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Dirty paper coding (DPC) is known to achieve the capacity region of a Gaussian Multiple Input Multiple Output-Broadcast channel (MIMO-BC). Practical DPC schemes using finite length codes are still being actively studied. In this paper, we design a zero-forcing DPC (ZF-DPC) scheme using trellis shaping and Low Density Parity Check (LDPC) codes for a MIMO-BC with two transmit antennas and two users (receivers), each with one antenna. This is an extension of an earlier design for the single antenna Gaussian broadcast channel. One of the important aspects of the DPC code design is the introduction of a one block delay that enables the channel encoder (and decoder) and the shaping encoder (and decoder) to operate independently. In the ZF-DPC method, the MIMO precoder ensures that one user has no interference. The other user uses DPC to combat interference. The performance of this method is compared using simulations with the capacity limit and simpler precoder based methods like Minimum Mean Square Error-Vector Perturbation (MMSE-VP) and zero-forcing beamforming (ZF-BF). [ABSTRACT FROM PUBLISHER]

This section presents abstracts of studies on careers. Issues tackled include voluntary and involuntary job redundancy, extreme subjective career success, familial entrepreneurship and copreneurship, united careers, moderating effects of allocentrism and idiocentrism on work-family conflict and withdrawal intention, and the speed imperative in the attainment of community status, among others.

The acquisition of channel state information is a pressing issue in the implementation of network multi-input multi-output (MIMO) systems, where the base-stations coordinate across multiple cells for intercell interference mitigation. This paper proposes a two-stage channel quantization and feedback mechanism named agile scheduling-beamforming (ASB) for the downlink network MIMO system employing both spatial multiplexing and orthogonal frequency-division multiple-access (OFDMA). The proposed scheme polls the users for their best set of spatial-frequency resource blocks, then schedules the users according to the fairness criterion, and finally asks the selected users to feedback finer channel quantization. This paper utilizes insights derived from the scaling law of the optimal quantization bit allocation for this scheme, and evaluates its performance on realistic channel models. Rate map simulations based on ray-tracing-based wireless propagation models of realistic urban small-cell deployment show that the proposed scheme can already approach the performance of network MIMO with full channel state information with only modest amount of channel feedback. [ABSTRACT FROM PUBLISHER]

Cognitive radio is a popular research topic that has attracted considerable interest in the recent past. This paper aims at carrying out a literature review on the subject thus giving an overview of the concept with special emphasis on more popular research areas. The prime consideration for the selection of the papers has been their citations in the subsequent research work. The review has been followed with a summary of identified potential research areas that can assist future researchers. [ABSTRACT FROM PUBLISHER]

Modern technology and developments in signal acquisition and analysis techniques have provided new tools for transformer and bushing diagnostics. Of particular interest are dielectric response measurements where insulation properties of oil-paper systems can be investigated. Dielectric Frequency Response, DFR (also known as Frequency Domain Spectroscopy, FDS), was introduced more than 20 years and has been thoroughly evaluated in a number of research projects and field tests with good results. DFR data in combination with mathematical modeling of the oil-paper insulation is proven as an excellent tool for moisture and oil conductivity assessment of power transformers. Dielectric response measurements are usually performed at a much lower voltage level than traditional power frequency tan-delta measurements. Due to this, the signal-to-noise ratio may sometimes be extremely low, especially at low frequencies and when measuring low capacitance objects e.g. bushings and instrument transformers. The interference suppression capability of the test set thus becomes an important parameter when considering different methods and instruments. In this paper investigation of the electromagnetic interference in terms of AC hum currents, induced DC currents and low frequency interference in AC as well as HVDC substations are presented. Solutions to handle these different types and levels of interference are investigated and examples of measurements under those conditions are presented. The paper also covers DFR response analysis using the XY-model. Numerical analysis using COMSOL has been performed and compared with the simplified analytical XY-model to investigate how non-ideal conditions influence geometry parameters and results. [ABSTRACT FROM PUBLISHER]

The problem of optimally adjusting the power spectral density level, referred as power spectrum optimization, is a well-known and difficult nonconvex optimization problem. This paper investigates a class of local optimization methods based on a technique called iterative function evaluation. This idea, first proposed in our previous work, is based on the manipulation of the first order condition of the optimization problem into an algorithm. This paper shows that these manipulations are not unique, and proposes a new iterative-function-evaluation-based method for power spectrum optimization. In addition, this paper proposes methods based on the average channel gains for an orthogonal frequency division multiple access network. Finally, the performance of the proposed methods is evaluated in a wireless backhaul application. [ABSTRACT FROM PUBLISHER]

Instead of using hexagonal model to form cellular coverage, the clustering method is used in this paper. This method is rarely considered but suitable for cellular network planning. We propose an idea by using clustering method considering geographical elements to obtain better solution called Geo-Clustering Algorithm. Usually the simulated terrain is modeled as regular area such as urban, metropolitan, with general assumption that all areas have the same user's dissemination. In this paper, we provide a simple but representative as logical thinking of geographical model in a given area. This geographical model represents the possible areas that users can be located. Comparison of cellular planning with traditional K-means cluster and Geo-Clustering model is presented in simulation results. In addition, coverage probability and required SINR are taken as main performance metrics. [ABSTRACT FROM PUBLISHER]

In this paper, a novel fire recognition algorithm based on muti-features fusion(MFF) with self-adaptive, self-learning and fault tolerance is proposed after analyzing the characteristics of the burning fire, and taking the flame's twinkling frequency and its dynamic contour into account. First, picking up the dynamic video of fire, extracting the eigenvector of suspicious fire area, and using disperse FFT to the eigenvector to build a quantified distinguishing rule; then, checking the nearby frame which changes most, qualitative and quantitative analyzing its changes to form a quantified edge feature. After quantifying all the characteristic parameters, a probability update function is used to fusion such muti-features to carry out the probability recognition of fire. Tests show that MFF algorithm of this paper has the abilities of self-adaptive, self-learning and anti-interference to white spots from moving or static objects, even under a very complex circumstance with spotlight, automobile light and illumination changing. [ABSTRACT FROM PUBLISHER]

This paper presents the joint interference cancellation and equalization for space-time block coded (STBC) orthogonal frequency division multiplexing (STBC-OFDM) transmission over underlay cognitive radio network. In this work, pre- and post-FFT adaptive antenna array is employed at secondary user receiver to find optimum antenna weights that place nulls at the primary transmitters. The paper discusses the performance of using both systems in STBC-OFDM receiver and presents the optimum weight determination for beamformers based on the minimum mean square error (MMSE) criteria. Simulation results demonstrate that post-FFT is optimum in terms of maximizing signal-to-noise-and-interference power ratio (SINR) and provides a lower bit error rate (BER) under existence of several primary users. [ABSTRACT FROM PUBLISHER]

In this paper we assess how coordination among base stations can be exploited to improve downlink capacity in fourth generation (4G) cellular networks. We focus on heterogeneous networks where low-power pico cells are deployed within the coverage area of an existing macro network with the aim of offloading traffic from the (potentially congested) macro cells to low-power cells. Firstly, we describe an enhanced inter-cell interference coordination scheme which is shown to achieve a significant capacity gain in such deployments by leveraging a loose coordination among neighbor base stations. Secondly, we explore how a tighter coordination among base stations can be exploited to further improve the network capacity. Even though the schemes described in this paper apply to long term evolution (LTE) wireless networks, we point out that most of the findings and conclusions we draw apply to any cellular network. [ABSTRACT FROM PUBLISHER]

Interference problem makes a significant impact on the performance of a mobile ad hoc network. The paper studies TDMA-based timeslot allocation to schedule links efficiently, and presents an efficient distributed timeslot assignment algorithm, which is used together with the route discovery mechanism of AODV to setup bandwidth-aware QoS routes B-AODV. Simulation results show that compared with the shortest path routing, our proposed QoS routing algorithm increases packet delivery ratio and improve end-to-end average packet delay. [ABSTRACT FROM PUBLISHER]

In the satellite communication system, Doppler spread is caused by the movement of the mobile receiver such as high speed aircraft, vessel, and so on. To overcome Doppler spread in the satellite communications, we propose the novel FDE (Frequency Domain Equalizer) and turbo code in order to compensate Doppler spread efficiently in this paper. And we adapt single carrier system in order to save power in satellite system. Also, in order to guarantee channel capacity, we have to reduce interference such as Doppler spread by using FDE. To overcome such shortcomings and secure high SINR (Signal to Interference and Noise Ratio), we propose FDE and turbo code. If we reduce interference and secure high SINR by using FDE and turbo code, the Shannon's channel capacity is guaranteed. Therefore, the purpose of this paper is to improve system performance with low BER (Bit Error Rate) and high SINR. In this paper, we adapt comb type pilot in order to estimate and compensate Doppler spread. As the simulation results, the proposed algorithm has high performance which is satisfied with 2.5dB at 10−4 where the number of iterations is 4. [ABSTRACT FROM PUBLISHER]

In this paper, we study the problem of distributed spectrum allocation under a vertical spectrum sharing scenario in a cognitive radio network. The secondary users share the spectrum licensed to the primary user by observing the activity statistics of the primary users, and regulate their transmission strategy in order to abide by the spectrum sharing etiquette. When the primary user is inactive in a subset of the available frequency bands, the secondary users share the spectrum using the recently proposed GADIA algorithm [1]. In this paper, we present analytical and numerical results on the performance of the GADIA algorithm in conjunction with the above-mentioned vertical spectrum sharing scenario. These results reveal near-optimal performance guarantees for the overall vertical spectrum sharing scenario. [ABSTRACT FROM PUBLISHER]

A key challenge is how to improve the wireless capacity of cellular networks for both outdoor and indoor users. Whilst deploying low power femtocells can significantly improve the indoor capacity, its interference can erode the outdoor capacity. In order to maximise the performance of the co-frequency two-tier network, the research challenge is how to minimise their mutual interference through coordination and other methods. This paper proposes a controllable interface that acts as a dynamic barrier between the outdoor and indoor networks. The interfaces comprises of a frequency-selective-surface (FSS) which is a band-stop filter. The paper also demonstrates that without any FSS interfaces, the mutual interference between indoor and outdoor networks erodes the capacity of each other significantly. The benefit of the FSS interface is that it is able to mitigate the mutual interference to the extent that their capacities are maximised. The results show that by deploying FSS interfaces, an improvement of up to 1.3 fold in mean throughput, 4.6 fold in throughput fairness for outdoor users and 1.2 fold in mean throughput, 2 fold in throughput fairness for indoor users can be achieved. The analysis is conducted using both a theoretical stochastic geometry analysis and multi-cell simulation results. [ABSTRACT FROM PUBLISHER]

This paper presents a performance comparison of local interpolation techniques based on Delaunay triangulation in generating interference maps for cognitive radio networks. The performances of nearest and natural neighbor and linear, quadratic and cubic interpolations have been evaluated in terms of primary emitter localization accuracy and RF field strength estimation efficiency for given Delaunay triangulations. The simulation results show that the linear interpolation technique provides the same level of accuracy with the other higher complexity interpolation techniques evaluated in this paper. The Delaunay triangulation is a frequently used technique for many networking tasks in wireless networks and further utilization of the actual triangulation in interpolation may provide a computationally attractive solution for the interference map generation problem in cognitive radio networks. [ABSTRACT FROM PUBLISHER]

This paper proposes a user pairing control method for multi-cell shared multi-user MIMO relay (MC-MU-MIMO relay) to improve the throughput of cellular networks. MC-MU-MIMO relay system sets a multi-antenna relay station (RS) at the cell boundary and the RS is shared with adjacent cells. The proposed relay system can improve the throughput of cell boundary due to increasing signal to noise ratio and reducing adjacent cell interference. Since MC-MU-MIMO relay system transmits the data simultaneously toward multiple users located in adjacent cells, a user pairing control for simultaneous data transmission is important to improve the efficiency of channel. This paper proposes a user pairing control method with distributed ordering users for communication by considering the effectiveness of the relay. From computer simulations, we can confirm that the proposed method can improve the throughput performance without increasing the number of RSs. [ABSTRACT FROM PUBLISHER]

Computer electromagnetic radiation Trojan arouses concern gradually due to its particularity in route of transmission. Currently, technologies for preventing electromagnetic radiation are mainly divided into two types of software and hardware. Hardware has a high cost and limited range of application, while most of current software protection mechanism is in theoretical research stage with quite complex principles. This paper makes exploration on prevention methods for displayer electromagnetic Trojan. Trojans need to be realized through changes of pixel on the displayer when working, their function called by their bottom of system would also present characteristics of corresponding sequence. Based on this characteristic, this paper proposes Trojan detection methods based on API sequence cycle mining, and pixel interference is also proposed as a prevention method at the end of this paper. It is indicated by experiments, the method could better detect displayer electromagnetic Trojan programs and has a strong versatility, low cost, and easy to deploy applications. [ABSTRACT FROM PUBLISHER]

In the wireless communication system, interference is considered harmful. Wireless networks strive to avoid scheduling multiple transmissions at the same time in order to prevent interference. While Physical layer Network Coding (PNC) was proposed to embrace interference in order to improve throughput performance. During the second stage of PNC, the intermediate node broadcast the mapping signal to all of destinations, and PNC uses the TDM in order to avoid the interference from same frequency. As a result, when the user receives the mapping signal from the relay station, we could not send the second frame. In this paper, an improved scheme based on PNC is proposed in Two-way system. The paper adopts the Paired Communication Multiple Access (PCMA) idea to handle the mixed signal in the same slot, and implements the scheme that the sender could send the frames continuously. Extensive simulation studies show that the new Continuous PNC scheme is feasible and improves the communication throughput effectively by 60%. [ABSTRACT FROM PUBLISHER]

Multi Radio Multi Channel Wireless Mesh Networks (MRMC-WMNs) are undergoing rapid progress and inspiring numerous deployments. These networks require carefully assignment of resources and load balancing to provide the quality guarantees to traffic flows. Load balancing avoids the creation of bottlenecks and increases the network efficiency. Certainly, we need a benchmark to compare the performance of different load balancing mechanisms. In this paper, we consider the scenario of bandwidth-guaranteed broadcast sessions, where each session has a specific bandwidth requirement. The aim of this research is to analyze the performance of broadcasting in small-scale MRMC-WMNs. By considering Wireless Broadcast Advantage (WBA), we formulate channel and node constraints and propose “Traffic Engineering Efficiency” to evaluate the load balancing ability of algorithms. Deriving analytical relationships between throughput, number of transmissions, node and channel utilization is other contribution of this paper. In order to confirm the accuracy of derived analysis, we present some simulations on typical networks. [ABSTRACT FROM PUBLISHER]

When the gain of a wireless repeater is larger than the isolation between transmit and receive antennas of the repeater, the feedback signal that comes into the receive antenna from the transmit antenna of the repeater causes the repeater to go into feedback oscillation regardless of the input signal. In this paper, we propose adaptive equalizer and phase noise compensator in order to effectively cancel feedback channel and phase noise in wireless repeater system based on LTE-Advanced uplink system. In a repeater system, the performance has got worse caused by feedback channel and phase noise. Thus, the interference cancellation system requires to removing the interference signal in wireless repeater. In this paper, in order to cancel feedback channel, we use adaptive equalizer such as NLMS and RLS. And, in LTE-Advanced uplink standard, block type pilot is a common pilot pattern in wireless communication systems. So the phase noise compensator exploits block type pilot. Instead of estimating phase noise in other algorithms, which are pretty difficult and complex to get accurate estimation results, the proposed method directly estimates the interference components caused by phase noise and improves estimation accuracy. After that, we reconstruct the interference matrix and suppress the interferences by the inverse matrix method. BER performance of proposed method is satisfied 12.5dB at 10−4. [ABSTRACT FROM PUBLISHER]

This paper presents an improved carrier recovery method for Chinese Digital Terrestrial Multimedia Broadcasting (DTMB) system especially in multi-path channels. The conventional methods are mostly derived from the AWGN channel model. In the real propagation environment, multi-path distortions are much more common, which may result the conventional carrier recovery loop locked at an undesired point. In this paper, an improved method using as many as observations of carrier frequency offset in one frame is introduced to reduce the estimated variances. Lab tests and Field trials have proved that it can dramatically reduce the probability of fake lock in real propagation environments. [ABSTRACT FROM PUBLISHER]

In this paper, a precoding OFDMA uplink technique is proposed for the upcoming 4G cellular system. Such as IEEE 802.16m and 3GPP LTE, both of them are 4G candidates. We especially tackle the common carrier frequency offset (CFO) problem which brings the inter carrier interference (ICI) and multiple access interference (MAI). The main idea of this paper is the proposed QR dirty paper coding (QR-DPC) method, which is based on QR decomposition. Assisted with block diagonalization (BD) algorithm, we successfully utilize the precoding technique to eliminate the annoying MAI in a multiuser uplink system. Thus, the combination of BD and QR-DPC can significantly increase the BER performance as compared to conventional DPC. Moreover, we can further enhance the performance of QR-DPC by using the famous Water Pouring algorithm. Simulation results confirm that the proposed system can provide excellent performance under the ICI, MAI, and multipath interference environment. [ABSTRACT FROM PUBLISHER]

In this paper, on the basis of the computational verb theory, we set special local verb rules and specific initial conditions to try to simulate some phenomena in two dimensional computational verb cellular networksthen we get some diffusion and wave propagation patterns. We pick up three typical types to be shown in this paper, that is, ripple propagation patterns, target wave propagation patterns and diamond propagation patterns. And we use ripple propagation patterns to model raindrops ripple. Compared to the traditional physical methods of water wave modeling, the 2D CVCNs could model the phenomena by an easier way. The models which are based on the 2D CVCN reveal that computational verb cellular networks have good capabilities for physical modeling. [ABSTRACT FROM PUBLISHER]

The scheduling problem in downlink of the cooperative multi-cell system with random packet arrivals is investigated in this paper. On the one hand, multi-cell cooperative processing (MCP) has the potential to boost spectral efficiency and improve fairness. However, the traditional centralized multi-cell cooperative scheme, in which a central processing unit is assumed with the global knowledge of all the required downlink channels and user messages to jointly design the transmitted signals for all BSs, incurs significant overhead and complexity, and will hinder the practical implementation of MCP. On the other hand, in case of the random packets arrivals, the relevant fairness criterion will be the stabilization of all buffer queues which guarantees a bounded average delay for all users. In this paper, we adopt the decentralized cooperative scheme with adaptive linear preprocessing transmission. A queue-aware scheduling scheme is considered which maximizing the queue-length-weighted sum of the users' rates. The performance of proposed scheme is evaluated through the computer simulation. Simulation results show that the proposed scheme can achieve better tradeoff between system throughput and fairness among users. [ABSTRACT FROM PUBLISHER]

This paper introduces a method of modulation and coding scheme (MCS) selection, which is based on channel quality indicator (CQI) feedback. Effective CQI feedback schemes by mapping signal-to-interference plus noise ratio (SINR) to CQI type based on effective SINR mapping (ESM). This paper improves system reliability by optimizing some parameters. The simulation shows optimized effective MCS selection schemes that not only ensure the BLER performance with bad channel condition but also improve system throughput with good channel condition. [ABSTRACT FROM PUBLISHER]

In this paper, a new method to improve system performance is presented. In Het-Net of LTE-Advanced system different cells are loaded with difference number of User Equipment (UE). This is because the different transmission powers between macro cell and pico cell are used and the UE moves randomly in the network. Sometimes, a cell could be overloading to server many UEs such that the frequency resource is used up. Due to overload, the throughput of each US is significantly reduced. However, other cells may still be lightly loaded while serving a small number of UEs. The imblanance of the resource degrades the network performance. In this paper, we analyze the load balance problem and an approach is proposed to improve the system performance. [ABSTRACT FROM PUBLISHER]

This paper examines a practical way of mitigating interference in multi-input multi-output (MIMO) interference channel when each user is constrained to use a point-to-point code. It was recently shown that the capacity region of interference channel with point-to-point codes can be established by a combination of two schemes: treating interference as noise and joint decoding. In practice, a straightforward implementation of a joint decoding receiver could be significantly more complex than treating interference as noise. Thus, as a low-complexity approach to joint decoding, this paper proposes a successive single-user soft decoding receiver, which performs interference-aware detection with a priori log-likelihood ratio (LLR) and single-user soft decoding for every user successively. The proposed receiver is compared with a receiver treating interference as noise and a receiver performing interference-aware detection without a priori LLR and single-user decoding for the desired user only. Simulation results show that the proposed receiver significantly outperforms these existing receivers. [ABSTRACT FROM PUBLISHER]

In this paper, chirp spread spectrum (CSS) based modulation schemes for capsule endoscopy applications are proposed. The On-Off-Keying (OOK) technique has been conventionally used for the capsule endoscopy applications, but it is known to be susceptible to narrow-band interference such as TV signals. In order to enhance robustness to interferences, we propose two CSS based modulation schemes which are chirp spread spectrum differential binary phase shift keying (CSSDBPSK) and chirp spread spectrum on-off keying (CSS-OOK). The CSS-DBPSK scheme performs better than the CSS-OOK scheme in terms of BER, but it has high implementation complexity due to the strict synchronization requirement. On the other hand, the CSS-OOK scheme has both low receiver complexity and comparable BER performance. A key contribution of this paper is to use a low complexity chirp spread spectrum technique for interference mitigation in capsule endoscopy. A human body channel model is used in the simulations. Simulation results show that the BER performance of the CSS-OOK modulation is in between the CSS-DBPSK and the OOK schemes. We will show that the CSS-OOK modulation is a practical solution that achieves good compromise between the interference robustness and the receiver complexity. [ABSTRACT FROM PUBLISHER]

Adaptive beamformers attempt to eliminate loud interferers in order to facilitate the detection of quiet sources. The Dominant Mode Rejection (DMR) beamformer does this by placing notches in its beampattern corresponding to signals contained in the interference subspace. This subspace is defined by the eigenvectors associated with the largest eigenvalues of the sample covariance matrix. A companion paper derives an analytical model for the notch depth of the DMR beamformer using results from random matrix theory (RMT) on the statistics of the sample eigenvectors. This paper explores the validity of the DMR notch depth model using data from the 2010 Philippine Sea experiment. The measured average notch depths agree with the predictions of the RMT model. [ABSTRACT FROM PUBLISHER]

Based on the requirements of cognitive antijamming, this paper proposes a method to accurately estimate sweeping spectrum range and the instantaneous frequency of the nonlinear chirp signal. Considering the lack of study in nonlinear chirp signal, we utilize Short Time Fourier Transform(STFT) to analyze the non-linear chirp signal, then obtain the time-frequency distribution. The transferred results are utilized to estimate the sweeping spectrum range and the instantaneous frequency, with the use of curve fitting tool. Simulation results are well consistent with our expectation. [ABSTRACT FROM PUBLISHER]

The paper investigated education capture and the interference of teacher unions in schools by their involvement in the corruption of selling teacher posts. Qualitative approach, an interpretive paradigm and capture theory of regulation were used in understanding the phenomenon of education capture. Methods used in gathering information consist of a literature review and document analysis. In addition, the final report of 16 May 2016 of the Ministerial Task Team appointed by the Minister of Basic Education to investigate allegations into the selling of posts of educators by members of teachers' unions and departmental officials in provincial education departments was also used as a source in investigating education capture. [ABSTRACT FROM AUTHOR]

A bipartite experiment consists of one set of units being assigned treatments and another set of units for which we measure outcomes. The two sets of units are connected by a bipartite graph, governing how the treated units can affect the outcome units. The bipartite framework naturally arises in marketplace experiments where, for example, experimenters may seek to investigate the effect of discounting goods on buyer behavior. In this paper, we consider estimation of the average total treatment effect in the bipartite experimental framework under a linear exposure-response model. We introduce the Exposure Reweighted Linear (ERL) estimator, and show that the estimator is unbiased, consistent and asymptotically normal, provided that the bipartite graph is sufficiently sparse. To facilitate inference, we introduce an unbiased and consistent estimator of the variance of the ERL point estimator. In addition, we introduce a cluster-based design, Exposure-Design, that uses heuristics to increase the precision of the ERL estimator by realizing a desirable exposure distribution. Finally, we demonstrate the application of the described methodology to marketplace experiments using a publicly available Amazon user-item review dataset. The full version of the paper is available at: https://arxiv.org/abs/2103.06392. [ABSTRACT FROM AUTHOR]

This paper answers a simple but important question in VANET research: what is the optimal data rate to be used in DSRC-based vehicle safety communications? While it is generally accepted that the default choice is 6 Mbps, this assumption is not rooted in strong technical considerations. This paper provides a systematic evaluation of optimized data rates choices in a variety of scenarios. The answer found enables researchers to generally eliminate one dimension of complexity in relevant VANET studies. Additionally, the methodology used in this paper is possibly as interesting as the conclusion. [ABSTRACT FROM AUTHOR]

WiFi and Zigbee sensor networks have their own usage and market but they both work in ISM frequency bands, thus causing coexistence issues. The difference of their transmission powers makes the problem even worst, as Zigbee transmission power is overruled by WiFi nodes. In this paper, we propose an interference coordination scheme based on the infrastructure operational mode. Our scheme uses the inherent feature of Zigbee to generate the channel scan report and communicate to the server connecting both networks, which in return directs the nodes to decrease their power in order to decrease the interference between both networks. [ABSTRACT FROM PUBLISHER]

This paper considers the problem of dynamic spectrum allocation (DSA) in the adjacent regions controlled by each spectrum broker (SB). In this scenario, the SB has a responsibility to allocate the spectrum to network service providers (NSPs) in region that SB controls. However, the SB cannot manage the interference arising between regions, and, therefore, the quality of allocated spectrum cannot be maintained. Thus, we introduce the spectrum broker coordinator (SBC) for managing the internal and external interference effects in the region. In this paper, we propose a physical interference based geographic coupling parameter to capture the impact of the internal and external interference of each NSP within each region. The proposed parameter is then used to derive the quality of spectrum applied to the spectrum allocation algorithm called as the simulated annealing (SA) to determine the optimal spectrum allocation. Simulation results demonstrate that our scheme can coordinate the DSA-enabled band size to maximize the spectrum utilization in accordance with changes of the density of BSs in NSPs. [ABSTRACT FROM PUBLISHER]

Nowadays with the developing augmentation system or regional satellite systems, the performance of GNSS for civil users is extremely improved especially on the error budget from system characteristics. However, unpredictable factors on the ground user environment, such as intentional or unintentional interferences, strongly degrade the performance of GNSS receiver. It is a significant issue to monitor and investigate the interference effect while applying GNSS for safety of life applications, aviation applications especially. In this study, a low-cost GPS interference monitoring system was deployed at a civil airport for the long-term interference monitoring, and so far several interference events were observed during this period. This paper focused on the reorganization of what the interference observed is, and identifications of the interference characteristics and the influence on navigation service. The Fourier-sine-spectrum-based time-frequency method analyzed the recorded intermediate frequency signal to speculate the interference statistics such as the period, the duration, the frequency of occurrence, and so on. In addition, the interference influence was evaluated on the criterion of the positioning results and the estimated Carrier-to-Noise ratio (C/N0) in GNSS signal tracking process. In summary, this paper offers the possibility to find useful information of these interference events for the airport environment in locating jammers or mitigating the effects of interference signals. [ABSTRACT FROM PUBLISHER]

This paper presents experimental results showing the impact of the proposed LightSquared Long Term Evolution (LTE) signals on reception of both Global Positioning System (GPS) and Galileo civil signals in the L1/E1 band. A model for determining the impact of the interfering signal on the victim Global Navigation Satellite System (GNSS) receivers is also provided and this model is validated against the experimental data. It is shown that Galileo E1 Open Service (OS) receivers will be, in general, marginally more susceptible to this form of interference due to its greater proximity to the edge of the L1 band (as will be the new GPS III civil signal receivers in this band). While it appears that, for now, the LightSquared network will not be deployed, the approach taken and the results obtained herein can be readily adapted for any future signal that may take the place of LightSquared. [ABSTRACT FROM PUBLISHER]

This paper gives the results of the performance measurement that has been conducted in order to determine a grade of intersystem interference impact from DVB-T signal to downlink data throughput in LTE system, both operating in the digital dividend band. The measurement method and the results are described in this paper. [ABSTRACT FROM PUBLISHER]

The WRC-07 (World Radiocommunication Conference 2007) co-allocated the band 790–862 MHz (channels 61 to 69) to mobile services from June 2015. There is a lot of interest to use this part of the spectrum before 2015 for mobile services, especially LTE (Long Term Evolution) services. Before the introduction of these new mobile services, the influence of these mobile services to the reception of existing DVB-T (Digital Video Broadcasting-Terrestrial) networks operating on adjacent channels needs to be assessed. This paper describes the measurements conducted on the subject of interference caused by the LTE system to the DVB-T system. The aim of this paper is to present the measurement results of both LTE Base Stations and LTE User Equipment on DVB-T reception operating on adjacent channels. [ABSTRACT FROM PUBLISHER]

It has been predicted that the recent explosive growth in wireless data traffic will continue for the foreseeable future. To date, attempts to address this explosive growth have included increasing base station density through smaller cells, and to a lesser extent, by improving spectral efficiency using close-to-capacity channel coding and MIMO techniques. Providing further capacity and coverage improvements through ever shrinking cells could lead to large infrastructure costs and operating expenses. In this paper we propose a far less expensive alternate solution using a topology which employs mobile User Equipment (UE) nodes as virtual infrastructure to enhance the cellular capacity while also improving network coverage. The improvements in capacity and coverage are achieved by enabling cellular controlled direct Device to Device (D2D) links to carry relayed traffic. Each terminal UE (T-UE) with an active connection could potentially be assigned a Helper UE (H-UE), depending on the network conditions and traffic requirements to improve the system capacity. In addition, T-UEs which are out of coverage can also be assigned a H-UE, which would extend the typical coverage of a base station and lead to improved network coverage. In this paper, we present both coverage enhancement and system capacity results using Monte Carlo simulation techniques for both uplink and downlink communications. Our results indicate that cell edge percent throughput capacity improvements as well as percent throughput coverage improvements of more than 150% may be realized using idle UEs in the system as mobile relays. [ABSTRACT FROM PUBLISHER]

In this paper, we consider a cooperative jammer to improve secrecy of the wireless transmission in a cellular downlink network. The private message intended for a single user should be kept from the remainder of the users who are regarded as internal eavesdroppers. To improve the secrecy of the intended user, we propose an employment of a helper with multiple antennas and design its optimal transmit beamforming vector. Specifically, the helper node generates the artificial interference to the internal eavesdroppers and so enhances the security by increasing the ambiguity at the eavesdroppers. Based on a framework of power gain region in [1], we optimize the transmission strategy for the helper which maximizes the secrecy capacity of the intended user. The analytical and simulation results show that the proposed scheme enhances the secrecy capacity. In addition, all users whose secrecy rates are zero with no helper's cooperation can achieve the positive secrecy rate by the proposed scheme. [ABSTRACT FROM PUBLISHER]

Using coding artificial point can match the homonymy points during multiple images automatically in the photogrammetry. A method of identifying and locating 8 bits encoded points automatically has been presented in this paper. The experimental results show that the accuracy of center coordinate of encoding point reaches sub-pixel level. And decoding method is simple. The robust of decoding and recognition rate is high. So it can meet the requirements of close range photogrammetry fully. [ABSTRACT FROM PUBLISHER]

It is critically important to understand steady-state and dynamic performance of phasor measurement units (PMUs) to ensure reliable and secure operation of the synchrophasor based wide area monitoring, control, and protection systems. The recently published IEEE Standard C37.118.1 provides necessary guidelines to characterize both steady-state and dynamic performance of a PMU. This paper presents a performance evaluation methodology according to the IEEE Standard C37.118.1 and discusses the practical issues in the test environment. Results of the steady-state and dynamic responses tests on an actual PMU are also presented. The PMU performance evaluation approach of this paper is simple, repeatable, and can be performed at any facility with commonly available standard signal playback equipment. The method is based upon using test signals that are mathematically generated from a signal model and play backed into the PMU with precise global position system (GPS) synchronization. [ABSTRACT FROM PUBLISHER]

GTRI is developing an 8-channel X-band experimental radar for a small unmanned aircraft system (SUAS) for adaptive multi-channel, MIMO, and waveform diversity test bed studies. New adaptive algorithms, one of which is covered in this paper, are also part of the test bed. Estimation of the statistical covariance matrix forms a central role in radar detection and adaptive beamforming algorithm. For example, the optimal (adaptive) linear combiner (beamformer) weights for a radar sensor array are expressed in terms of the inverse of the multi-channel (MC) covariance matrix for MIMO problems. Rather than form an estimate of the covariance matrix directly from the available data and inverting (sample matrix inversion [SMI]), an alternative direct estimate of the inverse may be obtained by forming parametric MC linear prediction estimates and then expressing the inverse in terms of these parametric MC estimates. The resulting parametric inverse estimate will be more accurate than inverting the estimate of the covariance matrix, leading to greatly improved detection performance over conventional methods of covariance estimation and inversion. This paper reveals the structure of the inverse of the covariance matrix for one parametric technique. The inverse structure involves products of triangular block MC Toeplitz matrices, which leads to a fast computational solution. Performance improvements over classical sample covariance matrix estimation are illustrated. [ABSTRACT FROM PUBLISHER]

This paper analyzes the possibility to introduce a WiFi type of secondary network containing multiple secondary access points (SAPs) in TV bands. In particular, the analysis investigates the limitations of TV whitespace (TVWS) usage imposed by the aggregate interference of the secondary users towards the primary and secondary system, assuming different levels of penetration of the TVWS-operating technology. The implementation of CSMA/CA MAC protocol within the secondary network has a high impact on the tolerable density of SAPs, as well as on the achievable throughput. The introduction of different TVWS sharing management can improve the secondary network deployment density and its throughput. However, the study reveals that the secondary system performance is poor regarding the achievable throughput in cases when densities of SAPs are high and comparable to the current WiFi technology penetration in urban areas. [ABSTRACT FROM PUBLISHER]

In ubiquitous computing, systems evolve surrounded by a heterogeneous smart-devices and software services, offering functionalities that enable new applications to be created. In such system, we need to consider the unpredictability of software infrastructure changes. To tackle the issue of the dynamic variation of the software infrastructure, compositional adaptation is now often used. The problem is that adaptation entities are independent-written. In such case, they may interfere when they are composed. In this paper, we propose a formal approach that allows composing applications at run time and managing these interferences. The formal model of the system and adaptations are defined in term of graphs. In particular, we demonstrate the symmetry property of our composition process. [ABSTRACT FROM PUBLISHER]

Wireless technologies are well known to provide tremendous benefits to the healthcare sector. In the evaluation of the wireless technologies, ZigBee is found specifically suitable for monitoring due to its low cost, long battery life and widely accepted standard. But ZigBee uses the same ISM free band with other wireless techniques, such as Wi-Fi, which is also widely deployed in health care. The coexistence of these techniques in the crowded ISM band will cause mutual interference, which in medical environment has death indication. This paper aims at providing a comprehensive evaluation of the interference between Wi-Fi and ZigBee technologies. Constructing on earlier work led by researchers in Schneider Electric [2], real-time tests were performed in research laboratory and residential environment and results were analyzed to provide a reference for the deployment of multiple wireless technologies to avoid mutual interference. [ABSTRACT FROM PUBLISHER]

Nowadays, power quality detecting devices have some problems in the applications. The low cost and the multi-function have been the main contradiction. For these, this paper designs a dual-core power quality detecting system based on the latest TI's OMAP-L138 chip, which has both ARM and DSP core. With the high-speed ADS8556 chip, the system achieves real-time data acquisition, processing and analysis. The hardware design makes the system highly integrated, lower cost and easy to be integrated into enterprise information management system. The windowed fast flourier transformation is adopted to detect harmonic, and S-Transform is used to detect interferences automatically and quickly, wavelet transform and binary tree support vector machine are also used to make interference classifications. Experiment results show that this design meets the requirements and different algorithms make the system more automatic and intelligent, it can reduce labor costs significantly. The system with low cost and the multi-function is better than others. [ABSTRACT FROM PUBLISHER]

This paper presents a maximum likelihood (ML) approach to mitigate the effect of narrow band interference (NBI) in a zero padded orthogonal frequency division multiplexing (ZP-OFDM) system. The NBI is assumed to be time variant and asynchronous with the frequency grid of the ZP-OFDM system. The proposed structure based technique uses the fact that the NBI signal is sparse as compared to the ZP-OFDM signal in the frequency domain. The structure is also useful in reducing the computational complexity of the proposed method. The paper also presents a data aided approach for improved NBI estimation. The suitability of the proposed method is demonstrated through simulations. [ABSTRACT FROM PUBLISHER]

Femtocells, which are low cost low power, stand alone cellular access points, are a potential solution to provide good indoor coverage with high data rate. However, the femtocell deployment may also increase the co-channel interference (CCI) by reducing the distance reuse of the spectrum. In this paper, we introduce methods to cancel out the interference among the femtocells while considering that macrocells operate orthogonally to the femtocells. The femtocells may also cooperate through joint detection of the received signal and improve the overall error performance at the expense of an increased computational complexity. In this paper, the performance-complexity tradeoff of cooperative detection is investigated for uplink transmissions. Numerical results show that the cooperative detection gain may reach 10 dB at a Bit-Error Rate (BER) of 10−2 when compared to the case without cooperation. [ABSTRACT FROM PUBLISHER]