Receivers

This paper presents the wireless network architecture to provide multilingual speech translation and local positioning system during Hajj operations. The pilgrims require low power, low cost and compact ear connected devices to receive the information in their native language. The proposed RF transceiver front-end design consists of multiple numbers of oscillators tuned within spectrum of 5-to-8.5GHz. In transmitting mode, oscillators

A critical component of the millimeter-wave superheterodyne receiver is the local oscillator (LO) which is used to pump the low-noise mixer. Frequency multipliers have been used for many years to produce LO power. Current technology uses the whisker-contacted Schottky varactor diode which is inherently very fragile, expensive to fabricate, difficult to optimize, and requires as many as three mechanical tuners. This report describes the design, fabrication, and evaluation of four planar frequency multipliers. The 'direct-replacement' design demonstrates how a discrete planar varactor can replace a whisker-contacted varactor in a waveguide-type 75/225 GHz tripler and yield comparable performance. The fully monolithic (MMIC) balanced-varactor 80/160 GHz doubler and balanced-varactor 80/240 GHz tripler designs illustrate that MMIC technology is practical throughout the millimeter-wave band. Finally, a high-power 31/94 GHz tripler design is presented. These MMIC multipliers are t...

: Emitter location finding enables important functionality for both military and civilian applications. GPS is the most recognized and widely used positioning system, but it is a receiver location system that functions in a markedly different manner from emitter location. Many geo-location techniques predate and have been proposed as an alternative to GPS. Some of the more commonly used and exploited of these techniques are angle of arrival, time of arrival, frequency difference of arrival, and time difference of arrival (TDOA). This thesis is primarily focused on TDOA. These techniques are important for military applications. Location finding is a part of electronic warfare support, which is one of the main braches of electronic warfare. Because these techniques are platform independent, they can be used with any system or platform, such as UAVs, manned aircraft, ground locations, etc. In Turkey it is vitally important for the army conducting search and destroy operations against t...

ABSTRACT In the recent year’s vehicular ad hoc networks VANETs has received significant attention in the intelligent transport system research. Vehicle-to-vehicle V2V communication can be considered an important approach to help the drivers to satisfy requirements like less congestion, accident warning, road exploration, etc. The propagation issues such as path loss, multipath fading, shadowing loss, depolarization loss, and polarization mismatch loss significantly affect the reliability of V2V communication. The goal of this paper is to evaluate the performance of the PHY layer in V2V communication using a modified Spatial Channel Model SCM-MIMO. The simulation results observed that the transmitted signal is affected by a multipath fading channel.

Abstract The scale limitations of conventional silicon based electromagnetic systems and the potential benefits of nanoscale devices, have spurred significant interest in studying nano-scale computation, electronics and communication. Nanonetworks, the interconnection of nanomachines, provide the means for cooperation and information sharing among tiny nanomachines, allowing them to fulfill more complex tasks. The ability to create communication networks of biological nanoscale devices has the potential to open up ...

In this paper, we analyze the performance of a secondary link in a cognitive radio (CR) system operating under statistical quality of service (QoS) delay constraints. In particular, we quantify analytically the performance improvement for the secondary user (SU) when applying a feedback based sensing scheme under the "SINR Interference" model. We leverage the concept of effective capacity (EC) introduced earlier in the literature to quantify the wireless link performance under delay constraints, in an attempt to opportunistically support real-time applications. Towards this objective, we study a two-link network, a single secondary link and a primary network abstracted to a single primary link, with and without primary feedback exploitation. We analytically prove that exploiting primary feedback at the secondary transmitter improves the EC of the secondary user and decreases the secondary user average transmitted power. Finally, we present numerical results that support ou...

Online social networks have witnessed massive increase from the point of view of users during last decade. However, it is also becoming center of attraction for spammers. It is a complex problem to trace spammers on a large scale. Since spammers communicate ...

Satellite Low Noise Block-down convertors (LNBs) have been evaluated for use in amplitude and intensity interferometry. LNBs have been found to have a high performance to cost ratio which is beneficial for any sensor system. They are investigated here for a diversity of applications from the derisking of subsystems for next generation aperture synthesis imagers having hundreds of channels [1] to a platform for the investigation of phase recovery in intensity interferometry and experimentation in entangled photons. Measured noise temperatures of LNBs were found to lie between 170 K and 300 K which is higher than typical manufacturers' specifications. A twin channel interferometer system was developed using satellite receiver feeds and LNBs at the front-end, other amplifiers, mixers, filters and local oscillators at intermediate stages, and 8-bit USB ADCs sampling synchronously at 100 MHz and a PC for data processing. LabVIEW was used to digitally demodulate the sampled data and p...

ABSTRACT Many studies analyze the encrypted transmission using the synchronization of chaotic signals. This requires the exchange of an analog synchronization signal, which almost always is a state of the chaotic generator. However, very few different chaotic structures are used for this purpose, still. The uniqueness of their dynamics allows the identification of these structures by simple autocorrelation. In order to thwart all cryptanalytic attacks based on the identification of this dynamics, we propose a numerical method without memory in order to reversibly destroy the shape of the transmitted signal. After analog-to-digital conversion of the synchronization signal, we apply permutations of the weights of its bits to each binary word. These permutations significantly change the shape of the transmitted signal, increasing its versatility and spreading its spectrum. If the message is simply added to the synchronization signal, being the easiest to decrypt, it undergoes the same transformation. It is therefore extremely difficult to detect the message in the transmitted signal by using a temporal analysis, as well as a frequency one. The present work illustrates the proposed method for the chaotic Colpitts oscillator. Nevertheless, the algorithm does not depend on the chosen chaotic generator. Finally, by only increasing the size of the permutation matrix, the complexity of the change in the waveform is increased in a factorial way.

Processing massive data flow in intrusion detection systems (IDS) become a serious challenge. It is considered as a major deficiency while handling heterogeneous and non-stationary data stream to uncover anomaly in the online operational mode. This paper proposes a novel online method that constructs connections from the massive data flow for evaluating IDS models. The proposed method overcomes this challenge by using a queuing concept of dynamic window size. It captures network traffic and hosts events constantly and handles them synchronously within time slot windows inside the queue in order to construct connection vectors based on certain features. We have evaluated the method in offline mode using DARPA dump data flow and in online mode using a simulated network at the university campus. In addition, we have evaluated our IDS model using the constructed connections to proof the feasibility and plausibility of the proposed method in IDS area. The performance evaluation confirms that, the proposed method is able to operate in offline as well online modes efficiently. Moreover, constructed connections are very adequate for training and evaluating IDS models.

A Doppler estimation system using a maximum likelihood criterion is presented in the context of underwater acoustic communications between moving transmitter/receiver. We simulate the method for the estimation of the Doppler effect induced by an underwater acoustic channel (UWA) using Zero Padded-Orthogonal Frequency Division Multiplexing (ZP-OFDM). Among the wide range of physical processes that impact OFDM communications through the underwater environment, Doppler effect is an important cause of loss of orthogonality and must be compensated before discrete Fourier transform based demodulation can be performed. The proposed approach is based on the perfect knowledge of the emitted signal during one block and rely on the assumptions of a small variation of the Doppler effect induced by the canal between two ZP-OFDM blocks and, above all, during one block.

: Analysis of data from the NPAL04 experiments has shown that there are three principal types of arrival in long-range ocean acoustic propagation: 1) arrivals predicted by PE model calculations (RR, RSR, RBR, SRBR ray paths and the mode-like finale region), 2) deep shadow zone arrivals arising from the spread of energy below PE predicted turning points (caustics) and attributed to internal waves (Van Uffelen et al., 2009), and 3) deep seafloor arrivals which can be the largest arrivals observed on seafloor receivers and do not correspond to turning points or any other features in the PE predicted path (Stephen et al., 2009; Stephen et al., 2008). Coda and "bottom junk" have been ubiquitously observed on acoustic receptions on seafloor receivers and are traditionally attributed to incoherent reverberation and scattering. The OBS data on NPAL04 has shown that there are robust, coherent, discrete arrivals that contribute to the coda and bottom junk. The long-term goal of this...

Wireless adhoc networks are infrastructureless networks that consist of a number of autonomous, wireless devices. The data exchange through the nodes is coordinated by routing algorithms like DSDV so that any node may forward data from a sender to a receiver. Because the network resources such as bandwidth and energy are scarce, power control algorithms have been developed in order to reduce the interference and the contention among the nodes, as well as to save energy. However, a power control algorithm should be thoroughly examined in order to verify if and when these goals are achieved. We ran simulations comparing the performance of DSDV and DSDV-based CLUSTERPOW control algorithm and found that CLUSTERPOW presents scalability issues and enhances network performance only under specific conditions.

We consider block transmission techniques combined with rate-1 space time block coding (STBC) for two or four transmit antennas. Since our STBC with 4 transmit antennas is not orthogonal, our receiver includes the cancellation of the residual interference, allowing performances close to the ones of an orthogonal code. We propose an iterative STBC receiver with joint detection and channel estimation. Our performance results show that the proposed single channel - frequency domain equalization (SC-FDE) STBC receiver allows excellent performance with the use of channel data obtained from channel estimation.