Communication In Tunnels Research Articles

A Printed Dipole Array with Bidirectional Endfire Radiation for Tunnel Communication.

Tunnel communication always suffers from path loss and multipath effects caused by surrounding walls. Meanwhile, the traditional leaky coaxial cables are expensive to deploy, inconvenient to operate, and difficult to maintain, leading to many problems in practical use. To solve the abovementioned problems, a low-profile printed dipole array operating at 3.5 GHz with bidirectional endfire radiation is designed based on the method of maximum power transmission efficiency (MMPTE). By setting two virtual test receiving dipoles at the two opposite endfire directions and then maximizing the power transmission efficiency between the printed dipole array to be designed and the test receiving antennas, the optimal amplitudes and phases for the array elements are obtained. Based on the optimal distributions of excitations, the simulation results show that the proposed eight-element printed dipole array can simultaneously generate two mirrored endfire beams towards opposite directions. Furthermore, the corresponding normalized cross-polarization levels are lower than -22.3 dBi both in the azimuth and elevation planes. The peak endfire gain is 10.7 dBi with maintenance of higher than 10 dBi from 3.23 GHz to 3.66 GHz, which is suitable for tunnel communication.

Review on Tunnel Communication Technology

Tunnels account for an increasing proportion of highways. Due to the semi-closed structure of tunnels, signal communication is difficult in tunnels. This review analyzes the signal data transmission requirements of intelligent network management systems, such as lighting systems, wind protection systems, fire protection systems, and vehicle and pedestrian positioning systems in tunnels. The selection of signal coverage and transmission methods are also discussed. The advantages and disadvantages of various networking methods are analyzed. This paper summarizes the wireless signal transmission, wired signal transmission and signal transmission modes of different tunnel types.

Bidirectional Scanning Antenna Based on Surface Wave Mode

A bidirectional scanning antenna (BSA) based on surface wave mode is proposed. The bidirectional scanning capacity is achieved by two back-to-back placed frequency scanning tapered slot antenna (FSTSA) elements. The corrugated slot array in inner edges enables the BSA to support two surface wave modes to propagate along the inner edges with different phase constants. Due to the dispersion characteristic of surface wave mode, the phase difference between two modes varies with frequencies, then frequency scanning is achieved at the endfire. Slot arrays are also etched on the outer edges to reduce current flowing. By separately configuring two back-to-back FSTSA elements, the BSA could form a rotationally symmetrical, mirror symmetrical, or asymmetrical bidirectional scanning pattern. Three prototypes with rotationally symmetrical, mirror symmetrical, and asymmetrical pattern are designed and fabricated to verify the principles. Since the scanning plane is parallel to antenna surface, the proposed BSA has a low cross section, which makes it suitable for wireless communication in tunnels and coal mines where good air ventilation is required.

Research on Vehicle-to-Vehicle MIMO Wireless Channels in Various Tunnels

In this paper, we propose a geometry-based channel model for multiple-input multiple-output (MIMO) vehicle-to-vehicle (V2V) communications in practical tunnel scenarios. In the proposed channel model, the waves transmitted from the transmitter experience line-of-sight (LoS) and non-LoS (NLoS) before arriving at the receiver. The time-varying parameters of the propagation paths and angles are derived to characterize the channel non-stationarity. Furthermore, we derive the correlation property functions of the proposed V2V channel model; they are space cross-correlation functions (CCFs), temporal auto-correlation functions (ACFs), frequency CCFs, as well as the Doppler power spectrum distributions (PSDs). Numerous simulation results of the propagation characteristic for different physical properties of the tunnel, as well as the different motion properties of the transmitter and receiver, are studied and discussed; they demonstrate that the proposed channel model is suitable for describing the practical V2V tunnel communication scenarios.

High-Resolution Delay Spread of Wide-Band Wireless Link in Long Tunnels—Theory and Experimental Verification

The need for wireless communication appears everywhere, and with as few interruptions as possible. An extensive and in-depth study has been conducted on the limitations of wireless communication in pedestrian tunnels. Using an analytical mathematical ray tracing model, and performing tunnel measurements, with an autonomous measuring setup, the model was validated. An extraordinary wide band was used for the experiments, which also featured optical systems to ensure accurate results. Since the tunnel is narrow, the differences between the different paths are small, and in order to distinguish them a resolution of 0.2 ns was used. The RMS delay spread, στ, decreases throughout the tunnel, and at no point exceeds 1 ns.

Issues with Modeling a Tunnel Communication Channel through a Plasma Sheath.

We consider two of the most relevant problems that arise when modeling the properties of a tunnel radio communication channel through a plasma layer. First, we studied the case of the oblique incidence of electromagnetic waves on a layer of ionized gas for two wave polarizations. The resonator parameters that provide signal reception at a wide solid angle were found. We also took into account the unavoidable presence of a protective layer between the plasma and the resonator, as well as the conducting elements of the antenna system in the dielectric itself. This provides the first complete simulation for a tunnel communication channel. Noise immunity and communication range studies were conducted for a prospective spacecraft radio line.

Position Estimation in Corridors Along the Coupled Mode of Radiating Cables.

Radiating cables are mostly used to provide radio communication in tunnels or corridors, but they can also be used to estimate the position of a mobile terminal along the cable. In this paper, a measuring receiver’s position was estimated by measuring the difference in the direct signal’s reception time, which was generated by a transmitter connected to one end of the radiating cable, and the delayed signal retransmitted from another end. During tests, a relatively narrowband (23 MHz) signal was used in the unlicensed band (2.4 GHz) and 50 m long coupled mode radiating cable. The cable was installed along a corridor in the office building. Measurement results used different equipment configurations (i.e., return signal only amplified or amplified and frequency-shifted), which presented possible sources of errors.

Effect of traps-to-gate tunnel communication on C-V characteristics of MIS capacitors

The admittance measurements are commonly used for extraction of parameters of the traps located in the gate stack of the metal-insulator-semiconductor structures. The extraction procedures are based on models of the MIS structure, which are usually based on a modified Nicollian-Brews' equivalent circuit but do not comprise charge communication between the traps and the gate electrode. The model proposed in this work includes the traps-to gate tunnel communication and is used to discuss its impact on the capacitance-voltage characteristics of a MIS capacitor with a double-layer insulator gate stack.

Determination of border/bulk traps parameters based on (C-G-V) admittance measurements

Admittance parameters analysis can give useful information on border and bulk traps, including the traps located at the inner interface inside high-k gate stacks. The authors present a theoretical model of the high-k dielectric based MIS tunnel diode that comprises the small-signal response of the traps. The traps are charged and discharged not only by charge exchange with the substrate but also by tunnel currents between the traps and the gate electrode. The assumption of tunnel communication between the traps and the gate electrode enables arbitrary traps geometric distribution and makes the model valid not only for surface and border traps but also for the bulk ones, including traps located at the inner interface inside the gate stack. The small-signal equivalent circuit of the considered MIS structure is transformed into series (CSm, RSm) and parallel (CPm, GPm) depictions, which are commonly used in admittance measurements (C-G-V). The comparison between simulation results and measurement data may be used to determine the trap parameters in the investigated device as it is presented in the paper.

3D Non-Stationary Wideband Tunnel Channel Models for 5G High-Speed Train Wireless Communications

High-speed train (HST) communications in tunnels have attracted more and more research interests recently, especially within the framework of the fifth generation (5G) wireless networks. In this paper, based on cuboid-shape, three-dimensional (3D) non-stationary wideband geometry-based stochastic models (GBSMs) for HST tunnel scenarios are proposed. By considering the influence of the tunnel walls, a theoretical channel model is first established, which assumes clusters with an infinite number of scatterers randomly distributed on the tunnel walls. The corresponding simulation model is then developed and the method of equal areas is employed to obtain the discrete parameters, such as the azimuth and elevation angles. We derive and investigate the most important channel statistical properties of the proposed 3D GBSMs, including the time-variant autocorrelation function, spatial cross-correlation function, and Doppler power spectrum density. It is indicated that all statistical properties of the simulation model, verified by simulation results, can match very well with those of the theoretical model. Furthermore, a validation is presented by comparing the stationary regions of our proposed tunnel channel model to those of relevant measurement data.

Comparison of Tunnel Enlargement and Clinical Outcome Between Bioabsorbable Interference Screws and Cortical Button-Post Fixation in Arthroscopic Double-Bundle Anterior Cruciate Ligament Reconstruction: A Prospective, Randomized Study With a Minimum Follow-Up of 2 Years

To investigate the tunnel enlargement rate and clinical function by comparing double-bundle anterior cruciate ligament reconstruction (ACLR) using different fixation devices. Patients receiving primary arthroscopic double-bundle ACLR were screened and divided into 2 groups on the basis of the method of graft fixation: bioabsorbable interference screw (BS) group and cortical button (CB) group. Bone tunnel size was assessed digitally using magnetic resonance imaging, which was performed a minimum of 2years postoperatively. Clinical evaluations were performed using the Knee Injury and Osteoarthritis Outcome Score, International Knee Documentation Committee score, and KT-1000 arthrometer 2years postoperatively. Sixty patients receiving primary arthroscopic double-bundle ACLR were included. Overall, the BS group showed greater tunnel enlargement than the CB group, as well as a significantly increased rate of tunnel communication (P= .029). The average anteromedial tunnel enlargement rates for the BS and CB groups were 50% and 28%, respectively. The enlargement rate of the posterolateral (PL) femoral tunnel was similar in both groups. In the PL tibial tunnel, the CB group showed a significant increase in enlargement compared with the BS group (64% vs 45%, P= .0001). Both groups showed functional improvement in the Knee Injury and Osteoarthritis Outcome Score and International Knee Documentation Committee score. No significant difference in postoperative functional outcomes was found between the 2 groups. The BS group showed significantly greater tunnel enlargement in anteromedial tunnels and an increased tunnel communication rate compared with the CB group. On the other hand, the CB group showed greater tunnel enlargement in tibial PL tunnels. Tunnel communication was observed mostly on the tibial side in the BS patients. Equivalent clinical function outcomes were noted at 2years after surgery in both groups of patients. Level II, randomized controlled clinical trial.

Deterministic Modeling of 5G Millimeter-Wave Communication in an Underground Mine Tunnel

This paper presents broadband simulations and measurements of Millimeter-Waves (mm-wave) propagation in a rugged underground mine environment. Mathematical formulation was carried out in the framework of Uniform Theory of Diffraction (UTD) to develop a deterministic Ray-Tracing (RT) model under Line-Of-Sight (LOS) condition. The developed theoretical model was then validated experimentally in Frequency Domain (FD) and Time Domain (TD). A significant agreement between simulations and measurements is achieved in both domains. The rough surfaces of the mine are modeled deterministically as groups of diffracting wedges having random dimensions (heights, angles) being transversely oriented throughout the gallery. Acute (inferior to 30°) and obtuse (superior to 120°) wedges angles are found to have significant effects on the overall propagation performance. In the mm-wave band, the UTD diffraction phenomenon is evident and must be considered in the design of underground mine channels. In fact, the presented model is found to be capable of predicting the complex multipath of underground mine channels, due to the ray-optical behavior at mm-wave bands.

A General 3D Non-Stationary Wideband Twin-Cluster Channel Model for 5G V2V Tunnel Communication Environments

In this paper, we propose a general three-dimensional (3D) non-stationary wideband two-cluster channel model for fifth-generation (5G) vehicle-to-vehicle (V2V) tunnel communication environments. In the proposed model, the received signal is constructed as a sum of the components with line-of-sight (LoS) propagations and the components via the two-cluster model, i.e., non-line-of-sight (NLoS) propagations; therefore, the model has the ability to sufficiently describe a variety of 5G wireless communication scenarios. In order to investigate the non-stationary properties of clusters, we introduce a birth-death algorithm to model the appearance and disappearance of clusters on both the array and time axes. The impacts of the non-stationary properties of clusters on the multiple-input and multiple-output (MIMO) channels are investigated via statistical properties, including spatial cross-correlation functions (CCFs), temporal spatial auto-correlation functions (ACFs), and Doppler power spectrum densities (PSDs). Numerical results of the proposed propagation properties fit the simulation results and prior measured results very well, which demonstrate that the proposed 3D model is able to describe the real 5G V2V communications in tunnel environments.

全双工光载无线隧道通信系统

全双工光载无线隧道通信系统

Good clinical results can be obtained along with reduced risk of tunnel communication with a new technique in concomitant meniscus transplantation and ACL reconstruction.

The purpose of this study was to introduce our technical modification for concomitant meniscus transplantation and ACL reconstruction with preliminary results of our cases. The current study comprised of two sections: first is the cadaveric study of 20 specimens. The distances between tunnel entry and exit points of tunnels for 27 meniscal transplants and ACL reconstruction in CT slices were measured. The second section was evaluation of our cases including six patients. The selected patients were scored preoperatively and post-operatively with KOOS, Lysholm and VAS Scoring systems, joint ROM and stability. In cadaveric study section, the minimum distance between tunnels was found 1.9±0.4cm on tibia plateau and 1.8±0.9cm on tibial crest. No overlapping or communication of the tunnels was seen on any CT slice. In case series section, the mean age of patients was 36±12.7years and mean follow-up period was 30.8±11.3months. The KOOS total, VAS and Lysholm scores of the patients were significantly increased (p=0.012, 0.036 and 0.001, respectively). The stability of operated knees was normal or near normal. The results of this study have demonstrated that our technical modification seems to be an effective method in concomitant medial meniscus transplantation and ACL reconstruction. There is a reduced risk of tunnel communication, and the medial bone stock is protected so the risk of potential fracture in the medial tibia plateau and revision rates may be reduced. Although it seems successful in respect of the short-term results, further studies with a greater number of patients would provide clearer results.

Femoral and Tibial Tunnel Diameter and Bioabsorbable Screw Findings After Double-Bundle ACL Reconstruction in 5-Year Clinical and MRI Follow-up.

Background:Tunnel enlargement is frequently seen in short-term follow-up after anterior cruciate ligament reconstruction (ACLR). According to new evidence, tunnel enlargement may be followed by tunnel narrowing, but the long-term evolution of the tunnels is currently unknown.Hypothesis/Purpose:The hypothesis was that tunnel enlargement is followed by tunnel narrowing caused by ossification as seen in follow-up using magnetic resonance imaging (MRI). The purpose of this study was to evaluate the ossification pattern of the tunnels, the communication of the 2 femoral and 2 tibial tunnels, and screw absorption findings in MRI.Study Design:Case series; Level of evidence, 4.Methods:Thirty-one patients underwent anatomic double-bundle ACLR with hamstring grafts and bioabsorbable interference screw fixation and were followed with MRI and clinical evaluation at 2 and 5 years postoperatively.Results:The mean tunnel enlargement at 2 years was 58% and reduced to 46% at 5 years. Tunnel ossification resulted in evenly narrowed tunnels in 44%, in conical tunnels in 48%, and fully ossified tunnels in 8%. Tunnel communication increased from 13% to 23% in the femur and from 19% to 23% in the tibia between 2 and 5 years and was not associated with knee laxity. At 5 years, 54% of the screws were not visible, with 35% of the screws replaced by a cyst and 19% fully ossified. Tunnel cysts were not associated with worse patient-reported outcomes or knee laxity. Patients with a tibial anteromedial tunnel cyst had higher Lysholm scores than patients without a cyst (93 and 84, P = .03).Conclusion:Tunnel enlargement was followed by tunnel narrowing in 5-year follow-up after double-bundle ACLR. Tunnel communication and tunnel cysts were frequent MRI findings and not associated with adverse clinical evaluation results.

Bidirectional same‐sense circularly polarized antenna using slot‐coupled back‐to‐back patches

ABSTRACTIn this letter, a dual‐patch antenna with bidirectional circular polarization of the same sense is proposed for coal mine and tunnel communications and positioning systems. The proposed antenna consists of two back‐to‐back patches with a common ground plane. We only feed one patch on the front side by microstrip feeding line, and the energy is coupled to the other patch on the back side through a slot, which is etched on the common ground. By properly truncating the corners of the dual patches, bidirectional radiation pattern is achieved with the right‐hand circular polarization on both front and back sides. Compared to previous designs for the same purpose, the proposed antenna is with a compact structure using only two layers of substrate and without using complex feeding networks, benefiting from the merits of small dimension, low cost, and easy fabrication. We have built the antenna prototype and taken the measurement. The measured impedance bandwidth for S11<−10 dB is 90 MHz (2.44–2.53 GHz), and the measured 3‐dB axial‐ratio bandwidth is 20 MHz (2.455–2.475 GHz), agreeing well with the simulated results. The measured peak right hand circularly polarization gains are 3.70 dBic and 3.09 dBic for front and back directions. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:645–648, 2017

Scattering of Electric Field from Leaky Coaxial Cable in Confined Area

The new radiation model for the electric field scattering of single leaky coaxial cable (LCX) being a transmitting antenna in the rectangular blind zone at 1.8 GHz is reported. The effect of varying the receiving antenna distance from the LCX on the fluctuation of radiated field using Ray-Tracing Method is examined. The line of sight and reflected paths between the LCX and receiving antenna for both horizontal and vertical polarizations are considered. Furthermore, it is inferred that the selection of appropriate period of slots and distance of the receiver reduce the fluctuations of electric field. The theory and procedures used in this paper can be extrapolated in different slot patterns of the LCX and zones which have many valuable applications for mobile communication in underground mines, tunnels, and railways.

Graft quality and clinical outcomes of intraoperative bone tunnel communication in anatomic double-bundle anterior cruciate ligament reconstruction

Background/objectiveIn anatomic double-bundle anterior cruciate ligament reconstruction, it is crucial to create two separate bone tunnels within the footprints of the anterior cruciate ligament at the femur and tibia. This can occasionally be difficult to accomplish and the adverse effects of bone tunnel communication are unclear. The purpose of this study was to examine the effects of intraoperative bone tunnel communication on graft quality and clinical outcome. MethodsFifty-two patients (52 knees) who underwent anatomic double-bundle anterior cruciate ligament reconstruction with hamstring tendons were included. The mean age of the patients was 30.7 years. Clinical assessments were performed 1 year after surgery. Bone tunnel communication was evaluated using computed tomography 10 days after surgery. Graft quality was evaluated using magnetic resonance imaging 6 months after surgery and the signal/noise quotient was calculated using the region of interest technique. ResultsBone tunnel communication was observed in the femur of one knee (1.9%) and the tibias of 10 knees (30.8%). The knees with tibial bone communication were classified into Group C (N=16), and the knees without tibial bone tunnel communication were classified into Group N (N=36). No significant differences were observed between Groups C and N in terms of clinical outcome. The signal/noise quotient of the distal portion of the posterolateral graft in Group C was significantly higher than that of Group N. ConclusionBone tunnel communication in anatomic double-bundle anterior cruciate ligament reconstruction did not affect clinical outcome, but it did affect posterolateral graft quality. Level of evidenceLevel 4, case series, therapeutic studies.

Accurate Electromagnetic Analysis of MF TL Backup Communications in Cylindrical Tunnels

Medium frequency transmission line (MF TL) communications in circular cylindrical underground tunnels critically depend on the soil return impedance. The soil impedance can be approximately calculated using a very simple closed-form expression based on an image method–the so-called Dubanton approach. In this paper, we present an analytical exact method, based on electromagnetic field analysis, using Bessel and Hankel functions to correctly evaluate the soil impedance and the wave propagation parameters (attenuation, phase velocity, and characteristic impedance) that characterize the fundamental quasi-TEM mode propagating along circular tunnels. By comparing the computation results of both methods we have been able to quantify the errors involved in the Dubanton approach. The approximation developed by Wait is also used for verification purposes.