关于SC网络的等效网络分析

本文提出了关于开关电容(SC)网络的z域等效网络分析的若干想法。首先,在导出等效网络时引用了一组基本积木块以及特定的积木块变换方法。其次,使用为人们熟悉的信号流图分析了等效网络。最后,应用信号流图的灵敏度拓扑公式求得了网络的灵敏度。全部工作均以观察法进行,因而具有一定特色。     

Simple technique for analysis of SC networks using general-purpose circuit simulation programs

A new technique is proposed which enables the transformation of a large class of switched-capacitor (SC) networks into equivalent time-continuous (analogue) circuits to analyse them by use of standard, general-purpose circuit simulation programs such as SPICE It is based on a block partitioning, i.e. a total SC network is divided into small building blocks. It is shown how basic SC building blocks like integrators and summers can be modelled by equivalent two-ports containing only resistors, lossless transmission lines and current-controlled voltage sources. Furthermore, some new offset-free SC integrator schemes based on multi-step integration algorithms are also described.     

Synthesis of active inductors using SFG stamps

This paper proposes a new approach for the systematic synthesis of active inductors via signal-flow graphs (SFGs). The basic idea consists of proposing and using SFG stamps of active basic building blocks (ABBs) to construct the equivalent SFG of a classical inductor. We show that a large number of active inductors can be thus synthesized; twelve are proposed, most of them are novel. Known ABBs, as well as newly proposed ones are used, namely current conveyors (CC), operational transconductance amplifiers (OTA), current conveyor transconductance amplifiers (CCII-TA), current feedback operational amplifiers (CFOA), operational transresistance amplifiers (OTRA), current backward transconductance amplifiers (CBTA), current feedback transconductance amplifiers (CFTA) and voltage differencing inverting buffered amplifiers (VDIBA). SPICE simulations are given to show the viability of the proposed technique.     

KWTA networks and their applications

Winner-Take-All (WTA) or K-Winner-Take-All (KWTA) networks have been frequently used as the basic building blocks of complex neural networks. This paper introduces a new selection rule for network connections that implements stable KWTA networks. To widen the applications of WTA networks, a new class of WTA networks is proposed, and their efficient design methods are presented. We demonstrate the properties of the generalized class of WTA networks, through three application examples.     

Advanced intelligent networks: now a reality

This paper looks first at the background to the development of intelligent networking concepts and then tracks this development to the advanced intelligent networks (AINs) of today. The network architecture and basic nodal functions are explained, and a brief review given of the essential intelligent network building blocks, namely the IN (intelligent network) call model and the enhanced CCITT No.7 signalling system. Typical intelligent network services are examined and the tutorial finishes with a review of the latest IN standards     

Multiwavelength cross-connects for optical transport networks

Multiwavelength cross-connects (M-XCs) will play a key role in future optical multiwavelength transport networks. In this paper, we propose a class of optical wavelength interchange devices that can be used as basic building-blocks for multiwavelength optical cross-connects. We describe three different multiwavelength cross-connect structures that can be constructed using these building blocks. We investigate their blocking performance and examine issues such as complexity, modularity, and wavelength channel spacing associated with the proposed cross-connect structures     

Parallel,self-organizing,hierarchical neural networks with forward-backward training

A forward-backward training algorithm for parallel, self-organizing hierarchical neural networks (PSHNNs) is described. Using linear algebra, it is shown that the forward-backward training of ann-stage PSHNN until convergence is equivalent to the pseudo-inverse solution for a single, total network designed in the least-squares sense with the total input vector consisting of the actual input vector and its additional nonlinear transformations. These results are also valid when a single long input vector is partitioned into smaller length vectors. A number of advantages achieved are: small modules for easy and fast learning, parallel implementation of small modules during testing, faster convergence rate, better numerical error-reduction, and suitability for learning input nonlinear transformations by other neural networks. The backpropagation (BP) algorithm is proposed for learning input nonlinearitics. Better performance in terms of deeper minimum of the error function and faster convergence rate is achieved when a single BP network is replaced by a PSHNN of equal complexity in which each stage is a BP network of smaller complexity than the single BP network.     

Analogue neural networks with distributed neurons

A new technique is proposed for implementing neurons in analogue electronic neural networks. It features integrating a fraction of a neuron with each synapse. Each neuron is distributed over all associated synapses. This methodology operates with just one building block, the distributed-neutron synapse, in contrast to existing techniques which are based on two distinct blocks, the neuron and synapse. This approach can be applied to a variety of implementations, including transconductor and MOSFET-op-amp neural networks. Modularity, ease of interconnectivity, expandability and reconfigurability are the advantages of this technique.<>     

Simplified Analysis of Coupled Transmission-Line Networks

A relatively simple method is presented for analyzing coupled transmission-line networks by using network graphs and graph transformations. The network graph symbolism is easy to draw and to manipulate. All the graphs consist only of inductor, capacitor, and transformer symbols, and straight lines, which represent unit elements. The method of analysis is illustrated by several two-wire-line and multiwire-line examples. Also presented are several new useful transmission-line transformations and a graph equivalent for the general coupled transmission-line network. The graph-transformation method has four principal advantages: 1) explicit open-wire-line equivalent circuits of coupled line networks can be obtained relatively easily and without knowledge of network synthesis techniques; 2) the form of equivalent circuits can often be obtained without using any algebra; 3) at each step of the analysis, a positive-real network in graph form is available; consequently, in many analysis problems several equivalent circuits for the same network are derived; and 4) multiport networks are as easily dealt with as two-port networks.     

CAD tools for the synthesis and layout of SC filters and networks

This paper describes two programs for the synthesis and layout generation of SC filters and networks. The first part of the paper describes a technology-independent synthesis and optimization program for SC filters. The program allows for the exact synthesis of cascaded SC biquad and SC ladder filters. Two performance measures related to sensitivity and noise are employed to estimate the performance of the synthesized circuits and to select optimum realizations. The same measures are used in a novel capacitance assignment procedure. The second part of the paper describes a flexible SC layout generator, which can be adapted to various design rules and floorplans by means of a technology file. Area efficient layout is generated by placing individual circuit elements rather than building blocks. Crosstalk between conductors is minimized by a router that distinguishes between different kinds of nodes.1. The scaling of the biquad circuit is dependent on the position of the biquad in the cascade.2. This may not seem to be overly important, since high-pass-type filters do not occur that often in practical applications. If one considers, however, that SCSYN is to be used as a general filter synthesis program, thenevery filter must be automatically realizable. In such an environment, a CAD program that can design all but one type of filter is either quite useless or very limited indeed.3. Note that an SC filter, in contrast to a digital filter, may contain delay-free loops.     

Mesh networks: commodity multihop ad hoc networks

In spite of the massive efforts in researching and developing mobile ad hoc networks in the last decade, this type of network has not yet witnessed mass market deployment. The low commercial penetration of products based on ad hoc networking technology could be explained by noting that the ongoing research is mainly focused on implementing military or specialized civilian applications. On the other hand, users are interested in general-purpose applications where high bandwidth and open access to the Internet are consolidated and cheap commodities. To turn mobile ad hoc networks into a commodity, we should move to more pragmatic "opportunistic ad hoc networking" in which multihop ad hoc networks are not isolated self-configured networks, but rather emerge as a flexible and low-cost extension of wired infrastructure networks coexisting with them. Indeed, a new class of networks is emerging from this view: mesh networks. This article provides an overview of mesh networking technology. In particular, starting from commercial case studies we describe the core building blocks and distinct features on which wireless mesh networks should be based. We provide a survey of the current state of the art in off-the-shelf and proprietary solutions to build wireless mesh networks. Finally, we address the challenges of designing a high-performance, scalable, and cost-effective wireless mesh network.     

An introduction to local area networks

Within a restricted area such as a single building, or a small cluster of buildings, high-speed (greater than 1 Mbit/s) data transmission is available at a small fraction of the cost of obtaining comparable longhaul service from a tariffed common carrier. Local area networks use this low-east, high-speed transmission capabality as the basis for a general-purpose data transfer network. There are two basic issues in local area network design. First, how should the hardware realizing the network be organized to provide reliable high-speed communication at minimum cost? With the low cost of the raw transmission capability, care is required to keep the associated hardware costs correspondingly low. Second, what protocols should be used for the operation of the network? While many protocol problems are common to local area networks and long-haul networks such as the ARPANET, new protocols are required to exploit the extended capabilities of local area networks. This paper addresses these two basic issues. It also considers the interconnection of local area networks and long-haul networks and presents a case study which describes in detail the host computer interface hard-ware required for a typical local area network.     

Joint resource allocation for WLAN&WCDMA integrated networks based on spectral bandwidth mapping

Next wireless network aims to integrate heterogeneous wireless access networks by sharing wireless resource. The spectral bandwidth mapping concept is proposed to uniformly describe the resource in heterogeneous wireless networks. The resources of codes and power levels in WCDMA system as well as statistical time slots in WLAN are mapped into equivalent bandwidth which can be allocated in different networks and layers. The equivalent bandwidth is jointly distributed in call admission and vertical handoff control process in an integrated WLAN/WCDMA system to optimize the network utility and guarantee the heterogeneous QoS required by calls. Numerical results show that, when the incoming traffic is moderate, the proposed scheme could receive 5%?C10% increase of system revenue compared to the MDP based algorithms.     

Analysis of active networks using flow-graph technique

A simplified Coates flow-graph technique, applied to the analysis of an arbitrary active network, is presented. Flow-graph representations of building blocks of active networks are given, which permit construction of the graph from the given network. A flow-graph formula for the sensitivity investigation is also given.     

Star-delta transformations of bidirectional branches in probabilistic flow networks

An explicit set of star-delta transformations is given for probabilistic flow networks whenever the initial star branches are bidirectional with the same branch flow capacity in both directions. These transformations, together with their (already known) dual transformations, can be used to simplify the given network before applying the various algorithms available for the solution of the network flow problem. The superiority of the present star-delta transformations to other existing transformations is pointed out, and their usefulness is illustrated via the example of a small power generation and transmission network.     

By-inspection analysis of switched-capacitor networks †

The recent advances in implementation of analogue MOS switched-capacitor (SC) networks have established a need for new methods of analysis of these circuits. In this paper an analysis method of SC networks operating with an n-phase clock is presented. The method is based on a building block approach which facilitates the derivation of a z-domain equivalent circuit. The equivalent circuit is then analysed using the flow-graph technique.     

Negative feedback revisited

Rules are derived for choosing one among the four kinds of basic amplifiers to be embedded in a particular passive feedback network. The loop transmission is identified and conditions for mismatch are obtained from a unified analysis of feedback circuits. Past experience gained with voltage mode basic amplifiers, the laws of duality and mismatch are applied to choose the building blocks employed in the design of the remaining three kinds of basic amplifiers. This intuitive synthesis is confirmed by formal network transformations employing nullors.     

Toward green 5G heterogeneous small-cell networks: power optimization using load balancing technique

The overwhelming demand for data by an ever-increasing number of users is a great challenge wireless cellular networks are faced with. One potential solution to this issue is deploying a massive number of small cells (SCs) in the existing macro network. As SC overlay has a big role in the future wireless networks that can overcome the data traffic upsurge at little power cost, heterogeneous network (HetNet) has been viewed as a promising technology for 5G networks that extends cell coverage, improves network capacity and offloads the network traffic from the macro cell (MC) to the SCs. However, the hyper-dense SCs and their uncorrelated operation raise an important question about the joint power consumption of the macro base station (MBS) and the small base stations (SBSs) in the HetNet since the aggregate power consumption of the dense SBSs cannot be ignored. Recently, the SC sleeping technique has become a hot topic for saving energy in HetNets. To minimize power consumption in HetNets, we propose three algorithms to dynamically adapt the operation of the SBSs to active/sleep (on/off) for non-uniform user distribution in the HetNet. We investigate the general optimal power minimization problem for HetNet that requires relatively high computational complexity. Taking into account the additional increase of the traffic load brought to the MBS, a key design principle of the proposed algorithms is to switch off the SBSs gradually based on their locations, user densities in their coverage areas or the highest power that can be saved by switching some of them off, respectively. Then, we enhance the mathematical framework to make the analysis more realistic by considering the offloading between the SCs and the MBS that occurs when the traffic load exceeds SCs’ capacity. In this paper, based on the fact that user densities of SCs and MC change with time, we model the traffic on the European traffic profile and portray the power consumption of the HetNet throughout the day. Simulation results show that by applying SC sleeping and our proposed algorithms, the HetNet can save about 20% power daily. The performances of our proposed algorithms are close to that of the optimal algorithm and their computational complexities are remarkably lower.     

Classification of multisensor remote-sensing images by structuredneural networks

Proposes the application of structured neural networks to classification of multisensor remote-sensing images. The purpose of the approach is to allow the interpretation of the “network behavior”, as it can be utilized by photointerpreters for the validation of the neural classifier. In addition, this approach gives a criterion for defining the network architecture, so avoiding the classical trial-and-error process. First of all, the architecture of structured multilayer feedforward networks is tailored to a multisensor classification problem. Then, such networks are trained to solve the problem by the error backpropagation algorithm. Finally, they are transformed into equivalent networks to obtain a simplified representation. The resulting equivalent networks may be interpreted as a hierarchical arrangement of “committees” that accomplish the classification task by checking on a set of explicit constraints on input data. Experimental results on a multisensor (optical and SAR) data set are described in terms of both classification accuracy and network interpretation. Comparisons with fully connected neural networks and with the k-nearest neighbor classifier are also made