Coaxial Cable Network Research Articles

Channel Modeling and Optimization of Leaky Coaxial Cable Network in Coal Mine Based on State Transition Method and Particle Swarm Optimization Algorithm

As a continuous antenna, the leaky coaxial cable (LCX) is widely used in wireless communication of closed or semi-closed areas such as the subway, mine, tunnel, etc. Usually, LCX networks are required in coal mines. Its channel characteristics are of great significance to mobile communication and mine safety. This paper presents an effective channel modeling and optimization method that combines the state transition and the particle swarm optimization (PSO) algorithms for the LCX network. First, a channel model can be established with a few parameters based on the state transition method, which can describe the complex transfer function of the LCX network; then, taking the transfer characteristics of the LCX network as the optimization objective, which should be consistent with the measured results. And the established objective function is optimized and designed with the PSO algorithm. Finally, the proposed method is validated by comparing the measured results and the model-based simulations on two test LCX networks. The experimental results show that the absolute error between the proposed model and the measurement model is less than that of other models at any frequency point. The proposed model can accurately obtain all responses between point-to-point channels at one time. It will help to accurately obtain the performance of different LCX networks and help to detect and locate faults in future studies.

An Effective Method Based on Time Reversal and Optimization Techniques for Locating Faults on Power Grids

Electromagnetic time reversal (EMTR) has recently emerged as a promising technique applied for locating faults in power networks. It directly transposes the idea of focusing energy back to its source introduced in original time-reversal (TR) methods. Accordingly, we present in this paper, FasTR, a method based on the tenets of TR, that estimates the fault location by employing optimization based algorithms for fetching the highest peak amplitude with maximum coherence in space and time . However, it uses an alternative approach for executing the cumbersome TR post-processing, thanks to a simplified analytical model capable of evaluating the voltage (or current) at any position and any instant of the tested network resulting from the back-injection of the recorded time-revered signals. FasTR is shown to accurately locate a fault in a complex network with just a basic knowledge of its topology in no more than a couple tens of seconds. More importantly is its ability to locate multiple faults in non-homogeneous networks. The performance of the proposed method is validated by numerical simulations as well as an experimental setup by making reference to a reduced-scale coaxial cable network where real faults are hardware-emulated.

Fiber to the Tap: Pushing Coaxial Cable Networks to Their Limits

We explore the potential of a future cable access technology that pushes the capacity of coaxial cable networks to its limit. We show that it is possible to achieve symmetric data rates of multiple tens of gigabit per second using the same coaxial drop cables in use today to connect households to the cable network, and discuss its feasibility and deployment characteristics.

A facile Schiff base chemical approach: towards molecular-scale engineering of N-C interface for high performance lithium-sulfur batteries

Nitrogen-doped (N-doped) carbon has great potential in lithium-sulfur (Li-S) batteries, since N-doping can not only enhance the reaction activity of the cathode but also suppress the shuttle effect. Unfortunately, the N-C interface as a critical chemical active site is still short of a deep and detail understanding owing to the difficulty of interfacial structure engineering on the molecular scale. In this work, an interwoven coaxial cable network with ultrahigh nitrogen content of 9.56 wt% has been successfully fabricated through engineering a rationally designed Schiff-base chemistry. This in-situ bottom-up strategy enables the targeted heteroatom doping throughout the entire networks on molecular scale. Thus, a homogenous interface between nitrogen and carbon matrix can be achieved even at such a high doping level, which is demonstrated to play the key role in facilitating the chemical absorption of sulfur/polysulfides, and eventually improving the cycling stability of the electrode. Consequently, the composite demonstrates outstanding long cycling performance with a high specific capacity of 729 mAh g−1 after 500 cycles and a superior rate capability. The bottom-up strategy for fabricating the N-doped carbon networks will open up a new avenue for deeply understanding the critical role of interface in rational designing of N-doped carbon materials.

Characterising micro‐reflections in coaxial cable network

In this study, the authors propose a method to estimate information on impedance mismatches in coaxial cable networks. This information can help maintenance crews to locate and repair these mismatches. The information is estimated under the framework of DOCSIS preventive maintenance, and is based solely on equaliser coefficients already known by the system. Thus, it does not require any change to the system or the standard. The authors will show that, in contrast to the current DOCSIS approach, the proposed method provides a finer estimate, and allows for the estimation of information even when more than one micro-reflection is present.

Performance improvements of wire fault diagnosis approach based on time‐domain reflectometry

The aim of this study is to improve the performance of a wire fault diagnosis approach based on time-domain reflectometry (TDR). In this approach, the TDR response collected from measurements for a given (faulty) coaxial cable network is used as a reference for the cable network model response computed by an accurate analytical transmission line (ATL) method. The ATL model is iteratively tuned according to the outcome of the optimisation algorithm proposed. The advantage of the proposed ATL method over the more classic finite difference time-domain method is the extremely faster computational time which represents a significant factor for the diagnosis of faults in wiring networks. The proposed ATL method accurately provides the features of the resistance-inductance-conductance-capacitance-based model of a RG-58 coaxial cable employed as a device under test. The ATL model has been validated by comparison with measurement based and circuit simulations. Furthermore, seven experiments have been investigated in order to evaluate the performance of the ATL method for the diagnosis of wiring networks. The obtained results reveal that the ATL method together with the efficient optimisation algorithm is a reliable, efficient and fast method for the diagnosis of wiring networks.

Propagation and Responses of EMP on Transmission-Line Networks

This paper discusses the use of Baum-Liu-Tesche (BLT) equation for analyzing and calculating the propagation and load responses of transmission-line networks in frequency domain and time domain. The derivation and each parameters of BLT equation is introduced, and using BLT equation, two examples of specific coaxial cable networks are established, and the propagation and responses of networks are analyzed and calculated. The responses of networks terminals are measurement, and calculation results and measurement results are compared. The results show the excellent agreement between measurement and calculation results. The study results of this paper can be used for cable networks design and protection against EMP.

Software Structure of Embedded Test Device for High Performance Network over Coax

HINOC (High Performance Network over Coax) is a coaxial cable network access system self-developed by China. In this paper, we discuss the software architecture of an embedded test device designed for it. The device integrates the functions of modem and terminal to help to solve the network problem. The software uses the hierarchical model to realize its multiple functions. The test results show that the design of device has a good performance.

RECONSTRUCTION OF FAULTY CABLE NETWORK USING TIME-DOMAIN REFLECTOMETRY

Based on Time-Domain Re∞ectometry (TDR) technique, a novel method which could locate faults on the coaxial cable distribution network by using Support Vector Machine (SVM) is proposed in this paper. This approach allows the faulty network to be reconstructed by estimating the lengths of branches. A State-transition Matrix model is employed to simulate the TDR response at any port and evaluate the transfer function between two points. SVM is used to solve the inversion problem through training datasets created by the State-transition matrix model. Compared to the existing re∞ectometry methods, our proposed method can tackle multiple faults in the complex cable networks. Numerical and experimental results pointing out the performance of the SVM model in locating faults are reported.

Practicable model of coaxial cable channel with splitter and tap via state-transition matrix

Due to the impedance mismatch happening at the terminals and ports of components (splitters, taps, etc.), the frequency-selective fading characteristic exists in the coaxial cable channel. In this paper, the transfer characteristics of each component of coaxial cable network is analyzes. Moreover, a new algorithm to calculate the frequency responses is proposed. This algorithm can estimate all responses of any point-to-point channel accurately at one time. The results have been verified successfully by measurement on actual network, the absolute error of attenuation at any frequency point is less than 0.5dB. This modeling approach can be used to model any coaxial cable network, so long as the construction and dimension are known. It is helpful to analyze the performance of different distribution networks and to identify potential difficulties. It is also useful in the fault diagnosis and location for the further study.

A Simulation Model of the DOCSIS Protocol

The number of households and businesses using hybrid fiber coaxial cable networks for Internet access is rapidly approaching 40 million in the United States. The cable industry has standardized on a single medium access control (MAC) and physical layer standard, the Data Over Cable Service Interface Specification (DOCSIS). The MAC layer of the emerging IEEE 802.16 broadband wireless access standard is also based upon DOCSIS. Thus, the performance of DOCSIS is now and will remain a critical element in the overall performance of shared medium broadband access networks. Despite this fact, public domain tools that may be used to assess and improve the performance of DOCSIS have been slow to emerge. To address this problem, we have implemented a simulation model of the DOCSIS MAC layer for the ` ns' network simulation tool. Due to the complexity of DOCSIS and because the specifications are purposely incomplete, developing an accurate simulation is quite challenging. In this paper we present analytic and live network evidence that the simulation accurately reflects the behavior of a DOCSIS network under a limited set of workloads.

An introduction to future communications services and access

Lucent Technologies is well positioned to create the elements required for its customers to offer a wide array of future services to their customers. A vision of these services includes richly detailed and personalized multimedia environments used to conduct transactions and to communicate, integrate, and investigate information from applications created across a set of independent components in a geographically and functionally diverse network. Creation of such environments requires development of new network elements, architectures, and tools for ongoing individualized service creation. A particularly critical element is access to customers. This can be provided over a wide variety of transmission media, such as paired cable, coaxial cable, optical fiber, and wireless networks.

Applications of Chaotic Digital Code-Division Multiple Access (CDMA) to Cable Communication Systems

In this paper the technical details of chaotic digital code-division multiple access ((CD)2MA) communication systems used in cable communication systems are presented. The cable communication system may be a pure coaxial RF cable network, a hybrid fiber-coax network, or a pure optical fibre network for high-capacity data link. As an example of its many potential applications in cable communication systems, (CD)2MA is used to support the upstream digital data communications in cable TV systems occupying the very noisy 5–40 MHz portion of spectrum. Although the (CD)2MA proposed in this paper is only used to support current Internet services via cable TV networks, it can also be used to support the high-speed data-link provided in the 550–750 MHz band in hybrid fiber-coax networks. (CD)2MA is a new communication framework which uses band-limited chaotic carriers insted of linear ones. For the purpose of generality, in this paper the band-limited chaotic carriers are approximated by groups of linear sub-carriers, which distribute within the same bandwidth with a fixed amplitude, random phases and uniformly distributed frequencies. The theoretical result of the performance of (CD)2MA is given. We also provide the simulation results of the bit-error-rate (BER) performances of a synchronous (CD)2MA used in cable communication systems. The results show that the (CD)2MA system has a better performance than the synchronous CDMA system proposed for the same cable communication system. Technical details of (CD)2MA are also presented for the future design of prototype systems. We present the framework of the whole (CD)2MA system including carrier syncronization, timing recovery and the details of nonlinear carrier generators.

SUPER PON-a fiber to the home cable network for CATV and POTS/ISDN/VOD as economical as a coaxial cable network

A complete super PON fiber to the home cable network as economical as the classic coaxial cable network, designed for application in the local loop is presented. The concept uses high power lasers, remote pumped erbium doped fiber amplifiers (EDFAs) to reduce cost by high splitting ratio, economical receivers for the downstream direction and economical CD player lasers for the upstream direction. Several novel technical solutions for this application (a new method to avoid stimulated Brillouin scattering (SBS), remote pumping of the EDFA and a compensating technique to adapt the CD laser to the normal fiber) are presented.

Coaxial cable passive mesh networks

This paper presents a new type of fault-tolerant access network: an all-passive coaxial cable mesh network. The passive mesh network could have any topology, with cycles allowed. A technique for calculating the multipath response of the passive mesh network is presented. Both the delay and attenuation of a coaxial cable are represented by a single transform variable. The mesh network is modeled as a linear system with a state space that represents signal propagation. The channel responses of the individual sections of cable define the entries of a state-transition matrix. Using this theory, expressions are given for the overall mesh-network channel response. These expressions are manipulated to derive equalizer structures. The equalizers are zero-forcing and use decision feedback. It is shown that signals transmitted on any mesh network can be equalized. An example mesh topology, and equalizers for it, are presented. Signal and interference attenuation, and opposite-phase received carrier cancellation, are also discussed. The passive mesh network could be an inexpensive fault-tolerant architecture for residential access to telephony, cable TV, and future services.

The Development of Cable Data Communications Standards

Commercially successful application of data communications technology to coaxial cable distribution networks requires the creation of systems useful to large numbers of subscribers sharing common communications procedures. Furthermore, it is desirable, particularly in entertainment CATV networks, that subscriber ownership of some or all terminal equipment and peripheral attachments be possible since such ownership enables the sharing of capital costs between the network operator and the subscriber. Systems designers are led inescapably to the need for standard interfaces and protocols. The paper describes some of the major types of cable data systems currently under development for both institutional and entertainment network applications. Common to both is the concept of a local interface unit to act as a link between the subscriber's terminal equipment and the cable drop. The design of the drop-side interface of this unit raises some major standardization issues. Another important issue is that of compatibility between data and video channels where both types of services are offered on the same cable television plant. The major thrust of present standardization activity has been founded upon the open systems interconnection (OSI) reference model and has taken place within a joint CVCC/EIA committee on teletext and within the IEEE Project 802.6 subcommittee on metropolitan area networks. The paper reviews this activity and explains the principal issues to be resolved.

Confidence Estimates for Acquisition Times and Hold-In Times for PN-SSMA Synchronizer Employing Envelope Correlation

Pseudonoise-modulated spread spectrum communication transceivers enable utilzation of broadcast communications facilities including satellite links, radio networks, and coaxial cable networks for point-to-point communications. In this paper, a bound on the acquisition time probability distribution is obtained by calculating the variance of the acquisition time and using Chebyshev's inequality. Recursive computer calculations are used to show that the hold-in time distribution is approximately exponential. The means and variances of the acquisition and hold-in times, together with the distribution estimate and bound, are determined in terms of the number of users and power-to(Gaussian) noise density ratio of the channel. These calculations pertain to a receiver used by Hopkins, which combines acquisition and tracking in a way which facilitates implementation. The utility of the distribution estimates in comparing and relating synchronization times, failure to achieve synchronization, message transmission times, and message error rates is illustrated for two data transmission protocols. The dependence of these quantities on the number of users, information bit rate, data block format, and power-to-noise ratio of the (Gaussian) transmission channel is also illustrated.

Comparison of Technology and Capital Costs for New Home Services

This paper compares on a per subscriber basis the capital cost requirements of several new home services provided via a number of delivery system alternatives. The study was limited to alarm monitoring, electronic information, messaging, energy load management and pay-TV services, since it is expected that these services will play an important role among new telecommunicatin services offered to homes during the 1980' s. Since the role and penetration of new network architectures and technologies in the local distribution plant during the 80's is uncertain only existing off-air broadcast, telephone and coaxial cable networks and their suitably augmented versions have been considered as delivery network alternatives.

An Intercity Broadband Network for Rural Manitoba

This paper presents the development of a medium haul broadband coaxial cable network using superlinear amplifiers to deliver high quality CATV and other broadband signals to communities in rural Manitoba within 225 miles of the City of Winnipeg.

Design of RL networks beyond 100 MHz

This paper presents methods used in the design of precise coaxial cable simulation networks for digital line repeaters. The insertion loss of the longest simulated cable varies between 5 and 54 dB from 2.7 to 275 MHz. The design combines classical <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RL</tex> synthesis, precise modeling and optimization techniques. Success depends on systematic minimization of and design with unavoidable parasitic capacitances.