DEERE AFFIDAVIT Attachment PPP

Transcription

1 DEERE AFFIDAVIT Attachment PPP

2 DEERE ATTACHMENT PPP VERY LOW-BAND SYMMETRIC TECHNOLOGY NETWORK INTERFACE/INTERCONNECTION SPECIFICATIONS TP76750 ISSUE 1 February 1999 Southwestern Bell Telephone Pacific Bell Nevada Bell WD Attachment PPP-1

3 REVISION HISTORY (FUTURE) February, 1999: Previous draft versions of this document were entitled, ISDN BASED DSL SERVICE, Network Interface/Interconnection Specification. The title has been changed to conform to the American National Standards Institute (ANSI) draft standard, Spectral Management. Previous contributions to ANSI, in this area, were titled Low-Band Symmetric because that was the previously assigned name. WD Attachment PPP-2

4 TECHNICAL REFERENCE NOTICE In this document SBC LECs means Southwestern Bell, Pacific Bell, and Nevada Bell. This technical reference is published by the SBC LECs to provide the spectral requirements for Very Low-Band Symmetric technologies, in the SBC LEC s network. SBC LECs reserve the right to revise this document for any reason including, but not limited to, conformity with standards promulgated by various regulatory or other agencies, use of advances in the state of the technical arts, or the reflection of changes in the design of any equipment, techniques or procedures described or referred to herein. The SBC LECs make no representation or warranty, expressed or implied, with respect to the sufficiency, accuracy, or utility of any information or opinion contained herein. the SBC LECs expressly advise that any use or reliance upon this technical reference is at the risk of the user and that none of the SBC LECs or their affiliates, or the directors, officers, employees, or other authorized representatives of each shall be liable for any damage or injury incurred by any person arising out of the sufficiency, accuracy, or utility of any information or opinion contained herein. This document is not to be construed as a suggestion to any equipment manufacturer to modify or change any of its products, nor does this document represent any offer or commitment by the SBC LECs or any affiliate thereof to purchase any product, whether or not it provides or meets the described characteristics. The SBC LECs do not recommend products or services, and nothing contained herein is intended or should be construed as a recommendation or an endorsement of any product, service, vendor, or manufacturer to anyone. Nothing contained herein shall be construed as conferring by implication, estoppel, or otherwise any license or right under any patent, whether or not the use of any information herein necessarily employs an invention of any existing or later issued patent. The SBC LECs reserves the right not to offer any or all of these services and to withdraw any or all of them at any future time. WD Attachment PPP-3

5 With respect to services offered pursuant to tariff, the terms and conditions of the service offering are determined by the tariff itself, applicable laws and regulations, and contractual agreements. WD Attachment PPP-4

6 SBC LEC CONTACTS To obtain additional copies of this document, contact; Southwestern Bell Telephone Technical Publication Information 530 McCullough Room 2-E-02 San Antonio, Texas For questions concerning this document, contact; Mel Smith Area Manager Transmission Engineering Southwestern Bell Telephone For questions concerning the Very Low-Band Symmetric spectral masks, contact; Mark Russell Senior Member of Technical Staff SBC Technology Resources, Inc or Clifford Yackle Senior Member of Technical Staff SBC Technology Resources, Inc WD Attachment PPP-5

7 CONTENTS Page 1.0 General Description Spectrum Management Spectrum Management Masks for Very Low-Band Symmetric Technologies Deployed in the SBC LECs Background on Spectrum Management Accuracy vs Complexity Method Based on Spectral Masks ANSI T1E1.4 Spectrum Management Standards Project Spectrum Management Masks for Very Low-Band Symmetric Technologies Testing Compliance to the SM Masks 9 References 9 WD Attachment PPP-6

8 1.0 General Description This publication provides the power and spectral specifications of Very Low-Band Symmetric technologies. 2.0 Spectrum Management The SBC LECs reserve the right to spectrum manage all types of loop facilities. Spectrum management is necessary in order to prevent analog and/or digital signals and services from interfering with each other, a recognized form of harm to the network and to existing customers and services. Signal interference can occur in facilities composed of copper cable or other types of facilities such as electronic transport systems. Administratively controlling the assignment location and/or type of transmission equipment used to transport the wide variety of analog and digital signals is especially important as different transport technologies, many with overlapping frequency spectrums, are introduced into the SBC LECs respective networks. Without spectrum management, signal interference between different transport technologies can occur, causing harm to the network and disruption to existing customers and their services. The SBC LECs will manage the frequency spectrums used in the feeder and distribution loop cable facilities. An aspect of spectrum management is maintaining cable binder group separation for disturbers ( such as repeatered DS1 and ADSL), where technically and physically possible. The amount of binder group separation is dependent upon the number of pairs in the feeder or distribution cable. All CLECs desiring to provide Very Low-Band Symmetric technology based services, using a SBC LEC s network, must be in compliance with the spectral requirements set forth in section 3.0 of this document. 3.0 Spectrum Management Mask for Very Low-Band Symmetric Technologies Deployed in the SBC LEC s Network 3.1 Background on Spectrum Management Twisted wire pairs used to transport digital subscriber line (DSL) services typically are housed within binder groups with other pairs for at least part of their run length. Electromagnetic coupling, termed crosstalk, will result in the signal from one pair generating noise onto other pairs. Crosstalk coupling is most significant between pairs in the same binder, but significant coupling can also occur between pairs in adjacent binders. The impact of crosstalk depends on the power level and frequency usage of the interfering technologies, but can often be a limiting factor in service performance. In order to ensure proper performance of all services, the spectral usage of the technologies used for DSL services must be carefully managed. WD Attachment PPP-7

9 3.2 Accuracy vs Complexity Ideally, spectrum management would entail taking into account the exact spectral characteristics of all equipment on lines that could impact the loop in question. In actuality, variations between equipment makes the complexity of this method extend well beyond the limits of practical implementation. Variations between equipment occur not only between different technologies, but also between different vendors for a particular technology, and sometimes even between different generations of a technology from a particular vendor. The other extreme would be to choose the simplest spectrum management process. This could be done by defining a single, worst case crosstalk model, and associating it with all equipment. Unfortunately, the assumed crosstalk would often be significantly worse than reality, and lead to an unacceptably pessimistic assumption on DSL performance, and an inefficient use of the transport capability of the copper plant. Therefore a compromise procedure is required. The compromise entails adherence to the following conditions: Actual performance of the network should with high probability be no worse than the performance predicted through spectrum management. Otherwise a situation will occur where services fail in an unpredictable manner. This is of critical importance, because determining the source of service failure after the fact can be a difficult and time-consuming process. Complexity must be reduced to a level where implementation is possible. Accuracy must be maintained at a level that ensures efficient use of the network. 3.3 Method Based on Spectral Masks SBC has found that the best compromise is a spectrum management procedure based on spectral masks, where spectral mask means an upper bound on the transmitted signal energy as a function of frequency. Spectral masks are sometimes referred to as power spectral density (PSD) masks. Since the spectral masks found in the open literature can serve an array of purposes, we will use the term Spectrum Management (SM) Masks for the masks used for spectrum management. The method is as follows. First a set of SM masks is defined, with the mask defined in this technical publication being one of the set. Each piece of equipment deployed in SBC s network is then associated with a particular SM mask. All equipment associated with a particular SM mask is then modeled as having the same crosstalk impact, based on a crosstalk model associated with that SM mask. This method allows SBC to both predict the performance of a particular loop for loop qualification, as well as manage the efficient use of the available spectrum in the network. The fact that the SM masks are each closely coupled to a crosstalk model makes them different than other spectral masks, such as the PSD masks given in technology-specific standards. PSD masks given in technology-specific standards serve to define limits on the peak spectral energy as a function of frequency, but do not necessarily represent an approximation of the actual transmitted signal characteristics. For some technologies, most notably ADSL, it is quite possible for the actual spectral response to adhere closely to the PSD mask given in the standard, thus making that PSD mask also useful as a SM mask. Other technologies, such as 2B1Q-based technologies like ISDN and HDSL, have significantly less energy at some frequencies than allowed by the PSD mask in their respective standard. Use of the PSD mask in the standard would thus result in a significant reduction in accuracy of the spectrum management process, and WD Attachment PPP-8

10 thus inefficient use of the copper plant. This leads to a reduction in the number of customers who can benefit from high-speed access. 3.4 ANSI T1E1.4 Spectrum Management Standards Project The American National Standards Institute (ANSI) subcommittee T1E1.4 currently has a project pursuing a standard on spectrum management. This project is currently targeted to reach the voting stage on a draft standard by mid SBC is heavily involved in this project, and is committed to using the results of this standard for spectrum management of SBC s network. Until this standard is completed, SBC is obliged to publish its own requirements for spectrum management, represented in part by this Technical Publication. These requirements are designed according to our best understanding of where the Spectrum Management project is heading. 3.5 Spectrum Management Masks for Very Low-Band Symmetric Technologies The very low-band symmetric category is intended for technologies with data rates the same or lower than ISDN/IDSL. Therefore the strongest disturber will likely be ISDN, which we define as 2B1Q transmission at 160 kbps over a single pair. The very low-band symmetric SM mask is designed with the greatest consideration given to ISDN. The same transmitted spectrum is assumed for both network-to-user (downstream) and user-to-network (upstream) transmission. Thus only one mask need be defined. The very low-band symmetric SM mask is defined in Table 1. It is also given graphically in Figures 1 and 2. The equipment is further restricted to have a transmitted power of no more than 14 dbm, which is the maximum power allowed in the T1.601 standard [1]. Between MHz and 30 MHz, the requirement is that the power in any 1 MHz bandwidth must be less than 60 dbm. Adherence to the mask is required for all equipment, whether it is deployed at the network side, at the user side, or in regenerators. The very low-band symmetric SM mask was designed taking into consideration the measured transmitted spectral response of a variety of ISDN equipment. All equipment used the 2B1Q line code, and complied with T1.601 [1]. A more detailed description of how this SM mask was designed can be found in contribution T1E1.4/ and associated revisions submitted to the Spectrum Management project of ANSI committee T1E1.4. WD Attachment PPP-9

11 3.6 Testing Compliance to the SM Masks Testing compliance to the appropriate SM mask is a critical aspect of the SM process. Conformance testing to the very low-band symmetric SM mask requires measurement of the transmitted power spectral density of the equipment under test. The PSD will be measured across a 135 Ohm termination on the transmitter. PSD measurements will be made at multiples of 1 khz from 1 khz to MHz, using a 1 khz resolution bandwidth. Compliance is achieved if the following conditions are met: 1. Condition 1a OR condition 1b is met 2. The total power in any 1 MHz band between MHz and 30 MHz is less than 60 dbm 3. The total transmitted power is no greater than 14 dbm Condition 1a Condition 1a requires that the measured PSD of the equipment under test be below the SM mask at all measurement points below 2.06 MHz Condition 1b Condition 1b requires that the following condition be met: n+ 99 i= n PSD n+ 99 Test Mask i= n 1.5 () i ( 1000 i) PSD () i ( 1000 i) n 2067, where PSD Test () i and PSD Mask () i are the measured PSD values of the equipment under test and the SM mask, respectively, in units of mw/hz, and n is an integer and represents frequency in 1.5 khz. The factor i approximates the frequency dependent nature of near-end crosstalk coupling. Condition 1b is a somewhat looser criterion than Condition 1a, and is intended as an alternative when Condition 1a is not met. Applicable DSL equipment will typically exhibit several modes of operations, such as steady state and one or more initialization modes. All modes of operations must be tested for compliance with the SM mask. Currently, ISDN, and likely other 2B1Q equipment, are designed such that the PSD during training is 2.55 db higher than in steady state. Therefore, the SM mask used for compliance during training is the one defined in Table 1 raised by 2.55 db at all frequencies. An example test setup would be to connect the transmitter output to the 50 Ohm port of a spectrum analyzer via a 135:50 Ohm balanced to unbalanced transformer (balun). As such a connection is inherently single ended, the modem must be placed into a mode where it is transmitting in full power mode while no data is being received. If this is not possible, then a more complicated test setup is required which includes steps to ensure that the far-end signal does not contribute to the measured values of the near-end signal. As some of the PSD levels defined in section are rather low, experience has shown that care must be taken in assuring that the noise floor of the measurement equipment is well below the levels of the equipment that is being measured. References [1] ANSI T , Integrated Services Digital Network (ISDN) Basic Access Interface for Use on Metallic Loops for Application on the Network Side of the NT (Layer 1 Specification), American National Standards Institute. WD Attachment PPP-10

12 Table 1: Very Low-Band Symmetric SM mask definition Frequency Range 0 < f < 78 khz SM Mask (dbm/hz) πf sin 2 5 ( 2.78) 2 86,000 10*log ,000 πf 86, khz < f < 115 khz khz < f < 2067 khz 10 + f 51 55*log10 115,000 f > 2067 khz Figure 1: Very Low-Band Symmetric SM Mask WD Attachment PPP-11

13 Figure 2: Very Low-Band Symmetric SM Mask Expanded View WD Attachment PPP-12