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Increasing the number of simultaneous users is one of the challenging issues in incoherent and asynchronous optical CDMA systems. One solution is to increase the value of cross- correlation, λc. In [3] neglecting the effect of noise, optimum value of λcwas obtained. In this work, with considering noise, the simultaneous effect of λc and transmitted power on the probability of bit error (pbe) is investigated...
The paper presents a three-dimensional localization algorithm for Wireless Sensor Networks (WSN) based on Particle Swarm Optimization (PSO). According to a direct proportion relationship of the measured distance with the measuring errors, an improved three-dimensional localization objective function is defined with weighted the measured distance, and which is optimized by using PSO. In the process...
Power line communication (PLC) channels may have entirely different physical characteristics. In order to establish reliable communication systems operating in power line networks (PLNs), characteristics of power line channel have to be investigated very carefully. In this paper, noise and multipath characteristics of PLC channels are examined. A unique experimental setup is established for noise...
A novel approach based on Dezert-Smarandache Theory (DSmT) is proposed for scheduling in opportunistic beamforming (OBF) systems. By jointly optimizing among system throughput, fairness and time delay of each user, the proposed algorithm can achieve larger system throughput and lower average time delay with approximately the same fairness and acceptable complexity, as compared with the proportional...
In this paper, we investigate the relay selection, sub-carrier pairing, and power allocation problems in a two-hop, multi-relay-assisted cooperative OFDM system with amplify-and-forward (AF) relays. We study the application of selective sub-carrier relaying, where the relays collectively forward only a subset of the available sub-carriers, in a multi-relay-assisted environment. Transmit power allocation...
This paper presents a performance study of a low power non-coherent multi-band IR-UWB system based on energy detection for future wireless high data rates communications. The studies presented in this paper are based on the statistical multipath model of the UWB channel proposed by the IEEE 802.15.3a task group. A new simple model of the received signal is proposed. The main objective of this model...
Field Programmable Gate Arrays (FPGA) offer a unique combination of software abstraction and hardware performance, enabled by programming languages such as VHDL or Verilog. Inherent from this capability is a multitude of different design possibilities for a single implementation problem. A system can be designed which allows for real world evaluation at real time speeds of algorithms ordinarily restricted...
Pervasive devices possess restricted capabilities in terms of processing, information display and network data rates due to their mobile nature. Therefore in order to provide content to users with pervasive devices, the quality of the media presentation often needs to be adjusted according the different characteristics of those devices, and it is not efficient for content and service providers to...
In this paper we present a methodology for detecting web crawlers in real time. We use decision trees to classify requests in real time, as originating from a crawler or human, while their session is ongoing. For this purpose we used machine learning techniques to identify the most important features that differentiate humans from crawlers. The method was tested in real time with the help of an emulator,...
The Resilient Packet Ring (RPR) is a packet network technology designed to provide broadband traffic transport in a metropolitan area according to IEEE 802.17 specifications. Its advantages include flexibility in bandwidth allocation, fairness and traffic shaping criteria for the acceptance of elastic transit traffic, as well as highly reliable transport. Here we focus on possible future amendments...
3GPP is investigating uplink transmit diversity alternatives for HSUPA. This paper addresses uplink transmit diversity from the perspective of open loop where additional feedback information is not available. Furthermore, the focus will be on switched antenna transmit diversity where only one antenna is active at the time even though UE is equipped with multiple transmit antennas. Five different algorithms...
Event Detection is one of the main applications of wireless sensor networks (WSN). However, due to the noisy sensed data of sensors and the wireless channel noise, it's difficult to guarantee the accuracy of detection, especially in multiple event detection. In this paper, we proposed a multiple event detection scheme using compressed sensing (CS). By analogy with CS problem, the efficient recovery...
The proposed technique applies to full duplex mobile-to-mobile pair wise communication via a common centralized node such as a base station or satellite. In the uplink, a multiuser receiver is employed using Turbo Code Division Multiple Access (TCDMA) optimized for two narrowband bursts generated by the two users. In the downlink, a single burst using network coding is addressed to both users. Applying...
3GPP is investigating uplink transmit diversity alternatives for HSUPA. This paper focuses on a transmit diversity scheme using switching between two transmit antennas without additional feedback information. The special focus of this paper is on various non-ideal conditions that occur in real implementations, such as antenna imbalance, correlation and the existence of multiple different SATD algorithms...
The global concern on environmental issues is placing its mark on all sectors of the society, including of course, the wireless telecommunications industry. In this paper, we develop a microeconomic-based ‘green’ radio framework in which a network operator shifts some of its responsibilities towards the intended destination to one of these inactive end-users with the specific intention of reducing...
The everlasting bandwidth limitations in wireless communication networks has directed the researchers' thrust toward analyzing the prospect of overloaded Code Division Multiple Access (CDMA). In this paper, we have proposed a Genetic Algorithm in search of optimum signature matrices for binary-input synchronous CDMA. The main measure of optimality considered in this paper, is the per-user channel...
Recently, a new class of binary codes for overloaded CDMA systems are proposed that not only has the ability of errorless communication but also suitable for detecting active users. These codes are called COWDA. In [1], a Maximum Likelihood (ML) decoder is proposed for this class of codes. Although the proposed scheme for coding/decoding shows impressive performance, the decoder can be significantly...
Large scale deployments of small, wireless, networked, embedded systems demand for cost reduction in development and maintenance. Most often, this translates into the need for reliable methods for energy conservation as it is the case for wireless sensor networks (WSNs). Our work considers energy harvesting system (EHS)-enhanced WSN technology which is the state-of-the-art technology for perpetual...
As Wireless Sensor Networks are evolving to applications where high load demands dominate and performance becomes a crucial factor, congestion remains a serious problem that has to be effectively and efficiently tackled. Congestion in WSNs is mitigated either by reducing the data load or by increasing capacity (employing sleep nodes). In either case due to the energy constraints and low processing...
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