectangular perimeters

In this paper, we are interested in a single robot detecting intrusions across a rectangular perimeter. We build a stochastic model to analyze the detection quality achieved by a single robot moving along the rectangular perimeter, based on the velocity and the mobility pattern. We define the following intrusion event mode: intrusions occur at a random point along the rectangular perimeter, and stay at that point for a random length of time. In our model, a robot is set to periodically move along a certain route at a variable speed. We derive the general expression for intrusion loss probability. Under the reasonable assumption that, once an intrusion takes place at a random point in the rectangular perimeter, it stays there for a random length of time, which follows an exponential distribution, we then derive the solution to the above problem.

A survey of security visualization for computer network logs

Network security is an important area in computer science. Although great efforts have already been made regarding security problems, networks are still threatened by all kinds of potential attacks, which may lead to huge damage and loss. Log files are main sources for security analysis. However, log files are not user friendly. It is laborious work to obtain useful information from log files. Compared with log files, visualization systems designed for security purposes provide more perceptive and effective sources for security analysis. Most security visualization systems are based on log files. In this paper, we provide a survey on visualization designs for computer network security. In this survey, we looked into different security visual analytics, and we organized them into five categories. Copyright

Hidden information in Microsoft Word

There is no doubt that Microsoft Word is the leading personal word processing software on the Windows platform. The intuitive user interface provides convenient editing as if it was doing so on a real note pad for publication. Even though users apparently see what they put on the electronic document in Word format, not-apparent information is recorded by the software itself based on the users| behaviour or identification. This information is called |Hidden Information|. In this paper, we discuss what is concealed in the Word file and its related issues.