Transmitter Locations Research Articles

The Benefits of Hybrid Caching in Gauss–Poisson D2D Networks

Device caching has recently been proposed as an efficient way to offload traffic from congested cellular networks. However, previous works usually ignore the fact that, in practice, the user device may not be willing to help others due to the limited battery capacity. In this paper, we introduce cooperation among the device-to-device (D2D) transmitters and propose two novel hybrid caching strategies—single-point caching combined with two-point cooperative caching with joint transmission (SPC-CCJT) or multi-stream transmission (SPC-CCMT)—aiming at saving the energy cost of content deliverers. Using tools from stochastic geometry, we propose an analytical framework of the hybrid caching strategies by modeling the locations of the D2D transmitters as a Gauss–Poisson process (GPP) to accurately capture the clustering and cooperative behaviors. First, we consider a probabilistic caching placement and optimize the caching distribution to maximize the cache hit probability. Second, to compare the performance between different content delivery strategies, we derive the success probability and per-user capacity for SPC, CCJT, and CCMT, respectively. These results are then applied to evaluate the offloading gain and the distribution of the content retrieval delay for SPC-CCJT and SPC-CCMT in the GPP-based D2D networks. It turns out that significant offloading gain and delay improvement can be achieved by hybrid caching with cooperation while the energy cost of each cooperator is kept low.

Node Placement and Distributed Magnetic Beamforming Optimization for Wireless Power Transfer

In multiple-input single-output (MISO) wireless power transfer (WPT) via magnetic resonant coupling, multiple transmitters are deployed to enhance the efficiency of power transfer to a single receiver by jointly adapting their source currents/voltages so as to constructively combine the induced magnetic fields at the receiver, a technique known as magnetic beamforming . In practice, since the transmitters (power chargers) are usually at fixed locations and the receiver (e.g., mobile phone) is desired to be freely located in a target region for wireless charging, its received power can fluctuate significantly over locations even with adaptive magnetic beamforming applied. To achieve uniform power coverage, the transmitters need to be optimally placed in the region such that a minimum charging power can be achieved for the receiver regardless of its location, which motivates this paper. First, we derive the optimal magnetic beamforming solution in closed form for a distributed MISO WPT system with fixed locations of the transmitters and receiver to maximize the deliverable power to the receiver subject to a given sum-power constraint at all transmitters. By applying adaptive magnetic beamforming based on this optimal solution, we then jointly optimize the locations of all transmitters to maximize the minimum power deliverable to the receiver over a given one-dimensional (1D) region. Although the formulated problem is nonconvex, we propose an iterative algorithm for solving it efficiently. Extensive simulation results are provided that show the significant performance gains by the proposed design with optimized transmitter locations and magnetic beamforming as compared to other benchmark schemes with nonadaptive and/or heuristic transmitter current allocation and node placement. Last, we extend the node placement problem to the case of 2D region, and propose efficient designs for this case.

Wireless Indoor Resource Optimization Meeting Prescribed User Capacity Requirements

The optimal locations of transmitters in a building, that best meet the bandwidth requirements of all users, was studied in the past by a small number of authors. They used empirical path loss models to constrain an optimization cost function. This paper concentrates on using a signal-to-interference ratio cost function with realistic field parameters obtained using a fast ray-tracing algorithm. The solution obtained is shown to perform well in realistic scenarios, meeting a large proportion of user bandwidth requirements. However, it does not perform well in an oversaturated environment.

Crowdsourcing-Assisted Radio Environment Database for V2V Communication.

In order to realize reliable Vehicle-to-Vehicle (V2V) communication systems for autonomous driving, the recognition of radio propagation becomes an important technology. However, in the current wireless distributed network systems, it is difficult to accurately estimate the radio propagation characteristics because of the locality of the radio propagation caused by surrounding buildings and geographical features. In this paper, we propose a measurement-based radio environment database for improving the accuracy of the radio environment estimation in the V2V communication systems. The database first gathers measurement datasets of the received signal strength indicator (RSSI) related to the transmission/reception locations from V2V systems. By using the datasets, the average received power maps linked with transmitter and receiver locations are generated. We have performed measurement campaigns of V2V communications in the real environment to observe RSSI for the database construction. Our results show that the proposed method has higher accuracy of the radio propagation estimation than the conventional path loss model-based estimation.

3D forward modeling and response analysis for marine CSEMs towed by two ships

A dual-ship-towed marine electromagnetic (EM) system is a new marine exploration technology recently being developed in China. Compared with traditional marine EM systems, the new system tows the transmitters and receivers using two ships, rendering it unnecessary to position EM receivers at the seafloor in advance. This makes the system more flexible, allowing for different configurations (e.g., in-line, broadside, and azimuthal and concentric scanning) that can produce more detailed underwater structural information. We develop a three-dimensional goal-oriented adaptive forward modeling method for the new marine EM system and analyze the responses for four survey configurations. Oceanbottom topography has a strong effect on the marine EM responses; thus, we develop a forward modeling algorithm based on the finite-element method and unstructured grids. To satisfy the requirements for modeling the moving transmitters of a dual-ship-towed EM system, we use a single mesh for each of the transmitter locations. This mitigates the mesh complexity by refining the grids near the transmitters and minimizes the computational cost. To generate a rational mesh while maintaining the accuracy for single transmitter, we develop a goal-oriented adaptive method with separate mesh refinements for areas around the transmitting source and those far away. To test the modeling algorithm and accuracy, we compare the EM responses calculated by the proposed algorithm and semi-analytical results and from published sources. Furthermore, by analyzing the EM responses for four survey configurations, we are confirm that compared with traditional marine EM systems with only in-line array, a dual-ship-towed marine system can collect more data.

The problem of position determination of signal transmitting device in 3D road

With the development of social economy, the current urban traffic problem is more prominent. In order to solve this problem very well, the idea of establishing intelligent traffic management came into being. The establishment of intelligent traffic management, cannot do without the signal launch and reception. Therefore, how to set up some wireless signal transmitting device in time to travel on the road motor vehicles to send traffic information and how to achieve full coverage of the signal and signal stability is our article to discuss the issue. For the first question, we must separate the motorway and non-motorway from all roads. Motorway lanes are usually straight and long. While the bends are usually just sidewalks or bike lanes (non-motorized lanes). So the 121 road can be clustered analysis, clustering of the two indicators for each road length (the distance between the adjacent points) and the collection point of density (by drawing, you can observe the more curved the denser the road collection point, so the road curvature into the collection point of the intensity), the result of clustering can get 48 motor lanes. And then through regress function regression and data fitting to achieve an approximate description of each type of motor vehicle description model, so that each road in a given latitude (latitude) coordinates to determine the latitude (longitude) coordinates and the corresponding altitude. For the problem of two, according to the meaning of the road to know the signal strength is only related to the distance between the sampling point and the launch device, so you can 'the motor vehicle between the signal reception is relatively close to' this indicator into ' The average of the distance between all the sampling points and the transmitting device is close to '. By reading the data will be latitude and longitude conversion distance length, so that the maximum value as small as possible. The position of the launcher can be obtained by programming by MATLAB. When considering the altitude, only the position of the transmitting device can be changed. (9.7824,56.7720), and the position coordinates when considering the altitude are D (9.7459, 56.7586, 73.5645), and the position coordinate of the signal device is B (9.7824, 56.7720). For question three, note the effect of the original signal device A on the result. We still use the average of the distance between all the sampling points of the road and the launcher to characterize the stability of the signal reception. The average distance of all non-motorized trains to the original signal device A is first determined, and then the average distance of all non-motorized lanes from the new signal device B is set, and the signal acceptance strength of the non-motorized lane can be used to characterize. And then use the same method in question two to determine the location of the new signal transmitter. Finally, the coordinates of the position of the new signal device are E (9.7459,56.7586,73.5645).

Simulation and analysis of the effect of ungrounded rectangular loop distributed parameters on TEM response

An ungrounded loop in the shallow subsurface transient electromagnetic surveys has been studied as the transmission line model for early turn-off stage, which can accurately explicate the early turn-off current waveform inconsistency along the loop. In this paper, the Gauss-Legendre numerical integration method is proposed for the first time to simulate and analyze the transient electromagnetic (TEM) response considering the different early turn-off current waveforms along the loop. During the simulation, these integral node positions along the loop are firstly determined by solving these zero points of Legendre polynomial, then the turn-off current of each node position is simulated by using the transfer function of the transmission line. Finally, the total TEM response is calculated by using the Gauss-Legendre integral formula. In addition, the comparison and analysis between the results affected by the distributed parameters and that generated by lumped parameters are presented. It is found that the TEM responses agree well with each other after current is thoroughly switched off, while the transient responses in turn-off stage are completely different. It means that the position dependence of the early turn-off current should be introduced into the forward model during the early response data interpretation of the shallow TEM detection of the ungrounded loop. Furthermore, the TEM response simulations at four geometric symmetry points are made. It shows that early responses of different geometric symmetry points are also inconsistent. The research on the influence of turn-off current position dependence on the early response of geometric symmetry point is of great significance to guide the layout of the survey lines and the transmitter location.

Retrorflective Using Optical Communication

This article deals with visible light communication (VLC) based on retroreflective principle. Visible light communication presents great potential in terms of possible communication bandwidth, transmitter localization, spectral, power and spatial effectively and more. In the article, the retroreflective communication itself is introduced and compared to common VLC and RFID systems. Essential parts of power balance are mentioned and discussed. The last part of the article discusses benefits of retroreflective communication for Internet of Things.

Position Determination for Moving Transmitter Using Single Station

A common case in location problem is that the terminal is unstable or moving. The classical methods construct equations related to the measurements observed at the individual receivers first, and then solves the problem to localize the source. In this paper, we focus on the moving transmitter localization problem using only one station. The thinking of inverse synthesis aperture is implied, which takes advantage of the motion model to increase the equivalent aperture for higher accuracy. The proposed method formulates the problem through the angle of arrival and Doppler frequency measurements that are obtained from independent observations. After pseudo linearization by ignoring higher order noise terms, the estimator of position and velocity is easily solved through weighted least squares method. The bias reduction (BR) is utilized for lower bias and better root-mean-square error (RMSE). Using the result of BR as an initial solution, the maximum likelihood estimator (MLE) is realized through Gauss–Newton iteration. Theoretical analysis verifies that the BR estimator is efficient, which has Cramer-Rao Lower Bound (CRLB) accuracy if the noise level is mild. While MLE attends CRLB in higher noise situation albeit the possible divergence problem. Simulations indicate the feasibility and validate the advocated performance. The RMSE and bias match the theory very well.

Quality of Service Based NOMA Group D2D Communications

Non-orthogonal multiple access (NOMA) provides superior spectral efficiency and is considered as a promising multiple access scheme for fifth generation (5G) wireless systems. The spectrum efficiency can be further enhanced by enabling device-to-device (D2D) communications. In this work, we propose quality of service (QoS) based NOMA (Q-NOMA) group D2D communications in which the D2D receivers (DRs) are ordered according to their QoS requirements. We discuss two possible implementations of proposed Q-NOMA group D2D communications based on the two power allocation coefficient policies. In order to capture the key aspects of D2D communications, which are device clustering and spatial separation, we model the locations of D2D transmitters (DTs) by Gauss–Poisson process (GPP). The DRs are then considered to be clustered around DTs. Multiple DTs can exist in proximity of each other. In order to characterize the performance, we derive the Laplace transform of the interference at the probe D2D receiver and obtain a closed-form expression of its outage probability using stochastic geometry tools. The performance of proposed Q-NOMA group D2D communications is then evaluated and benchmarked against conventional paired D2D communications.

Analysis of Heterogeneous Wireless Networks Using Poisson Hard-Core Hole Process

The Poisson point process (PPP) has been widely employed to model wireless networks and analyze their performance. The PPP has the property that nodes are conditionally independent from each other. As such, it may not be a suitable model for many networks, where there exists repulsion among the nodes. In order to address this limitation, we adopt a Poisson hardcore process (PHCP), in which no two nodes can be closer than a repulsion radius from one another. We consider two-tier heterogeneous networks, where the spatial distributions of transmitters in the first-tier and the second-tier networks follow a PHCP and a PPP, respectively. To alleviate inter-tier interference, we consider a guard zone for the first-tier network and presume that the second-tier transmitters located in the zone are deactivated. Under this setup, the activated second-tier transmitters form a Poisson hard-core hole process. We first derive exact computable expressions of the coverage probability and introduce a method to efficiently evaluate the expressions. Then, we provide approximations of the coverage probability, which have lower computational complexities. In addition, as a special case, we investigate the coverage probability of single-tier networks by modeling the locations of transmitters as a PHCP.

A MoTe2-based light-emitting diode and photodetector for silicon photonic integrated circuits.

One of the current challenges in photonics is developing high-speed, power-efficient, chip-integrated optical communications devices to address the interconnects bottleneck in high-speed computing systems. Silicon photonics has emerged as a leading architecture, in part because of the promise that many components, such as waveguides, couplers, interferometers and modulators, could be directly integrated on silicon-based processors. However, light sources and photodetectors present ongoing challenges. Common approaches for light sources include one or few off-chip or wafer-bonded lasers based on III-V materials, but recent system architecture studies show advantages for the use of many directly modulated light sources positioned at the transmitter location. The most advanced photodetectors in the silicon photonic process are based on germanium, but this requires additional germanium growth, which increases the system cost. The emerging two-dimensional transition-metal dichalcogenides (TMDs) offer a path for optical interconnect components that can be integrated with silicon photonics and complementary metal-oxide-semiconductors (CMOS) processing by back-end-of-the-line steps. Here, we demonstrate a silicon waveguide-integrated light source and photodetector based on a p-n junction of bilayer MoTe2, a TMD semiconductor with an infrared bandgap. This state-of-the-art fabrication technology provides new opportunities for integrated optoelectronic systems.

A Framework for Improving the Performance of Direct Position Determination by Normal Hedge Algorithm for Emitter Localization in Indoor Applications

Indoor localization is a way to determine the location of transmitter(s) by using wireless network sensors without using GPS. In this paper, it is assumed that a random signal is transmitted by an unknown-position emitter through a noisy and lossy channel and then is received by known-position wireless sensors. Unlike the classical algorithms such as TDOA or AOA, the direct position determination (DPD) approach estimates the position of emitter in one step using the observation signal from all the collector receivers. In this paper a framework of methods is proposed to develop the DPD formulations. Originally, a preprocessing is applied on signals and later, a tree search algorithm and a fine localization algorithm will be proposed in order to achieve a higher resolution and with a less volume of computing. Furthermore, an approach is proposed to increase the performance of this algorithm. Using Normal Hedge algorithm with a proposed loss function, fuses the estimation results of several runs of the fine DPD algorithm. The simulation results are shown that the proposed framework would eventually improve the performance of the DPD algorithm.

Uplink modeling of cognitive radio network using stochastic geometry

In this study, we investigate the coverage probability and spectral efficiency of a cognitive radio network with a single-tier uplink model based on a stochastic geometry framework. The locations of cognitive transmitters, cognitive receivers, primary transmitters, and primary receivers are modeled as independent Poisson point processes. We derive the mathematical expressions for the coverage probability and spectral efficiency of this network, as well as closed-form expressions for a path-loss exponent equal to 4. For the uplink transmission, truncated channel inversion power control is employed for the cognitive transmitter with a cutoff threshold at the cognitive receiver because of the limited transmission power. We consider two locations of the cognitive receiver (i.e., inside and outside the primary exclusion region) for uplink transmission. We found that the location of the cognitive receiver impacts on coverage probability and spectral efficiency. Numerical analysis confirms that (i) the coverage probability is higher and (ii) the spectral efficiency is higher when the cognitive receiver is outside the primary exclusion region.

Energy Harvesting Based Multihop Relaying in Cognitive Radio Network

In this paper, a multihop cognitive radio network using a series of multiple decode and forward (DF) energy harvesting relays is proposed to enhance the spectrum utilization and lifetime of the network. A time switching based energy harvesting scheme is considered for the DF relays. An analytical expression has been derived for evaluating the transmission power of the secondary source and secondary relays (SR) as well as SNR at SRs and secondary destination. The corresponding transmission power and signal to noise ratio (SNR) profiles are also analyzed for several numbers of relays under various locations of the primary transmitter (PT). An expression for a critical number of relays, for which the performance of the network is worst, has also been derived. It is seen that upto a critical number of relays the SNR decreases. However the SNR again increases with further increase in number of relays. Further secondary outage probabilities have been compared for several locations of PT. Analytical results following our development are presented and validated by MATLAB based simulation.

On Wi-Fi Model Optimizations for Smartphone-Based Indoor Localization

Indoor localization and indoor pedestrian navigation is an active field of research with increasing attention. As of today, many systems will run on commercial smartphones, but most of them still rely on fingerprinting, which demands high setup and maintenance times. Alternatives, such as simple signal strength prediction models, provide fast setup times, but often do not provide the accuracy required for use cases like indoor navigation or location-based services. While more complex models provide an increased accuracy by including architectural knowledge about walls and other obstacles, they often require additional computation during runtime and demand prior knowledge during setup. Within this work, we will thus focus on simple, easy to set up models and evaluate their performance compared to real-world measurements. The evaluation ranges from a fully-empiric, instant setup, given that the transmitter locations are well known, to a highly optimized scenario based on some reference measurements within the building. Furthermore, we will propose a new signal strength prediction model as a combination of several simple ones. This tradeoff increases accuracy with only minor additional computations. All of the optimized models are evaluated within an actual smartphone-based indoor localization system. This system uses the phone’s Wi-Fi, barometer and IMU to infer the pedestrian’s current location via recursive density estimation based on particle filtering. We will show that while a 100% empiric parameter choice for the model already provides enough accuracy for many use cases, a small number of reference measurements is enough to dramatically increase such a system’s performance.

Wideband passive source localization

This paper develops a mathematical method for determining the locations of multiple transmitters from passive measurements of the signals at two or more receivers. The method applies to the case of emitters transmitting either wideband or narrowband signals.

Indoor‐to‐outdoor empirical path loss modelling for femtocell networks at 0.9, 2, 2.5 and 3.5 GHz using singular value decomposition

Two empirical indoor-to-outdoor path loss models to facilitate femtocell network deployment are derived from continuous wave power measurements. A large set of indoor-outdoor transmitter locations in two residential streets in an urban setting and operating at 900 MHz, 2 GHz, 2.5 GHz and 3.5 GHz have been used to derive the model parameters by using singular value decomposition (SVD). The path loss models have been compared and validated against existing models as well as independent measurement data and good comparison is shown. The root mean square error of the residual path loss data obtained from the measurement data, which directly relates to the channel shadowing characteristics, is compared and validated with known results and has led to new model parameters being proposed. The expressions derived from the modelling can be used in system-level simulators, as well as for shadowing interference analysis of two-tier heterogeneous networks operating in indoor-outdoor scenarios at or close to the operating frequencies considered. In this study, the models extend the operating frequency range compared to related models and introduce SVD as a convenient means of deriving parameters from measured path loss data.

Analyzing Large-Scale Multiuser Molecular Communication via 3-D Stochastic Geometry

Information delivery using chemical molecules is an integral part of biology at multiple distance scales and has attracted recent interest in bioengineering and communication theory. Potential applications include cooperative networks with a large number of simple devices that could be randomly located (e.g., due to mobility). This paper presents the first tractable analytical model for the collective signal strength due to randomly-placed transmitters in a three-dimensional (3D) large-scale molecular communication system, either with or without degradation in the propagation environment. Transmitter locations in an unbounded and homogeneous fluid are modelled as a homogeneous Poisson point process. By applying stochastic geometry, analytical expressions are derived for the expected number of molecules absorbed by a fully-absorbing receiver or observed by a passive receiver. The bit error probability is derived under ON/OFF keying and either a constant or adaptive decision threshold. Results reveal that the combined signal strength increases proportionately with the transmitter density, and the minimum bit error probability can be improved by introducing molecule degradation. Furthermore, the analysis of the system can be generalized to other receiver designs and other performance characteristics in large-scale molecular communication systems.

Network capacity analysis for cellular based cognitive radio VANET in urban grid scenario

The spectrum scarcity of VANETs (Vehicular Ad hoc Networks) can be alleviated by spectrum sharing technology. We present a framework of CCR-VANETs (Cellular-based Cognitive-radio Vehicular Ad hoc Networks). In CCR-VANETs, cellular network performs as primary network while VANET shares the downlink spectrum of cellular network. We consider a scalable urban grid scenario in which vehicles detect available spectrum holes and opportunistically access them according to a carrier-sensing multiple-access protocol. To restrict vehicles’ interference to primary receivers, we set a square preservation region around each particular street block where an active base station is located. The number of street blocks in the preservation region is calculated with the practical assumption that vehicles only know the locations of primary transmitters. We analyze the aggregate interference power from primary and secondary networks, then derive the lower-bound of downlink capacity for the primary network and lower-bound of V2V (Vehicle-to-Vehicle) channel capacity for the secondary network respectively. The numerical results demonstrate the impacts of different network parameters on inter-networks interference level and network capacities.