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It takes many years for more efficient electronic payments to be widely used, and the fees that merchants (consumers) pay for using those services are increasing (decreasing) over time. We address these puzzles by studying payments system evolution with a dynamic model in a two-sided market setting. We calibrate the model to U.S. payment card data and conduct welfare and policy analysis. Our analysis shows that the market power of electronic payment networks plays important roles in explaining the slow adoption and asymmetric price changes, and the welfare impact of regulations may vary significantly through the endogenous R&D channel.

In this paper, we investigate the average achievable data rate (AADR) of the control information delivery from the ground control station (GCS) to unmanned-aerial-vehicle (UAV) under a 3-D channel, which requires ultra-reliable and low-latency communications (URLLC) to avoid collision. The value of AADR can give insights on the packet size design. Achievable data rate under short channel blocklength is adopted to characterize the system performance. The UAV is assumed to be uniformly distributed within a restricted space. We first adopt the Gaussian-Chebyshev quadrature (GCQ) to approximate the exact AADR. The tight lower bound of AADR is derived in a closed form. Numerical results verify the correctness and tightness of our derived results., Comment: Accepted in IEEE Wireless Communications Letter

Read disturbance is analyzed in vertically channel-stacked NAND flash memory, which has string select transistors (SSTs) to access each channel layer independently. Additional read disturbance is observed at the cells adjacent to the selected cell in the unselected channel layers as well as typical read disturbance caused by repetitive Fowler–Nordheim tunneling (F-N) stress. Technology computer-aided design simulations and measurements are performed to investigate the disturbance mechanisms. It is found that bitline-side [common-source line-side] adjacent cell is disturbed by the hot carrier injection (HCI), which results from positively [negatively] boosted channel potential by the rising [falling] of the voltage ( ${V}_{\text {unsel}}$ ) applied to unselected cells, respectively. A novel read operation, in which the selected cells are maintained in turned on state during the ${V}_{\text {unsel}}$ rising/falling and then are restored to their own states, is proposed to suppress the occurrence of the HCIs. As a result, it is revealed that the HCI-induced read disturbances are successfully suppressed by the proposed method.

Ferrofluid channel flows have been used for many non-invasive flow manipulation applications, including drug-delivery, heat transfer enhancement, mixing enhancement, etc. Heat transfer enhancement is one of the most coveted outcomes from novel cooling systems employed for electronic cooling. While using Ferrofluids for heat transfer enhancement, the external magnetic field usually induces Kelvin Body Force, which causes the ferrofluid to swirl or ‘mix’. This mixing process causes extra convection over what is induced through fluid inertia and is responsible for heat transfer enhancement. In order to understand the phenomenon of heat transfer enhancement, it would be logical to view it from the perspective of mixing enhancement. Moreover, channel flows are most common in liquid cooling of electronics equipment, and hence such a fundamental understanding of synergies between mixing and heat transfer enhancement can help pose design rules for advanced cooling configuration for electronics cooling. In this work, a Ferrofluid channel flow is analyzed in the presence of an external magnetic field. A 2-D 90° bend channel ferrofluid flow is considered, with a significant length scale of 0.01 m, where two external current-carrying wires provide an external magnetic field. An external inward heat flux of 1000 W/m2 is applied on the walls of the channel. The channel flow is studied numerically by varying different parameters relating to the external magnetic field and flow conditions. The ferrofluid used is considered magnetite based on water as the carrier fluid, and the properties of which are modeled using appropriate mixture models for nanofluids. The mixing induced in the flow is characterized by using two different mixing numbers based on the flow velocity. This type of characterization is analogous to characterizing flow turbulence. The heat transfer enhancement is characterized using Nusselt numbers. These non-dimensional numbers (mixing) are studied in congruence with the Nusselt number to understand the relationship between the mixing and heat transfer and draw comparative inferences with flow conditions without heat transfer enhancement. Finally, conclusions are drawn between the mixing & heat transfer intensification at local and global levels and choosing the apposite mixing numbers to characterize heat transfer enhancement.

This paper investigates a UAV-enabled wireless downlink system, where a UAV-enabled base station flies above a group of Internet of things devices (IoTDs) and transmits data to them. In order to ensure the fairness among all IoTDs, we jointly optimize scheduling association and UAV trajectory to maximize the minimal throughput of all IoTDs under the 3dimensional (3-D) channel model. Meanwhile, to ensure the stability of communication, we aim to guarantee a high probability of line-of-sight (LoS) links between the UAV and all IoTDs. The optimization problem is non-convex and we propose an iterative algorithm based on the block coordinate descent and successive convex approximation to solve it. Furthermore, we show the convergence of the algorithm through simulations. It is shown that the proposed algorithm achieves higher data rate than the traditional scheme without guaranteeing the LoS probability.

To solve the problem that 2-D wideband HAP-MIMO model cannot accurately describe the spatial channel characteristics, this paper analyzes the spatial correlation of the channel based on 3-D HAP-MIMO model. A 3-D model introduced an elevation parameter, can more appropriately describe the channel to obtain more accurate spatial correlation characteristics of the channel. Simulation results show that by increasing the base station elevation, and reducing the degree of non-isotropic scattering, and increasing the degree of scattering dispersion, and increasing the maximum horizontal distance between scatter and terrestrial mobile station. All of these cases can reduce correlation and increase channel capacity.

A novel method for displacement monitoring by using RGB+D data has been recently proposed. RGB+D data is created by fusing image and laser scan data, where the D channel represents the distance, interpolated from laser scanner data. RGB+D image combines the advantages of the two measuring methods. Laser scans for distance changes in the line of sight and high-resolution image data for displacements perpendicular to the viewing direction of the camera. Image feature detection and matching algorithms detect and match discrete points within RGB+D images from different epochs. 3D coordinates of the points can be easily calculated from RGB+D images. In this paper, implementation of this method is proposed for measuring displacements and monitoring the behavior of structural elements under constant load in field conditions. Displacements measured with a high precision LVDT sensor will be used as a benchmark for displacement calculated from RGB+D images.

An approximate closed-form expression for 3-D channel spatial correlation (SC) is derived, given cross-polarized rectangular arrays and standards-based antenna radiation patterns. Furthermore, we evaluate the impact of 3-D SC on system performance and derive the capacity relationship between 2-D and 3-D channels. As expected, the 3-D channel is characterized by lower SC and higher channel capacity than its 2-D counterpart by taking the advantage of the additional degrees of freedom in the elevation domain, where the 3-D antenna arrays and the 3-D channel propagation are considered.

In this paper, we consider the Stokes equations in a two-dimen- sional channel with periodic conditions in the direction of the channel. We establish null controllability of this system using a boundary control which acts on the normal component of the velocity only. We show null controllability of the system, subject to a constraint of zero average, by proving an observability inequality with the help of a Muntz-Szasz Theorem., Accepted in Evolution Equations and Control Theory, 2018

In this paper, a massive multiple-input multiple-output (MIMO) channel measurement campaign with 256-element virtual rectangular array at the base station was conducted. The typical hotspot scenario, subway station, is considered, and the measurements were conducted at 6 GHz with a bandwidth of 100 MHz. A hybrid clustering approach is proposed to characterize the cluster evolution over the large-scale array. In the hybrid approach, we apply the space-alternating generalized expectation maximization algorithm to estimate the multipath components (MPCs), and use the multipath component distance-based tracking algorithm and the KPowerMeans algorithm for MPCs tracking and clustering. A cluster partition algorithm is further proposed to adjudge the clusters association over the array, and output the final clustering results. Under such a scheme, cluster-based model parameters are provided with detailed analysis. The extracted parameters include overall angle distribution, global angular spread, inter-cluster parameters, and intra-cluster parameters. The obtained model parameters can be fed into the new channel simulator for massive MIMO. This is useful for the design and application of the practical massive MIMO system in the future.

In this paper, a transfer function that models Molecular Communication via Diffusion (MCvD) between a point transmitter and a fully absorbing circular receiver in an unbounded 2-D environment is analytically derived. The analytical derivation of the transfer function of the 2-D channel in MCvD is proposed for the first time in the literature. The transfer function is obtained by solving the molecule concentration equations around the receiver considering diffusion dynamics, using some initial and boundary conditions, and some reasonable assumptions. Analytical results are compared with the results of Monte Carlo simulations.

IoNanofluids are a recent class of nanotechnology based heat transfer fluids synthesized by suspending nanoparticles in ionic liquids. These IoNanofluids are superior to conventional nanofluids due to their higher thermal stability and are more suitable for high temperature applications. In this study, a numerical analysis of laminar forced convection in a 2-D channel using Al 2 O 3 in ([C4mim][NT f2]) IoNanofluids has been presented. Flow Reynolds number (Re) is varied from 250 to 1000, particle volume fraction ranges from 0 % to 2.5 % and three inlet temperatures of 293 K, 313 K and 333 K have been taken into account. A uniform heat flux of 1000 W m −2 is applied on the top wall to resemble the scenario in a flat plate solar collector. Governing equations of flow and heat transfer has been solved using a Finite Volume Method based commercial software ANSY S F luent 15.0. Furthermore, unique feature of this study is that the thermo-physical properties of IoNanofluids are considered to be temperature dependent. Results indicate that IoNanofluids provide better cooling than conventional water based coolants. The top surface of the channel experiences a decrease of upto 4 K at an inlet temperature of 333 K. Mean Nusselt number and heat transfer coefficients increase by the addition of nanoparticles to the ionic basefluid. IoNanofluids show better heat transfer enhancement than conventional water based nanofluids at higher temperatures. Hence, it can be concluded that IoNanofluids have a higher potential to be employed in high temperature applications.

A coupled one-dimensional (1-D) and two-dimensional (2-D) channel network mathematical model is proposed for flow calculations at nodes in a channel network system in this article. For the 1-D model, the finite difference method is used to discretize the Saint-Venant equations in all channels of a looped network. The Alternating Direction Implicit (ADI) method is adopted for the 2-D model at the nodes. In the coupled model, the 1-D model provides a good approximation with small computational effort, while the 2-D model is applied for complex topography to achieve a high accuracy. An Artificial Neural Network (ANN) method is used for the data exchange and the connectivity between the 1-D and 2-D models. The coupled model is applied to the Jingjiang-Dongting Lake region, to simulate the tremendous looped channel network system, and the results are compared with field data. The good agreement shows that the coupled hydraulic model is more effective than the conventional 1-D model.

In this paper, we consider a dual-hop multiple-input-multiple-output (MIMO) wireless relay network in the presence of imperfect channel state information (CSI), in which a source-destination pair, both equipped with multiple antennas, communicates through a large number of half-duplex amplify-and-forward (AF) relay terminals. We investigate the performance of three linear beamforming schemes when the CSI of the relay-to-destination ( ℜ-D ) link is not perfect at the relay nodes. The three efficient linear beamforming schemes are based on the matched-filter (MF), zero-forcing (ZF) precoding, and regularized ZF (RZF) precoding techniques, which utilize the CSI of both the S-ℜ channel and the ℜ- D channel at the relay nodes. By modeling the ℜ-D CSI error at the relay nodes as independent complex Gaussian random variables, we derive the ergodic capacities of the three beamformers in terms of instantaneous signal-to-noise ratio. Using the Law of Large Number, we obtain the asymptotic capacities, upon which the optimized MF-RZF is derived. Simulation results show that the asymptotic capacities match the respective ergodic capacities very well. Analysis and simulation results demonstrate that the optimized MF-RZF outperforms MF and MF-ZF for any power of the ℜ-D CSI error.

Due to copyright restrictions, the access to the full text of this article is only available via subscription. In this letter, we investigate cooperative diversity with relay selection over cascaded Rayleigh fading channels. In particular, we analyze the performance of a relay selection scheme for cooperative vehicular networks with the decode-and-forward (DF) protocol. Only the “best” relay, which satisfies an index of merit, is selected. We ignore the direct transmission between the source (S) and its destination (D) and assume that the destination has perfect knowledge of the S→R and R→S channel gains. We study the performance of the underlying scheme in terms of outage probability and investigate its achievable diversity order. the Natural Sciences and Engineering Research Council (NSERC) of Canada

An Intelligent Network (IN) is a general concept network command architecture to enable the rapid introduction of new services by rearranging the basic functions of transport information mainly (voice, data, and images). Modern telecommunication networks are complex distributed systems that require high monitoring level using specific management network tools. An IN management scheme for ISO Interface is presented in this paper. The interface ensures different interactions through a set of services called Input/Output Services between desktop applications and voice terminals. Such services are designed in order to allow computer applications to provide users with enhanced features tacking advantages from the wide variety of telephony device characteristics and types. Basically, we suggest a software switch-based interaction scheme. The switch-based software object called Information-Path, is associated with the device that allows input to be received from the device and output to be sent to the device. The management scheme is suitable for multimedia interactive telecommunications. It covers applications that involve only voice calls (Integrated Services Digital Network (ISDN) B channel), only data calls (ISDN D channel), or both voice calls and data calls (both ISDN B channel and ISDN D channel). This makes the proposed system suitable for multimedia communications that involve voice, data and graphics. The feasibility and applicability of our proposal is demonstrated through a set of applications scenarios that involve multimedia mails exchanges.

A 15-bit 125-MS/s two-channel time-interleaved pipelined ADC is fabricated in a 0.18 mum CMOS technology, and achieves 91.9 dB SFDR, 69.9 dB SNDR for a 9.99 MHz input. This ADC incorporates a single sample-and-hold amplifier which employs a precharged circuit configuration to mitigate performance requirements for its opamp. Digital background calibration is applied to maintain the conversion linearity of each A/D channel and also correct both gain and offset mismatches between the two channels. Excluding I/O buffers, the chip occupies an area of 4.3 times 4.3 mm2 and dissipates 909 mW from a 1.8 V supply.

This paper reports the evaluation results of the channel boron (B) distribution in the sub-0.1 μm n-MOSFETs. Two types of n-MOSFETs (the post-source/drain (S/D) channel ion implantation (I/I) device and the pre-S/D channel I/I device) were fabricated and their channel B distributions were evaluated by using an advanced process simulator as a common measure. In the post-S/D channel I/I devices, the reverse short channel effect (RSCE) is not observed because the transient enhanced diffusion (TED) of B due to the high-energy channel I/I occurs uniformly in the channel. On the other hand, it has been found that the B depletion due to the transient enhanced drift pulled by the built-in electric field between the S/D-extension and the channel regions becomes significant in the sub-0.1 μm region. In the post-S/D channel I/I devices, it has been found that the sheet charge distribution responsible for the RSCE is localized within a distance of 100 nm from the S/D-extension junction. This localization contradicts the large interstitial diffusivity experimentally confirmed by the diffusion of the buried B marker layers. Another interesting feature in the post-S/D channel I/I devices is that the sheet charge distribution suddenly decreases where the distance from the S/D-extension junction is smaller than 30 nm. From this result, it is expected that the RSCE becomes less significant in the sub-0.1 μm n-MOSFETs.

This paper presents an application of Matched Spectral Null (MSN) coding to the magnetic recording channel that allows increased recording densities. A PR1 1+D partial response channel is used in combination with a DC and Nyquist free code to provide coding gain. A Viterbi detector based on the combined trellis of the code and channel is used for decoding. Using this scheme, increased user linear recording density over current PR4 systems can be obtained.

This paper proposes a novel three-dimensional (3-D) geometry-based stochastic channel model (GSCM) for high-speed railway (HSR) communications in mountain scenario. The proposed model not only takes the local scatterers into consideration, but also accounts for the effect of mountains on the wireless channel, which is not considered in existing models for HSR. The mathematical representation of the channel impulse response is given in this paper. Then the cumulative distribution function (CDF) of angle of departure (AoD) and space-time correlation function (STCF) are derived based on the proposed model. Finally, some numerical results and comparisons are given.

The specifications of the Next Generation Networks (NGN) agree on the need for migration mechanisms that enable the replacement of traditional networks, highlighting the ISDN networks. This requirement has a notable impact on NGN in terms of network design. Recent solutions proposed by ITU-T and ETSI for ISDN migration only include support for a subset of current ISDN services, not covering in detail the multi-channel circuit-mode bearer services. This paper examines the use of TDM pseudowires for NGN emulation of ISDN multi-channel calls between ISDN terminals, proposing new payload types.

How to prolong the multimedia application based on multi-hop wireless mesh networks powered by finite energy resource is a critical issue. In this paper, we propose a new approach to extend network lifetime by maximizing energy-balancing between routers while satisfying minimal multimedia service quality requirement. Specifically, a new channel coding scheduling algorithm is proposed to allocate the optimal channel coding redundancy to each multimedia packet to achieve both the maximal energy-balancing of the network and the lower bound of multimedia Quality of Service (QoS) requirement. The simulation results show that the proposed approach can significantly improve the energy-balancing of the multi-hop wireless mesh networks.

This paper proposes a three dimensional channel model for the study of distributed MIMO communication systems, where the transmit antennas may be at different directions when viewed from the receiver. Examples of such systems include cooperative satellites and air based base stations. Both line of sight and multipath signal components are considered. A common difficulty of such channel models is that there are too many geometric parameters to produce analytical correlation functions of the antennas in order to gain insight on how the channel depends on those parameters. The difficulty is solved here by identifying a single key parameter, the projected distance, to summarize the effect of all the geometric parameters, and thus, the model is simple enough to be useful for system designers. Analytical correlation functions are provided, which is used to compare the rate of the MIMO and SIMO systems in order to demonstrate that with high probability, significant rate gain can be obtained by the distributed MIMO systems.

An 8-channel 6-bit 16-GS/s time-interleaved ADC was fabricated using a 65nm CMOS technology. Each A/D channel is a flash ADC using latch-type comparator with background offset calibration. Timing skews among the channels are also continuously calibrated in the background. The chip achieves 42.3dB SFDR and 30.8dB SNDR at 16 GS/s sampling rate.

An IN (Intelligent Networks) management scheme for ISO Interface is presented in this paper. The interface is for interactions, via services called Input/Output Services, between desktop applications and voice terminals. These services allow computer applications to provide users with enhanced services by exploitation of the characteristics of a variety of telephony device types. This is by interacting with a switch-based software object, called Information-Path, associated with the device that allows input to be received from the device and output to be sent to the device. The management scheme is suitable for multimedia interactive telecommunications. It covers applications that involve only voice calls (ISDN B channel), only data calls (ISDN D channel), and both voice calls and data calls (both ISDN B channel and ISDN D channel). So, it is suitable for multimedia communications that involve voice, data, and graphics. The applicability is demonstrated by applications scenarios that involve multimedia mail.

The capability of EdotX would be improved by increasing the instrument's dynamic range to expand the range of signals measurable by the device. The heart of the EdotX system is a two channel analog to digital (A/D) conversion card with two analog to digital converters tightly coupled to a field programmable gate array (FPGA). Signals are continually digitized by the A/D and processed by the FPGA. When the FPGA detects a trigger condition, the data are transferred using direct memory access to the host computer memory, which in turn saves the data to disk. The original design utilizes a single A/D channel for data acquisition. The task was to increase the dynamic range of the system by enabling the second A/D channel, allowing the simultaneous acquisition of the original A/D channel and the additional second A/D channel. The input signal would be fed to the original channel and to the second channel with the second channel input being attenuated. When a signal hits the maximum range of the first channel, the data from the second channel, which is attenuated, are then used. Because both A/D's acquire data simultaneously, they may be used as a single expanded dynamic range channel.

Pilot-aided channel estimation for multi-carrier systems can be significantly improved by exploiting time and frequency correlations between the channel frequency response coefficients. But in practice, the knowledge of channel correlation function is not accurately available, thereby necessitating the need of an estimator that employs a fixed correlation function and is robust to mismatches with the actual one. While the maximally robust channel estimator for multi-carrier systems for the case of an infinite number of observations is well known for almost a decade, the one for the case of a finite number of observations has been only recently proposed. We extend the proposed maximally robust estimator to the practical case of small finite dimensional pilot grids by taking into account the grid edge effects. This paves the way for application of the estimator to practical systems such as 3G LTE. Simulation results for an LTE uplink system under different transmission scenarios demonstrate the superiority of the proposed maximally robust estimator over the heuristic one by as much as 1.35 dB in terms of the coded BER.

Hybrid simulation is important to the modern power systems which include high frequency components such as HVDC or FACTS with switching processes. Full digital model has its limit on its finite simulating frequency due to its discreteness, as a result , it's not available to describe the high frequency responses accurately and a more efficient simulating method-the digital-analog hybrid model comes into being, which's based on circuit substitution theorem. An interfacing method via node overlap is presented in this paper: the node voltage variable from interface point is outputted through D/A channel to form analog Thevenin source branch, meanwhile, the digital Norton source of interface branch is formed from the branch current variable inputted via A/D channel. Then the discriminate of model stabilization is deduced, based on which the hybrid model is proved to be conditional numerical stable system. Finally the digital-analog model interfacing experiments for verification is performed.

The paper extends the recently proposed concept of finite dimensional robust 2-D MMSE channel estimation to the staggered pilot grids in multi-carrier systems. The proposed scheme is particularly useful once the receiver has no knowledge of the channel correlation function and it intends to pursue the MMSE channel estimation for improved performance. We build a minimax optimization setup, as a function of the pilot grid structure, that leads to the Least Favourable (LF) channel correlation sequence, which is then employed by the receiver to obtain the maximally robust channel estimation coefficients guaranteeing the best worst-case performance. For staggered pilot grid, such as the one found in LTE Downlink specifications, we present three implementation variants for the maximally robust 2-D MMSE channel estimation and compare their performance in terms of coded BER.

In this paper we consider two-terminal channel routing problems in a Diagonal Model (DM), where the grid consists of right and left tracks displayed at +45° and −45° on two layers. As in the Manhattan Model, the tracks are displaced in two layers with the left tracks on one layer and the right tracks on the other. InDM we prove a new lower bound to the channel width equal to d , and present an algorithm that obtains 2 d + 3 as an upper bound, where d is the channel density.

We suggest a 3-D channel structure flash named Lambda-like active profile cell (Lambda cell), aiming to archive good short channel immunity, high on-cell current and lower random telegraph signal (RTS). The results show that 'Lambda' cell has more channel punch-through margin and higher on-cell current than that of normal planar cell. Especially, the RTS current fluctuation of 'Lambda' cell was reduced from 4% to 1.2% in comparing with planar cell due to enlarged active area and lower channel doping concentration. These advantages of 'Lambda' cell make it a promising structure for the continuous scaling of the NOR flash memories to 45 nm and beyond.

ISDN basic access interface provides transmission capability of two B channels and one D channel for various telecommunications services. The electrical characteristics of this interface are strictly regulated in CCITT recommendation I.430 to allow up to eight terminals to be connected in a bus wiring system. This paper describes a design method for achieving desired line interface characteristics, including output voltage with specified loads, transmitter output impedance at inactive state, receiver threshold voltage and cut-off frequency of a low-pass filter. The electrical characteristics of the line interface circuit based on the proposed design are measured by using practical bus wiring systems and are confirmed to satisfy recommendation I.430.

How to introduce packet switching into ISDN and, in particular, whether frame switching should be privileged are addressed in the context of NUMERIS. In addition to 64-kb/s access to Transpac, the national packet-switching public data network (PSPDN), it has been decided to offer packet-mode data communications services on the D channel of the user access to provide access to switching facilities as well as other applications and services such as telex, videotex, or teleactions through so-called access points. Layer-2 frame-switching capabilities are being developed for this purpose in Alcatel E10 switching systems to operate permanent logical links (PLLs) in a first stage, to be complemented by switched logical links at a second stage. The implementation of the switched access to a PSPDN gateway known as the packet access point (PAP) in Transpac is reviewed, and a description is given of the network equipment and interfaces being implemented in the E10 switching system to support the PLL services in conformance with CCITT Recommendation X.31 (maximum integration on the D channel, without incoming call notification). >

In this paper a queueing model for the D-channel access protocol recommended by CCITT is developed, and delays of both signalling and packet messages are analyzed using the model. Behaviors of packet and signalling messages in the D-channel access system are also investigated. The analytical results have been verified by simulation.

Integrated Services Digital Networks (ISDN) will play an increasingly important role in the field of communications in the coming few decades. This paper discusses the design and implementation of a pilot narrowband ISDN. A personal computer (PC) based ISDN user terminal and a time/space switch with the facility for the transmission of voice (at 64 kb/s) and data (at 64 kb/s or 16 kb/s) have been designed and tested. The overall configuration tested includes three PC based user terminals and the time/space switch. The implementation consists of the hardware and software for ISDN layers 1, 2 and 3. The software covers the signalling precedures and Link Access Procedures on the D channel (LAPD). Full implementation is according to the recommendations specified by CCITT in the Red Book [1] and in particular it covers the recommendations I.430, I.440 and I.450.

A human-machine interface has been created for an integrated services digital network (ISDN) network control unit (I-NUU). I-NUI is a sophisticated terminal device that allows a voice communication channel and two data channels to be connected through an ISDN I-series interface. ISDN communication functions and network control operations were analyzed to determine the required characteristics of I-NCU. I-NCU features the minimum number of control buttons and a liquid crystal display. Visual and audible information are used to keep the operator fully informed about the state of the communication channels. >

In this paper, we present a generic approach for modeling a communications protocol with state transitions and window and timer mechanisms, and for generating conformance test sequences automatically. Based on this model, minimum-cost (i.e., minimum run time) conformance test sequences can be generated by using a method based on unique input/output sequences and the Rural Chinese Postman tours. As a case study, this method is applied to the Integrated Services Digital Network link-access protocol on the D channel.

The problem of sending channel state information from the receiver to the transmitter of a wireless link is investigated in this paper. If the channel state is Gaussian distributed, this problem is equivalent to that of transmission of a Gaussian source over a noisy channel. We focus on a model in which the source outputs are statistically independent and the feedback channel is either AWGN or Rayleigh fading. Due to the strict delay constraints, information theoretic results are hardly applicable to the analysis of such a setting. As a consequence, despite its simplicity, little is known about its fundamental performance limits. Here, two different delay limited digital transmission approaches and a linear analog transmission approach are discussed and compared. If D channel uses per source output are allowed, it is shown that for the AWGN feedback channel delay limited digital approaches can achieve a distortion decay of at least D/2 dB per dB of SNR. This decay rate is 1 for the linear analog approach regardless D. For Rayleigh feedback channels the distortion decay rate is shown to be upper bounded by 1 for digital approaches and is asymptotically 1 for the analog approach. This fact and simplicity are good reasons for the use of analog transmission for feedback purposes over fading channels.

In a WCDMA system, the feature transport channel switching assigns to each best-effort user a transport channel that is appropriate for the user's bit-rate requirements and radio conditions. In this paper, we compare fixed rate channel allocation with several channel switching schemes, where the user is switched between transport channel rates based on the user's current code power consumption. Results show that with channel switching the capacity and/or the user throughput are increased compared to fixed transport channel allocation. The best channel switching scheme from system capacity perspective is a scheme that gradually increases the channel bit-rate. Due to variations in the radio environment there is always a risk that a connection is lost. Therefore, there must exist a mechanism for down-switching the bit-rate of the transport channel to retain the coverage.

Packet-switched based Telecommunication services are es sential to a competitive ISDN service offering and FRANCE TELECOM is now enhancing NUMERIS, the French ISDN, to introduce improved packet switched data communication capa bilities on both the B and the D channels of the user access. This is made possible on the basis of the development of a Packet Access Point equipment which will give access to packet switch ingfacilities and ofFrame Handlingfunctions within ISDN local erxhanges. Thispaperdescribes the mainfeatures of these developments andfocusses on the implementation offrame handlingfunctions in the ALCATEL EI0 switching system which have been used to support the digitalization of the french network, thus allowing a quick evolution to ISDN with a rapid deployment of newfeatures throughout the national network. After describing the nationally defined interface between the frame handler of the local ex changes and various Access Points (referred lo as IheAPI) which may be reached via the D channel of the user access, the paper shows the benefits and the new applications users may gain finom these features and then discusses further evolutions currently under consideration for the NUMENS network architecture and for the packet switched based data communication services.

ATM has been selected as the transer mode for future integrated broadband networks. It has already been highlighted in numerous papers that ATM is capable of transferring voice, video and data. This paper describes the capability of ATM to transfer also signalling information and the impact of ATM on signalling as well as the capability of ATM to build a very powerful maintenance concept which can be used ubiquitous; i.e. as well in the transmission as in the switching systems. First this paper will describe the impact of ATM on signalling. This impact can be seen on all levels of the protocol stack. On level one the disappearance of a fixed D channel as in NISDN introduces the need for a meta-signalling concept for multidrop environments. The opportunities generated by this meta-signalling are described here. The impact on level 2 is the need to introduce a segmentation and reassembly layer On level 3 the impact of ATM is mostly reflected through the deftnition of the ATM bearer service. The maintenance philosophy of a future broadband network is also a keypoint to its success. Since ATM can be considered as a switching as well as a transmission principle, a universal maintenance concept can be defined This maintenance philosophy includes where and what sort of maintenance information and how this is gathered. Secondly, how this information is then transported to the maintenance centers and finally how this information is interpreted.

An economical multipoint audiovisual communicating system technology for the ISDN basic rate interface is introduced. The system offers multipoint audiovisual communication using the ring-type connection via the two B channels in the ISDN basic rate interface for each terminal. The system's connection control offers a terminal skipping procedure. Multipoint image processing produces a divided display by digital data manipulation. Finally, an ISDN basic rate interface videophone using this system technology is described.

The performance of channel estimation can be improved by employing a channel estimation filter (CEF) that can adjust its bandwidth in response to the channel condition. For coherent OFDM receiver, we consider the use of two-dimensional (2-D) moving average (MA) FIR filter with a linear interpolation filter as the CEF that can provide good performance without requiring large implementation complexity. The optimum tap size of 2-D MA FIR CEF is analytically determined in terms of the pilot spacing, the channel spectrum and pilot signal to interference power ratio. The performance of the proposed channel estimator is evaluated by computer simulation.

In this work we design a sliding threshold implementation of a Viterbi detector for a ternary 1-D recording channel. We show that the final detection scheme is both simple and easy to implement in analog fashion, much like the binary equivalent.

International audience; Good knowledge of transmission channel properties is necessary to study the performances of future UWB systems. Thus, efficient equipment is required to characterize and model the UWB propagation channel. This paper proposes a basic idea to convert a SIMO wideband channel sounder into an UWB channel sounder. These minor changes were applied to the France Telecom R&D channel sounder. The modified equipment enables real time measurement in the 3.1 10.6 GHz frequency band with more than 1 GHz bandwidth.

We investigate the capacity of various ISI channels with adaptive white Gaussian noise. Previous papers showed a minimum E/sub b//N/sub 0/ of -4.6 dB, 3 dB below the capacity of a flat channel, is obtained using water pouring capacity formulas for the 1 + D channel. However, these papers did not take it into account that the channel power gain can be greater than one when water pouring is used. We present a generic power normalisation method of the channel frequency response, namely peak bandwidth normalisation, to facilitate the pair capacity comparison of various ISI channels. Three types of ISI channel, i.e., adder channels, RC channels and magnetic recording channels, are examined. By using our channel power gain normalisation, the capacity curves of these ISI channels are shown.