The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Feedback reputation systems are gaining popularity as dealing with unfair ratings in reputation systems has been recognized as an important but difficult task. This problem is challenging when the number of true user ratings is relatively small and unfair ratings plays majority in rated values. In this paper, we propose a new method to find malicious users in online reputation systems using Mean Bisector...
This paper discusses the possible application of a particular family of binary sequences, the De Bruijn ones, as spreading codes in a vehicular scenario, by evaluating their performance according to different analytical tools. In an unfriendly environment, such as the vehicular one, that poses several constraints on transmission techniques for their reliability, it might be useful to have a wide set...
The problem of providing a collaborative early warning system for multiple moving vehicles against a small size fast moving object like a motorbike. This approach consists of three stages: The first stage consists of detecting the incoming object using a highly directive antenna at 5.0 GHz in license free industrial, scientific and medical (ISM) band. The second stage consists of broadcasting the...
In wireless communication systems, physical layer elements are open to possible attacks by eavesdroppers and undesired entities. The basic premise of spread spectrum techniques is to mask user information by spreading the original message over the whole bandwidth. To this aim, pseudorandom codes may be used. However, traditional families of codes are publicly known and no longer trustworthy to provide...
The need for a more efficient and reliable use of available radio resources has led to the developement of Spread Spectrum based communication networks, like WCDMA. Even though the Spread Spectrum signals are inherently robust, and provide significant level of security, it has been shown that the use of interference suppression techniques can result in a substantial performance improvement. This paper...
The Discrete Cosine Transform (DCT) is largely used for image and video compression in standards like JPEG and MPEG2. Its simplicity coupled with the fact that it can be computed faster than the Discrete Wavelet Transform (DWT) makes it an attractive option for image and video compression. Consequently a lot of research is in progress to determine novel architectures and algorithms for faster DCT...
In recent years the technological development has encouraged several applications based on node to node communications without any fixed infrastructure. This paper presents preliminary evaluation of popular estimating techniques to populate active nodes in the neighborhood using De Bruijn sequences. They have much higher cardinality compared to any other family of binary sequences at a parity of length...
In bandpass sampling (BPS) a band limited signal is sampled at ratio below the Nyquist rate and is still able to be reconstructed without significant damage. Optimizing sampling ratio in a multiple input multiple output (MIMO) system is complicated and filled with several dependent variables. In the wake of present development the Space Time Coding (STC) is prevalent among the MIMO systems, which...
Unmanned Aerial Vehicles (UAVs) coordinated path planning and intercommunication for visual exploration of a geographical region has recently become crucial. Multiple UAVs cover larger area than a single UAV and eliminate blind spots. To improve the surveillance, survivability and quality of the communication, we propose two algorithms for the route planning of UAV cluster operated in obstacle rich...
Today, both the military and commercial sectors are placing an increased emphasis on global communications. This has prompted the development of several Low Earth Orbit satellite systems that promise a worldwide connectivity and real-time voice, data and video communications. Constellations that avoid repeated uplink and downlink work by exploiting Inter Satellite Links have proved to be very economical...
In recent years the technological development has encouraged several applications based on distributed communications network without any fixed infrastructure. The problem of providing a collaborative early warning system for multiple mobile nodes against a fast moving object. The solution is provided subject to system level constraints: motion of nodes, antenna sensitivity and Doppler effect at 2...
In this area of high performance systems and sophistication, the antenna size is shrinking drastically. This paper reviews the fundamental limitations in electrically instigated small antennas and their implications on multiple input multiple output (MIMO) systems. An optimum performance of the antenna can be obtained by considering three main factors. (1) maximum gain for given frequency (2) minimum...
Self organizing mobile Ad-Hoc networks have gained much attention in the last decade particularly due to their ease of deployment in war zones and natural disasters. Because of the fact that the Ad-Hoc network is a virtual network created by the participating nodes, this approach can be applied to remote areas with no fixed networking capability, and is ideal for coordination in remote locations....
Emergency Medical Services (EMS) accident notification time is often delayed in areas with sparse cellular coverage and non-periodic communication access points. It is possible to mitigate such coverage gaps using cooperative communication which, by its distributed nature, does not rely on fixed base stations in remote areas. In the event of a collision EMS notification can be relayed through surrounding...
This paper proposes an optimal relay selection criteria based on the location of the relay (0 ≤ λ ≤ 1) relative to source and destination in the cooperative coded system. The proposed optimization algorithm employs distributed turbo product coding technique with hard and soft decoding. It is shown that the link quality depends on the location of the relay which in turn affects overall system Bit Error...
Satellite communication systems operate in the presence of path loss and atmospherically induced fading, which results in waveform distortion, altering phase and bit time period. After penetrating through several atmospheric layers, the signal experiences Doppler shift which results in frequency change and phase reversal, thus to sync the receiver to the incoming signal we make use of the Phase Locked...
When it comes to space communication networks, there are many different kinds of space vehicles that need to communicate with each other, in space as well as with ground terminals and air borne platform. Example: Geosynchronous Earth orbit (GEO), Low Earth Orbit (LEO) satellites and UAVs. There is an ever growing demand for higher data rates and minimal redundancy, with satellites and various space...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.