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The initial quantization parameter for the first I-frame is vital for the rate-control performance of an H.264 scalable video encoder. In this paper, we propose an efficient method for determining the initial quantization parameter. The initial quantization parameter is derived from both the target bit rate and the content complexity of the first I-frame, where the latter is calculated in terms of...
Traditional processes involved in coding and billing for medical services performed by physicians present many inherent challenges in complete charge capture, accurate coding and entry as well as timely submission for reimbursement. Process improvement facilitated by the adoption of mobile electronic billing management systems has demonstrated the potential for considerable financial benefit. This...
Tuple space model is a simple and efficient data-driven coordination model, suitable for different mobile middleware platforms. A significant performance factor of this model is tuple space structure. Existing tuple space models have sequential tuple space structure, which works efficiently with tuple-producing primitives. But, tuple-reading and -consuming primitives that drive overall performance...
We introduce the Membership Degree Min-Max (MD-Min-Max) localization algorithm as a precise and simple lateration algorithm for indoor localization. MD-Min-Max is based on the well known Min-Max algorithm that uses a bounding box to compute the position. We present an analysis of the Min-Max algorithm and show strengths and weaknesses in the spatial distribution of the position error. MD-Min-Max uses...
Wireless sensor and actor networks (WSANs) are composed of static sensor nodes and mobile actor nodes. We assume actors have a random initial location in the two-dimensional sensing area. The objective is to move each actor to a location such that every sensor node is within a bounded number of hops from some actor. Because sensor nodes have limited energy, the new actor locations are chosen as to...
This paper explores the possibilities of how the value system around wireless networks could be organized in the future and what would be the underlying market dynamics given the introduction of Cognitive Radio and Dynamic Spectrum Access technologies. Using a combination of systems thinking tools and platform theory four value system configurations around the future radio platform are introduced...
This paper deals with the characterization of security-related vulnerabilities based on public data reported in the Open Source Vulnerability Database. We focus on the analysis of vulnerability life cycle events corresponding to the vulnerability discovery, the vulnerability disclosure, the patch release, and the exploit availability. We study the distribution of the time between these events considering...
Mobile Digital TV environments demand flexible video compression like Scalable Video Coding (SVC) because of varying bandwidths and devices. Since existing infrastructures highly rely on H.264/AVC video compression, network providers could adapt the current H.264/AVC encoded video to SVC. This adaptation needs to be done efficiently to reduce processing power and operational cost. This paper proposes...
Nodes in large-scale network are always divided into many clusters in order to facilitate network management. Super-node based P2P network is an example. The physical scope and the number of clusters are two conflicting objectives and clustering algorithm should strike a balance between them. In this paper, nodes clustering problem is formally described and pre-optimized k-means algorithm is put forward...
Understanding the mobility of a traveller from mobile sensor data is an important area of work in context aware and ubiquitous computing. Given a multimodal GPS trace, we will identify where in the GPS trace the traveller changed transportation modes. For example, where in the GPS trace the traveller alight a bus and boards a train, or where did the client stop running and start walking. Using data...
With the rapid development of sensor and communication technology, wireless sensor networks (WSNs) have become a new emerging type of real-world applications. With the escalating exploration missions, two-dimensional(2D) WSNs can not meet demand. Therefore, we present an accurate coverage of complex target algorithm in three-dimensional(3D)mobile sensor network in this paper. The algorithm is a mobile...
Adaptivity, which is the most important requirement for any video streaming systems, is usually supported by creating multiple versions of video content at the server. A practical question in this context would be “Which versions should be generated to support adaptivity?” For this purpose, we investigate, through subjective tests, the number of JND (Just Noticeable Difference) levels existing in...
Video calling incurs very high power consumption on mobile platforms usually powered by capacity-constrained batteries. To remedy this problem, we develop a cross-layer energy-aware optimization framework to reduce CPU energy consumption for mobile video calls. We explore the texture similarity between neighboring macro blocks during H.264 coding and control the quality-complexity tradeoff with a...
Target coverage is an important problem in wireless sensor networks (WSNs), whose goal is to cover points of interest to collect data for further processing. With the emergence of mobile sensors, many researchers have exploited the mobility of sensors to improve coverage quality. However, little attention has been paid to minimize the sensor's movement, which consumes the majority of a sensor's limited...
A new method of RAKE reception for Impulse Radio Ultra Wideband (IR-UWB) systems in high mobile environments is described. The conventional multipath diversity reception method for UWB is RAKE receiver, which is usually applied under static environments. In high mobile environments, due to extremely wide bandwidth of UWB signals, frequency components are shifted differently and this makes the pulse-width...
In this paper, we investigate the impact of fixed relay deployment on coverage in a wireless infrastructure. We consider a realistic scenario with OFDM based transmission which takes into account some practical constraints and assumptions (path-loss models, power, etc…). We analyze and compare scenarios with relays which operate in both half-duplex and full-duplex modes. Relays are assumed to perform...
In this work, we study the localization of mobile signal emitters using time of arrival (TOA) measurement and additional urban street information. Two algorithms are proposed to improve the localization performance by integrating street information with the TOA measurement. The first algorithm exhaustively searches of all possible road paths. For each possible path, the source location is estimated...
In this paper, we propose a compact yet discriminative local descriptor which tackles the wireless query transmission latency in mobile visual search. The descriptor captures gradient statistics of canonical patches over a log-polar location grid whose parameters are optimized using training samples. We quantize the resulting descriptor using product quantization. The descriptor achieves about 95%...
We extend one of our recently proposed anchorless mobile network localization algorithms (called PEST) to operate in a partially connected network. To this aim, we propose a geometric missing link reconstruction algorithm for noisy scenarios and repeat the proposed algorithm in a local-to-global fashion to reconstruct a complete distance matrix. This reconstructed matrix is then used in the PEST to...
\label{abstract} Code division multiple access (CDMA) has become a widely adopted technology for wireless communications, particularly in mobile third generation systems (3G) and global positional system (GPS). In CDMA, a particular class of pseudonoise (PN) spreading codes yields a code-set Grammian with only two distinct eigenvalues. For these spreading codes, we propose a computationally efficient...
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