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With the development of the wireless communications technology and the multimedia technology, the wireless internet multimedia transport of real-time becomes an important applications field. We will meet a problem that the distinguish of the status of package loss is not very good which will affect the QoS when we transport multimedia data in wireless internet. Based on this problem the article comes...
We derive closed form expressions for the second-order statistics of the spectral power gain of wide-band microwave indoor channels. We obtain our results within a framework general enough to be compatible with several popular channel models, such as those proposed by the IEEE 802.15.3a task group, as well as the Saleh-Valenzuela channel model. As all these models, our channel description is based...
Along with LTE-Advanced system and standardization investigation progress, the requirement for verifying relevant key technologies become more and more urgent. This article summarizes the progress of Huawei 4G Test-bed “HEART” (Huawei Experimental Advanced Radio Test-bed). CoMP technology is considered as a launch point to build up this test-bed competence. Some initial analysis and results are addressed...
This paper proposes an analytic model to study queuing effect on the handoff performance of Mobile IPv6 (MIPv6), which has not been particularly investigated in previous literature. The presented model regards handoff process as tandem service system, and adopts a simple two-moment approximation throughout the theoretic modeling. Without other specific assumptions, the model presents a generic approach...
Wireless Body Area Network (WBAN) allows the integration of low-power, miniaturized, intelligent, invasive or/and non-invasive wireless sensor nodes that are used to monitor the health status of a patient with real-time updates to a base-station/physician. Since multiple low-power sensor nodes are deployed in/on a human body, Medium Access Control (MAC) protocols are required to share the channel...
In many emerging wireless scenarios, consensus among nodes represents an important task that must be accomplished in a timely and dependable manner. However, the sharing of the radio medium and the typical communication failures of such environments may seriously hinder this operation. In the paper, we perform a practical evaluation of an existing randomized consensus protocol that is resilient to...
Mobile ad hoc networks are self organizing multi-hop wireless networks with no fixed infrastructure. All the users in these networks are mobile. The mobiles communicate either directly or via other nodes of the network by establishing routes. The mobility of nodes causes the existing links to be break frequently. So if we can predict future movement, the resources reservation can be made before be...
The network throughput will decrease dramatically and collision rate increases severely when active nodes increase in WLAN. Breaking through the limitation of the Binary Exponential Backoff algorithms, we provide a new backoff algorithm which utilizes the linear contention window based on the node numbers. To attain better performance, we derive that the contention window is selected as an approximate...
This paper presents results of experiments on characterization of wireless channels inside a tall building in Hung Hom, Hong Kong with the transmitter located atop the DE Block of the Hong Kong Polytechnic University and the channel measurements are made inside a nearby tall residential building. The channel probing signal centered at 1.8 GHz had a bandwidth of 60 MHz. The results were analyzed for...
Intelligent Transportation Systems are based on the acquisition of urban traffic information timely and accurately. This paper puts forward a prototype system of Wireless Traffic Information Service System(WTISS). In WTISS, vehicles equipped with wireless communication module are regarded as moving sensors on traffic network. Road-side station can get traffic status by analyzing data collected by...
Wireless sensor network (WSN) has become a significant technology and Wireless (body) sensors can be deployed on patients to continually monitor their physiological health conditions. These body sensors are very tiny devices and when attached to the human patient body would eliminate the need for continuously monitoring by a nurse/doctor. The wireless body sensors can then be configured to convey...
Wireless mesh networks (WMN) provide network access for mobile users. Therefore, most traffic flows in WMNs are to and from the wired networks. Some mesh nodes, called Gateways connect directly to the wired networks, through which mesh clients can access the resources that reside on the wired networks. However, there are usually only a few of Gateways in a WMN. The packet processing ability of every...
This paper is mainly concerned about the propagation measurements in the presence of the human activity for a wireless channel. By means of an appropriate method, the obstruction phenomenon due to human bodies and their activities which cause attenuation and coherence bandwidth are characterized. For such kind of experiment the test has been taken with a 60 GHz channel and series of 40 minutes long...
In order to establish a trusted and secure wireless mesh network, routing protocols should not only ensure the integrity, confidentiality and authentication, but also take into consideration the fact that the application of routing strategies should not impact the performance of routing protocols to a severe extent. This paper adopts Node's Trust as a routing parameter, and some improvements are made...
We show that for a large class of scheduling algorithms, when the algorithm minimizes the drift of a Lyapunov function, the algorithm is optimal in maximizing the asymptotic decay-rate of the probability that the Lyapunov function value exceeds a large threshold. The result in this paper extends our prior results to the important and practically-useful case when the Lyapunov function is not linear...
This paper considers the problem of routing packets across a multi-hop wireless network while ensuring throughput optimality. One of the main challenges in the design of throughput optimal routing policies is identifying appropriate and universal Lyapunov functions with negative expected drift. The few well-known throughput optimal routing policies in the literature are constructed using simple quadratic...
We consider a wireless downlink shared by a dynamic population of flows. The flows of random size (bits) arrive at the base station at random times, and leave when they have been completely transmitted. The transmission rate supported by the wireless channel of each flow while the flow awaits transmission varies randomly over time and is independent of that of the other flows. The scheduling problem...
With the development of wireless and mobile Internet technology, people in everyday life and business hope for access to the Internet even while they are in movement. IEEE 802.20 technology is mobile and can effectively address high-speed network access. In this paper the PHY layer model for simulating 802.20 in SIMULINK and subsystems in MATLAB S-function files are presented. To evaluate the performance...
Success of emerging satellite-based services depends on the performance of communication protocols like TCP, which degrades in wireless environments. TCP with delayed fast recovery and adaptive flow control (TCP-AFC) has been evaluated through simulation experiments showing significant performance enhancement in wireless environments in general and satellite networks in particular. TCP-AFC enhances...
In this paper we evaluate the influence of radio propagation modeling on VoIP quality in wireless network simulations. How propagation modeling can influence classification of strategies concerned in improving VoIP quality? We analyze reactive AODV and proactive OLSR approaches in a simulated 802.11 mesh backbone and calculate the VoIP quality by means of a reviewed version of ITU-TE-Model. Results...
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