Thomas C. Banwell

A novel approach to the modeling of the indoor power line channel-Part II: transfer function and its properties

In Part I of this work, we introduced multiconductor-transmission-line (MTL) theory to model the indoor power-line (PL) channel. We have also shown that the proposed MTL approach can also be used to take into consideration both the topology of the link and particular wiring practices such as bonding. In this contribution, we continue our bottom-up approach to indoor PL channel modeling and we show that the circuit model found in Part I can be represented in terms of cascaded two-port networks (2PNs) coupled through a single modal transformer. Once the equivalent 2PN representation is obtained, it is possible to represent the whole PL link by means of transmission (ABCD) matrices only. The results presented here allow us to reveal that the PL channel is a more deterministic media than commonly believed and also allows us to unveil interesting properties of the PL channel, such as symmetry, that were previously unknown.

A novel approach to the modeling of the indoor power line channel part I: circuit analysis and companion model

Multiconductor Transmission Line (MTL) theory is utilized here for modeling the transfer function of power cables in the indoor environment. This approach allows us to determine a circuit model that well characterizes the underlying physics of signal propagation over power-line (PL) cables and that also allows us to account for particular wiring practices common in residential and business environments. In Part II of this work, we will show how the proposed approach allows one to compute a priori and in a deterministic fashion the transfer function of any PL link by using two-port transmission matrices, as commonly done for telephone channel modeling. In this two-part work we will cross several layers of abstraction following a bottom-up approach: starting from the definition of circuit models in this paper, we will arrive at a method for the computation of the transfer function of an indoor PL link in Part II of this work. Moreover, as discussed in Part II, the approach followed here allows us to unveil some special properties of the PL channel that were never reported earlier, such as the symmetry of the transfer function.

A deterministic frequency-domain model for the indoor power line transfer function

The characterization of the transfer function of the power line (PL) channel is a nontrivial task that requires a truly interdisciplinary approach. Until recently, a common attribute and limitation of existing models for the PL channel transfer function lay in the phenomenological or statistical approach usually followed. This approach allows one to describe the channel only partially, e.g., as dominated by multipath-like effects, and prevents one from unveiling special properties of it. Multiconductor transmission line (MTL) theory was recently found by the authors to be a useful and accurate tool in modeling the PL transfer function while, at the same time, taking into account the wiring and grounding practices mandated by several regulatory bodies for commercial and residential premises. Crossing several layers of abstraction and following a bottom-up approach, complex circuit-level models originating from MTL theory can be manipulated and represented in terms of cascaded two-port networks (2PNs), thus allowing one to compute a priori and in a deterministic fashion the transfer function of any PL link. In the present contribution, we present additional analysis and data that validate the accuracy of the MTL approach and further justify its use in the PL channel context. Moreover, we also describe in detail the methodology to follow for modeling both grounded and ungrounded PL links in a unified framework. A consequence of the validity of the proposed modeling is that it can facilitate the process of standardization of the PL transfer function, an important step toward the availability of a commonly agreed upon (set of) channel transfer functions.

Fully programmable ring-resonator-based integrated photonic circuit for phase coherent applications

A novel ring-resonator-based integrated photonic chip with ultrafine frequency resolution, providing programmable, stable, and accurate optical-phase control is demonstrated. The ability to manipulate the optical phase of the individual frequency components of a signal is a powerful tool for optical communications, signal processing, and RF photonics applications. As a demonstration of the power of these components, we report their use as programmable spectral-phase encoders (SPEs) and decoders for wavelength-division-multiplexing (WDM)-compatible optical code-division multiple access (OCDMA). Most important for the application here, the high resolution of these ring-resonator circuits makes possible the independent control of the optical phase of the individual tightly spaced frequency lines of a mode-locked laser (MLL). This unique approach allows us to limit the coded signals spectral bandwidth, thereby allowing for high spectral efficiency (compared to other OCDMA systems) and compatibility with existing WDM systems with a rapidly reconfigurable set of codes. A four-user OCDMA system using polarization multiplexing is shown to operate at data rates of 2.5 Gb/s within a 40-GHz transparent optical window with a bit error rate (BER) better than 10/sup -9/ and a spectral efficiency of 25%.

Physical design issues for very large ATM switching systems

The authors examine the physical design issues associated with terabit/second switching systems, particularly with regard to the customer access portion of the switch. They determine the physical design requirements in the areas of backplane interconnections, integrated circuit packaging, and circuit board technology and identify areas where existing- or near-future physical design technologies are inadequate to meet the requirements of this application. A new 3D interconnection architecture that solves some of the problems encountered at the backplane level is suggested. It is also suggested that multichip module technology will help meet some of the speed and density requirements at the chip packaging level. Some of the system-level consequences of the proposed model are discussed. >

Powering the fiber loop optically-a cost analysis

Recent successes in transporting optical power near the 1-W level via optical fiber suggest that it may be possible to operate conventional telephone station sets using electricity derived photovoltaically from light in a fiber. The authors investigate the constraints on optical powering in fiber-in-the-loop (FITL) applications and assess its applicability in terms of end-to-end efficiency, loop length, and system cost. To make this assessment, they look at several different optical-powering system architectures and components vis-a-vis their cost-versus-delivered-power capability. Related issues such as safety and reliability are discussed. >

Automatic Identification of Impairments Using Support Vector Machine Pattern Classification on Eye Diagrams

We have demonstrated powerful new techniques for identifying the optical impairments causing the degradation of an optical channel. We use machine learning and pattern classification techniques on eye diagrams to identify the optical impairments. These capabilities can enable the development of low-cost optical performance monitors having significant diagnostic capabilities

Experimental results on the simultaneous transmission of two 2.5 Gbps optical-CDMA channels and a 10 Gbps OOK channel within the same WDM window

We propose and experimentally validate a novel method for transmitting several OCDMA channels in the unused bandwidth of a single WDM channel thus allowing the OCDMA and SONET signals to share the same WDM channel.

Modeling the indoor power line channel: new results and modem design considerations

Considerable effort has recently been devoted to the determination of accurate channel models for the power line (PL) environment, for both the indoor and outdoor cases. The common denominator (and limitation) of the known and previously published models is the particular type of approach followed. In fact, until now, the PL channel (PLC) has been treated from a mere phenomenological or statistical point of view. This allows us to describe the channel only partially, e.g., as dominated by multipath-like effects, and prevents us from unveiling any of its particular properties. We report results about a new approach to the modeling of the PLC based on multiconductor transmission line (MTL) theory. The need for an MTL approach arises from the fact that indoor power cables consist of three conductors, and not just two as for classical twisted-pair and coaxial cable cases. This approach allows us to include wiring and grounding practices dictated by the United States National Electric Code (NEC). On the basis of this modeling, we reveal that the PLC is a more deterministic medium than commonly believed. Moreover, it is also possible to prove an interesting symmetry property of the PLC that was previously unknown: the PLC, regardless of its topology, exhibits the same transfer function when driven from either side, provided that the source and load impedances are the same.

DWDM-compatible spectrally phase encoded optical CDMA

We present initial results on a WDM compatible spectrally phase encoded optical CDMA (OCDMA) system that uses 16 phase-locked laser lines within an 80-GHz tunable window and an ultrahigh frequency resolution encoder/decoder. The described system differs from conventional OCDMA systems by independently phase encoding individual spectral line of a mode locked laser (MLL). We report here novel properties of phase codes and we also demonstrate compatibility of the proposed OCDMA system with conventional WDM networking by simultaneous transmission of two 2.5 Gb/s OCDMA users in one DWDM window along with six DWDM channels in other DWDM windows through a transparent reconfigurable network having 25 km node spacing.